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  1. #1
    Join Date
    Nov 2018
    Posts
    1
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    Everything works, except the burners

    90% of the time, everything works. For days, it will work like a charm. Then, it does this:

    Thermostat calls for heat, exhaust blower starts, ignitor glows, pilot lights... But no main burners. Circulation blower comes on and blows cool air constantly (since thermo is still calling for heat) until I shut it off at the thermo or main switch. I have to wait 20-30 minutes to turn it back on or it will still do the same thing. After waiting long enough, everything goes back to normal.

    I have had two techs come out. One went away scratching his head, told me to call another tech that knows the brand. The second tech replaced in order: pressure switch, high limit switch, rolloff switch, and ignitor/flame sensor (which is every switch in the works, I believe). All to no effect. He suggested a new gas valve or fan control board, but I was already in it for more money than I was able to spend. Also, I don't think the fan control does anything to start the main burners.

    I replaced the thermostat, just in case and also because I wanted a "Smart" one.

    I want to call out another tech but I thought I'd check here for ideas in case the next guy is stymied or wants to swap the gas valve for no other reason than it's the only thing left.

    Please help!?

    Equipment list:
    Tempstar SP80 made by Inter-City Products
    Fan-assisted 80% efficiency
    MODEL# NUG5075BFB2
    Honeywell SV9051M gas valve
    Honeywell ST9120B fan timer

    Air conditioner connected, works perfectly.

  2. #2
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    9,775
    Post Likes
    Quote Originally Posted by siobhter View Post
    The second tech replaced in order: pressure switch, high limit switch, rolloff switch, and ignitor/flame sensor (which is every switch in the works, I believe). All to no effect. He suggested a new gas valve or fan control board, but I was already in it for more money than I was able to spend. Also, I don't think the fan control does anything to start the main burners.

    I want to call out another tech but I thought I'd check here for ideas in case the next guy is stymied or wants to swap the gas valve for no other reason than it's the only thing left.

    Please help!?

    Equipment list:
    Tempstar SP80 made by Inter-City Products
    Fan-assisted 80% efficiency
    MODEL# NUG5075BFB2
    Honeywell SV9051M gas valve
    Honeywell ST9120B fan timer
    WOW!

    They were parts changers and not troubleshooters - sorry.

    You have a system that uses a “SmartValve” (SV9501M), which is known for intermittent issues as they age.

    The troubleshooting of this system should be left to a tech who is familiar with these valves, and knows how to test and isolate the problem.

    As “Professional” members of this forum, we are not allowed to provide diagnostic help to homeowners seeking DIY assistance in repairing their own system.

    A call to a competent service provider who is familiar with these Valves will be the quickest way to get you back heating again.
    Instead of learning the tricks of the trade, learn the trade.

  3. Likes DeHeatify liked this post
  4. #3
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    17,078
    Post Likes
    Troubleshooting is a Skill.

    Unfortunately too many techs confuse parts changing with troubleshooting!

    Good Luck


    https://www.tempstar.com/en/us/find-a-dealer/

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