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  Can anyone give me a link to the install instructions for a gu95a125v20-2b  S# s8499c31282. It is overheating on high fire and I want to change the motor speed, the dips are on the motor, I think 10 of em.
When I arived at this call w was hooked to w1 and y was hooked to w2. What were they thunkin
Thanx in advance.

Davenet doesn't have Armstrong manuals.  Are you sure the dip switch settings aren't printed on the back of the furnace door?

What type of thermostat do they have, single stage or two stage?

How is the low voltage wiring hooked up at the furnace?

Is this a variable speed DC motor?

It's a single stage t-stat wired as such on furnace, the board blew at w1 so I had to fire it @ w2 only (boards are in the $400 + range for these units 50a50-210) So we are hoping to get the thing to work that way. Not much info on the door. Yes it's a dc motor. It's been 2 weeks and Emco hasn't given me any tech support yet. The guy isn't freezin but it would be nice to get this thing running the way it should.
30 years @ this and I am still learning every day.

If you're using a single stage thermostat, then the board itself controls the staging.  If the W1 terminal is damaged replace the board.  Tell the customer he risks damaging the furnace by leaving it running on low fire.  It's a great way to put a hole in the heat exchanger.

Rarely should you ever have to adjust the heating fan speed on a variable speed furnace.  Just worry about adjusting the cooling speed.  Did you find the dip switch settings on the back of the blower door?

As a courtesy to my customer and information to myself I would llike the install instructions. I am having a hard time getting them. My supplier says he is havig the same problem. Ecco not emco as I previously stated. Maybe I'll try davenet since all these dc motors seem the same there might be one the same there. Thanx admin

I have a pdf document I found on ECM motors that might help but don't see any way to attach it to this message.

Thanks rmuntz!

You can download the ECM Service Guide - Here

i just came across this posting today. whats your reasoning behind this quote? how would this cause a crack?

"Tell the customer he risks damaging the furnace by leaving it running on low fire.  It's a great way to put a hole in the heat exchanger."

An underfired furnace can cause a hole, and a overfired furnace can cause a crack.
I have a guide to heat exchangers I will scan when I have time.  I don't really know why it would... Now that I think about it, it may have said an undersized furnace will cause a hole.  I'll double check and post back.  Running on low fire 100% would be like being undersized.  I guess the prolonged cycle would be the cause.

Yup, it said undersized furnace will cause rusting, pitting and holes in the heat exchanger.  In his case the same could happen.

well, I guess thats true regarding the prolong run times by leaving the unit's high fire setting off or having an undersized unit. But, when a home tstat settings are fairly steady with very little temperature difference between program periods or even using a non-programmed tstat, then the unit will maintain that temp. setting. Thats the system job anyways.

Like i was mentioning in another post, i have a two stage variable speed hi.eff/ furnace in my home, and i have disabled the high fire setting for extra gas savings. to give you the specs, home 2400 sq ft low fire input 49,000 btus, high fire input 80, 000 btus and i dont find any unusual long run times on my furnace on low fire. Let me know what u think

49,000 BTU's seems low for a 2400sq ft home, but I guess it depends where you live.  Is the home R2000 or Energy Star rated?  I would expect to see anywhere from a 60,000 - 90,000 BTU furnace in there, depending on house efficiency, at least with Ottawa winters.  I would check the rating plate for low fire temperature rise rating.  As long as the return air and supply air temperatures are within that rating, I wouldn't worry.

As far as for what's more efficient, I couldn't say for sure.  You'd have to test to see what actually saves you money.  Running longer seems more efficient that starting and stopping to me.  Of course running too long could be inefficient as well.  How long does the furnace fire for and how cold is it outside at the time?

Home is a r2000 rated and sorry its 2200 sq ft. Delta T is within manufacturers ratings. I live  just East of Toronto so weather is for the most part comparable to Ottawa.