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Dettson Hydra Electric Boiler Shutting Off

HeatingHelp Administrator Posts: 654
This discussion was created from comments split from: Dettson hydra Electric boiler keeps shutting off.


  • DettsonHydra3Newbe

    On February 18th 2023 I purged all zones in the house by closing each zone and opening only one individually and flushing fresh water through the system out into the driveway via a garden hose attached to valve just in front of the circulating pump. When I started I noted the water pressure on the furnace had in the past few weeks dropped from 15psi to 5psi. We had noticed some gurgling in the zones when they call for heat, and this is what prompted me to do the purge. I thought the air that was trapped in some areas had finally moved through the system. During the process I discovered that I did not hear the make up valve engage automatically until the pressure dropped to 5psi. I thought it was supposed to maintain 15psi but that was just an assumption. I need to double check this…. And see if we have a defective make up valve.

    Upon completion I increased the water pressure to 20psi from the previously set 15psi assuming some residual air may be purged from the system via air relief valve on the furnace and settle out at 15psi.

    Week of February 20th furnace started shutting off on it's own. I first thought it was a faulty breaker because there was no power to the unit as the display was blank and resetting the breaker reset and restarted the furnace however the breaker did not appear to be tripped. I reduced the water pressure from 20psi to 15psi and it shut down again a day later. Next I reduced the pressure to just below 15psi at perhaps 13psi.

    I called Dettsion and spoke to a customer service agent who really wanted to just talk to and HVAC specialist on site. I explained I have a plumber and I have an electrician but not and HVAC service provider. I told him what was happening and that the furnace was set to max 165c and this was a 4 zone home with hotwater baseboard. He suggested I increase the upper limit from 180c to 195c which he says is their recommended setting for this type of setup. It came from the factory with a setting of 149c and limit switch set to 180c. His only suggestion as to what could be causing the problem is a sticking solenoid valve or switch.

    BTW their phone system is terrible. No one answers the various departmental extensions and they don't respond to online email inquiries. He said they are only two guys handling all the calls. How I got through was by selecting the french line and choosing customer service.

    I am waiting to see if the reduced pressure solved the problem before increasing the upper limit to 195c but all the comments about a common board problem is causing me concern. The furnace is 5 months old at time of this posting and came highly recommended by my plumber who says he installs same unit in small apartment buildings. I have the 20k version.

    Does anyone have any insight as to the solution in this situation?
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,346
    @DettsonHydra3Newbe, I've created a new thread for you here so that your post doesn't get lost at the bottom of that old thread.


  • Jamie Hall
    Jamie Hall Member Posts: 23,649
    Well, to start with, I hope your temperature settings are in degrees F, not degrees C.

    Pressure reducing valves usually do not have high enough flow rates to maintain pressure during purging. However, I expect you still need more purging -- you had the right idea, but likely neither enough flow nor pressure to do the job. Hopefully there is a bypass valve which you can use to increase the flow during purging. If not, you may need to figure out away to hook up to your domestic water or use a pump to purge.

    There is likely to be an expansion tank somewhere on your system. If it is set up properly, when it is empty of water it will have a certain pressure. The system pressure should be set to match -- most commonly 12 to 15 psi.

    This, however, probably has nothing to do with the boiler shutting down. You need to find out what control is turning it off to get anywhere with that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England