Question on Oil Burner please

Manuel

Hi,
After 12 years of working perfectly (and having been serviced only two months ago), the other day my oil burner just didn't kick in on the timer. I then tried to start it by switching it to ON. Not a peep. I could hear the pump kick in through the heating system, so there's nothing wrong with the switch in the house. I called out the plumber who had serviced it, and he says that it somehow went into (I think he called it) "High Limit". If I understood him correctly, this is equivalent to an electrical item in the house tripping the circuit breaker. He got it started again, but doesn't know what caused it to "trip".

Any ideas before I call out my electrician (and pay another call-out fee)?

As I said it's fine now, but I guess could trip again at an inopportune time of the day, which would be any time of the day in this weather ....

Many thanks,
/M.

Billy Bunting

"High limit" is the actuation of the high limit thermostat, ie, it overheated, not uncommon and unless it's persistent problem i wouldn't worry much about it.

aujopimur

Your boiler overheated, usualy caused by lack of circulation i.e.faulty pump, air or gunge in the system, or circuits closed.
If you have upped the boiler temp it may also be tripping if there is'nt a pump overun fitted

meercat

sometimes,if your heating is on for a prolonged period and your heating turns off(timed or otherwise)the hot water in your system stops circulating and builds temperature up around the boiler and controls.this sometimes causes the high limit stat to activate.
to prevent this you can fit a pipestat to the circulation pump to ensure pump circulates until water in heating system cools down

Billy Bunting

You may also have a dual fuel system, in which case the secondry heat source (stove/range/back boiler) could raise the temperature of the water to the 95o cut out tempreture on the hi stat..

Bruthal

meercat wrote: »

sometimes,if your heating is on for a prolonged period and your heating turns off(timed or otherwise)the hot water in your system stops circulating and builds temperature up around the boiler and controls.this sometimes causes the high limit stat to activate.
to prevent this you can fit a pipestat to the circulation pump to ensure pump circulates until water in heating system cools down

Works even better if a relay is used to power the pump on boiler startup maybe. Relay coil energised by timer feed to boiler, and a permanent feed to the pipe stat and pipe stat terminals in parallel with relay n/o contacts. So boiler starting brings on pump straight away, but it continues running via the pipe stat each time the boiler goes off.

Or is there another way you would do it?

Bruthal

Maybe the pipe stat on its own will work if installed right beside boiler as the pipe will get hot enough to start pump before boiler gets hot enough to trip on overheat.