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Oil burner not firing

rayians Member Posts: 1
Hello everyone. I ran into a problem with my oil burner yesterday. I

have a hot water baseboard system that includes a low water cutoff, an

aquastat relay, and a Taco 4 zone switching relay. The house was a bit

chilly yesterday so I went to check on my furnace and I found that the

low water cutoff had sprung a water leak. It got into the electronics

end of it and completely fried it to the point that the 120V hot wire

was burnt off the circuit board. Luckily I found one locally and

changed it out easily enough, but the burner still will not fire. Now I

am wondering if the aquastat relay and/or switching relay are also bad.

The way this is wired is the 24v "isolated end switch" of the switching

relay runs into the low water cutoff. The "TT" line of the aquastat

relay then runs into the furnace's "TT" input. There is a 110V line

tapped off of the switching relay that comes into the aquastat. That

input is then tapped to power the low water cutoff, and of course the

output of the aquastat goes to the furnace.

How can I test the aquastat relay and the switching relay to see if they

are working properly, and is there something else I should check to see

if it is functioning also? Thank you kindly for your help!<span style="color:#000000">



  • Weezbo
    Weezbo Member Posts: 6,232
    tell us something ,

    about the low water cut off and the leak at the low water cut off.

    is it a manual reset or auto .

    what condition was the probe ..

    did you refil the boiler , gate it off and purge air?

    do you have a way to identify the low water manufacturer or a picture of it ?
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    edited November 2013
    Just for checking, not for full time operation...

    What happens if you connect the xx (end switch) on the Taco 4 zone to tt on the aquastat?

    I wouldn't leave it this way without solving the low water cut off problem.

    Did you check for proper voltage? Is your burner locked out on safety?

    If it works after you bypass the LWCO, then obviously the LWCO is wired incorrectly, faulty, or installed incorrectly.

    You didn't state where the 'leak' exactly came from?
This discussion has been closed.