Furnace help!

[Swamp Donkey]

What would cause my thermostat to spark and smell funny? I put in a new themostat in my mobile home and the new one started sparking and smelling funny also. My worst nightmare would be the wire's going to the furnace had a short in them. Wishing it is an easy fix somewhere on the furnace. It is an older furnace. Don't want to spend a bunch of money, I am building my own log home! Thanks.

 

[illflem]

Need more info, how many wires, is it for air conditioning also? I think you may have landed the wires on the wrong terminals.

 

[Swamp Donkey]

2 wires, 24v, no a/c and the original one smoked and sparked as well, that is why I switched it out. Problem seems to be a bit deeper. I will switch around the wires to see though. I put the white wire on the "w" and the black was labeled with a "r" I just finished switching wires around, still nothing. Furnace does nothing. Thanks.

 

[illflem]

Just shorting the wires together on a two wire system should fire up the furnace. Sounds like your 24v transformer is shot or the wire back to the furnace (not the hot one) is grounding out somewhere turning the T-stat into a mini heater. Jump the wires together at the furnace, if it fires up the problem is the wiring. New T-stat wire may be in order, sometimes you can connect the new wire to the old and use the old wire to pull the new one in as long as it doesn't go though too many curves. You can also try this trick at both ends to get the wire up into the wall and heater area. Most mobiles I've worked on have the t-stat wire running underneath on the frame where it has the chance to short on the frame after critters get to it. I don't envy you, it's no fun crawling under those things.

 

[Swamp Donkey]

Thanks, I will try shorting them. I was going to do it last night, but I already had enough smoke and sparks. But I thought what's 24 volts going to hurt? LOL It's getting cold way up here in Canada with no furnace for 3 days now! Good thing for my wood stove!

 

[HVAC]

You Need A Multimeter

Check for 24v on the gas control with the t/stat closed. If you have 24v then the valve is bad. If you have no power then you prob have a bad wire.

 

[Swamp Donkey]

Ok, I now have my multimeter. Not getting anything at the thermostat. I was looking for 24v. Went back to furnace and checked things out. Not sure what wires are supposed to be the 24 v ones to check at furnace. Going to try and make some sparks now... ... ..... its getting chilly up here in northern Canada with no furnace.



Procrastinator extrodinair!

 

[Swamp Donkey]

Getting it narrowed down, finaly found where the thermostat wires go! Still not getting anything, but when I push down on this metal doohickey it stars running. I think a replacement of the dohickey is in order!



Thanks.

 

[JohnE]

Something is wrong in the circuit board(s) on the furnace itself. Most times a relay will either hangup and it will draw full current. The poor thermostat contacts can only sustain the fill current draw of a relay coil for the brief time it takes to close. The coil on a closed relay draws less than 10% of the amperage required to initiate closing.



Transformers are relativelt a low cause of control system failures.



What type of heating system do you have and what vintage?



Better yet, email me <a href=mailto:4ericksons2@home.com>JohnE</a> and I'll try work this through with you.

 

[Papa Joe]

Yup, HVAC's still readin' em... ... ... ... ... .

 

[HVAC]

Talkin' Old!

Donkey, what starts running when you push the doohickey? The main blower fan or the burners light?



I just recalled you are in a mobile home right? That means you have a Coleman or a Duotherm or an International. They are the clunkyist most antiquated furnaces as compared to the residential stuff currently being used.



I'm going out on a limb. I'm guessin' you have a standing pilot light? And although it's lit, the furnace doesn't come on when you turn the stat up. When you push the reset on the gas control the burner lights.



If this is accurate then you need a new gas control most likely. It could be a safety switch too. There are high limit switches, roll out switches, etc.



JohnE. I don't think this furnace has a circuit board. Not unless it's a VERY new mobile home.



Need more info.

 

[willyslover]

Papa Joe. . most of the good ol guys read 'em just no longer post, and they read the names that have always had good stuff v/s what oil or what this or what that... would be much better if the new guys had to read the archieves first. . IMHO

not troing to pi** off anyone. . it just makes the threads less interesting to some of us.

 

[Papa Joe]

Good to hear from you, Gary !!! Know what you mean.



My brother just left for Boulder Creek on his Honda Valkyrie after visiting for a while. He's racing the latest storms home.



Nowell, go get 'em guy.



Joe



PS Porky still kicking in MO ?

 

[Papa Joe]

Oops, forgot. What oil do you recommend

 

[Swamp Donkey]

HMMMM, This is getting interesting. I do have an old Coleman furnace. When I push the Dohickey, (it has 4 wires going to it, with a L shaped plate on top of it with two contacts that when contacted make my combustion fan run, and it is the 24v converter/transistor/relay I think. Is located very near the combustion motor. ) As for the thermostat, well I think I fried it! Not a problem, the make them every day!



Also while I am fixing stuff, what on this old beast would make my air fan blow all winter. It never turns off, all winter it runs blowing cold air, except for when the flames come along and then it blows some toasty warm air. Been this way for 5 years.



Coleman Mobile Home Furnace

Model 8866-701



As it is now, I cleaned up the Dohickey, and the furnace works as it should when I touch the 2 wires together at the Thermostat. So maybe all I need is a new thermostat! Or maybe I should just get my butt in gear and move into the log home... ... .



Standing pilot light... . Yes.



Thanks for your help guys!

 

[illflem]

Swamp Donkey, you must be one tough dude living in a unheated mobile up in the northland. It always seemed to me that those things get colder than it is outside.

 

[Swamp Donkey]

Cold? Its only been snowing for the last 4 days! I have it narrowed down to a new relay for the combustion motor. Converts to 24 volt I think. Also a new thermostat because my initial hookup fried this one! Good thing it comes with a good warranty! As for me being tough, I do have a wood stove, but Ms. Swamp Donkey does not think it is to funny. Gotta keep Momma HOT!