Hydroflame Furnace

[3Lakes_Steve]

I have a hydroflame 8900 II furnace in my RV, which will not ignite. Does anyone know a way to verify the gas valve is opening? The led on the circuit board indicates power to the valve, which I verified with a meter, and the coils on the valve tested OK as well.

I can hear the igniter clicking, but don't hear anything from the valve itself. Propane tank is about 1/3 full, and the heater worked fine before. If the valve is opening, but failing to ignite, I think you would get some faint smell of propane from the exhaust port?

I pulled the burner assembly, the electrodes look good, and have about the 1/8" gap recommended.

Looking for ideas before I buy a new valve

Thanks
Steve

[3Lakes_Steve]

Board is brand new dinosaur. Thought that was my problem. Some where in the past, the lead at the board (red) to the Gas valve has a splice in it that goes to the unknown switch or device, and returns to the gas valve. The power from the board is a steady 12.4V, but by the time it gets to the gas valve via the device, voltage becomes erratic, jumping all over between 2-3-5-12V

[enblethen]

The on/off switch shuts off the 12 volts DC to furnace so nothing would be working.
Are you using a good ground for the meter at the same location the valve is getting ground?
Have you cleaned the multi-wire connection on the circuit board?
Look closely at the circuit board, then look closely at the one for the water heater. They could be exactly the same. If they are switch them out to eliminate the board as problem. Your refer if it is a Norcold could be the same as well.

[3Lakes_Steve]

Well, I pulled the burner assy out again, and the orifice seems to be clear. Also applied 12V to gas valve, and it appears to operating as it should.

I also verified the electrode is working properly, yet still not firing. Yesterday, I checked the lead to the valve with a multi meter, and it appeared to send voltage, but the reading was erratic. Thought maybe the contact on the meter wasn't secure.

The sequence of operation says the sail and limit switched need to be working properly to sent power to the ignition board. I checked voltage at the board and it was 12.4V. The lead to the gas valve from the circuit board travels via some device I'm not sure what it is.
On some models an on/off switch is in this location, but not on the 8900-II. I cannot find any kind of switch anywhere, and as I said, the furnace worked fine before.

Any thoughts on the unknown device/switch? I'm thinking of by-passing it to see the results.

[John_Joey]

For some odd reason spiders love the smell of propane. They build little webs in the tubes prior to the orifice. You would think you would still smell the gas at the exhaust port, but it seems to get diverted away. :h

On edit:

Should have read "after" the orifice. This mostly happens on water heaters, but is worth checking regardless on you furnace. Running a steel brush over the burner, then blowing a little compressed air into the burner is good for it anyways. Helps knock the rust out of the holes.

[3Lakes_Steve]

Great idea on cleaning the orifice, I'll pull the burner out again and check. No unburned gas smell at all.

[John_Joey]

Easiest way for me is to have someone inside turn up the heat while I'm outside with my nose by the exhaust vent. You'll hear the sparker, then smell the gas. If you hear ignition jump back fast. :B

If you want to....I suppose, you could disconnect the sparker first and just smell for the gas. There is no mistaking it if the valve is opening when it should, you should smell the gas.

Also make sure you don't have air in the line first. Run the stove and your other gas appliances. If those aren't working then either air is in the line or the safety valve on the tank is shut and needs to be reset by turning off the propane, waiting about 5 minuets, then VERY SLOWLY open the valve.

I've worked on a few furnaces now, and also have helped others, and none of them ever had a gas valve go. The last one the orifice was plugged. Took a plastic toothpick and knocked out the debris, and it kicked right off. Hint, hint....

[MEXICOWANDERER]

Piezo ignitors can click like a Western Union office and not ignite squat. So verifying would be high on my list. I believe in hammer and chisel troubleshooting. Use a long-neck barbecue lighter and put the fire right to the outlet to see if anything gets excited. I have a made in Mexico stove with piezo burners that sounds like a battalion of maracas. Ignite anything? Shirley you jest.

Love the brand name of your heater. Herb Tarlick at work... 🙂

HYDRO-
combining form
Indicating or denoting water: hydrolysis, hydrodynamics
Indicating a hydroid: hydrozoan


An alien life-form listening in and reading earth buzzwords will never attack. They would be convinced we discovered and wield an alternative reality that would destroy them in seconds...

[3Lakes_Steve]

Both checked out between 30-50 as per spec

[enblethen]

There is two coils on the gas valve. You need to separate them and measure them individually. Readings should be the same.