Thermostat wire insulation melted on start-up

[sperry]

Forced air residential furnace. Re-install of Armstrong Ultra III last July - (contractor = Friend of Friend) AC/Blower worked fine. Just turned on Heat - worked for about 10 minutes and shut off. Smelled melted wire insullation. Inspected unit and fried insullation on all thermostat wires.

Cut off power to unit.

Also - recently (8 AC running hours ago) installed April Air Cleaner.

Also - I believe 2 speed fan running at low speed for AC. Hear blower vibration when Heat is on (running at higher speed ?)

Can't find short - suspect a mis-wiring. Hope this is common wiring oversight that can be diagnosed corrected. If not will probably replace entire unit.

[lynn comstock]

I have seen shorts in the low voltage blow a fuse or burn up the transformer or relay coil all without damaging the stat wire.

I am inclined to suspect that line voltage is involved. That could be miswiring, or unintentional contact of line voltage with the low voltage circuit. Check the "low" voltage wiring to ground. I have seen factory miswiring create some interesting failures. Was the furnace replaced as well? I suspect the heating circuit of circuit board may be miswired.

Lynn

[pecmsg]

Please call a professional before some one gets hurt.

[raidersfan7]

yes u agree this is not a diy forum:eek:

[lolson]

I'm sure there's a qualified contractor in your area to call or you can just replace it

[lolson]

And keep on replacing it until you get it right

[eglide99]

And keep on replacing it until you get it right

I suspect the "magic smoke" has escaped..:(...sniff sniff yeah i smell it from here:D

[pecmsg]

Forced air residential furnace. Re-install of Armstrong Ultra III last July - (contractor = Friend of Friend) AC/Blower worked fine. Just turned on Heat - worked for about 10 minutes and shut off. Smelled melted wire insullation. Inspected unit and fried insullation on all thermostat wires.

Cut off power to unit.

Also - recently (8 AC running hours ago) installed April Air Cleaner.

Also - I believe 2 speed fan running at low speed for AC. Hear blower vibration when Heat is on (running at higher speed ?)

Can't find short - suspect a mis-wiring. Hope this is common wiring oversight that can be diagnosed corrected. If not will probably replace entire unit.

Sperry
http://www.hvac-talk.com/vbb/showthread.php?t=180396
Read the last reply by HeyBob

[smittyii]

Sperry
http://www.hvac-talk.com/vbb/showthread.php?t=180396
Read the last reply by HeyBob
some folks just never learn! who can be selling this stuff to H.O.s in good conscience? hopefully the blaze doesn't melt the serial #s off all this equipment, so it can be traced back to the scumbag that keeps sellin it to him:eek:

[tinknocker service tech]

if lowvoltage wires melted you have a very serious problem and could be in serious danger

CALL A PRO AND STEP AWAY FROM THE SMOKE

[lolson]

Its just a thermostat wire
http://www.youtube.com/watch?v=AJdW0WaE048

[beenthere]

Is that friend of a friend a contractor, or just a side jobber?
Does he have liability insureance incase he does damage to your house?

Have contractor look at it, and tell you how much damage was done. And what it will cost to repair it.

[Admin]

Thread closed. No DIY allowed.