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GV90+ continually turns on and off ~ ever few minutes

NoCoPerson Member Posts: 2
Hello. I have a Weil McLain GV90+ Furnace. New about 5 years ago. It won't stay running. It fires and gets the water temp up to about 185 then shuts off. The water temp drops after about a minute or two to about 155 then fires again. The pumps are continually running calling for water to be circulated to the heating zones throughout the house. House get cooler, but never "freezes" since the furnace does regularly fire, but won't stay running adn thus does't maintain desired temp. I will be contacting the company that did the install but I'm 99% certain this is now the 3rd time this has happened with the same exact symptoms. First 3 years, and next time 2 years ago. I think both times the "controller" was replaced. I'm nervous that the true problem isn't identified. I know this isn't ver specific but should I be wise to be cautious since it's a repeating problem? Thanks!


  • Zman
    Zman Member Posts: 7,446
    It sounds like the boiler is running normally . It heats to the setpoint, then shuts off. It turns on again at it's programmed differential.

    Your problem is likely in the distribution. The boiler cannot get rid of the heat.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • pecmsg
    pecmsg Member Posts: 3,878
    You don't have a furnace you have a Boiler.

    There should be an internal circulator that's not operating.
  • NoCoPerson
    NoCoPerson Member Posts: 2
    Thanks @Zman @ @pecmsg. Also, you are right @pecmsg - I used the wrong terminology. It's a boiler for sure...
  • SuperJ
    SuperJ Member Posts: 605
    edited November 2018
    Weird that your problem is intermittent. If it was just an oversized boiler it would behave like this all the time. Are all your rads getting warm? Maybe you have an airlock in the system, that's block flow to some zone?
    The boiler is doing the right thing by cycling off when it hits 185F. Ideally you wouldn't be running it that hot unless it was the coldest day of the year.

    You need to figure out why the house isn't taking the heat out of the water as fast as the boiler is putting it in. Probably some sort of flow issue somewhere.
  • Tim McElwain
    Tim McElwain Member Posts: 4,588
    Do you have the I and O manual for the GV90? If so there are troubleshooting charts in it under troubleshooting.

    Make sure the system circulator and the bypass circulator are both running. Check your return temperature as there is a thermister on the return that if return water is too hot it will shut it off. It will then do what you say yours is doing.