Reducing the flow will reduce the efficiency, if the water is almost boiling leaving it means that the temperature differential between the gas and water will be reduced and therefore result in less energy transfer. Think about it this way, if you want more cooling an engine you don't throttle down the cooling water flow. Increased flow means greater temperature differential between gas and water and maximum heat transfer as well as creating turbulent flow around the exchanger tubes which will help with the heat transfer. The only thing is that eventually the extra energy consumed by the circulating pump will be more than the extra heat being recovered. Insulate everything and try to get the exhaust outlet after the cooler as cool as possible. Great video, very interesting, keep it up.
The water in the exchanger will get hotter but the system will be operating at lower efficiency because the exhaust gas will not have as much cooling. You are trying to remove as much heat as possible from the exhaust. Granted that efficiency is calculated based on the differential between initial and final temperature but it’s per mass unit of water in this case. If you stop the flow completely the water in the exchanger will get very hot but your drum of water will stay cold.
@@josephinring well the way I see it, with our gas Combi boiler in the house, if you run the warm tap slowly the water gets so warm you can’t put your hand under it, but if you run the tap hard the water won’t get a chance to warm up, so I think the same principle will apply here.
@@Diesel8290 instant hot water from a tap is different to what he’s doing here. In a boiler you take cold water and heat it extremely fast for a one time use after which you drain it away. This guy who commented is saying that if you ran the water in this system very slowly then yes THAT water would get very hot, but the very slow flow rate would not heat the whole tank. You cannot create nor destroy energy as far as we are aware. Therefore the cooler the exhaust gas gets the warmer the water will get. Running the water fast will introduce more cooler water to the exchanger faster and suck more heat from the exhaust. Ergo the cooler the exhaust is outside, the more heat has been transferred to the tank. You just can’t compare this to a dedicated combi boiler like you have at home.
@@mundaysappliancerepairs1065 but surely the principle is the same no? Lower flow higher water temp, water heats faster and more efficiently.? But I guess to as the water heats. It will eventually reach equilibrium and not get any warmer. Especially with the lowish temperature from the diesel heater exhaust. I’m not arguing either I’m an engineering student I love discussing crap like this :)
Thanks for your videos they have been very helpful. My first diesel heater install, yesterday finished. Ran great! Was 17° this morning so i ran it for an hour on 1.7 hz, with exhaust fan running was 24° inside for an hour. Very impressive. Used the cheap tubing and mounted the fuel pump on to my frame with the rubber holder and can't hear it at all!
How about surrounding your exhaust pipe with a vertical column of water contained in a pipe that is capped off at each end. Basically a pipe within a pipe. Add in and out fittings to extract the heated water to the tank. Ross
Thanks for posting. I wanted to see this for months. You said if you could get the water to its boiling point before it exits the heat exchanger it would be better. My 2cents is to put a "floppy ball" check valve in the intake line so the every time the water inside the heater exchanger brings the water to a boil it the pressure slams the check valve closed thus pushing the water flow in only 1 direction.. Think coffee pot👍
Even before watching this video, YES tbis6 is something i been thinking about from the beginning. First time i am watching a video of someone actually tackeling the issue. That is a huge ammount of energy being thrown out. 👍
An idea would be to measure the exhaust fumes before and immediately after the heat exchanger. Just to know how efficient your heat exchanger is at variohs water temperatures.
Just from the FLIR the exhaust in was roughly 150ºC and the outlet of the exchanger was 30-40ºC. So it seems to be doing a good job of extracting the heat.
@@DavidMcLuckie try building your own exchanger. Copper or aluminium oipes, multiple passes, or split oasses. Dont do coils, as the exhausts cools the carbons will condense inside the tubes and eventually block your exhaust EGR. Try multiple straight oarrelel pipes that are easily taken apart and cleand out for maintanance. I hope that i managed to explain my self... Look for stove pipes heat exchangers for a basic idea of what i am trying to explain. Scaled diwn and fit for water obviously. Id love to show you a few drawings of ideas to work from. Cant be done here, or can it?
On my proper heater I extended the exhaust by 6 metres to see how far the heat worth recovering would go it went about 8 ft and you could touch it but at 6 ft it would burn your hand ..so 8 ft of recoverable heat potentially
Skoty, there are diesel heaters with internal hot water heat exchangers available for sale on the internet ! Then you just build a safety shroud and capture that exhaust heat for the room you re in.
Build a 1 meter liebig condenser for the exhaust out of 19mm and 25 mm copper plumbing parts. Similar device used in distilling to condense 75 C alcohol vapor to liquid. David is correct that it need valving to control cooling water flow rate to absorb more heat.
The heat exchanger will transfer more heat when the difference temperature is higher. It's proportional to the temperature difference. So a higher flow is better not lower.
Exactly what I was thinking, efficiency will certainly decrease as flow/return temperature increases. If the water was at 100°C and the exhaust gas was at 100°c then the efficiency is zero!
That's why you need multiple stage heat exchangers like the high efficiency gas furnaces have. You bring in the coldest fluid or air at the end of the exhaust output and have the hot working fluid, or air, leave at the hottest part of exhaust at the beginning. That way you'll have the hottest fluid or water possible. Higher flows without doing this will result in lower temperature working fluid or air.. in fact this makes higher flows much better
Someone may have already said this in the comments but the further away one uses the temp measuring gun you are using, the wider the "view" and measurement it takes. If the item you're trying to measure is small/thin, and you don't put the temp gun pretty much right up against the item you're trying to measure, you're just getting an average temperature of the item you're trying to measure and the surrounding materials. There is a chart online of the correlation between the distance and width of measurement.
Great idea, but you have to keep in mind when you condense the exhaust gas the condensate it very corrosive and can even eat most stainless steels. Using a truck egr cooler is probably your best bet as they have some of these issues solved.
That was awesome. Can't wait to see how you ultimately set up the coiled copper tubing version. Heating a water-filled compartment is of course useful (warm/hot water for showers, tea, "what have you'). Originally, simply, my thoughts were around heating a physical-solid and having that as a heat sync along the floor, for example, a la radiant heat. Of course running heated fluid through a mini-sized radiator (inside the cabin of a van or Class A or what ever) and blowing air across, over, or through it (or not) would have the identical effect to heating up a passive solid (except that you could now run water over that radiator. To sum up, I'm loving what you're doing and can't wait to see your copper tubing set up. IF a copper tube add-on apparatus can be manufactured and easily slid over and permanently and safely attached/fastened over the exhaust, and IF you can then feed the liquid (radiator fluid; under pressure i.e. so it can get over 100C; under pressure) THEN a mini radiator could be a very versatile add-on heat source to allow one to squeeze out even more watts per ml of diesel. You're doing great! Nice! Thank you.
Wonder how it would do with a thermocycling radiator setup similar to what was used in some antique tractors. The very heating of the coolant, was what caused it to circulate
I wonder how an Air to Water Inter-cooler would do plumed up the same way? could also use either the exhaust as the heat source or... have it connected direct to the hot air outlet. you'd need a diverter valve so as to have hot air or hot water if it was installed in a van though as you'd never get any heat out the other end of the inter-cooler
Thanks SO MUCH for your experiments. I found an OIL COOLER / power steering pump cooler ($24-$35!) looks promising. You can either use it as a sub-heater for air, or just drop it in a tank of water.
David, great idea, I just picked up an Heat X 200XS heat Exchanger from ebay for 40bucks, I think it work as well or better then your example, thanks for the great idea.
As of today, Ebay has many options for ‘heat exchangers’. BTW, Thanks for initial post on exchangers. i never knew there were so many optional sizes. And low prices. 👍🏻👍🏻👍🏻
A gas water heater already has a chimney through it. Maybe restrict exhaust chamber to slow down heat (in a safe manner). A thermostat controlled exhaust diverter/bypass could be used to avoid over heating the water and even to heat another tank. 🤔
It takes some time as it's pretty clean the combustion. Maybe clean it using a pipe clean once it's up to temp every 6-12 months. That's my experience and I use my 8Kw a fair amount. The cleaning I had to do from getting from a car was yuck.
Have putting a pipe that's 2x the diameter of the exhaust pipe over top of the exhaust but leave the actual exhaust pipe longer than the outer pipe and elbowing the intake pipe into that large pipe so that your intake gas gets pre heated by your exhaust? Would that increase efficiency of the heater. Being that most people will have their intake and exhaust outside in the cold it would seem to me that it would be nice to only have to drill one hole in your house and also it should heat up faster and hotter with less fuel ?
I reckon that if you get rid of the supplied exhaust pipe with the exception of maybe enough to bend into a right angle bend the fabricate your own stainless exhaust shroud of larger surface are and have some sort of internal labyrinth of coiled pipes that causes the exhaust gasses to be circulated around inside the exhaust before they escape. More time spent in the exhaust is more time to exchange heat.
The heat exchanger needs to be side ways in middle of water column slightly down on exit to allow condensation to go out of exhaust and water tank outlet up, and inlet down.
Do you know the temp of the exhaust 3-6” from the heater? It’s my intention to send the exhaust out the insulated wooden wall of my shop. I’m trying to work out the clearance I need too keep from burning everything down. My plan as there’s an old stove pipe hole already cut in the wall @6” is to place a piece of 6” stove pipe with a cap on it through the hole and drill two holes in it one for intake and one for exhaust then stuff the pipe with muffler packing and place another cap on the back. Think a 2” spacing from the wooden wall pieces is enough if it’s inside a stove pipe?
Hi David. I’ve got an EGR valve and looking to do something very similar. Could I heat, store and use the water for shower? Would the water be somewhat corrosive? Any thoughts around this? Top videos btw
Great video. Looking to buy some air/water heater for my camper van. Do you think it's a better deal to get an air/water heater or modify air heater to also heat water like in this video or with egr? Thanks!
I just went looking, you are the first I'm come across. What about running exhaust tube straight through a 4" metal pipe full of water. I'm thinking of using heater in fithwheel trailer. The 4" water pipe would look like the capital letter L. The heater would be mounted in a box outside close to the ground. A short leg of 4" pipe surrounding exhaust tube (open no pressure at heater end) 90 degree at ground level then horizontal running under insulated skirt of trailer, and out the other side. The far end of 4" horizontal metal pipe would have a cap and sealed hole to hold water and allow exhaust tube to exit. Thought? No pumps, no fuss? Heat the under regions of insulated trailer, at least keeping it above freezing
I had a same setup and it runs great but you do get a massive soot build up and effects the heater massively after a while you have to take it all off and give it a blow out as the performance of the heater drops dramatically so I had to give up on that idea
@@DavidMcLuckie yeah had a play with both just delayed the inevitable still lots of soot build up, might just tig weld a little valve to give it a blow out now and again, mines used as a workshop heater and the heat exchanger pumps water to a radiator work well surprisingly
How much of the exhaust energy do you reckon you captured then? I've been sort of dreaming up an idea to have a heat capture on the exhaust of a genset and get it to run a tesla turbine. Still firmly in the fantasy stage at the minute though
@@DavidMcLuckie Yeah about 30% of the thermal energy comes out the exhaust and another 30% in the cooling system. My idea has evolved towards thermal-electric generators now though, the turbine thing seems a bit complicated.
Because of the high temperature and the high speed of the exhaust gas, both, the pressure and the density are very low. In other words, that gas contains a very small amount of energy. Hence the small increase in temperature of the water. Still, that exhaust gas could be routed through the floor, heating the air above it. Of course, you shouldn't expect much but...better than the cold air in you room.
Hi dave enjoying your channel I just have a quick question I've I've broken one of the small all pipes running into my fuel pump on an eberspacher D4 I just wondered if one of the Chinese copies fuel pumps would work ? Would appreciate if you could help thanks
From my Googling the D4 uses a 22ml3 pump. Which is the most common one on the chinese heaters. So although many aren't listed with the size the pump in the picture has the size, like this - www.ebay.co.uk/itm/Car-Air-Diesel-12V-Oil-Fuel-Pump-With-Bracket-Holder-Fit-For-1KW-5KW-Air-Heater/313017758265?hash=item48e14ff239:g:Kx4AAOSwPRteX002
My question is, under ideal conditions, IE, max output, are these TEG's capeable of generating enough power to provide ANY worthwhile power to the heater?
Yes. www.europeanthermodynamics.com/products/datasheets/GM200-49-45-30%20(2).pdf If you can get the hot side 200ºC and the cold side 30ºC they should output 7.5W each. I think this is where the solar MPPT controller would shine, if we had enough volts to get it running it can match the load resistance and extract max power. If I've correctly understood how MPPT works.
@@DavidMcLuckie That being the case, here is my worthless suggestion. Put an elbow on the exhaust outlet and direct it back to toward the intake of the heater. Have the exhaust going through a block that had suitable baffles / turbulators to break up the boundary layer of gasses and extract all the energy. The TEGS would be attached to this on the hot side. The intake for the burner would be ducted to pull across the TEGS with the heatsink attached on the cold side with a manifold. This would provide the cooling air for the tegs and preheating for the intake. I set up a HE like this for my heater. Exhaust was plumbed back to a he which the intake drew across. It made about 8oc difference to the output air at 3/4 setting. You point of the area getting warmer and cooling getting less efficient is noted however I ran my heater last winter pulling cold air from outside. It worked extremely well and there was never any stuffiness in the house, in fact we all noted the complete opposite. Always seemed nice and fresh and Furthermore, pushing the warmed air in meant the place was pressurized somewhat so all the cracks and draft points were pushing out not in which added to the comfort. Have to say I really think one is chasing their tail on this idea . I just don't think the efficiency is in the tegs to make up for the inevitable losses but interesting to see what you come up with.
@@DavidMcLuckie Problem with an MPPT is you are going to have maybe 5% loss on a little one and that may make things difficult to get the required outputs.
I fibreglass moulded a computer cpu cooler radiator to heater outlet, I pump water through 1/4 bsp connectors 12mm pipe to 60 litre tank. on full power d2 eberspacher takes between 20 to 30 minutes to heat to 40 degrees, its all set on a digital thermostat to stop circulating water when temperature is reached. if i wrap 12mm copper pipe around exhaust and insulate then it should heat alot quicker
Maybe you could just pipe exhaust into the bottom of an old radiator and then from other side of radiator to outside I think I’ve seen some one else do it on UA-cam
Can you say if this was a ok test or not? Is it ok to do? How much effect in watt did you finally get out of the car EGR cooler? Compared to the pool heater? Both looks small.
Hi there David! I've been looking for air + water heater you were testing recently. Do you know any ebay or ali links with delivery form eu? Only seen one on aliexpress and alibabba but the delivery is like €150.. Thanks :)
Here is a challenge you might want to look into, can you use an EGR to recover heat to heat a radiator to expel more heat to the room you have installed the heater in?? over to you David, love your videos.
It's for people that want both. You could build it with a Y piece in the exhaust and a valve so if you only want hot air or if you want hot air and heat a tank of water.
@@DavidMcLuckie Hi David. Cobbled the combi boiler heat exchanger together today, got a good temperature difference exhaust in and out, but could not get the water to revolve, will need to add a pump. Looks promising as I run the heater to warm my workshop hot water to clean my hands would be a bonus. Cheers, Jim.
just tested my old brass pool heater. like a ptat i ran it dry.....well....it de-soldered itself lol it reached over 210c so i pulled it off and scraped of the gloss paint that stunk the place out lol. i really want to try mineral oil to make storage haters. do u think a central heating pump can take it or will heat itself flow the oil around the system??????? maybe a vid for u to try lol go for it buddy
One simple way to get the water out the top of the heat exchanger as hot as possible, just turn the tap down on the container, granted it's no thermostatic valve or something, but simple solutions and all... :)
Yes, but the problem there is if the flow is slow enough and the inlet temperature gets high enough it'll eventually start boiling in the heat exchanger. Sounds like a job for an arduino. :)
@@DavidMcLuckie Nah, just need a thermostatic valve like that in a car engine cooling system, but instead of totally blocking off flow, just use it to restrict the flow 'til the water is hot enough to open it... :)
Soooo, based on the £150 pool heater, could you possibly do a similar test ((Mimic the pool heaster)) using something like off the shelf copper pipe 37-42mm incorporating the side ports for the unrestricted exhaust flow and through the middle something like 10-15mm copper (for the water) and test :) was thinking of somthing like that as cost effective method. Obviously this would mean a horizontal method as opposed to the vertical :)
Build a 1 meter liebig condenser for the exhaust out of 19mm and 25 mm copper plumbing parts. Similar device used in distilling to condense 75 C alcohol vapor to liquid. David is correct that it need valving to control cooling water flow rate to absorb more heat.
Silly question alert !!! How would you plumb this into a camper for hot water ? I already have a cold water system ( tank, pump, kitchen sink) Could you put the hot water from the egr outlet direct to the tap ? Or would you need other stuff.
Ironic that gas heaters don't utilize exhaust gas heat through a chamber like a normal gas heater does. (Air heat exchanger). I have so many ideas, maybe you can patent a few ? ......Like for example, why isn't this a window unit ? It could even be low profile for a van or a roof unit like R.V.'s have. I intend on hanging one on my camper window with only the fresh air intake and outputs fitted into the slightly opened, but sealed window. An aerodynamic housing would keep it from being an eye sore......
Great movie :) Does any one now why I can't switch of my chinese heater? It's switch on one night and the controler doesn't work. I can't switch it of. The other think is that heater it doesn't give a heat :) I hear the fun but no heat... Is it pump or glow, hmmm?? Thanks for any answer :)
@@DavidMcLuckie tried heating the pipe up? And wrapping it round a solid pipe? That's what I was going to try. But I've only ever seen it done with 3/16th pipe
The delta T heat exchange efficiency using a single coiled tube around the exhaust will not be as good as multiple tubes inside a tube-in-tube heat exchanger. And remember to use counter current. Have the the flow going in the opposite direction of the exhaust flow. Designing it for ease of cleaning the tubes is important. It seems rifle cleaning brushes could be used to rod out the tubes if the end comes off the heat exchanger. Has anyone found a heat exchanger with a removable end? It seems the dairy industry might use them as they need to be cleaned and sanitized. The stainless tubing and clamps used in dairy industry would make a awesome exhaust. Cheeers
A normal radiator no. In theory it would work but not sure what the reaction between the exhaust gases and the mild steel of the radiator would be like.
The pool heater is rated for many, many times the KW power the heater will ever produce. But it also designed to be much more efficient than the EGR cooler.
@@gerardmcgee the only issue I see with the egr variant is that the egr would have to be outside unless it was chopped/welded to allow the extention of the actual waste fumes. ??
Because of the way I had to mount everything, and I have other plans to put something else inline. That and the 8 inches will not make much difference, the FLIR showed maybe a 10ºC variation from top to bottom.
Reducing the flow will reduce the efficiency, if the water is almost boiling leaving it means that the temperature differential between the gas and water will be reduced and therefore result in less energy transfer. Think about it this way, if you want more cooling an engine you don't throttle down the cooling water flow. Increased flow means greater temperature differential between gas and water and maximum heat transfer as well as creating turbulent flow around the exchanger tubes which will help with the heat transfer. The only thing is that eventually the extra energy consumed by the circulating pump will be more than the extra heat being recovered. Insulate everything and try to get the exhaust outlet after the cooler as cool as possible. Great video, very interesting, keep it up.
Interesting. I thought the longer the water could stay in contact with the hot surfaces the more heat it could absorb?
The water in the exchanger will get hotter but the system will be operating at lower efficiency because the exhaust gas will not have as much cooling. You are trying to remove as much heat as possible from the exhaust. Granted that efficiency is calculated based on the differential between initial and final temperature but it’s per mass unit of water in this case. If you stop the flow completely the water in the exchanger will get very hot but your drum of water will stay cold.
@@josephinring well the way I see it, with our gas Combi boiler in the house, if you run the warm tap slowly the water gets so warm you can’t put your hand under it, but if you run the tap hard the water won’t get a chance to warm up, so I think the same principle will apply here.
@@Diesel8290 instant hot water from a tap is different to what he’s doing here. In a boiler you take cold water and heat it extremely fast for a one time use after which you drain it away. This guy who commented is saying that if you ran the water in this system very slowly then yes THAT water would get very hot, but the very slow flow rate would not heat the whole tank. You cannot create nor destroy energy as far as we are aware. Therefore the cooler the exhaust gas gets the warmer the water will get. Running the water fast will introduce more cooler water to the exchanger faster and suck more heat from the exhaust. Ergo the cooler the exhaust is outside, the more heat has been transferred to the tank. You just can’t compare this to a dedicated combi boiler like you have at home.
@@mundaysappliancerepairs1065 but surely the principle is the same no? Lower flow higher water temp, water heats faster and more efficiently.? But I guess to as the water heats. It will eventually reach equilibrium and not get any warmer. Especially with the lowish temperature from the diesel heater exhaust. I’m not arguing either I’m an engineering student I love discussing crap like this :)
I really enjoy your work, I'm going to give the whole vanlife thing a go and your investgations are giving me a million ways to tackle the challenge.
My understanding is the water should be counter-flow to the exhaust for best efficiency.
Thanks for your videos they have been very helpful.
My first diesel heater install, yesterday finished. Ran great! Was 17° this morning so i ran it for an hour on 1.7 hz, with exhaust fan running was 24° inside for an hour. Very impressive. Used the cheap tubing and mounted the fuel pump on to my frame with the rubber holder and can't hear it at all!
Mate you’re bloody awesome love your work really helpful thanks again.
From Australia
How about surrounding your exhaust pipe with a vertical column of water contained in a pipe that is capped off at each end. Basically a pipe within a pipe. Add in and out fittings to extract the heated water to the tank.
Ross
Been waiting so long for this mate. All heat ideally should be recovered and put back into warming water.🥶🥵😄
Hi Just to say thank you for your super videos all are 5 stars. Please keep them coming Thank you .
Thanks for posting. I wanted to see this for months. You said if you could get the water to its boiling point before it exits the heat exchanger it would be better. My 2cents is to put a "floppy ball" check valve in the intake line so the every time the water inside the heater exchanger brings the water to a boil it the pressure slams the check valve closed thus pushing the water flow in only 1 direction.. Think coffee pot👍
Thanks for uploading this.
Even before watching this video, YES tbis6 is something i been thinking about from the beginning. First time i am watching a video of someone actually tackeling the issue. That is a huge ammount of energy being thrown out. 👍
An idea would be to measure the exhaust fumes before and immediately after the heat exchanger. Just to know how efficient your heat exchanger is at variohs water temperatures.
Just from the FLIR the exhaust in was roughly 150ºC and the outlet of the exchanger was 30-40ºC. So it seems to be doing a good job of extracting the heat.
@@DavidMcLuckie try building your own exchanger. Copper or aluminium oipes, multiple passes, or split oasses. Dont do coils, as the exhausts cools the carbons will condense inside the tubes and eventually block your exhaust EGR. Try multiple straight oarrelel pipes that are easily taken apart and cleand out for maintanance. I hope that i managed to explain my self... Look for stove pipes heat exchangers for a basic idea of what i am trying to explain. Scaled diwn and fit for water obviously. Id love to show you a few drawings of ideas to work from. Cant be done here, or can it?
Just discovered you have answered my previous question.
On my proper heater I extended the exhaust by 6 metres to see how far the heat worth recovering would go it went about 8 ft and you could touch it but at 6 ft it would burn your hand ..so 8 ft of recoverable heat potentially
Skoty, there are diesel heaters
with internal hot water heat
exchangers available for sale
on the internet ! Then you
just build a safety shroud and
capture that exhaust heat for
the room you re in.
Love your videos and have subscribed. Keep up the good work btw :)
Build a 1 meter liebig condenser for the exhaust out of 19mm and 25 mm copper plumbing parts. Similar device used in distilling to condense 75 C alcohol vapor to liquid. David is correct that it need valving to control cooling water flow rate to absorb more heat.
Great vids man. Thanks
The heat exchanger will transfer more heat when the difference temperature is higher. It's proportional to the temperature difference.
So a higher flow is better not lower.
Exactly what I was thinking, efficiency will certainly decrease as flow/return temperature increases. If the water was at 100°C and the exhaust gas was at 100°c then the efficiency is zero!
That's why you need multiple stage heat exchangers like the high efficiency gas furnaces have. You bring in the coldest fluid or air at the end of the exhaust output and have the hot working fluid, or air, leave at the hottest part of exhaust at the beginning. That way you'll have the hottest fluid or water possible. Higher flows without doing this will result in lower temperature working fluid or air.. in fact this makes higher flows much better
Someone may have already said this in the comments but the further away one uses the temp measuring gun you are using, the wider the "view" and measurement it takes. If the item you're trying to measure is small/thin, and you don't put the temp gun pretty much right up against the item you're trying to measure, you're just getting an average temperature of the item you're trying to measure and the surrounding materials.
There is a chart online of the correlation between the distance and width of measurement.
Awesome stuff. I have been looking into using an EGR cooler or some sort of heat exchanger, and this is some really good information!
Great idea, but you have to keep in mind when you condense the exhaust gas the condensate it very corrosive and can even eat most stainless steels.
Using a truck egr cooler is probably your best bet as they have some of these issues solved.
That was awesome. Can't wait to see how you ultimately set up the coiled copper tubing version. Heating a water-filled compartment is of course useful (warm/hot water for showers, tea, "what have you'). Originally, simply, my thoughts were around heating a physical-solid and having that as a heat sync along the floor, for example, a la radiant heat. Of course running heated fluid through a mini-sized radiator (inside the cabin of a van or Class A or what ever) and blowing air across, over, or through it (or not) would have the identical effect to heating up a passive solid (except that you could now run water over that radiator. To sum up, I'm loving what you're doing and can't wait to see your copper tubing set up. IF a copper tube add-on apparatus can be manufactured and easily slid over and permanently and safely attached/fastened over the exhaust, and IF you can then feed the liquid (radiator fluid; under pressure i.e. so it can get over 100C; under pressure) THEN a mini radiator could be a very versatile add-on heat source to allow one to squeeze out even more watts per ml of diesel. You're doing great! Nice! Thank you.
Was pretty convinced this was being presented by Billy Connelly for a long time
That EGR heat exchanger might be the best option. Brilliant.
Surprised you are managing to extract 800W. Good job!
I love it. It’s great
Wonder how it would do with a thermocycling radiator setup similar to what was used in some antique tractors. The very heating of the coolant, was what caused it to circulate
This in conjunction with a heat exchanger on the outlet of the heater would be awesome
I wonder how an Air to Water Inter-cooler would do plumed up the same way? could also use either the exhaust as the heat source or... have it connected direct to the hot air outlet. you'd need a diverter valve so as to have hot air or hot water if it was installed in a van though as you'd never get any heat out the other end of the inter-cooler
Next video, how to cook potatoes with a diesel heater - haha. Cool video :-)
Thanks SO MUCH for your experiments.
I found an OIL COOLER / power steering pump cooler ($24-$35!) looks promising. You can either use it as a sub-heater for air, or just drop it in a tank of water.
_Cool, and thanks!_
Great Idea...
David, great idea, I just picked up an Heat X 200XS heat Exchanger from ebay for 40bucks, I think it work as well or better then your example, thanks for the great idea.
I looked it up on ebay and only found one for like $61, who did you buy from?
As of today, Ebay has many options for ‘heat exchangers’. BTW, Thanks for initial post on exchangers. i never knew there were so many optional sizes. And low prices. 👍🏻👍🏻👍🏻
Any dimensions on the exhaust size?
A gas water heater already has a chimney through it. Maybe restrict exhaust chamber to slow down heat (in a safe manner). A thermostat controlled exhaust diverter/bypass could be used to avoid over heating the water and even to heat another tank. 🤔
Love your work
I can see one small problem here, how much of the exhaust gasses condense and slime up the heat exchanger.
It takes some time as it's pretty clean the combustion. Maybe clean it using a pipe clean once it's up to temp every 6-12 months. That's my experience and I use my 8Kw a fair amount. The cleaning I had to do from getting from a car was yuck.
If you wrap the copper pipe round can you test it insulated and uninsulated? Cheers
Have putting a pipe that's 2x the diameter of the exhaust pipe over top of the exhaust but leave the actual exhaust pipe longer than the outer pipe and elbowing the intake pipe into that large pipe so that your intake gas gets pre heated by your exhaust? Would that increase efficiency of the heater. Being that most people will have their intake and exhaust outside in the cold it would seem to me that it would be nice to only have to drill one hole in your house and also it should heat up faster and hotter with less fuel ?
Love the “hicklety picklety “ fashion
I reckon that if you get rid of the supplied exhaust pipe with the exception of maybe enough to bend into a right angle bend the fabricate your own stainless exhaust shroud of larger surface are and have some sort of internal labyrinth of coiled pipes that causes the exhaust gasses to be circulated around inside the exhaust before they escape. More time spent in the exhaust is more time to exchange heat.
I saw someone actually just plumbed the exhaust into an old household radiator to extract the heat.
how about trying to capture more heated air from the exhaust. not to heat water but air
The heat exchanger needs to be side ways in middle of water column slightly down on exit to allow condensation to go out of exhaust and water tank outlet up, and inlet down.
I've been looking at the chinese diesel heaters that have the heat exchanger built into the housing, have you taken a look at them?
Do you know the temp of the exhaust 3-6” from the heater? It’s my intention to send the exhaust out the insulated wooden wall of my shop. I’m trying to work out the clearance I need too keep from burning everything down. My plan as there’s an old stove pipe hole already cut in the wall @6” is to place a piece of 6” stove pipe with a cap on it through the hole and drill two holes in it one for intake and one for exhaust then stuff the pipe with muffler packing and place another cap on the back. Think a 2” spacing from the wooden wall pieces is enough if it’s inside a stove pipe?
Hi David. I’ve got an EGR valve and looking to do something very similar. Could I heat, store and use the water for shower? Would the water be somewhat corrosive? Any thoughts around this? Top videos btw
They add salt to the hot side water so about 150/170 before boiling
Love your videos .been looking into diesel heaters for my work shop .do you think it would heat a work shop 12'×20' .?
Is it insulated? One problem is uninsulated buildings need a heater that can keep up with the buildings heat loss and still make it feel warm.
Question will the large metal vice sink the heat 🤔 away
just thought, looks like it would be better to have the water go end to end and the exhaust to go in the side?
Thanks for sharing your hard work with us. The link in your discrimption is dead. Do you have a part number?
Great video. Looking to buy some air/water heater for my camper van. Do you think it's a better deal to get an air/water heater or modify air heater to also heat water like in this video or with egr? Thanks!
I'd buy the normal air heater and use an EGR cooler to heat some water. Not as tidy as the all in one version but certainly cheaper.
Thanks for the advice David!
Ah, ok, you have already tried the Koi Pond heat exchanger :D
I just went looking, you are the first I'm come across. What about running exhaust tube straight through a 4" metal pipe full of water. I'm thinking of using heater in fithwheel trailer. The 4" water pipe would look like the capital letter L. The heater would be mounted in a box outside close to the ground. A short leg of 4" pipe surrounding exhaust tube (open no pressure at heater end) 90 degree at ground level then horizontal running under insulated skirt of trailer, and out the other side. The far end of 4" horizontal metal pipe would have a cap and sealed hole to hold water and allow exhaust tube to exit.
Thought? No pumps, no fuss? Heat the under regions of insulated trailer, at least keeping it above freezing
I had a same setup and it runs great but you do get a massive soot build up and effects the heater massively after a while you have to take it all off and give it a blow out as the performance of the heater drops dramatically so I had to give up on that idea
Did you tweak the pump settings to reduce fuel or increase fan speed to compensate?
@@DavidMcLuckie yeah had a play with both just delayed the inevitable still lots of soot build up, might just tig weld a little valve to give it a blow out now and again, mines used as a workshop heater and the heat exchanger pumps water to a radiator work well surprisingly
How much of the exhaust energy do you reckon you captured then? I've been sort of dreaming up an idea to have a heat capture on the exhaust of a genset and get it to run a tesla turbine. Still firmly in the fantasy stage at the minute though
I can't remember the numbers off the top of my head, but there is a lot of wasted heat coming out the exhaust.
@@DavidMcLuckie Yeah about 30% of the thermal energy comes out the exhaust and another 30% in the cooling system. My idea has evolved towards thermal-electric generators now though, the turbine thing seems a bit complicated.
You could make an exhaust heater box like a VW bug hads. extract a bit more heat by Making a aluminum heat sink attached to a piece of pipe.
Because of the high temperature and the high speed of the exhaust gas, both, the pressure and the density are very low. In other words, that gas contains a very small amount of energy. Hence the small increase in temperature of the water.
Still, that exhaust gas could be routed through the floor, heating the air above it. Of course, you shouldn't expect much but...better than the cold air in you room.
How the hll do you get 8mm microbore pipe formed tightly around such a small diameter without flattening???
Hi dave enjoying your channel I just have a quick question I've I've broken one of the small all pipes running into my fuel pump on an eberspacher D4 I just wondered if one of the Chinese copies fuel pumps would work ? Would appreciate if you could help thanks
From my Googling the D4 uses a 22ml3 pump. Which is the most common one on the chinese heaters. So although many aren't listed with the size the pump in the picture has the size, like this - www.ebay.co.uk/itm/Car-Air-Diesel-12V-Oil-Fuel-Pump-With-Bracket-Holder-Fit-For-1KW-5KW-Air-Heater/313017758265?hash=item48e14ff239:g:Kx4AAOSwPRteX002
My question is, under ideal conditions, IE, max output, are these TEG's capeable of generating enough power to provide ANY worthwhile power to the heater?
Yes. www.europeanthermodynamics.com/products/datasheets/GM200-49-45-30%20(2).pdf
If you can get the hot side 200ºC and the cold side 30ºC they should output 7.5W each. I think this is where the solar MPPT controller would shine, if we had enough volts to get it running it can match the load resistance and extract max power. If I've correctly understood how MPPT works.
@@DavidMcLuckie That being the case, here is my worthless suggestion.
Put an elbow on the exhaust outlet and direct it back to toward the intake of the heater. Have the exhaust going through a block that had suitable baffles / turbulators to break up the boundary layer of gasses and extract all the energy. The TEGS would be attached to this on the hot side.
The intake for the burner would be ducted to pull across the TEGS with the heatsink attached on the cold side with a manifold.
This would provide the cooling air for the tegs and preheating for the intake.
I set up a HE like this for my heater. Exhaust was plumbed back to a he which the intake drew across. It made about 8oc difference to the output air at 3/4 setting.
You point of the area getting warmer and cooling getting less efficient is noted however I ran my heater last winter pulling cold air from outside. It worked extremely well and there was never any stuffiness in the house, in fact we all noted the complete opposite. Always seemed nice and fresh and Furthermore, pushing the warmed air in meant the place was pressurized somewhat so all the cracks and draft points were pushing out not in which added to the comfort.
Have to say I really think one is chasing their tail on this idea . I just don't think the efficiency is in the tegs to make up for the inevitable losses but interesting to see what you come up with.
@@DavidMcLuckie Problem with an MPPT is you are going to have maybe 5% loss on a little one and that may make things difficult to get the required outputs.
I fibreglass moulded a computer cpu cooler radiator to heater outlet, I pump water through 1/4 bsp connectors 12mm pipe to 60 litre tank. on full power d2 eberspacher takes between 20 to 30 minutes to heat to 40 degrees, its all set on a digital thermostat to stop circulating water when temperature is reached. if i wrap 12mm copper pipe around exhaust and insulate then it should heat alot quicker
Maybe you could just pipe exhaust into the bottom of an old radiator and then from other side of radiator to outside I think I’ve seen some one else do it on UA-cam
Nice video sir. what app are you using for FLIR, any special phone etc? thank you
That is a Flir One.
@@DavidMcLuckie thank you David
Can you say if this was a ok test or not?
Is it ok to do?
How much effect in watt did you finally get out of the car EGR cooler?
Compared to the pool heater?
Both looks small.
Hi there David! I've been looking for air + water heater you were testing recently. Do you know any ebay or ali links with delivery form eu? Only seen one on aliexpress and alibabba but the delivery is like €150.. Thanks :)
As far as I know they are the only manufacturer / seller.
Hi mate what’s the flow rate of your pump? interested to know due to feeling that slow a rate might change heat thermal exchange? Many 🙏
I think it's 10L per minute.
Here is a challenge you might want to look into, can you use an EGR to recover heat to heat a radiator to expel more heat to the room you have installed the heater in?? over to you David, love your videos.
What is the end game here? Having hot water available, keeping the heat inside the air space you are trying to keep warm, or both?
How about trying the heater version with built in heat exchanger combined with an exhaust heat exchanger? 🤓
It's for people that want both. You could build it with a Y piece in the exhaust and a valve so if you only want hot air or if you want hot air and heat a tank of water.
Hi David. Do you think that a combi boiler heat exchanger would work? Yip happen to have one, will give it a try. Cheers. Jim.
It would yes. Let us know how you get on.
@@DavidMcLuckie Hi David. Cobbled the combi boiler heat exchanger together today, got a good temperature difference exhaust in and out, but could not get the water to revolve, will need to add a pump. Looks promising as I run the heater to warm my workshop hot water to clean my hands would be a bonus. Cheers, Jim.
just tested my old brass pool heater. like a ptat i ran it dry.....well....it de-soldered itself lol it reached over 210c so i pulled it off and scraped of the gloss paint that stunk the place out lol. i really want to try mineral oil to make storage haters. do u think a central heating pump can take it or will heat itself flow the oil around the system??????? maybe a vid for u to try lol go for it buddy
One simple way to get the water out the top of the heat exchanger as hot as possible, just turn the tap down on the container, granted it's no thermostatic valve or something, but simple solutions and all... :)
Yes, but the problem there is if the flow is slow enough and the inlet temperature gets high enough it'll eventually start boiling in the heat exchanger. Sounds like a job for an arduino. :)
@@DavidMcLuckie Nah, just need a thermostatic valve like that in a car engine cooling system, but instead of totally blocking off flow, just use it to restrict the flow 'til the water is hot enough to open it... :)
Soooo, based on the £150 pool heater, could you possibly do a similar test ((Mimic the pool heaster)) using something like off the shelf copper pipe 37-42mm incorporating the side ports for the unrestricted exhaust flow and through the middle something like 10-15mm copper (for the water) and test :) was thinking of somthing like that as cost effective method. Obviously this would mean a horizontal method as opposed to the vertical :)
Build a 1 meter liebig condenser for the exhaust out of 19mm and 25 mm copper plumbing parts. Similar device used in distilling to condense 75 C alcohol vapor to liquid. David is correct that it need valving to control cooling water flow rate to absorb more heat.
" LESS talking David " Ha,Ha !
Silly question alert !!! How would you plumb this into a camper for hot water ? I already have a cold water system ( tank, pump, kitchen sink) Could you put the hot water from the egr outlet direct to the tap ? Or would you need other stuff.
Ideally with a calorifier tank so you can heat and store the water. Directly to tap would give you hot water but would need to be at a very slow rate.
@@DavidMcLuckie thank you, trying to get my head around it all 😅
Could you test plumbing exhaust into another heater combustion in? And run its fan up?
You'd have to cool the exhaust gas first.
hi having a problem with intermittent pump working on startup do you know where i can get a circuit diagram
If you send me an email - me@davidmcluckie.com I'll send you a copy of the one I have.
My friend had one of these diesel heaters the pump reversed and started putting pressure in his diesel container. Any idea why that would happen.
You know, now that I think about. I've never tried reversing the polarity to see if the pump works backwards as well as forwards.
@@DavidMcLuckie if it’s ac please don’t!
@@DavidMcLuckie It's just a solenoid pump, makes no difference polarity wise, only way to reverse pump flow is to reverse the .....erm, pump.
Did you try reversing the polarity yet? What happened.
Ironic that gas heaters don't utilize exhaust gas heat through a chamber like a normal gas heater does. (Air heat exchanger). I have so many ideas, maybe you can patent a few ? ......Like for example, why isn't this a window unit ? It could even be low profile for a van or a roof unit like R.V.'s have. I intend on hanging one on my camper window with only the fresh air intake and outputs fitted into the slightly opened, but sealed window. An aerodynamic housing would keep it from being an eye sore......
Great movie :)
Does any one now why I can't switch of my chinese heater?
It's switch on one night and the controler doesn't work. I can't switch it of.
The other think is that heater it doesn't give a heat :)
I hear the fun but no heat...
Is it pump or glow, hmmm??
Thanks for any answer :)
👍👍👍
Hi, do you have another link for this?
Did you do the test with just wrapping some copper pipe around the exhaust instead ?
I have not. Mostly as I've been unable to coil a good sized copper pipe tight enough. I've tried salt and sand and just made split copper pipes. :S
@@DavidMcLuckie tried heating the pipe up? And wrapping it round a solid pipe? That's what I was going to try. But I've only ever seen it done with 3/16th pipe
The delta T heat exchange efficiency using a single coiled tube around the exhaust will not be as good as multiple tubes inside a tube-in-tube heat exchanger. And remember to use counter current. Have the the flow going in the opposite direction of the exhaust flow. Designing it for ease of cleaning the tubes is important. It seems rifle cleaning brushes could be used to rod out the tubes if the end comes off the heat exchanger. Has anyone found a heat exchanger with a removable end? It seems the dairy industry might use them as they need to be cleaned and sanitized. The stainless tubing and clamps used in dairy industry would make a awesome exhaust. Cheeers
@@DavidMcLuckie how about trying coiling the maximum amount of flexi exhaust pipe it can cope with and put it straight in the water tank
When are you going to do the copper pipe wrap attempt?
I've tried unsuccessfully to wind copper tight enough.
What heat exchanger it is the link
Don’t work
What‘s the power rating of the diesel heater? Thanks!
8KW
I can't tell where the exhaust gases are venting to?
Inside the workshop, it's a test environment.
The exhaust lost it's heat before it got to the heat exchanger. Put some more water in the white container, then it will syphon.
It lost some. But we're talking 10s of degrees, and I said in the video it could be improved with insulation.
Have you ever considered sending the exhaust gasses through a normal household radiator before venting to recover waste heat that way ?
A normal radiator no. In theory it would work but not sure what the reaction between the exhaust gases and the mild steel of the radiator would be like.
Water should be above return hose. Convection.
The pool heater is sexier than the egr cooler. I don't know if it's 100 dollars sexier though.
The pool heater is rated for many, many times the KW power the heater will ever produce. But it also designed to be much more efficient than the EGR cooler.
did you do the copper pipe wrap experiment?
I could never get my pipe wrapped tight enough. Except for copper brake pipe, but then you've got a tiny amount of water flowing.
@@DavidMcLuckie I was thinking about a copper brake pipe myself as an option..
@@DavidMcLuckie .. I think the egr video you put up hooked up to the flexiexhaust and it wrapped well in rockwool is the most feasible option
@@gerardmcgee the only issue I see with the egr variant is that the egr would have to be outside unless it was chopped/welded to allow the extention of the actual waste fumes. ??
the link for the heat exchanger is bad...
Does the heat exchanger restrict the exhaust?
The link doesn't work
Why don’t you bring the heat exchanger closer to the Chinese heater ?so you maximize the heat recovery instead of it being radiated in the air.
Because of the way I had to mount everything, and I have other plans to put something else inline. That and the 8 inches will not make much difference, the FLIR showed maybe a 10ºC variation from top to bottom.
link is dead, noooo
This must act like a muffler?
It does a little.
500W is quite a lot . I thought it would be less.
The top pipe should be below the water level in the tank
Why?
hot water rises so in heat exchanger systems that are not powerd by pumps alow convection currents to continually transfere heat to the header tank
That’s a free radiator