When the hobby spills into real life...

Big Monk

Well-known member
I have a pretty old furnace (~ 20 years old) that utilizes the Honeywell "Smart" Gas Valve system. Essentially it moves the normal ignition and firing sequence circuit board onboard with a gas solenoid.

When we bought the house the valve was replaced by the previous owner. They have a bit of a dodgy track record and when our furnace guy was here early last week, he had trouble getting the furnace to fire.

Fast forward to yesterday and the overnight lows were going into the 40s here in Central NY. We let it ride overnight because it had been reasonably warm during the day. In the morning we kicked it on to take the chill off. Furnace wouldn't kick on. Went through an abnormal ignition and firing sequence and then the pilot went out, which I believe is a normal safety mechanism if the firing sequence is unsuccessful.

The valve head contains the circuit board and solenoid. Power, common and fan control come in on a 4 prong Molex-type clip connector and flame sensor, etc. come in on a 3 prong connector.

I found that if the abnormal firing started, I could wiggle the power connector and get the furnace to fire. That tells me that there is either:

a.) Bad contact on the connector pins;
b.) Cold/cracked solder joint on the circuit board.

I'm trying to save myself $730 worth of parts and labor.
 

Blooze

Active member
Could be.

I had an intermittent garage door opener that I lived with for months. Finally took the control board out and there were a couple of cracked solder joints. 20 seconds with an iron and I saved myself the cost of a new opener.
 

carlinb17

Well-known member
I've been lucky enough to repair a bunch of stuff around my house with knowledge gained from building amps and pedals. I fixed my dryer because I was able to figure out that a thermal fuse went bad. I had to take the dam thing completely apart to get to the fuse but at least I didn't pay someone. More recently I fixed my furnace, a 7 dollar relay went bad. Way cheaper than having someone come out and look at it only to tell me it was a 7 dollar part. I'm sure many people on here have similar stories.
 

Dan0h

Well-known member
This is the “Thermistor” from my gas dryer. It’s a resistor that drops resistant value as it heats up. Room temp is normally 11k and as it drops down it kills the gas in the dryer to control temp. Long story short, dryer stoped drying. I used my DMM and found Mr. thermistor was 7k at room temp (worn out). Put a new one in for $8 and saved the dryer.
DIYer’s unite. Pedal Power!
85A561E7-15F0-411F-A774-13FB490CE58F.jpeg
 

benny_profane

Well-known member
I recently fixed a food dehydrator. The unit is 'non-serviceable' and replacement is the only support option. Took it apart, grounded the heating coil where it had broken, and it's good to go again.
 

Big Monk

Well-known member
I recently fixed a food dehydrator. The unit is 'non-serviceable' and replacement is the only support option. Took it apart, grounded the heating coil, and it's good to go again.

If things have electricity going through them, I'll attempt to fix them.
 

carlinb17

Well-known member
This is the “Thermistor” from my gas dryer. It’s a resistor that drops resistant value as it heats up. Room temp is normally 11k and as it drops down it kills the gas in the dryer to control temp. Long story short, dryer stoped drying. I used my DMM and found Mr. thermistor was 7k at room temp (worn out). Put a new one in for $8 and saved the dryer.
DIYer’s unite. Pedal Power!
View attachment 17244
Imagine if you put some NOS 1N34As in...
 

Big Monk

Well-known member
I'm much less eager to do so with mains voltages, but anything else I'll take apart and try to fix.

My line in the sand is always EXISTING mains electrical devices. When we moved in or house, I replaced every single receptacle, light switch and light fixture.

I'll add things that tap off of existing feeds but do not get into running new stuff to the breaker box. I did break this line once when we sold our old house when I tapped in a ground from the gas line to the neutral bar for our flexible gas pipe on our gas insert in our fireplace.
 

Barry

Well-known member
I have a pretty old furnace (~ 20 years old) that utilizes the Honeywell "Smart" Gas Valve system. Essentially it moves the normal ignition and firing sequence circuit board onboard with a gas solenoid.

When we bought the house the valve was replaced by the previous owner. They have a bit of a dodgy track recfor faing at the molex connectorord and when our furnace guy was here early last week, he had trouble getting the furnace to fire.

Fast forward to yesterday and the overnight lows were going into the 40s here in Central NY. We let it ride overnight because it had been reasonably warm during the day. In the morning we kicked it on to take the chill off. Furnace wouldn't kick on. Went through an abnormal ignition and firing sequence and then the pilot went out, which I believe is a normal safety mechanism if the firing sequence is unsuccessful.

The valve head contains the circuit board and solenoid. Power, common and fan control come in on a 4 prong Molex-type clip connector and flame sensor, etc. come in on a 3 prong connector.

I found that if the abnormal firing started, I could wiggle the power connector and get the furnace to fire. That tells me that there is either:

a.) Bad contact on the connector pins;
b.) Cold/cracked solder joint on the circuit board.

I'm trying to save myself $730 worth of parts and labor.
Yes the boards are notorius for that, I've stuffed a business card in them to put pressure and make contact, never tried to repair one, but I'd put money on cracked traces, I don't think cold soder joints would be as widespread, but I guess possible, and we refer to them as stupid valves in the industry here
 

Popnfreshbass

Well-known member
Those smart valves are the dumbest thing out there. Constant failures. And pricey as hell. And since the ignition circuit board and gas valve are one part, the whole damn things gotta be ordered and replaced.

Not to mention the ignitor and flame sensor are unique to them as well, so better stock a few of those weirdos on your truck just in case. Oh, and it’s also another 2 in 1 part.


Hate those damn things.
 

HamishR

Well-known member
I replaced the battery in a friend's Landrover keyfob remote. Landrover don't want you to do this - they would refer you spent a few hundred dollars buying a new one and getting them to program it for you. We saved quite a lot on that one.
 

Feral Feline

Well-known member
GEeZe Landrover... such money-grubbing jerkulatage.

I easily replaced the batteries in both our Toyota key-fob remotes (at different times), and that was before I found the spot in the owner's manual that tells you how to do it.
Fixing the seat latch was not covered in the manual, however, a rear seat got stuck upright. Nonetheless I got it apart and got the seat down to haul some large pieces — Toyota's Ractus has awesome interior space btw, only rivalled by the Honda Jazz/Fit; interestingly, the Honda is smaller overall, but still beats the Ractus for interior luggage space.


More in line with the OP, I have to get the furnace's humidifier going again —

1) Decalcify it with vinegar/water solution and some scrubbing — install new pad.
2) test the transformer that knocks 120v down to 24v
3) test the solenoid valve, replace if necessary (likely judging the amount of calcium and other mineral deposits.
4) test the motor (it's a rotating drum style of humidifier)
5) test all the H2O lines.
Did I miss anything?


Not sure I'd want to mess with anything gas-related (it's a gas furnace), especially gas and things that go spark (GAS is one thing I don't mind, but gas is another) — The humidifier I think I can handle, and it may require an entirely new unit (would be the third for the house, built '76).


Our pedal hobby, and building/repairing a few amps (thanks amp-sifu!), and especially the support from fellow pedal-builders and threads like this one has given me the confidence to tackle the humidifier.
Thank you all.
 
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