Boiler Firing on and off once heating is on

[jwelch]

I'm not sure if the boiler should do this or not, but i've recently moved into a rented house. Heating works fine, radiators heat up and have hot water at the times I set, however once the heating is up and running and I assume up to the boiler temp, the boiler will repeatedly fire off for approx 20-30 seconds then fire up for a bit longer than off again and will continue to fir on and off unless I turn the thermostat down to switch off the heating or turn the dial for the boler temp down. If I turn the boler temp down it will eventually start firing on and off again. Is this normal? Apart from this the heating system seems to be working fine, I just thought it was a bit weird for the boiler to do this. The boiler is Triancogas 24/45.

Thanks
James

 

[45yearsagasman]

The boilerstat is simply responding to the drop in temperature of the water returning to the boiler.If I remember these old Trianco boilers have a mechanical modulating gas valve and due now to its age would not be classed as accurate as a modern boiler.The 25/30 sec repeat firing should be checked out but it is ok to use.Flow and return temps need to measured and circulation checked.

 

[spraggo]

You have a faulty room stat, contact your Landlord to get it fixed

 

[jwelch]

The room stat seems to be ok... boiler switches on and off when I turn it above or below room temperature, the stat isn't clicking when the boiler is firing on and off

 

[spraggo]

You stat that, when you turn down the heating thermostat/room stat, that the boiler will shut down. This room stat switches off the central heating pump which in turn causes the boiler to switch off as there is no demand for hot water to the radiators.

If the room stat is faulty it will not turn off the pump when the room is up to temperature and will keep demanding hot water from the boiler. Which will cause the boiler to switch on and off at short intervals.

To prove a point listen to the pump and see if it is responding to you turning the room stat right up and down. Hope this helps.

 

[jwelch]

I think I understand what you are saying, however the room does take a while to heat up as it's quite a large open room with stairs upstairs and no door between. The room wouldn't heat up at first with heating on - turning up the boiler temperature improved this.

The temp on the stat when it clicks on and off does seem to change i.e. when no heating on the stat clicks at about 10 degrees, when heating been on this will click off when i turn it around 16-17 degrees so it does seem to record change in temp.

How do I listen for the pump? I can hear the boler switch on and off but not sure about the pump.

Thanks
James

 

[spraggo]

What I was trying to say was, that even though you can activate the room stat by turning it up or down by hand, the stat is not sensing the difference in the air temperature to enable it to switch on and off on its own. You have proved my point by saying that, you can hear the boiler switch on and off in response to you turning the room stat up or down

 

[jwelch]

I've found a radiator that needed bleeding (middle to top left of rad not heating up) could this cause a similar problem.

I'm also having real trouble heating the room up with the thermostat to to 20 degrees, would this radiator making heating less efficient i.e. harder to heat the room?