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Inspecting HVAC Systems Topics include heating, venting, and air conditioning inspections.

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Old 12/9/08, 5:03 PM
Dave Pursel Dave Pursel is offline
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Default Air handler blower speed

I recently installed a Goodman SSZ 16 seer unit with an AEPF Variable speed air handler. HVAC techs came and got it up and running. The one question I have is when I bump the thermo (Visionpro 8000) up 2 degrees the blower ramps up full speed like it's suppose to but when the heat pump kicks in to maintain the temp. the blower hardly pushes any air. You can feel heat at the registers but hardly any air and the Heat pump stays on for quite sometime. Is this normal? My first electric bill for November here in PA was $164 and I atribute $69 of that for the heat pump. Seems resonable to me.
Any thoughts, thanks
Dave
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Old 12/9/08, 5:50 PM
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Marc D. Shunk Marc D. Shunk is offline
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Default Re: Air handler blower speed

The fan speed is dictated by whether you have heat or cool selected. During heating, it does run slower so as to not make the air feel cool on your skin. An air handler equipped with an ECM motor will only run the motor as fast as it needs to to maintain the CFM's necessary for heat or cool.
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Old 12/9/08, 6:17 PM
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Bruce A. King Bruce A. King is offline
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Default Re: Air handler blower speed

My Carrier variable speed has lots of jumper selections in the air handler to choose many features that all affect the fan speed. Some only affect the fan speed when it is manually turned on but some others involve the auto speed.

Be advised that many installers do not know how to properly connect the control wires for a variable speed system. Mine was wired just like a unit without the variable speed and very weird things occurred.

You will need the installation manual and owners manual both to figure it all out if it has all of the multiple features mine does.

If you have the option to add the outdoor temp sensor, I would advise doing that since it should then let you program the aux heat to stay off even when raising the t-stat several degrees. For example, keep the electric strips off unless it is below a certain temp outside. They will still come on during the defrost cycle to help knock off some of the chill caused by that cycle.



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Last edited by bking; 12/9/08 at 6:20 PM..
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Old 12/10/08, 9:11 AM
Dave Pursel Dave Pursel is offline
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Default Re: Air handler blower speed

Yes I have the outside thermostat set at 0 as per instructions. Does the heat pump use the same ammount of electricty all the time, or does it cut down according to what the air handler is running at? If it does not it would seem a waste of energy if it doesn't blow the heat off the coil at a higher blower rate while it's running. The temp at the registers runs about 102 degrees regardless of outside temp. so far.
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Old 12/10/08, 11:14 PM
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Bruce A. King Bruce A. King is offline
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Default Re: Air handler blower speed

The current draw of the heat pump compressor varies some with the outside air temperature and other minor factors but does not adjust itself based on interior fan speed.

It sounds like your duct work was designed for some other system or maybe not installed very well. Variable speed systems are very well designed to obtain the best performance but as I said before, there are jumper/programming selections to check into.

I see many homes with very little airflow from some registers and more from others, sometimes the dampers are adjusted inside the ducts for this and sometimes its probably just poor duct sizing and distribution methods.

I inspected a new home the other day for an hvac tech and he showed me some poor ducting practices in the attic that I would not normally look for.

Where are you located?
Aux heat lockout down to zero does not sound right to me.
I keep mine on 30.



B.A. King Home Inspections, LLC
www.BAKingHomeInspections.com
Serving Charlotte NC area and Fort Mill SC areas.
CMI Certified Master Inspector and Independent
License NC2449 and SC1597



"Discovery consists in seeing what everyone else has seen and thinking what no one else has thought."
- Albert Szent-Gyvrgyi, Nobel Prize for Medicine 1937
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Old 12/11/08, 8:09 AM
Dave Pursel Dave Pursel is offline
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Default Re: Air handler blower speed

I'm located in central PA. I installed the duct work myself as per drawings an HVAC engineer drew for me. The air handler from time to time will run at full speed and when it does I get equal flow from all ducts so it's not a duct issue. It's just when maintaining temp that the blower hardly runs. I think it could be in the dip switch settings or maybe this is normal. I also was told this unit would operate down to 0 degrees. The coldest night we've had was 13 degrees and it was producing plenty of heat without the backup heat on.
Dave
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Old 12/11/08, 4:31 PM
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Bruce A. King Bruce A. King is offline
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Default Re: Air handler blower speed

It really sounds like the variable speed airhandler control wiring could be wired wrong.
You really need the installation manual, it will have 4-5 different wiring methods based on actual equipment present etc. Mine was not wired like any of the choices in the book, the guy had just wired it like any simple control wiring which is wrong.



Looks like you have a good system that will work well in low temps but part of the reason for allowing the backup heat to be available is in the event of an ice storm or malfunction of the compressor during the night.

If an ice storm hits, as it does here every few years, the outside unit will have a large amount of ice buildup on top where the defrost mode is not designed to help.



B.A. King Home Inspections, LLC
www.BAKingHomeInspections.com
Serving Charlotte NC area and Fort Mill SC areas.
CMI Certified Master Inspector and Independent
License NC2449 and SC1597



"Discovery consists in seeing what everyone else has seen and thinking what no one else has thought."
- Albert Szent-Gyvrgyi, Nobel Prize for Medicine 1937
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Old 12/11/08, 5:42 PM
Dave Pursel Dave Pursel is offline
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Lightbulb Re: Air handler blower speed

Thanks for the info, I'll have another tech come in and evaluate the problem.
Dave
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