any HVAC guys here?
 

damm furnace wont keep up.
its 0° outside and 60° inside.
furnace will run for 8 minutes , shut off for 20 seconds , then fire back up for another 8 minutes.
why does it keep shutting itself off?

HELP!!!!! BURRRRRRrrrrrrrr

winter sucks:(

Is it a oil furnace or gas? If it is oil it may not be seeing the flame with the photographic eye. Also is your tank inside or outside? If outside you may be having a issue with the oil gelling up. If it is gas you could have a problem with the control box.

its a gas furnace. 15+ years old. seams like i have to get the furnace guy out every 2 years to replace something. hell , everything should be replaced by now.
why buy a new one :crazy:

Is it a heat pump?

Duel fuel?

Are you sure it's lighting?

Is the circulating fan & the inducer fan running?

If its a heat pump is the outside unit running and sounding OK?

Who makes it?

What brand thermostat do you have?

Bad flame or fan sensor, could be a overheat switch too. Call the furnace guy. If it has a control board (electronic) It could be bad too. I just had the same thing on mine a week ago 0 outside and the best it could do was 66. It was a heat switch that was signalling too soon. replaced it and it has worked fine since.

not a heat pump.
not duel fuel.
it lights and runs fine .............i think.
i hear it fire up , a few seconds later the fan kicks on and blows warm air. it just wont run longer then 8 minutes or so.
dont know what brand any of it is and im at work now so i cant look.
had to come here to get warm :o

Well it sounds to like it has a cuircut or sensor problem, but it's hard to tell without being there. It might just be a bad thermostat.

This may sound stupid but have you changed your filter recently? You may have a clogged up filter and it is not allowing enough air to go over your exchanger and causing it to over heat (that would take about 10-15 min or so to happen. When the thing shuts off does the fan keep running or does that shut off also?

Jon

First thing I would do is eliminate the thermostat from the circuit in the event you have a bad thermostat. If you JUMPER "R" and "W" together, you are telling to furnace to run continuously. If the furnace runs, and runs, and runs, without any hiccups, then you have either a bad t-stat or t-stat wiring. If it continues to act up when jumpered, call a heating guy ;)

hmmmmmm:o

when i get off work in going to vacuum out the "A" coil and see if that helps.
oh , and replace the filter too.

Could the thermostat be too close to a supply vent??? The brainiac before me put the thermostat about 5' away from a vent in my house......the thermostat saw it was warm and shut the furnace off.....the rest of the house was frozen.... :mad: I moved it and no problems now.

no , dont have that problem. im hoping its just a clogged up "A" coil. if it doesnt warm up after i clean all the fuzz out ill call the "proper guy".
dont want to blow up the house :eek:

Check the fan switch[ It may not be heating up enough to get rid of heat in the chamber, When chamber cools down, furnace will fire up again. Also check for blocked flu & or flu pipe clogged. Most furn. have a limit switch & again when it cools down ,. the furn. fires for a few minutes. If you need any more info. call Dave at 203-380-2331

well i took the furnace apart enough to get to the "A" coil. one side on the inside of the A shape was completely covered with fuzz/dust. scraped it off the best i could. very hard to reach.
also changed the filter.
we'll see ..............

winter sucks!

Shop vac it out.

It's amazing what a $2 filter will fix!:D :D :D




Did that do it?

did the shop vac thing also.

dont think it fixed it :confused:

something else i noticed.
sat next to one of the registers and noticed after the burner shuts off the fan keeps running until cold air is coming out , then shuts off again. few seconds later it repeats the same cycle.
make any sense?
dammit:mad:

Jump the t-stat like hp500efi said.

how:confused:

Take it off the wall so you can get to the wires behind it. you will need a small flat head .

:crazy:

ok doctor lapse.
what next?
umm wait a sec .......... what does lapse of reason imply anyway :D

Take a wire and hold it on "RC" and hold the other end on the "W" :)

RC has the red wire attached to it (upper right) W has the grayish wire attached to it (lower right).

Be careful not to jiggle the wires you are holding around and accidently touch one of the other terminals otherwise you might short out the transformer and then have no 24v.

Those wires you are messing with are 24v so no big deal. If you have some small alligator clips, they work best...otherwise open the screw and attach the wire behind the screw.

Did you jump the R and W wires yet ?

Oh ya, I would prefer you go by the furnace and find the same 24v wires attached to the furnace because that way you are eliminating the WIRING and the T-STAT. By jumpering the wires at the T-stat, you could still have the same problem because you might have a problem with the wiring in the wall...

Find the furnace, turn off the line voltage (switch or circuit breaker), take bottom blower door off, locate the low voltage thermostat wiring connections. Find the R and W, jumper wire them together, install door back on, turn on line voltage power supply and stand back ;)...LOL see what happens.

If he kills himself are we responsible?:D :D

Unless he sticks his fingers in the blower or wall socket, I think we are OK. . . LMAO

holy chit that hurt:eek: :eek:
j/k

got a pm from Bossman with his phone number.
he walked me thru several possible causes and how to fix/diagnose them.

told me how to jump the stat from inside the furnace.
how to gently clean the sensor that the flame flows by.
and ............ what is probably the culprit. a clogged coil.
had trouble cooling the house last summer also.
soooooo , back down to the freezer called a basement with new found knowledge.

thankyou so much Rich (Bossman) and everyone else too!
OSO is a great place:)

Well, get it fixed and let us know what was wrong.

I am going home :)

Mine did that it kept bumping the limit switch. Then shutting off. Good luck

thermostat seams to be ok after jumping the circuit.
cleaned the sensor with steel wool.
took the "A" coil all the way out this time and completely cleaned it with a brush/shop vac/air compressor.
got my fingers crossed!!!!!

Make sure the flu is not clogged!!!!, snow up against it will shut off the furnace!! Limit switches will also go on & off.

no improvement:( :confused:
60° again this morning ning ning ning.

Your limit switch could be bad. I had to replace mine If the switch senses that there is to much temperature in the chamber it will shut down the heater like you are describing. Mine did it because the genious put in a heater that was to large and then died on me. I learned a lot about the electronics in them as the electronic parts went bad from a poor install. A limit swicth will get worse the more it gets tripped. You can buy this at your local heating and cooling supply house and it should not be to difficult to find on your unit. It is the same as a circuit breaker a breaker will get weak and trip easier the more it trips. Sorry you are freezing. I don't think our heaters have shut off all night.
Jeff will be able to help you more than me I just had to repair my own because it got to expenssive to have some one come out all of the time. I could not afford to replace the units all over again.

loto,

Time for me the exact time it RUNS as well as the exact time it is OFF. Wait for it to trip and time again, and finally once more. Get three accurate TIMES recorded and let me know exactly how many (minutes or seconds) for each.

Also, do you have a wiring diagram for that furnace? usually on the back of one of the doors. Can you snap a picture and post it?

If your furnace is running 8 minutes, that is usually a pretty good amount of run time. Usually a limit trips in a few minutes and then is off for the same amount of time until it cools.

Keep me posted, I am in the office right now and maybe can help.

Jeff

Also, as long as you are freezing your ass off, see if you can locate a model number or make of the furnace.

Trane
Lennox
Heil
Bryant
etc

Is it vented in PVC pipe? or vented in metal stove pipe?

Hell, just take a picture of it and post :eureka:

HP500,I was thinking the same thing but 15 years old I don't believe it would be a 90+, I've had problems with those when there is no pitch in the exaust and it ices up. Does exactly the same thing, short run cycle off a few and short run again

man o man its toasty in here:D :D :D

Bossman (Rich) walked me thru the entire trouble shooting process over a half dozen phone calls.
i cant thankyou enough Rich!!!!!!!

the problem all stemmed from a extremely dirty coil.
because it was so dirty , the furnace was getting hot very quickly and shutting off.
dummy me made the problem worse by closing off vents in parts of the house in order to try and heat the areas i was using. that created back presure which made the furnace overheat even more. another problem was the fan wasnt pushing enough air so Rich talked me thru switching some wires around to get a higher speed fan.
he also had me wire a jumper in so i get the high speed fan in winter and summer. the end result should be a less expensive utility bill , winter and summer!!!!! more gas money for the boat;)

ive already told Rich on the phone but ill do it here also.
if you ever want to take a trip down to LOTO you have a place to stay and the drinks are on me.

thankyou to everyone else who replied to the thread also!

now , back to your regularly scheduled program.
Apaches are better:D

loto, glad to hear you got it fixed.

Now get some of that beer out of the fridge and enjoy :)

I saw on your termostat that the fan was on auto. I would just leave it on. It helps prevent hot or cold spots in your house and keeps the air cleaner. You will need to change the filter every 30 days, unless you buy the real big high dollar ones.