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brobinson68 01-15-2007 11:07 AM

NOMA Thermostat

I just purchased a NOMA 5+1+1 thermostat. After replacing the old thermostat, the furnace stilll works. The problem is my furnace has a 4 speed fan blower motor. It is wired to permanenlty run the fan on low speed. With my previous thermostat, when the heat came on, after the furnace warmed up (matbe 10 minute) the fan would switch to medium speed until the set point was reached.

With the new thermostat, the motor does not seem to do this (it just stays on low speed). Consequently, it takes over an hour to bring the house up to temperature, were before it would take only 15 or 20 minutes.

I have matched the wiring from the old thermostsat to the new (ie G to G, Y to W, etc.) Is something wrong or is the fan supposed to stay on low speed?

#CARRIERMAN 01-15-2007 11:51 AM

Hi brobinson68

The question you have asked could have several answers. Number one, is the furnace a two speed or variable speed. If it is you may have the wrong thermostat. If its not a two speed you could have the proper stat, but may need to set temperature rise. If you could give us a little more information, one of us can answer your question.

Good luck

brobinson68 01-15-2007 12:08 PM

Noma Thermostat
The fan motor is a 4 speed motor. It is wired to run continuously on low speed. It normally runs at either the 2nd or 3rd speed for heating, and high speed for cooling. From what the last guy who worked on my furnace told me, only 3 of the 4 speeds are wired up.

#CARRIERMAN 01-15-2007 03:13 PM

Hi brobinson68

It sounds to me like you are working with a Lennox product. If that be so, look on the blower board. You will see ACB Heat, this is your blower speed for heat. You will also see ACB Cool, this is you cooling blower speed. You will also see one marked fan, this is your continuous blower speed. You should also see terminals marked park, These are the blower speeds not being used, these are dummy terminals. The blower speeds should be as follows, Black (high speed) ,Blue (medium high) ,Yellow (medium low) ,Red (low). If you know how to do a temperature rise calculation, you will have no problem deciding what to use where.

Good luck

diywoman 01-17-2007 07:58 AM

Quick question...what is leave the furnace fan on all the time, or to let it come on and off as needed. Just wondered for air circulation whether having it on through the day would be beneficial, and allow the heat to circulate more efficiently.

#CARRIERMAN 01-17-2007 02:36 PM

Hi diywoman

I like to run my blower all the time, this helps with many things. It helps keep all the rooms similar in temperature, air from stratifying, controlling humidity, etc. Simple answer is yes, any time you run the blower it has many advantages.

Good luck

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