Help with a Chromalox EDB-25-1-A
I have a Chromalox EDB-25-1-A boiler for my radiant heating system, and recently it's been cutting out randomly. Once I reset the breaker, it turns back on and heats up again.
The pressure in the system seems normal, and the radiators have all been purged of air.
My thermostat is calling for heat, but the system, while energized, clearly isn't operating until the breaker is reset.
How should I go about troubleshooting this?
The wiring diagram and circuitry is the same as in this post:
https://www.reddit.com/r/thermostats/comments/1gdkdy9/can_a_common_be_added_to_this_boiler/
Comments
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I would start by opening the control panel up with the power off and spend some time just looking around. Electric heat is fairly simple. If it is tripping a circuit breaker you probably will find a loose connection, discolored insulation on a wire, burned or discolored wire termination, bad contacts in a contactor etc.
I would also call or find out from Chromolox what the ohm readings should be on the 5 heaters. Then I would disconnect the wiring to the heaters and ohm them all out and check to see if any are grounded.
Any muck or sludge in the boiler can cause the heaters to fail
That's for starters.
If one heater is bas you could disconnect and run on the others until you get it fixed.
An amp meter would probably be a good thing to have.
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hello kin101,
When you say " cutting out randomly " you mean tripping the circuit breaker ?
As EBEBRATT-Ed states visual inspection, there could be a chafed wire getting grounded somewhere. It could just be the circuit breaker has gone soft or a poor connection at the circuit breaker causing abnormal heating there.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
If it has big contactors for the elements, the points can arc cause high resistance and trip a breaker. Usually there will be a burnt smell when you remove the jacket if electrical components are over-heating.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Hi All, thanks for the replies so far. The breaker at the panel is NOT tripping. The system itself just stops heating.
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Well that's something anyway… I'm afraid you may have to take the covers off the thing and find which relay or contactor(s) is not closing, and why. A non-contact voltage tester can be mighty handy and save you from some nasty surprises — and so can a clamp on ammeter…
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Other than visual inspection for overheated and/or loose wires, a tug test for loose power / control wires. Usually the fastest way to find a defect like this when it fails is to troubleshoot it live (powered up), but that takes a person that is skilled and competent in this type of work.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
Update: I opened the panel and started checking the sequencers and relays. One of the relays is clearly not working, has visible cracking, and has intermittent contact. I've ordered a new one and will swap it out once I get it. Hopefully this resolves the issue.
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When installing the new contactor make sure those overheated connections are clean and tight and the wire is undamaged.
Looks like there was a hot spot at some point (Red arrow).
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System
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