Blower Speeds

[prh]

I have a Janitrol GMP 125-5 5 ton furnace. It appears to have a three speed blower. Black wire is High, Blue is Med, Red is Low.

Can anyone tell me how many CFM each colored wire represents? It's a 3/4 Hp blower.

[4l530]

[Mr Bill]

Every furnace is going to be different you will need the literature that come with it to figure that out, we would not even know without the spec. literature.

Did you already ask this under a different name? because someone ask the same question earlier.

[falkenater]

Your amount of cfm is determined by fan speed and static pressure. If you have your installation instruction book you can have someone qualified check your static pressure and look at fan curve chart and determine your delivered cfm or have someone measure your cfm with a flow hood. Chances are high that it is not close to good design.

Good Luck!

[prh]

No, I haven't asked before, and no, I don't have any literature on this furnace, installation or otherwise.

[emcoasthvacr]

The manufacturer should provide that.

If you use a fan chart, .5 to .7 SP should be a reasonable assumption, but the AHU should provide that on the data sheet; otherwise take measurements.

Originally posted by prh
I have a Janitrol GMP 125-5 5 ton furnace. It appears to have a three speed blower. Black wire is High, Blue is Med, Red is Low.

Can anyone tell me how many CFM each colored wire represents? It's a 3/4 Hp blower.

[prh]

Thanks, johnnyde. That's the approximate answer I'm looking for! Thanks again.

[duxinaroe]

You also should know that cooling requires high speed for the maximum amount of airflow. Heat is typically placed on low for the maximum temperature rise. the heat speed can be adjusted to get more air but you will get less temperature rise. Whats your actual issue low airflow in certain rooms now that your heating?

[prh]

.

[Edited by prh on 12-16-2006 at 03:22 PM]

[Mr Bill]

Originally posted by prh
Nope. The Med speed fan wire was hooked to the Heat terminal; it was blowing hot air around like a blast furnace. I've since hooked the Red wire to that terminal and parked the blue.

Part of the issue is that the furnace is oversized for the house.

I don't want to be of any help here because I can see you are getting in over your head, but I will tell you if you slowed down the motor because of what you described you are really messing up and if you keep it up you will be buying a new "right size" furnace soon, that is my kind of advise.

Slower fan speed= more heat= common sense.

[prh]

I've got the 5 ton furnace covered under a home appliance replacement warranty. Thanks for your reply mrbillpro.





[Edited by prh on 12-16-2006 at 03:24 PM]

[prh]

Thanks for your help guys.

[Edited by prh on 12-16-2006 at 03:25 PM]