Any HVAC people in here?

[Paul408Notch]

I just have a question about the blower in my house (Or blowers in general I guess.)

Will heating/AC blowers kick into a low speed if they've been on for a certain amount of time? Or are there some that do?

The reason I ask is that I like to leave the blower running all the time. I like the air circulating through the house, and the compressor seems to kick on less often. Well after it's been on a while, I don't feel near the airflow out of the vents as when I first turn the blower on. I don't know if the blower is getting weak, or if it's just kicking into low speed, or what. If the thing is weak, I need to do something about it before my home warranty runs out next month, but if that's just how it is, I guess I'd just like to know.


Oh, and it seems I've asked this before, but is there any advantage/disadvantage to putting a return vent in the basement where it's nice and cool, but we hardly go down there? Seems like if the blower was sucking in air from the already cool basement and blowing it into the rest of the house, that would be pretty helpful. Like geothermal cooling or something, just on a very small level.

[bobtsgt]

the blower should be a one speed motor. if you can look at the wires on the motor count them. sounds like the blower is getting too warm and starting to slow down. One idea would to be to clean the squirrel cage real good and put an amp meter on the blower wires to see how much it is drawing.

As for the return in the basement it might not be a bad idea if you can do it pretty easily. It should suck up the colder air downstairs and redistribute it through the house.

[djom1cincy]

Unless its a blower design to ramp up and down then it should run one constant speed. The only reason it would ramp up is if it calls for cool air. Once the temp reaches a desired temp then it would ramp down to a lower speed to keep the air moving.

Disadvantage to putting a return in the basement would be that it would pull cool damp air out of the basement and put it into the rest of your house. Yes the air is cooler but in general it has a higher humidity level. Higher humidity level means you feel warmer even at a cool temp. That's why you take humidity out in the summer and add it in the winter.

[Mista Bone]

When was the last time the bearings were oiled on the blower?

[DeckerEnt]

It wouldn't take too much time to suck all the cool air from a basement and redistribute it through out the house. The point of leaving the fan run all the time is to not have hot or cold spots in the home. It is a good idea though. It is worth 2 degrees in the summer and winter to circulate the air constantly. That means less energy needed to heat or cool the home.

[Paul408Notch]

Unless its a blower design to ramp up and down then it should run one constant speed. The only reason it would ramp up is if it calls for cool air. Once the temp reaches a desired temp then it would ramp down to a lower speed to keep the air moving.

Disadvantage to putting a return in the basement would be that it would pull cool damp air out of the basement and put it into the rest of your house. Yes the air is cooler but in general it has a higher humidity level. Higher humidity level means you feel warmer even at a cool temp. That's why you take humidity out in the summer and add it in the winter.

I'll have to take my thermometer/humidistat into the basement and see how the humidity is. I have a dehumidifier down there that's cranking away most of the time, and it doesn't seem too bad.


When was the last time the bearings were oiled on the blower?

Pretty sure it was in 1972. I didn't even think to do that.


the blower should be a one speed motor. if you can look at the wires on the motor count them. sounds like the blower is getting too warm and starting to slow down. One idea would to be to clean the squirrel cage real good and put an amp meter on the blower wires to see how much it is drawing.

As for the return in the basement it might not be a bad idea if you can do it pretty easily. It should suck up the colder air downstairs and redistribute it through the house.

Seems like last time I looked at the motor, there were like 12 wires going to it, which is why I thought it was multi-speed. One day soon I'll have to get in there and see what I can find.

[Mista Bone]

Likely a multispeed blower with dry bearings. Normally one speed is selected per needs and hardwired, no changing speeds.

Newer units have sealed bearings and never need serviced.

Might be time to upgrade to a more efficient unit?

[cobrajoe]

Don't forget most of those blowers require oiling. Mine has two tubes running up from the bearing housing.

[Paul408Notch]

Thanks guys. I'll pop the cover off soon and see what I can find.

[cobrajoe]

If you do find oiling tubes, Try that MotorKote stuff. Heard it is kick ass!:bigthumb

[Paul408Notch]

Well I pulled the thing apart tonight, and did some research. It's a Carrier 58MVP furnace, which apparently has a multi-speed blower in it and a 92or-so% efficiency rating. The blower spins more freely than any fan I've ever felt in my life, and I don't see a lubrication point in there anywhere. Must be sealed bearings I guess.

The controller seems to be running in high speed for a while, then switching into low, but I can't figure out how to trick it into staying in high. I could probably put a jumper in the Hi-Lo relay output, but I don't think I really want to do that. Seems like they make it drop into low speed for a reason. I should probably just leave it alone.

[bobtsgt]

is the controller mounted to the motor or externally? Something is switching it to low speed like a heat sensor on the motor or maybe some sort of timer on the board. You could take a wire from the relay and hard wire it to run high at all times. May loose some of the efficiency but oh well. As long as the blade turns freely without binding I say look towards the controller.

[Paul408Notch]

is the controller mounted to the motor or externally? Something is switching it to low speed like a heat sensor on the motor or maybe some sort of timer on the board. You could take a wire from the relay and hard wire it to run high at all times. May loose some of the efficiency but oh well. As long as the blade turns freely without binding I say look towards the controller.

The controller is mounted externally to the motor. I could probably pop the cover off and rig it, but I'd have to disconnect about 25 or 30 wires to get the cover off, so I think I'll just leave it be for now.

[kennebellcobra]

I would not pull the air out of the basement...there is a newer code where the filter has to have a door on it so it can't draw the air from the basement...I was told because of all the stuff that grows in damp basements.