Electric boiler issues

[TwincamDave]

Any gurus that can shed some light on what would cause an electric boiler under a year old to burn up contactors on 6 of the 10 circuts(some were fried closed and it tripped the high temp safety)?Could bad water be causing this? any help is great, Dave...

[maustin]

overcurrent

[HVAC Teacher]

If it tripped on limit, sounds like operating controls are not working or:

Burnt contactors: not shutting off, maybe welding shut, not opening,

or: low resistance = high current.

Just some "guesses".

One other thing, obvious: sure this thing has water in it?

[redfive]

Cheep contactors that are barely sized properly. Loose electrical connections on the contactors or main disconnect (lugs/fuses) and elements. All these conditions would cause over amping or heat and start to burn the points. Low water or no water in the heater and scale build up on the elements themselves. Or one good power surge or lightning strike while the unit is running. Most of ours that eat contactors were due to bad elements. Also check the elements to see if they are rated for the voltage being applyied. 120/208 120/240 277/480. three phase or single. Plumbers know plumbing but I have had them breing me the wrong voltage rated heater on several occations.

Redfive

[redfive]

Forgot, had one at a fire station that the temp probe was off by about 60 degrees. It was set at 130 it was going to 190. It was gas but if it was electric this would cause it to draw greater amps as the elements cant get rid of as much heat. So I would take some temp readings and check the controls also. I'm assuming this is for domestic hot water as compaired to a closed loop hydronic system heating for heat coils and all. Allways gets me confused as to when a hot water heater becomes a boiler, besides boiling water. But then its a steem boiler. Size and btu output i guess. Hard water on anything is not good and will shorten the life. Most heaters/boilers should be flushed every year. Sediment builds up in the bottoms to. Even with the A.O. Smith sandblasters and all.
Redfive

Redfive

[dean59]

is this a steam boiler?

[Dilp172]

Maybe a silly a## step controller short cycling the p#ss out of the contactors.

[supertek65]

i would guess short cycling

can you adjust the span, deadband on the controller?

[madhat]

Spider webs/nests in the contactors.

[CesKrin]

Steam boiler or what? take some pictures