variable speed HVAC fan

[iron]

this year, we've been pretty happy with our setup. we have a ZC fireplace in the living room at the far end of the house. 3 bedrooms on the same floor - about 40-50ft away at the far points. basement with about 750 SF. using the ecobee 3 thermostat, i have the fans set to come on for 30 mins/hour. it helps to keep the living room not too hot, and the other rooms not too cold.

electric furnace is 1979 model with single stage fan. when the air comes on, it's moving pretty good. if heating with the furnace/heat pump, the house heats very evenly. when heating with the fireplace (oct - mar), living room is probably low to mid 70s and the far bedrooms around 67. basement around 65.

i'm wondering if replacing the fan to a variable speed and running it full time would make sense. bills are pretty low right now, so not too concerned about the costs. my logic in the variable speed fan would be to keep the air constantly circulating so that all rooms get to a near equal temperature. when you go to a costco and look up at their fans, they have like 30ft diameters, spin slow, and appear to do a great just keeping the air circulating without being overpowering. thinking this is repeatable, somewhat, in a house.

 

[coutufr]

I run my electric furnace fan 24/7 for the last couple of months and it even out the temperatures around the house and it heats the basement as well. I do use more wood but it is worth it

 

[Mike M.]

I have a variable speed furnace fan and run it 24/7 all year around. Balances temps, controls moisture and really filters the air. I have a 5 in thick air filter that we change twice a year. Its also much better for the fan motor than all the starting. Would highly recommend this configuration.

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[Mech e]

You need to be very careful about using a variable speed motor on your heat pump. If you do want to use your system as a heat pump, it is critical that the motor speed runs at the same rpm as the OEM motor. If you run the motor at a slower RPM when using the unit as a heat pump, you can damage the compressor on the condensing unit.

 

[EbS-P]

I just had replace my variable speed blower on my 10 year old heat pump unit. The unit is a two stage system. It can be configured to run as single stage. Variable speed blower was about 400$ more than a generic single speed unit. If I didn’t have a two stage compressor where the first stage is supposed be higher efficiency I would not think that the extra money was worth it. Let alone replacing a working blower.

The thermostat has t1 and t2 wires to send when to turn on stage one and two and the unit then controls the fan speed with very slow ramps to final rpm.

Short answer seems more trouble and money than it’s worth. I’d spend it on insulation or save it and get a top of the line heat pump 40 years is a good run.

 

[snaple4]

I just had replace my variable speed blower on my 10 year old heat pump unit. The unit is a two stage system. It can be configured to run as single stage. Variable speed blower was about 400$ more than a generic single speed unit. If I didn’t have a two stage compressor where the first stage is supposed be higher efficiency I would not think that the extra money was worth it. Let alone replacing a working blower.

The thermostat has t1 and t2 wires to send when to turn on stage one and two and the unit then controls the fan speed with very slow ramps to final rpm.

Short answer seems more trouble and money than it’s worth. I’d spend it on insulation or save it and get a top of the line heat pump 40 years is a good run.

Only $400 for a vs, you got out cheap. I work for an HVAC company and our cost for replacement ECM motors can be past 600. Glad you got one of the cheaper ones.

this year, we've been pretty happy with our setup. we have a ZC fireplace in the living room at the far end of the house. 3 bedrooms on the same floor - about 40-50ft away at the far points. basement with about 750 SF. using the ecobee 3 thermostat, i have the fans set to come on for 30 mins/hour. it helps to keep the living room not too hot, and the other rooms not too cold.

electric furnace is 1979 model with single stage fan. when the air comes on, it's moving pretty good. if heating with the furnace/heat pump, the house heats very evenly. when heating with the fireplace (oct - mar), living room is probably low to mid 70s and the far bedrooms around 67. basement around 65.

i'm wondering if replacing the fan to a variable speed and running it full time would make sense. bills are pretty low right now, so not too concerned about the costs. my logic in the variable speed fan would be to keep the air constantly circulating so that all rooms get to a near equal temperature. when you go to a costco and look up at their fans, they have like 30ft diameters, spin slow, and appear to do a great just keeping the air circulating without being overpowering. thinking this is repeatable, somewhat, in a house.

Do you know where your ductwork runs and if it has ever been sealed of original? Most likely, based on age of unit, your ductwork is outside of the envelope of your home and the duct connections/fittings are not sealed. What happens is as the fan moves the air you loose conditioned air out of the ductwork. The house then pulls outside air in to makeup the lost air. This, for many people, decreases overall comfort and increases energy usage.

Some ranch style houses were built with the ductwork inside of the envelope; this is usually in a drop down soffit in the middle of the house. If that is the case then the leaky ductwork isn't much of a problem. You may also have a basement setup that may or may not achieve similar results.

 

[EbS-P]

No the motor was 400$ more than a single speed. Whole job was 1300$.

Only $400 for a vs, you got out cheap. I work for an HVAC company and our cost for replacement ECM motors can be past 600. Glad you got one of the cheaper ones.

Do you know where your ductwork runs and if it has ever been sealed of original? Most likely, based on age of unit, your ductwork is outside of the envelope of your home and the duct connections/fittings are not sealed. What happens is as the fan moves the air you loose conditioned air out of the ductwork. The house then pulls outside air in to makeup the lost air. This, for many people, decreases overall comfort and increases energy usage.

Some ranch style houses were built with the ductwork inside of the envelope; this is usually in a drop down soffit in the middle of the house. If that is the case then the leaky ductwork isn't much of a problem. You may also have a basement setup that may or may not achieve similar results.

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[MTASH]

I have a Trane variable speed furnace. The fan speed is 100% during the heat cycle. When in circulation mode it falls back to something like 70% speed.

My Honeywell thermostat has two circulation modes. "On" which of course is 24/7, and "Circulate" which cycles the fan twice an hour for about 15 minutes each cycle.

 

[iron]

Only $400 for a vs, you got out cheap. I work for an HVAC company and our cost for replacement ECM motors can be past 600. Glad you got one of the cheaper ones.

Do you know where your ductwork runs and if it has ever been sealed of original? Most likely, based on age of unit, your ductwork is outside of the envelope of your home and the duct connections/fittings are not sealed. What happens is as the fan moves the air you loose conditioned air out of the ductwork. The house then pulls outside air in to makeup the lost air. This, for many people, decreases overall comfort and increases energy usage.

Some ranch style houses were built with the ductwork inside of the envelope; this is usually in a drop down soffit in the middle of the house. If that is the case then the leaky ductwork isn't much of a problem. You may also have a basement setup that may or may not achieve similar results.

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75% of the ductwork is in the envelop. only the part where the furnace connects to the duct work and about 20ft of dropdown duct is in the garage. there's drywall around it, so not perfect, but not horrible.

 

[snaple4]

75% of the ductwork is in the envelop. only the part where the furnace connects to the duct work and about 20ft of dropdown duct is in the garage. there's drywall around it, so not perfect, but not horrible.

That is MUCH better than most houses around here!

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