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Discussion Starter · #1 ·
Hi there,

I have a mechanical timer switch control for the gas boiler. Recently there was no power to the switch, no circuit breakers tripped in the main circuit box. I thought it might be the mechanical timer (apt model), but the following day the power to this point came back on and the boiler worked. Over the last week, the power to this point stops for approx 10 -15 hours and comes back again. Is it possible this circuit is overloaded or is shorting out?
 

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Is it a consistent 10-15 hours every day? Also, when the problem occurs, is it unusually warm in the room where the boiler is, in other words, will the boiler run for a while, get hot, then shut down for a while before coming back on?

Just based solely on what you mentioned in your post, it sounds like a thermal overload is tripping somewhere. A thermal overload is basically a fuse that trips when it gets hot, then resets itself as it cools down. During normal operation they shouldn't open, but if your boiler is running excessively hot for some reason, they could potentially open and close every day. It is possible an overload or short could cause this. I don't think it's a short, they don't usually have a tendency to fix themselves for any amount of time, an overload is more likely, but it may not necessarily be the issue.
 

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Discussion Starter · #3 ·
No power to gas boiler

I don't think its a thermal overload as the timer is only set for 3 hours a day. The boiler will run for the 3 hours if there is power to the switch, it doesn't run for a while, switch off and switch back on as you mentioned.There is a fuse ( 3 Amp) in a box directly above timer switch which has been replaced. Is this the thermal fuse you mentioned ( see picture attached), I presume this is linked to timer switch. Also if there was a thermal overload should a circuit breaker trip in the main circuit breaker box.
 

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A thermal overload is a little different from a fuse. Besides the fact that an overload is resettable, they are used in different places. A thermal overload is typically used to protect an electric motor, such as the one in your boiler. Also, you won't find a thermal o/l in a fusebox as they are normally part of the actual motor circuit. That's why I asked if the boiler room was running excessively hot whenever you lost power on your switch.

Just to clarify, was your timer offline for 10-15 hours total over the course of the week, or 10-15 hours per day? I thought you said per day, but now after rereading your post, I find myself slightly confused about it.

Lastly, it is possible for an electrical problem to trip both the breaker and the thermal o/l, but one doesn't necessarily affect the other. The o/l responds to heat only, while the breaker trips on excess amperage.
 

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Discussion Starter · #6 ·
No, the room where the boiler is located does not become excessively hot when i loose power to the switch, as the rad in that room is off. yes, It is approx. 5-15 hours per DAY the power is out to the switch, not sure about the exact time ( today out from 13:30 to approx 22:00)
Thinking of caling an electrician at this stage?
 
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