Worcester boiler wont come on when temperature drops

[Burtonian]

Hi, I have a Worcester Greenstar Ri. It comes on fine at the start of each timed period, but only if it is set at 20c on my honeywell T6360B wall thermostat (any lower wont work). When the temperature is warm enough, the boiler goes off and will not come back on, no matter how cold the house gets. The only way it will come back on is if you manually turn the wall stat to over 20c. Its the same when the wall timer is at "on" or "allday" - you only get one burst of heat and then thehouse goes cold. The boiler will only restart if you manually turn the wall stat up above 20c.
Any ideas?
Would replacing the honeywell T6360 help, or is there something not right with the boiler?

 

[dancinplumba]

hi and welcome if its 20c boiler isnt going to fire up, try it at 22c, temp is a personal thing. my stat is at 23c

 

[Nostrum]

I would check it's been wired right by a competent electrician/heating engineer. What boiler did this one replace?

 

[Burtonian]

Hi Sambotc, I dont know which boiler it replaced, I only moved here a few months back. The boiler is just out of warranty, and the records left show it was installed by British Gas.
I have taken the cover off the stat to look at the wiring and it seems to follow the little diagram stuck to the inside of the cover.

Hi Dancinplumba, there is a pencil mark on 19c, and any setting above this works. Any setting below this wont work....

 

[dancinplumba]

get a thermometer and make a comparison in temp, stat should have 3 wires inside it, neutral, live in and live out

 

[Nostrum]

I take it the room temp drops well below 19 and the heating doesn't fire?

I'd be verifying the boiler was wired to run the pump if it was me looking at it. If the stat turns the heating and pump off instantly it could take a long time for the boiler temp to drop low enough to run again.

 

[Burtonian]

Yup, house just goes cold (well below 19) - boiler stays off until you turn the stat up, or (if the wall timer is on auto) until the next "timer on" time starts.

 

[lame plumber]

could be the stat is sticking open, need to check its working ok. new stat only 20 notes or so.

 

[Nostrum]

Actually I think I heard mentioned on here recently something about Worcester PCB issues causing this fault?

 

[Burtonian]

Latest on this is that I got another Honeywell Room thermostat (same model) and the problem still exists. It appears that something in the boiler isnt quite right, why wont it come on when the temperature falls (even when its "ON" at the timer) ?
Is there some kind of over-ride within the boiler?
If there are issues with the pcb that have been discussed, can anyone give me a link to that thread?

 

[TBServices]

Latest on this is that I got another Honeywell Room thermostat (same model) and the problem still exists. It appears that something in the boiler isnt quite right, why wont it come on when the temperature falls (even when its "ON" at the timer) ?
Is there some kind of over-ride within the boiler?
If there are issues with the pcb that have been discussed, can anyone give me a link to that thread?

Could have spent that money on a heating engineer.