Camray3 boiler running then shutting down on constant cycle

[0liam0]

Hi,

I have a camray 3 boulter oil fired boiler that is used to run central heating only. I currently have an issue whereby;
1) room stat calls for heat
2) boiler and pump both fire and start to run
3) both boiler and pump run for approx 4 mins then shut down, stat stops calling heat ( light goes out on room stat)
4) after a period of approx 4mins shutdown the whole cycle from point 1 starts again( boiler subsequently firing over and over again in a short space of time).

This is causing the rooms to take along time to get to desired temperature ( if they ever do at all) and to me suggests something is going wrong along the way.

I have already replaced both the pump (grundfos selectric) and the room stat. Would I be correct in thinking this could be an issue with either the boiler stat, heat exchanger or build up of sludge in the system contributing to a poor flow around the system??

Any help would be greatly appreciated,many thanks in advance...
Liam

 

[Cpplumber]

The fact your light goes out on the room stat makes me think it's controls related. Do you have any zone valves?

Also what programmer?

 

[Cpplumber]

The reason I say this is, the light on your room stat would stay on regardless of what the boiler was doing if any of the faults on the boiler occurred.

Are you ok with the use of a multimeter? Might be worth checking the switched live to your boiler. If this drops out at the point of the fault occuring, it would be controls related (zone/three port, room stat or programmer)

Just a guess at this stage though...

 

[oilhead]

Definitely controls problem. What programmer and valves do oyu have?

 

[Boilerman2]

A lot of modern room stats are designed to cycle rapidly, which is fine with a gas fired boiler with more rapid response, but not so good with an oil fired boiler, where it takes a while to build up temperature it might be worth fitting a more basic room stat such as a Honeywell 6360B which is well suited to oil fired systems

 

[0liam0]

Great thanks everyone for the pointers and advice. Control issue seems feasible and have recently replaced room stat that I fitted only 12 months previous as I thought that may have been the problem back then

I overrode room stat last week before replacing room stat and boiler ran fine and didn't appear to shut down ( although not 100% sure as went out to get new room stat replacement). This would indicate controls again I guess??

CPPlumber- no zone valves and have an electronic programable timer. I will try the multimeter suggestion and post how I get on!

Thanks all, I will keep you posted...