Contractor Talk - Professional Construction and Remodeling Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
I have an Armstrong ultra sx 80 furnace. Having two issues that may be related. Unit cycles on and off when heating to 68, it's not really a short cycle, unit runs for approx 7-10 min shuts off for split second then restarts immediately and repeats. Maybe this is normal for this unit?

The other issue is I recently installed a new Honeywell smart stat that requires the common wire ( old stat was batt powered) screen intermittently goes blank as if losing the 24 volts. Is this a transformer problem or a board problem?
 

·
Wood Craftsman
Joined
·
7,324 Posts
Throw a meter on it,,,,,narrow it down....

If you didn't have any problems up until you replaced your old thermostat for the new one you have,,,

It may be your thermostat ,or something else,....narrow it down,,,,



JMPOV,


B,
 

·
Wood Craftsman
Joined
·
7,324 Posts
How's your burner flame.....:blink: normal,...med,...weak......does ithe blower shut off and the burner stay on.....


Just curious....:blink:

So your saying your furnace is not cycling correctly....

Not sure what your situation is.....

I'm not an hvac guy and I am sure Flashheat will be on to try and help....just I have had so many issues with mine that I am becoming familiar with the workings...and it was not an admiration of mine.....


Sucks when they mess up....but it helps to know how it works...sometimes - with all this new technology it's best to get a pro in......

But don't give up....

B,
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #7 ·
It's an Armstrong Ultra SX 80, guessing age is from the Mid 90's. Honeywell board and honeywell smart valve for the gas. Since it's not short cycling I'm guessing its not the flame sensor guessing it might be high limit switch on the cycling issue. Still perplexed by stat shutting off intermittently since every time I checked voltage at board and stat I have 28.6 volts between C & R. Might exchange stat to see if it's defective.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #9 ·
Yeah, after roaming around the internet on this, it seems the general consensus is these valves are junk. Any recommendations on a replacement? I know the 24v goes through the valve, would this impact the intermittent problem with losing power to stat?
 

·
Registered
Joined
·
3,920 Posts
It's not like smart valves are junk, but they are known to fail. You can't just get a universal valve, going to need to get the oem part. Granted, it's a lot easier for me to spend somebody else's money. But, now might be a good time to replace the furnace altogether.

Next year it could be the blower motor, the following year, the inducer motor...etc. Before you know it, you would have been better off with new gear.

I think you are better off getting a hvac guy to look at this. Replacing the smart valve, because some jamoke on-line is hypothizing is not wise. Who knows? It could be a loose connection. We all have mis-diagnosed at some point. It's an empty feeling to spend $150+ on a part, just to see the problem recur. Good luck
 
1 - 14 of 14 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top