Static pressure in ductwork
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- Опубліковано 14 гру 2013
- This is my attempt to explain air pressure in ductwork. This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits. - Навчання та стиль
Thank you very much for the valuable instruction.God bless you and your family.
Fantastic innovation - works well on CSOs to give a cost effective measure of Event Duration in real-time and also helps to generate alarms in the event of a dry spill that results from an up stream blockage
Thanks GFM. its helping me considerably. Instead of using my books I just use ur vids before a job. So much easier.
Thanks for the support
GFM
Thanks! good explanation. Trying to get into duct work deeper.
+Marat RPM SoCal I am preparing for more on ductwork. Hopefully soon.
GFM
Thanks, Ill keep an eye
If you have 1100cfm at .3" on the return and you want to be running 1100 at around .08", what size square or round duct you would have to add to lower the static? I want to know if I am figuring this right. I am having a hard time wrapping my mind around additional duct size = what static. I am not talking about removing what's there I am trying to figure out adding to reduce static.
I'm trying to figure this one out as well been searching for days and everybody's answer is your static pressure is high? You need to spend five digits and replace your entire duct system even though your system is brand new and our measurements were off when we installed your system we still want you to replace everything and pay us money cuz you waited over a year before saying anything about it" instead of estimating how many new runs or increasing my return or supply duct sizes to lower my pressures.
hi, i am reading the "evaporator coil static pressure drop" chart now. Why the pressure drop readings are different between wet bulb and dry bulb under the same condition. For example, when airflow is 800 CFM, the pressure drop readings of wet bulb is 0.21 and dry bulb is 0.18. It seems the wet bulb pressure drop always bigger than dry bulb pressure drop, whatever the coil type or airflow is.
XIAO JIE Are you sure that's not "wet coil"? That means if the coil has condensate on it.
GFM
I just discovered your video, and I must say, well done and easy to understand. I'm wondering what you think the maximum pressure in in/h2o you would expect to see within a duct. I'm designing an HVAC duct balancer, and would appreciate anyone who could give me input. Im trying to find the upper and lower bounds for my device. Thank you! Fellow HVAC guy.
Residential max 1" wc. Commercial can be very high but for conventional about 2". Hope this helps.
GFM
Thanks a bunch, I'll go for a sensor that can read up to 2" h20. It says I can go up to 1 psi without damage, so I think I'm good.
Thanks for the video it was very educational and helpful. I have a
Carrier 58mca-060-16110 furnace with air conditioning installed in a
small room at the center of the house with grates in all the walls to
the surrounding rooms(house is on a slab and doesn't have return
ducting). The filter is mounted on the side of the furnace(one side
exposed to the room) and sucks the air directly from the room.I have a
digital manometer and want to check pressures on the furnace. I have a
few questions if you don't mind.
1. Does the one probe need to
be held in front of the filter or just anywhere near the furnace. Or is
it needed at all, at least for the filter drop.
2. Does the
probe inserted above the heat exchanger and below the evaporator coil
need to be anywhere specific in the space. My coil is offset to the left
side directly over the heat exchanger (no room to insert it) but there
is a lot of open space to the right of it that's probably not directly
in the airflow.
Thanks
First question is what are you trying to test? Do you want to test pressure drop across a component?
GFM
Thanks for the reply. I'm going to check individual components and the overall. My main concern is the posoitioning of the probe between the Heat exchanger and the Evaporator coil as noted My coil is on top of the heat exchanger on the left side of the compartment but there is a lot of open space on the right side to put it. In most of the videos I've seen it is inserted between the two and I want to know if it can be inserted anywhere within that space and still produce a valid reading. Thanks
If you have a 10 horsepower motor (or above) - that is low on CFM - with an operating suction pressure of 0.05 and a discharge pressure of 3.35 - can you explain why the fan is low on CFM?
A question I would have is this, if I didn't want to use the furnace as a whole house air filter as some of them can become restrictive what is the best filter for the furnace. Private home, this one has tall vaulted ceilings.
Any of the medium efficiency (30-35% efficiency) pleated filters are ok. They are a compromise between filtration and pressure drop. The fiberglass filters have the least pressure drop and the lowest efficiency (10-15% efficiency). Hope this helps.
GFM
grayfurnaceman
If I could I would like to take this a little further to understand better and I think it might add to educating people.
I have the Lennox Elite series. It's the 32xx series I believe. The prior owner was running a 3M Filtrete 1000 and I reduced it to a 600. I don't know what the efficiency ratings are on these filters or if I can go lower still? I think it is safe to assume that the main purpose of the filter is to protect the furnace and it's longevity. A video on Filters, the purpose and any drawbacks would be greatly welcome. Thanks again for your reply and any feedback you can give on this topic. Love your work here!
Curiosity
Well interesting development... My freezer is located in the furnace / laundry room, I had talked about a need to turn on the Honeywell 360 humidifier in a past video and found a plastic bag tonight when looking for something to make for dinner. The pressure switch manuals and tubing were all there, it even included a DVD which I watched but it was lacking in exact procedures. It was worked up for the 260 and the 360 and referred you to the wiring diagram which is OK but as long as you are going to provide a DVD to the consumer why not just go into detail? If you are interested in seeing the DVD supplied I can send it to you. Can't wait to get the 360 working! :) I'll let you know the results after I hopefully get it working as it should.
Curiosity I will be doing some on filters. Its a subject that needs explaining. The video on the Honeywell is on youtube. I will be looking at it to see if I can add anything.
GFM
is there a second part of this vid ? i am retired but always learning a thing or 2 LOL ,,,,thanks for sharing this
There is a playlist that may help. ua-cam.com/play/PLItXrh64d2JMNrOaRe03sLnb2tqU0gr8J.html
GFM
wow thanks i did not know what a playlist was either oops ! i will listen to them in time , i even went through my old school books of HVAC school and i am not even finding nothing on static pressure ? i know its has to be in there cause i remember we went through it in class ! ,,,thanks dont get old LOL ,,,,,
Too expensive, others work the same for 1/2 that cost.
Why do we keep using this US Customary measurements! The rest of the world including England where it originated from is on the Metric system!
no one cares
Nicholas Hartzler Not true, I care.
It has to be frustrating if your from outside the US, especially since so much information comes from the U.S.
The whole world thinks we are stupid anyway. We think in inches, feet, miles. pounds, ounces, tons BTU's and degrees farenheight. If you want you can program your gauges to read metric all tape and speed odometers also have a metric scale. I would love to see the faces on the guys at the supply house when you place your order in metric
Brian Ellsworth BTU is British Thermal Unit, no?
If you have a 10 horsepower motor (or above) - that is low on CFM - with an operating suction pressure of 0.05 and a discharge pressure of 3.35 - can you explain why the fan is low on CFM?