Short burst by blower Fan YORK AFFINITY YP9C (97% Efficiency)

mrpatelr

We have the above mentioned natural gas furnace and it is about 6 years old. For pas two weeks I have been noticing that at the end of the cycle when the blower suppose to blow the air at high speed (typically this last up 40 to 50 seconds) it is lasting only 15 to 17 seconds and it dies off. I decided to monitor one day and sure the LED status light flashed 3 consecutive red flashes. The manuals calls for to check pressure switch.

Now the trouble shooting part - My house is 2750 sqft. So according to the municipal code, we need to have two furnaces. I have a 100,000 btu furnace for the main level and basement and a 80000 btu for the upstairs. The problem is with the 100000 btu furnace. Since it called for the pressure switch, I switched the two pressure switches from the 80000 btu to the 100000 btu and problem still persists. What else could be the problem? I have new air filters replaced as well.

Appreciate all the help I can get.

Jamie Hall

Just for curiousity, where are you that your municipal code calls for two furnaces for a 2750 square foot building? First I've heard of that -- but I learn something every day.

Since you switched the pressure switches and the problem persists, it's not that... could either be the pressure switch on the problem child can't properly sense the system pressure, or the control isn't interpreting the pressure switch correctly. I'd get your installer or service person to come and figure it out.

mrpatelr

I am up north in Calgary, Canada. Homes built above 2500 sqft calls for installing two furnace.

Thanks for the feed back. One last thing I haven't checked is the exhaust pipe, but then why would furnace run or the blower would run at normal speed and quit as it about to speed up at the end of the cycle.

Jamie Hall

An. Nice town, Calgary... is this the blower for the draught? If so, the problem could well be a partial blockage in either the intake or exhaust pipe.

icy78

> @Jamie Hall said:
> An. Nice town, Calgary... is this the blower for the draught? If so, the problem could well be a partial blockage in either the intake or exhaust pipe.

Yes, and/or the secondary htex.

DZoro

Make sure to put the pressure switches back to the original furnaces. They lookalike but are different operating pressures.
You have a few different pressure switches in the furnace, one should be a condensate box switch. Follow maintenance procedures if it has been a while, if your not sure on the procedures it is best left to your heating person.
D

mikeg2015

did you blow out all the hoses? Are the condensate trap and drains clear. that’s the first thing we ALWAYS check on all condensing furnaces.

FYI - if you have insulation to code, your furnaces are easily 2x the size needed. I lived in SE michigan and heated a 2200sqft home with a 40,000BTU furnace down to -5F. Current 3600sqft 1907 Victorian only needs an estimated 110k at -10F.

Solid_Fuel_Man

I'm sorry....I'm still stuck on the silly two furnace code? Why in the world? Eh?

Anyhow, I agree with others. Troubleshoot the LED error code. Check for stoppage in flue or heat exchanger(s). Have either (bother) of these furnaces been serviced in 6 years?