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25 votes
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What is causing the pilot light to go out with a loud clunk?

Fairly common on modern pilot lights to have a thermocouple heated by the pilot flame and a valve controlled by the thermocouple (with a manual thing you have to push and hold when lighting the pilot, ...
Ecnerwal's user avatar
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12 votes

What is causing the pilot light to go out with a loud clunk?

If the thermocouple that is heated by pilot flame does not report pilot flame is on, the main gas valve will shut down. That is done for safety reason. So check and clean or replace the thermocouple.
Traveler's user avatar
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10 votes

Can an occasionally squealing draft inducer motor be repaired instead of replaced?

Intermittent squealing is common for "permanently lubricated" sleeve bearings that are reaching the end of life (whoops, not so permanent after all.) Such bearings are typically a sintered (...
Ecnerwal's user avatar
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8 votes
Accepted

Why won't my furnace filter go in?

The thin (1") slot is for a standard passive filter. The larger slot is for an electronic air cleaner. A much more complex and expensive beast. I have them in my furnace. They haven't really ...
manassehkatz-Moving 2 Codidact's user avatar
8 votes

What is causing the pilot light to go out with a loud clunk?

Try snuffing the pilot manually: blow on it directly, blow through a straw or tube, or use compressed air. (These suggestions are all intended to simulate wind drafting through the flue.) Supposing ...
Greg Hill's user avatar
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8 votes

Is there a way to run my furnace fan intermittently without heating the house more?

I don't think most (any?) of the "dumb" programmable thermostats allow what you want, but I know (because I have one) that the ecobee3 has a setting where you can ask it to run the fan X ...
Huesmann's user avatar
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7 votes

What is causing the pilot light to go out with a loud clunk?

It could be that the draught is pushing the flame away from the thermocouple, or chilling it. So the valve could trip while the flame is still there, and kills the pilot light itself.
Paul_Pedant's user avatar
7 votes

What is causing the pilot light to go out with a loud clunk?

It's puzzling that the clunk occurs instantaneously when the pilot goes out. A thermocouple usually takes a few seconds to cool off and close the valve with a click rather than a loud clunk. I think ...
MTA's user avatar
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7 votes
Accepted

Connecting C Wire to Old furnace

The other transformer terminal is C The transformer terminal with the black wire coming off of it (the top terminal in your picture) is where your C wire needs to connect at. We know this because in ...
ThreePhaseEel's user avatar
6 votes

How to measure gas usage by appliance

Stove usage will be peanuts. We had neighbours who had standard gas range (4 burners and oven) that they ran off a pair of 100 lb propane tanks. They would go weeks to months between tank trips. ...
Sherwood Botsford's user avatar
6 votes

Bryant furnace under water. Doesn't run now

Given that the trouble indication shows polarity reversal you might as well get a volt meter and find out. Yes polarity reversal is a real thing. Some furnace controls test for it because this ...
Greg Hill's user avatar
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6 votes

What's wrong with my furnace blower wiring (only works on AUTO)?

Temporarily connect G to R, if the fan starts the problem is not on the controller board. In that case find the other end of the red cable and connect the red and black wires, if the fan starts now ...
Jasen's user avatar
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6 votes

What kind of drain pipe appears to be clay?

It is fired clay. It has metal bands to hold it in place. You can try and take it out a piece at a time, starting from the top. However, if the "grout" between them is strong then you just ...
Rohit Gupta's user avatar
  • 6,508
5 votes

Can I place a cap on my furnace exhaust to keep rainwater out?

Sounds like more of a drain problem than anything. These condensing furnaces are designed to condense and drain if rain gets in the flue, it just flows through the unit to the drain. I almost think ...
Alan Lucio's user avatar
5 votes

What kind of drain pipe appears to be clay?

Just to clarify, you want to gain access to the interior of the pipe so that you can use it as a conduit for various other services, not remove the pipe and use the resulting void? Note that either ...
HABO's user avatar
  • 1,637
4 votes

What keeps rain out of a Vertical PVC Concentric Vent?

There is no rain cap with this type of vent termination. "Why not?" you may ask? The exhaust piping from a condensing appliance is designed to carry liquid. The appliance category is named &...
Greg Hill's user avatar
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4 votes
Accepted

Connecting C-wire to 1989 Forced Air Electric Heater

I have colored the "C" wire cyan, also a link wire and an unused terminal I suggest running a wire from the unused C terminal through to an unused space on the the barrier junction block. ...
Jasen's user avatar
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3 votes

Should I replace an old furnace with a mini split unit?

I have doubts about the likely heating performance of a $1000 DIY minisplit, but you haven't specified which. Some crap out at +10°F, some work to -15 or even lower now. Really bad ones don't work ...
Ecnerwal's user avatar
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3 votes
Accepted

Furnace wiring diagram: HUM 120 VAC or 24 VAC can be used

“dry contact terminals” mean a connection that gets closed/opened (usually by a relay). No power is provided by the contacts - it’s just a switch. The power comes from the device being controlled. It’...
nobody's user avatar
  • 6,735
3 votes
Accepted

Should water be dripping from my furnace condensate line onto the basement floor?

You have a new AC system. It's making cold air. It also is making the condensation it produces cold, which in turn creates more condensation in the drip line itself. Simple fix. Add a series of 90 ...
RMDman's user avatar
  • 31k
3 votes
Accepted

Google Nest Causes Furnace to Need Reset

The solution that seems to be working so far is adding a 1kOhm 5W resistor between W and T, that being the call for heat voltage. After contacting Johnson Controls, I was redirected to an engineer at ...
Correllion115's user avatar
3 votes

How to measure gas usage by appliance

Assuming you live in the house year-round and have well-defined seasons (e.g., at least 3 months where it would be very rare to use the furnace) then you can figure it out a rough approximation from ...
manassehkatz-Moving 2 Codidact's user avatar
3 votes

Can heat pump completely replace natural gas furnace

Depends on how old and cruddy the heat pump design they're offering is. Technology Connections covers this in their heat pump series. The old-guard American makers like Trane and Lennox are not happy ...
Harper - Reinstate Monica's user avatar
3 votes

Trying to replace old thermostat

Your wires, though ancient, look like the standard furnace wire colors. Connect red and white together to turn on heat; or take 24V from red and blue to power a thermostat. You should be able to check ...
Glenn Willen's user avatar
3 votes
Accepted

How to prevent furnace fresh air intake pipe from disconnecting

Assuming that the pipe seats deeply enough in the collar you can secure it with three screws driven in 120° apart through the collar into the pipe. Running the furnace without the pipe connected ...
HABO's user avatar
  • 1,637
3 votes
Accepted

Replacing blower on furnace and it’s filled with water

I had a very similar problem a few weeks ago—furnace wouldn't run. There was water sloshing in the collector box (some kind of air manifold). Draining water out of the box through one of the hoses (...
Huesmann's user avatar
  • 3,680
3 votes

Connecting C-wire to 1989 Forced Air Electric Heater

Look closer. You have 24 Volt Transformer clearly labeled. On one side of it there is the C-wire and 24 volt coming out Two yellow wires. One goes to the R on the thermostat and other relays, the ...
Traveler's user avatar
  • 17.7k
2 votes

Is it safe to replace a Furnace pressure switch with a different one?

I know this is an older post: As a Lennox dealer for 40 years, I've installed many of the same EL19 models. The .90 pressure switch is no longer used in this model furnace as a replacement. Lennox ...
Dennis Treacy's user avatar
2 votes

Can a thermostats C-wire be connected to the furnaces R-terminal without issues?

I think this is a bad idea. Generally, as I understand it (I'm a physicist and not an HVAC specialist or electrician) the C is a common return that allows "smart" thermostats (like Nest or ...
PhyDav's user avatar
  • 21
2 votes

Should I run my furnace fan constantly to distribute heat and moisture?

If the ducts are in a cold enviroment such as attic or crawl space, having the fan on all the time will circulate cold air throughout the homes interior, causing the heating system to cycle more often....
RAK's user avatar
  • 21

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