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Car Guy 12-02-2010 11:46 AM

Coleman Echelon 9V - high fan speed in low stage??
Have a Coleman Echelon 9V in 120,000 Btu 2 stage furnace.

Connected to a two stage thermostate properly configured.

Calls for w1 and w2 heat are correctly applied to furnace.

Only problem is that the furnace runs on the high speed when only w1 heat is called for. Adjusting the thermostat to call for w2 heat works but the blower speed is the same, i.e. on high

It is supposed to run on the low speed of approx 1400 rpm instead of the approx 2100 rpm on high.

Any suggestions??

yuri 12-02-2010 04:38 PM

Yes, if it is running too fast on low fire it will cool down the heat exchanger too much and damage it.

Car Guy 12-02-2010 06:30 PM

I was under the impression that too much heat will damage the heat exchanger and not allowing it to cool down a bit after the burner cuts out.

I don't understand what mechanism would damage the heat exchanger from insufficient heating.

In any case I am waiting for a qualified service technician to complete the install wit the gas pressure, heat rise, fan speed etc adjustments.

Anyone have an idea of what room heat register temperatures should be on low and high? Realizing that distance from the furnace makes a bit of difference......what is a reasonable range of outlet temp that is workable.

yuri 12-02-2010 06:59 PM

If it runs too cool moisture in the exhaust will condense into water prematurely in the primary heat exchanger and corrode it etc. Supposed to stay warm and condense in the secondary exchanger which is stainless steel and designed for water.

Car Guy 12-02-2010 08:54 PM

I have switched it from the max "A" profile to the "C" profile and the motor rpm change is now noticeable from low to high.

Room outlet temperatures are in the 90 degree range depending on closeness to the furnace.

The ducting above the furnace is in the 100 degree range so a temp rise of about 30 degrees and I believe the specification on the plate on the inside of the front panel door is 40 - 70 on both low and high fire.

I am probably on the low side of the range. Using an infrared temp measuring device which reads a bit low on the outside of the duct. Inside duct will be higher. Vent temps should be petty accurate.

Anyway the noise level is way down and the motor ramps up as it is supposed to on high and ramps down on low and is within a reasonable range as per the temp rise criteria.

So we shall wait for the service guy to do the final tuning.

yuri 12-02-2010 09:08 PM

Sounds good to me. I try get them in the middle of the range ie: 50-60 deg rise. Usually around 125-130 deg supply temp is normal.

Car Guy 12-03-2010 01:36 PM

Thanks for your response yuri.

yuri 12-03-2010 02:28 PM

Your welcome. Make sure the tech uses a manometer for the gas pressure and stick thermometer in the ductwork to properly set it up and watch him. Some don't know how or just "talk the talk".

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