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Relay continues to click

My plumper installed the Burnham IN-7 Gas Boiler 10 years old. It was running well until the transformer was burned couple weeks ago. Once I reconnected the new transformer, the themosat relay continued to click like a short circuit. I then replaced a new relay and it did the same.  I unplugged and reconnected the probe cable inside the LWCO, it did not click anymore. Unfortunately, the new transformer went bad two days later !  Will the LWOC short the relay circuit. If true, how can I test it ? Why the transformer burned instead of the relay ?

Yesterday, I brought another transformer and put it on, it worked again. The relay is fine. I have no idea why it worked now and worried about that the transformer will burn again. I measured the current between the relay and it was 0.2A

Any idea ?

Thanks

Dominic

Comments

  • Zman
    Zman Member Posts: 7,330
    Short

    Dominic,

    Something is shorting out and letting the smoke out of your transformer. I sounds like it is the relay coil. I would suggest installing an in line fuse until you have this under control. You should be able to test the coil with an ohm meter.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Dom_C
    Dom_C Member Posts: 3
    Burn again !

    Hi Zman,



    Thanks for your response.



    You definitely right. The new transformer burned again today ! However, I found out the FRS (Flame -Roll-Out Switch) was shorted. I discounted the line from FRS to the VENT DAMPER and the other line to the Blocked Vent Switch (BVS), it still shorted ???? I then disconnected both line connectors of the FRS and it was then ok. Very strange. It was not possible that the connectors can touch the ground. It was so far away ...



    I am going to buy another transformer and new FRS tomorrow. If I want to put the fuse to the transformer, which size should I put, i.e. on 110V or 24V ? The power supply 110V size was burned, not on the 24V.



    Thanks a lot



    - Dominic
  • Zman
    Zman Member Posts: 7,330
    24v

    Put the fuse on the 24v side. You didn't miswire the transformer did you? Some of the ones with extra wires can be confusing. Have you checked the polarity and the output voltage?

    The fuse size needs to be smaller than the  transformer rating. A 40 VA would work with a 1.5 amp fuse. 1.5 x 24 = 36. Auto parts stores are a good source.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Dom_C
    Dom_C Member Posts: 3
    Found the problem

    I may be a potential detective. The cable connected to the FRS was melted. It exposed little copper wire and it is difficult to see. Since this cable is close to the fire and the copper expands and touches the metal piece of the boiler and it shorts.



    I replaced the transformer and put a 2A fuse with the holder from the autozone. Let's see what happen in the next couple days (The transformer usually burns in two days).



    - Dominic
This discussion has been closed.