Beautiful!!! Any idea of the water temp. difference when using this? I'd like to similarly recover heat for the home hot water tank with: 1. the shower drain water, 2. the dishwasher drain water, 3. the gas water heater exhaust, and 4. the gas home heater exhaust. All fluidic waste heat could conceivably be salvaged if it's worth it. These mentioned, plus the obvious one already mentioned many other times, the wood burning stove/fireplace, are the only ones I've concluded that MIGHT yield outputs worth the inputs. It seems like there are plenty of products on the market to recover heat from industrial waste, but for households, the numbers don't usually add up. But, I guarantee you that if our country ever gets into an energy rationing program like in WWII, or some other SHTF scenario, then we'll really appreciate a warm shower even it cost us a butt-load of resources to get it.
There's not a huge increase in temperature, as the specific heat capacity of water is really big; however, on laundry day, it brings the temperature of the incoming water from "really cold" to room temperature, which reduces the natural gas required to take it the rest of the way. For liquid to liquid heat transfer, like for gray-water heat recovery, the readily-available copper pipe to copper pipe exchangers are more efficient.
This is a great idea. I wonder if the air exiting the bottom is warm or humid at all? How has this held up over the years? Also what is the advantage to putting the cooled air into the forced air return (is that just to recover more heat into the house via the central air?) Last question, over time have you seen any noticeable change in your gas bill (assuming your new water heater is gas, replacing the heat exchanger one.)
Sorry I didn't check comments earlier! The air exiting is slightly warmer than room temperature -- significantly lower than the dryer vent temperature. There is still some moisture in it; I believe it would still be at 100% RH, but for the much lower temperature. The system has worked basically without issue for years now; I occasionally need to clean out the stack, and sometimes the aluminum foil tape needs touching up. I fed the air back into the central ducting to spread the remaining heat and humidity around the house instead of it being localized in the utility room. Sorry, I haven't really monitored the change in the gas bill. The new HW heater is high efficiency, so that change would be greater than the heat recovery system. Thanks for your interest!
I haven't done any exhaustive research on the reduction in cost. I did some calculations based on how much energy the drier consumed, and, based upon the drop in temperature and heat recovered from condensation of even 50% of the water vapour came to the conclusion that this was a worthwhile venture. That was a few years ago, so my calculations aren't readily available, or I'd give you a more quantitative response. The final heating is done in a high-efficiency hot water heater, not the heat recovery tank, so there's no difference in how long the hot water lasts.
Hi, i like this idea, could you clarify how the air to water heat exchange is actually taking place. Does the hot/warm air simply pass through a coil within the tank, and if so what diameter bore is the coil, standard water coils would create to higher back pressure for the dryer? Thanks James
Since this is a converted natural gas water heater, which runs its "chimney" up through the middle of the tank with an air baffle to increase turbulence, there's really no back pressure generated -- the chimney is about 4" in diameter.
We do that in the summer! But with more than half of the year at lower than freezing temperatures, we end up keeping the laundry inside for those parts of the year.
It's good to know they're available now. From what you've said, a disadvantage to the condensing dryer would be that it heats the room, which may not be desirable, particularly if it's not winter; mine heats water instead, something there's an all year demand for. Also, my hot water heater was free, so adding it to an existing dryer cost almost nothing.
@@matthewneuls8613 Tell me more -- would those bacteria grow in the heat exchanger or in the water tank? If they're in the heat exchanger, that could be a concern, as I'm currently venting the outgoing air into my force-air heating system. If you're thinking about inside the tank, are you suggesting it might be a problem because it would be closer to room temperature than either the pressure tank (cold) or the hot water heater (hot)? I would think that any bacteria from the heat recovery tank would be killed in the water heater before coming in contact with humans.
@@prosstaylor I would be concerned about it growing in the old hot water tank that you are using as a heat exchanger. Most home water heaters heat to 120deg f, where the bacteria can still survive, it just can't multiply. Even at 140deg it takes 2 minutes for the bacteria to die. If your new hot water heater is an on demand, that could definitely be a problem you may want to watch out for. I'm not an expert by any means, but I do know that it is very important to keep water either cold or hot, not in between. I don't think venting the dryer air into your Hvac would be an issue, i would think it would dry out between uses and water wouldn't be present long enough at room temperature to breed bacteria.
@@matthewneuls8613 Good to know. In my case, the real hot water tank is a big tank, and we run our water hot. However, this is a good warning for others with on-demand systems. In our case, I doubt that having the extra tank between our pressure system and the hot water heater makes much difference -- the water sits in a pressure tank inside the house anyway. Hopefully, as it is chlorinated city water, most critters are dealt with.
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Nice idea to warm the water this way before heating it which requires much less energy than heating it from cold.
Beautiful!!! Any idea of the water temp. difference when using this? I'd like to similarly recover heat for the home hot water tank with: 1. the shower drain water, 2. the dishwasher drain water, 3. the gas water heater exhaust, and 4. the gas home heater exhaust. All fluidic waste heat could conceivably be salvaged if it's worth it. These mentioned, plus the obvious one already mentioned many other times, the wood burning stove/fireplace, are the only ones I've concluded that MIGHT yield outputs worth the inputs. It seems like there are plenty of products on the market to recover heat from industrial waste, but for households, the numbers don't usually add up. But, I guarantee you that if our country ever gets into an energy rationing program like in WWII, or some other SHTF scenario, then we'll really appreciate a warm shower even it cost us a butt-load of resources to get it.
There's not a huge increase in temperature, as the specific heat capacity of water is really big; however, on laundry day, it brings the temperature of the incoming water from "really cold" to room temperature, which reduces the natural gas required to take it the rest of the way. For liquid to liquid heat transfer, like for gray-water heat recovery, the readily-available copper pipe to copper pipe exchangers are more efficient.
This is a great idea.
I wonder if the air exiting the bottom is warm or humid at all?
How has this held up over the years?
Also what is the advantage to putting the cooled air into the forced air return (is that just to recover more heat into the house via the central air?)
Last question, over time have you seen any noticeable change in your gas bill (assuming your new water heater is gas, replacing the heat exchanger one.)
Sorry I didn't check comments earlier!
The air exiting is slightly warmer than room temperature -- significantly lower than the dryer vent temperature. There is still some moisture in it; I believe it would still be at 100% RH, but for the much lower temperature.
The system has worked basically without issue for years now; I occasionally need to clean out the stack, and sometimes the aluminum foil tape needs touching up.
I fed the air back into the central ducting to spread the remaining heat and humidity around the house instead of it being localized in the utility room.
Sorry, I haven't really monitored the change in the gas bill. The new HW heater is high efficiency, so that change would be greater than the heat recovery system.
Thanks for your interest!
Any measure of if your hot water lasts longer or reduction in water heating cost?
I haven't done any exhaustive research on the reduction in cost. I did some calculations based on how much energy the drier consumed, and, based upon the drop in temperature and heat recovered from condensation of even 50% of the water vapour came to the conclusion that this was a worthwhile venture. That was a few years ago, so my calculations aren't readily available, or I'd give you a more quantitative response. The final heating is done in a high-efficiency hot water heater, not the heat recovery tank, so there's no difference in how long the hot water lasts.
Hi, i like this idea, could you clarify how the air to water heat exchange is actually taking place. Does the hot/warm air simply pass through a coil within the tank, and if so what diameter bore is the coil, standard water coils would create to higher back pressure for the dryer?
Thanks James
Since this is a converted natural gas water heater, which runs its "chimney" up through the middle of the tank with an air baffle to increase turbulence, there's really no back pressure generated -- the chimney is about 4" in diameter.
Neat idea, thanks!
Just put up à cloths line.
We do that in the summer! But with more than half of the year at lower than freezing temperatures, we end up keeping the laundry inside for those parts of the year.
Use a condensing tumble drier. Heats the room and dries the clothes. 100% cheaper.
It's good to know they're available now. From what you've said, a disadvantage to the condensing dryer would be that it heats the room, which may not be desirable, particularly if it's not winter; mine heats water instead, something there's an all year demand for. Also, my hot water heater was free, so adding it to an existing dryer cost almost nothing.
Do you have any concerns about Legionella or other such bacteria growing in your heat recovery tank?
@@matthewneuls8613 Tell me more -- would those bacteria grow in the heat exchanger or in the water tank? If they're in the heat exchanger, that could be a concern, as I'm currently venting the outgoing air into my force-air heating system. If you're thinking about inside the tank, are you suggesting it might be a problem because it would be closer to room temperature than either the pressure tank (cold) or the hot water heater (hot)? I would think that any bacteria from the heat recovery tank would be killed in the water heater before coming in contact with humans.
@@prosstaylor I would be concerned about it growing in the old hot water tank that you are using as a heat exchanger. Most home water heaters heat to 120deg f, where the bacteria can still survive, it just can't multiply. Even at 140deg it takes 2 minutes for the bacteria to die. If your new hot water heater is an on demand, that could definitely be a problem you may want to watch out for. I'm not an expert by any means, but I do know that it is very important to keep water either cold or hot, not in between. I don't think venting the dryer air into your Hvac would be an issue, i would think it would dry out between uses and water wouldn't be present long enough at room temperature to breed bacteria.
@@matthewneuls8613 Good to know. In my case, the real hot water tank is a big tank, and we run our water hot. However, this is a good warning for others with on-demand systems. In our case, I doubt that having the extra tank between our pressure system and the hot water heater makes much difference -- the water sits in a pressure tank inside the house anyway. Hopefully, as it is chlorinated city water, most critters are dealt with.