Furnace Malfunction

Discussion in 'Homesteading Questions' started by Nomad, Feb 10, 2005.

  1. Nomad

    Nomad Well-Known Member Supporter

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    Not sure where to post this. The wife has been keeping a log all morning and called me a few minutes ago. It seems that no matter where the thermostat is set, the heat won't come on until the house gets down to 58 degress. It then runs for a while until it gets to 59 or 60 and shuts off. I think it is probably the thermostat, but I don't know much about it. I've replaced small round ones before, but this is a large one and has batteries in it. The batteries were replaced yesterday. Assuming they are good, what other things should I look for?

    Thanks very much,

    Nomad
     
  2. agmantoo

    agmantoo agmantoo Supporter

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    A strong guess is that your thermostat is a programmable one. Sounds to me as if it is on a setback program where the temp was set to be lower. I "think" the furnace is fine. Try a google search to see if you can find how to program the thermostat if my guess is correct.
     

  3. jgbndaudio

    jgbndaudio Well-Known Member

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    Hello Nomad,

    A little more info would help.
    First off all what type of heating system is it? Gas, Oil, or Electric?
    Secondly how is the heat distributed? Forced hot air, hot water baseboard, electric baseboard, Steam?

    Why do you think it's the thermostat?

    The easiest way to check the system without the thermostat is to twist the two wires that are attached to the thermostat together. This assumes you have a two-wire system, which is likely unless you have central air. When you do this the device should start immediately and run until you disconnect the wires from each other. If it doesn't do this you have a problem somewhere else.

    Give me more info and I can be of more help.

    Know that someone or lots of people will probably say 'just call a professional"
    That's always an option.

    Here's why I don't recommend that option.
    Last Feb I bought a new house with about a fifteen-year-old propane boiler for both the baseboard hot water and the domestic hot water. Shortly after moving in, it started running for short periods of time and then shutting down. Then it wouldn't fire up unless I killed the power to it and waited a few minutes. Needless to say this got rather annoying very fast! So, I had three different companies out to look at it and not one of them could fix it. I don't really blame them I mean the guys they were sending to fix it were probably in Jr. High when this thing was made and just never had to work on this model. I understand that. What I don't understand is that they all offered to send a sales person out either later that day or early the next day to let me know how much it would cost to replace. Well, ok what did I have to lose to find out how much it would cost to have one that worked all the time. Three estimates later, the cheapest was $3500 and they couldn't do it till next week at the earliest. Well, F-them I said and went online and read about propane hot water systems. Then I got out my voltage meter and started poking around. That's when I found that I had a bad igniter. A very simple piece, that I think was about 25 bucks. Needless to say I'll never call any of those companies again. This summer I replaced the old junker with two new propane Takagi TK jr on demand hot water heaters. One for the domestic and one for the baseboard. It's been smooth sailing even though everyone I talked to and almost every web page I found said to let a professional install them. Oh yeah and I'm saving a ton of money! Because these hot water heaters are so efficient.
     
  4. Tax York

    Tax York Member

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    I have EXACTLY same problem of what you have problem I did same thing what you did until I finally replace the reply (a small box on furance that control with thermostat and furance) it finally return to working again and much better operator the furance than it used to be. Reply cost me almost 150 dollars.
    I hope it help solve your problem
     
  5. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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    Knowing the type of furnace would be helpful. If you have a forced-air, gas furnance check and see if the control unit has a little light on it. Right after the furnance shuts off, see if the light is flashing. These lights blink various codes of long and short flashes. The various codes signify problems with the furnace. Your owners manual should tell you what each code means.
     
  6. Nomad

    Nomad Well-Known Member Supporter

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    I have a forced air, gas furnace with central air. There appear to be a lot more than two wires. I don't want to screw with it too much because at least we can survive at 60 degrees. If I mess something up and lose everything it will get pretty cold in here. The local plumbing and heating company charges $75 just to walk through the door before they even start to do anything, so I'd rather not go that route if possible. I watched it through a cycle and it ran from 58 thru 61 degrees and shut off even though it was set at 67. It isn't progammable. It has an up arrow and a down arrow to raise and lower the setting. There is a switch for the fan for either auto or run. Another switch for heat or cool. There are 3 AA batteries in the unit. I can't get any deeper into it than to take off the cover. Then you see a circuit board. There is stuff behind the board but no apparent way to get to it. I'm going to go look at the furnace and see what is meant by control box. This is an older house and when we moved in 3 years ago there were no manuals for the furnace. If I knew for sure it was the thermostat I'd just get a new one. But I'm on a very tight budget and can't waste money shooting in the dark.

    Thanks for all the ideas and keep them coming if you can think of anything else.

    Nomad
     
  7. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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    Nomad, it sounds like your furnace is going into a "soft shutdown" after it operates for a while. The shutdown is a safety feature. It's letting you know that something is wrong. What usually happens is that it shuts down for 10-15 minutes or so (depending on brand) and then restarts. If the furnace does go into a shutdown, it's control box should have one or more LED lights that flash a code. You can use the code to troubleshoot the problem. I just google on "furnace troubleshooting" and found the service manual for several major brands...the manuals explain what each different code means.

    Our brand new furnance would not heat the house last winter. It would run for 15 minutes and then stop. 15 minutes later it would start again, run for another 15 minutes and then shutdown. The house never warmed up. ANd the furnace would not start up when in one of these shutdown modes even tho the thermostat called for heat.

    I watched the furnance thru a cycle, when it shut down the LED light flashed a code. (I could see the LED light blink thru a litte window in the furnance housing...the window was about the size of a penny. On some furnances, you may have to take the cover off to see the LED light.

    At any rate, my problem was that the combustion water drain trap was not primed, so water built up in the furnace (high efficiency furnaces have drain lines).
     
  8. Nomad

    Nomad Well-Known Member Supporter

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    Yes, I found the lights, but not being too bright I had the cover off at the time. When the cover is off a switch shuts everything down. I would hold in the switch and watch the lights. Every time I let go and pushed it again I would get a different series of light patterns. I guess maybe I should go look for the little window and let the cover alone. Sometimes I'm too stupid to be alllowed to live. I'll be back after I look through the little hole.

    Nomad
     
  9. mtman

    mtman Well-Known Member

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    dont be so hard on yourself
     
  10. Nomad

    Nomad Well-Known Member Supporter

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    Okay...breathing hard from run up the steps...the lights indicate:
    Primary/Secondary switch open.

    I have a feeling that's something I can't fix. Maybe if it could be explained in English exactly what it means.

    I forgot to mention that even though I don't have a manual, some thoughtful person has a chart stuck on the cover by the hole. If I wasn't running around like a headless chicken I would have noticed both of those things.


    Nomad
     
  11. Nomad

    Nomad Well-Known Member Supporter

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    Now gasping like a fish out of water from another run down and back. It said

    Primary/Secondary Limit Switch open


    I forgot the "Limit" part in my last post. In the minutes it took me to come up and post and go back down it had refired and that was with the house temp at 61. Maybe there's some hope yet.

    Maybe either the switch is going bad or it's receiving bad information from somewhere. Oops, it just shut off again. It only ran a few minutes and didn't raise the temp at all.

    Very frustrating. The heating folks do give free estimates. Maybe I could have them look and give me an estimate while telling me the problem. Then I could decide whether it's something I could fix or not before parting with any cash.

    Nomad
     
  12. seanpecor

    seanpecor Member

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    It sounds like it's overheating and the unit is shutting itself down so the furnace doesn't rapidly disassemble itself, possibly taking part of your house with it!

    I had a similar problem recently, although the house would be brought up to proper temperature and then not come back on again. It was a bad control board - the previous owners had let the condensor trap get plugged, and water had been dripping down the front of the unit. I fixed this as soon almost immediately, several months before the failure, but the damage was done. The water had corroded the circuit board and doomed it for eventual failure.

    My suggestion is not to wait on this repair, depending on what sort of climate you're in. Even at 60F inside, certain construction materials in your floor etc., can be cooled to the point where contraction begins to shift things out of alignment. For example, the house we're buying now, half of one room behind the garage is on a slab, the other half is not, and the vacant home was set to 50F. Well, it got real cold, and the subfloor shrunk unevenly and pushed up some Parquet flooring. Yay, fun!

    Sean.
     
  13. Nomad

    Nomad Well-Known Member Supporter

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    I decided to call about a free estimate. I called 4 places. The first one said they charge $60 to come look and tell me the problem. The next two only give free estimates on new furnaces not repairs. The fourth one is having the service person call me. Hope it's soon...the sun is going down and it's getting a wee bit frosty in here.


    Nomad

    Just saw the link. I'm going down to check the filter. I change them pretty often but who knows? Thanks.
     
  14. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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  15. Nomad

    Nomad Well-Known Member Supporter

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    I changed the filter. I bought some higher priced filters a few months ago and they really fill up. It was clogged. I put one of the old type back in, so I'll see what happens if it ever comes on again. Course I had to cut myself and am now sporting a fine Squidward bandaid. Darn kids used up all the regular ones. Guess I'll go eat and watch the news. Maybe it will be magically fixed by the filter change. Stranger things have happened.

    Nomad
     
  16. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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    ...and lastly, here is what a Service Manual says for Coleman Brand furnaces:

    4 FLASH: This indicates that a primary or auxiliary limit switch has
    opened its normally closed contacts. With this fault code the control will
    operate the supply air blower and inducer.

    CAUSE: This condition may be caused by: dirty filter, improperly
    sized duct system, incorrect blower speed setting, incorrect firing
    rate or faulty blower motor.
     
  17. Annie in MN

    Annie in MN Well-Known Member

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    You may also want to check your cold air returns to make sure they aren't blocked. Have you rearranged any furniture recently, or shut off rooms, which may have changed the airflow in your home?

    I had a similar situation, and in my case the furnace was new. I had the furnace guy out, and we went through all of the rooms checking the air returns. He determined that my ductwork probably wasn't sufficient for the new furnace. The solution to my problem was easy. We discovered that if we left the little cover that goes over the hole where the filter goes in off, it operated fine. As soon as we put that cover on, the furnace overheated immediately and shut down. He had a little digital thermometer thingy hooked up, and we could see the internal furnace temperature jump as soon as he put the cover on.

    Hope you stay warm!
     
  18. Nomad

    Nomad Well-Known Member Supporter

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    HOUSTON, WE HAVE LIFT-OFF!! :dance:

    It has been running for just about an hour and has rasied the house temp to 64. I believe it was the filter. I'll never use that kind again. Sure glad I didn't have to lay out some serious money for this. Thank you very much to everyone who gave helpful tips. A special thanks to Cabin Fever for going beyond the call to provide invaluable links.

    Nomad

    PS Just noticed the last post. I am a stickler for keeping the cold air returns clear, so at least I know that wasn't the problem. But thanks for the input.
     
  19. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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