House heat went out last night.

[Spikes]

I have a strange addiction. I have an insatiable drive to make things last way beyond their reasonable lifespan.
When I bought my current house 16 years ago, the inspector made a point of telling me the Rheem package unit (Mfg 04/2001) would need to be replaced within the next year. I've replaced the heat exchanger, AC condensor fan, exhaust ventilator fan, transformer, numerous contactors and capacitors... Still going.

Usually I have to clean the burners out once when switching to heat mode, this season the heat fired right up and has been running fine for a couple of months.
Yesterday evening it stopped heating. We noticed right before my bedtime, so I only spent a short while on it before setting up some space heaters and resting up for a week of 12 hour shifts. Call for heat is working, exhaust fan is working, direct spark igniter is working, seems there's no gas from the valve (gas is on). I'll double check that with a long lighter when I get back to it, but I'm not hearing a click from the valve.

My plan is to measure for 24 VAC at the gas valve while the igniter is on. If there's power, I'll replace the gas valve (I tried the usual rapping with a screwdriver handle to free the plunger, no go). If there's no power, I'll have to pull the board and hope I can repair it again - way past sourcing a replacement, so I'm hoping it's either a relay or gas valve. The flame sensor goes to the main board, rather than the gas valve. Any other things to check?

I'm fully prepared for the negative comments about safety, efficiency, etc. This unit is still pretty efficient in our relatively airtight house and doesn't cost much to operate. Once the AC side loses its charge or the compressor dies, I'll replace the package - although I'd much prefer to install mini-splits in each room. Love those things.

 

[Bert_]

My furnace is from the 90's so I'm right there with you. I've worked on the stuff for a few years and I'd actually rather have an 80% in my house, vs a condensing furnace.

Once you understand the basic operation they are usually simple to troubleshoot.

Is it direct ignition or intermittent pilot? The pilot orifice can plug. Generally you can hear the gas flow when the valve opens. Checking for power at the valve is the right test.

 

[Spikes]

Is it direct ignition or intermittent pilot? The pilot orifice can plug. Generally you can hear the gas flow when the valve opens. Checking for power at the valve is the right test.

It's direct spark. The spark seems strong and sounds normal.

 

[462867aa]

You can still get a board of needed. Haven't had any parts unavailability yet with my 2002 ruud.

 

[CoogarXR]

Nothing wrong with keeping things running. Isn't that the spirit of this site?

Hell, the house I just sold still had the furnace from 1971. I replaced about everything in it over the years, but it still ran great.

 

[PoorUB]

I'm fully prepared for the negative comments about safety, efficiency, etc.

Nothing more efficient than a unit that is still running!

I may be in a minority, but if the unit is running fine I generally see no need to replace it. It rarely pays back enough in savings to offset the cost of a new unit. Then the new one is more complicated and more money to repair.

Now if the l unit has failed beyond a reasonable repair, then buy a higher efficiency unit, but even that can get to the point of no return.

 

[fitter30]

Its a spark igniter and not hot surface? Hot surface needs a certain amperage to open the valve even if it glows red can be bad. Pull it take it to a appliance parts house see it they can match it. Might have to splice the old plug on or wirenut.

 

[finn]

My unqualified guess is a bad flame detector. The unit locks out the gas valve if it fails to ignite. There should be a manual reset, but it may shut down again.