Hydro Flame 7916 runs but no heat

Discussion in 'Heating / Cooling Systems' started by triskal, Apr 18, 2015.

  1. triskal

    triskal New Member

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    Last year I bought a 1990 Jayco Jayking that has a Hydro Flame (pre-Atwood apparently) 7916D with direct spark ignition - no pilot. I am getting no heat. It turns on/off correctly with the thermostat and the fan runs but I am getting nothing else - no clicking sounds and no heat. I have gas to both the internal and external stove locations. The heater does not appear to have a shut off valve on the gas line. I have found posts with slightly different symptoms but not exactly the same but from those I am guessing the sail switch at this point otherwise I would think that I would hear it trying to ignite or making some noise. Does that sound reasonable?

    I am no electrician so despite a good wiring diagram in the manual I am not sure I know to read it. But the parts diagram does show where the sail switch is. I am not 100% sure I can get to it however. I can't figure out how to remove the heater. I removed the screws holding it into the cabinet but it doesn't budge when I try to slide it out. The gas line is still connected but I would expect at last some movement even with that connected. I have a couple pictures of behind the front panel but I realize now they probably won't help much. Every time I want to work on it I have to go to the storage garage, roll it out a little bit and pop it up so I can get inside. So if I need better pics I can do that tomorrow. Any help would be appreciated.

    Here are the pics
    https://onedrive.live.com/redir?resid=299fc822d4dfee44!9214&authkey=!AA79VgxATlZhj_0&ithint=folder%2cjpg
     
  2. triskal

    triskal New Member

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    Well, I don't know if anyone is watching this thread but I have made some progress. I at least got the unit out of the camper and was able to get to the sail switch. I checked it with a multi-meter and it shows no continuity when open and continuity when closed. So I think that means the sail switch is good. It also seems to move pretty freely so I don't think it was hung up.

    So now it is back to that wiring diagram. At least I have it on a work bench now and can more easily take it apart.
     
  3. Davylee

    Davylee Camping = Life is Good

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    Not sure how much help i can be, had a similar problem with a different type unit. the problem ended up being a dead moth that was circulated by the fan and would keep the ignition from happening. If the sail switch functions, that doesnt mean it is all good, the cage/wheel has to turn fast enough to close the contact on the switch. With a DSi you should also have a circuit board which takes the sail switch signal and then starts the ignition process as well as the timing process if it doesnt light. I would search really good on your model there should be something out there but you are on the right track. You need gas, the sail switch has to give the signal there is enough air and the ignition circuit has to work (sometimes there is not enough battery power, but I'm assuming you are plugged in and trying to do this. Good luck
     
  4. Davylee

    Davylee Camping = Life is Good

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  5. triskal

    triskal New Member

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    Yes I am trying this while plugged in. And the manual you linked to is exactly what I have in hand - so, good find, but I already have that.

    I took out the limit switch and it checks for continuity. I found an Atwood troubleshooting doc and it tells me that the solenoid valve coil should have resistance of between 30-50 ohms. I think I can figure out how to test that and will do so next.
     
  6. efehser

    efehser New Member

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    1990 has to be one of the first years with the auto ignition, my 89 has a pilot model. I wouldn't be surprised if the circuit board took a dump, even if the other components are all good.
     
  7. triskal

    triskal New Member

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    Well the solenoid valve coils check out at exactly 40 ohms each. The igniter looks like, well, an igniter. Maybe I got lucky and just be jostling everything around and pulling and reseating connectors it will magically work. Here's hoping!

    But efehser you might be right. It is looking like the control board. I will hook it up and test electricity at a few places to see what I get. I was hoping to fix it on the cheap.

    thanks both of you for the help. We will see tomorrow.
     
  8. Nandy

    Nandy Active Member

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    Sorry no one got to you earlier. Efehser is probably correct but these boards are between $60 to $80 do you want to be sure before you order it.

    Other than the sail switch the board is looking for the limiter to be in a close position. The limiter will open up if the furnace heater exchange unit gets too hot. With the system powered off undo the connectors to the limiter and with the multimeter set for resistance/continuity it should show a short.

    To test your sail switch is best to test it while the system is working. If you set your voltmeter to dc voltage (set it for a range larger than 20 volts if it is not an auto range model) you will see some voltage across the contacts of the sail switch (you might have to move the connectors a little bit to get some metal expose to test), probably somewhere in the 12 vdc once you power the system. It will take about 15 seconds from "power on" to when the motor starts to turn. Once the motor starts to turn the sail switch will close and you will see no voltage across the contacts. Another thing you can do to try to isolate the problem out of the switch is to actuate the switch manually.

    After about 3 minutes (i cant recall the time period exactly) if the board senses the sail switch and the limiter to be in the proper state then the board will energize the gas valves, you will hear a click, then it will send a high voltage charge to the igniter to create a spark. The igniter assembly has an anode that senses the flame and tells the board to keep the gas valves open until the call for heat from the thermostat ends... If you can see the board you will see a rather large cylinder looking element with a thick cable on the top. If you follow that cable it will led to the ignitor. Next to that large cylinder you will see a light bulb, that light bulb will ligth up at the same time the board is sending the high voltage to the ignitor.

    These furnace are very simple, if all the sail switch is closing, the limiter is close and you dont hear the valves click nor see the spark on the ignitor you are very likely needing a board.

    Good luck!
     
  9. triskal

    triskal New Member

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    Well I did test the sail switch and limit switch while it was on my workbench. the sail switch showed open when not pressed and closed when it was pressed. The limit switch showed as closed (obviously I can't easily test it the other way).

    The sail switch is in a place that is not accessible when assembled let alone while running. I can see if I can check the wires from the sail switch where the come to the front of the unit. Otherwise I am leaning toward the control board. I would love to know where to find one for $60-80. I found this one for $128 which according to a local RV store, is the closest replacement part - http://www.americanrvcompany.com/Atwood-31501-Ignition-Board-Retrofit-Kit-With-Fan-Control-Universal-DSI-Furnace-Board-Furnace-Parts-Camper-Trailer-RV

    But I will try to reinstall again this evening and see if I get lucky and find it works!
     
  10. jrkrolikowski

    jrkrolikowski New Member

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    I put a lot of $ into my hydroflame last year and the circuit board was the issue. I chased around symptoms for a long time before I decided just to spend the money on the board. It was worth it though because the furnace works great now.
     
  11. Nandy

    Nandy Active Member

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  12. R00

    R00 Active Member

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    I'm in a different situation. I want to convert from a manual pilot to a digital ignitor on an HF8012
     
  13. efehser

    efehser New Member

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    I believe this would require a whole new gas valve. At the price for that plus electronics it would be easier to track down a used unit on CL or FleaBay.
     
  14. triskal

    triskal New Member

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    Well surprise, surprise, nothing changed when I reinstalled. After correcting a lose wire, it operated exactly the same as before. I think I am going to have to get a new control board. I will check out the links you gave and try to find the best deal. I will report back when it is installed if it fixed the problem. Thanks all for the help.

    ~Tony
     
  15. 8lugnutz

    8lugnutz New Member

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    Resurrecting an old thread.....were you ever able to fix this? I ran into the same issue this past weekend.
     
    Last edited: Sep 28, 2018
  16. 8lugnutz

    8lugnutz New Member

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    Update: Mine worked, just needed to cycle a couple more times go get LP from the regulator to the heater!
     

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