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Dettson hydra Electric boiler keeps shutting off

Radop Member Posts: 2
Good day all. Newbie here and hoping someone can help me out.
I have a Dettson electric boiler providing Hot water to my in floor heating system.
The problem Is that the boiler keeps shutting itself off. When the thermostat asks for heat the boiler won’t come on. Here’s what I have checked so far
- confirmed 240 to the unit.
- confirmed 120 at the transformer and 24V from the transformer to the board.
Only thing I can think of is a bad board.
If I remove the fuse on the boiler and put back in the boiler comes on. It does recycle a few times and sometimes stays on for a few hours but then shuts down.

Any ideas. Thanks in advance.



  • pecmsg
    pecmsg Member Posts: 4,373
    Sounds like it’s shutting down on a safety.
    Any trouble codes?
  • Jamie Hall
    Jamie Hall Member Posts: 22,050
    As Paul, says, sounds like a safety, and by removing and replacing the fuse you are resetting it. The first thing I'd do is check what safeties are present -- I'm not familiar with the unit, but there is almost certainly a high temperature limit on it, and there may be others. Then work to figuring out what is actually shutting the unit down.

    Do you have any way to measure the output and return temperatures? Flow rates?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Radop
    Radop Member Posts: 2
    Thanks for the feed back.
    I am unable to see any safety codes as there is no display window.
    As for water temp it doesn’t go above 100C and the max indicated for it is around 170c
    I agree removing the fuse is just resetting it.
    I think I added a pic of the board not sure.
    The only think I read is the top left is a spot to connect a ribbon cable I guess tobread codes. I don’t have that setup available to me.
    JUGHNE Member Posts: 10,886
    100 C or 100 F ?
  • neilc
    neilc Member Posts: 2,501
    there are no blinking LEDs?
    do you have the manual ?
    known to beat dead horses
    JUGHNE Member Posts: 10,886
    A remote possibility is if you have the electric company that controls demand. I can't imagine them cutting off all stages of the boiler, but if your first stage is defective and their controller wacky, things could happen.
    This has happened, especially with AC during the summer.
  • allndg
    allndg Member Posts: 1
    I have the same problem, the boiler shuts down randomly. How did you fix your problem?
  • acottinet
    acottinet Member Posts: 0
    Same problem here. All LEDs on the electronic board shut down at the same time. Sometimes it is able to restart on its own, sometimes it just stops. The board seems to latch and a power reset is needed.

    I have investigated a bit and I assumed it could be related to an over-temp protection on the board (there are a lot of hot parts on that board). I don't have the board's schematic but it looks like there is at least a PTC (self-resettable) fuse on it.

    As crazy as it might sound, I have put a fan in front of the board and it seems to work a lot better when it is being cooled down by fresh air.

    I will try to communicate with Dettson and see what they can tell me about this...
  • acottinet
    acottinet Member Posts: 0
    I have talked with Dettson technical support. They seem to have a lot of problems with the Hydra electronic card. I have ordered a new one through my local plumber.
  • mimeee
    mimeee Member Posts: 1
    i know your post is old but just wondering if changing the board fixed your problem.
    thanks having the same problem

  • rapeanu
    rapeanu Member Posts: 1
    I do have the same symptoms on my Hydra Evolution 24kW, 12 years after errorless function: occasional shut down, can only restart with a hard reset: cut power from the central panel breaker or from a small fuse holder on the side of the unit.

    Did the replacement of the main control board solve the problem?
    Thanks for a fast reply,

  • Henry
    Henry Member Posts: 996
    The Hydra series is a problem child. Get it replaced with a Thermolec. Everyone that I had specified is still running with no problems after over 25 years.
  • kurt2222
    kurt2222 Member Posts: 1
    I have the same problem. Has any one have any success with the board replacement?
  • jasonpitre
    jasonpitre Member Posts: 1
    kurt2222 said:

    I have the same problem. Has any one have any success with the board replacement?

    same problem too! any success with the board?
  • kgendron
    kgendron Member Posts: 1
    Hello, Me too ! Same trouble with my Dettson HYDRA EVOLUTION! What is the conclusion for this problem ?? Thank you 
  • AaronBridgewater
    AaronBridgewater Member Posts: 1
    edited December 2022
    I have the same problem. I checked the elements and discovered the top was not drawing any amps. Replaced it last night, but the same problem continues with the LEDs all shutting off and the unit turning itself off. It will restart if I reset the breaker. Any other ideas?
  • flowerpower
    flowerpower Member Posts: 1
    edited December 2022
    Hi, I have the same problem.  It will restart if I reset the breaker. What is the conclusion for this problem? Thanks
  • asaconj
    asaconj Member Posts: 2
    exactly the same issue, the board seems to engage the microswitches and then shut them off constantly. But the problem looks resolved when I was venting the board with a blower fan. 
  • asaconj
    asaconj Member Posts: 2
    Where can we order a new board.
    because I’ve temporarily bypassed the board and plugged the 3 micro switches that are activating the current on the 3 elements, but even though there’s a mechanical thermoswitch, there’s a risk for the boiler to get to high. 
  • 109A_5
    109A_5 Member Posts: 999
    Hello @asaconj,
    Maybe try https://www.dettson.com
    There are manuals there with wiring diagrams on that web site and maybe you can find other support there too.
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Normy
    Normy Member Posts: 2
    Hello all, So I am having the exact same issue. What is the best thing to do ? There was no final conclusion .