Furnace Blower Fan on 100% of the time - Good or Bad or it depends?

I was at a dinner party last night and two guests described how their HVAC reps told them to run their furnace blowers 100% of the time.  The HVAC reps reasons for the recommendation, as relayed by the dinner guests, were:
1. continuous running reduces the wear and tear on the blower motor that cycling on and off causes, thereby avoiding an earlier motor replacement
2. circulating the air around the home provides better balanced temperatures throughout the home and, 
3. continuous air flow would provide cleaner air due to the continuous filtering.

We live in northern Michigan and are a heating dominate climate.  I am curious to hear from the HVAC professionals about what they recommend to their clients and why.  At the moment I don't buy the above arguments and feel those customers end up paying more in energy costs for little benefit.  However I do understand there is no disputing tastes when talking about perceived comfort.  Also if anyone knows of a good source or any research done on this issue I would like to see a more in depth analysis (if its out there).

[NOTE: Neither home has an ERV, HRV, or other mechanical ventilation other than intermittent bath and kitchen fans.  Both are natural gas, forced air furnaces.]

Any discussion on this subject?
Thanks,
TJ

Tags: HVAC, IAQ, energy, motors

Views: 132146

Replies to This Discussion

Yes, I own a HVAC Company in central Kanas,  -  A slight pitch is not a problem but shouls be avoided if possible.  The A/C Evap coil and Recuperative coils in the furnace may hold more water.  If your furnace is lower at the back than the front by 1/2 "  I would not be concerned

 

I may not be around for a few days.  I will check emails as I can.      If you need to call another Trane dealer, look for one who is a "Comfort Specialist"  That is a designation Trane gives dealers who commit to a higher level of service.

 

Call the Dist. Phone number and ask when you should expect some one to call you back.  I would not expect to Dist Service rep to charge you for a visit so I would work through them as much as possible

I have a 3 ton GeoComfort geothermal unit with a ECM fan from Enertech. I can read my electric meter accurately to see the wattage used when in the 600 cfm fan mode (1300 cfm in 1st stage heat mode) and came up with 60 watts. So it appears as if the ECM motor is for real.

L.Klisch PE

Long thread - haven't read all the replies but "It Depends" is my right answer.

 

Good if:

ECM Blower

Air Filtration

Fix minor comfort imbalances (hopefully equipment is sized to run near-continuous anyway...)

 

Bad if:

Non-ECM fan

ECM with High Static

Leaky duct work 

Leaky Shell - continuous mechanically induced leakage.

The cons far outweigh the positives of removing potential temperature gradients and more filtration.

Sorry I disagree on the theory of using large amounts of electricity to run the fan. Yes when talking an older system you will use much more than a 3 or 2 stage however by not running all the time you loose in the amount of infiltration into the home. A properly balanced unit with ERV or HRV set up will save you allot more on fuel than the small amount of loss to run the blower. You also will pay in health. I have done studies with blowers on and with blowers off to see the difference in IAQ. There is no comparison to the quality of the air that is filtered properly verses no air movement.

Steps to Indoor Air Quality by Priority:

1.  Test for and Mitigate Radon as found.

2.  Seal the leaks for air infiltration.

3.  Moisture Control

4.  Pest Control

5.  Seal Ducts, Pressure Balance and ASHRAE 62.2

6.  Combustion Pollution Control - If you are keeping Combustion Appliances.  Could be #2

7. Attached Garage

8.  Materials Used for cleaning, etc

9.. Air Filtration

You don't need to filter what you keep out!

You forgot one John! 10. Co2 level for IAQ according to Environmental Sensitivity not minimal acceptance for Air Quality. This is like saying what I can do to get away with it. Reason I can say this is the acceptable level of Air required for someone sensitive is higher up to 30 cfm/ person fresh air and this is the only way to ensure success with a Client needing to feel well. Plus more than normal filtration or removal of particles, bacteria,viruses and voc's.

I consider that in 6.  Combustion Pollution Control. It means low level CO monitoring and CO detectors for the high level immediate issues.

John Co2 has nothing to do with Combustion pollution control. This is the indicator of not enough fresh air into the home.

http://fire.nist.gov/bfrlpubs/build97/PDF/b97044.pdf

I agree with point # 2 for heating purposes

1 & 3 are silly

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