Boiler does not maintain firing cycle when timed.

[krupatel]

Please forgive my description of my problem, but I'm not at all familiar with CH systems...

Last week my timed CH and HW failed to start in the morning. The pump was going, the controller was on but the boiler was not on. I set the controller to manual and switched the boiler off and on, still nothing.

A CH engineer replaced the pressure switch on the boiler and drained the CH before filling back up to 1.4 PSI. He said I may need to top this up over the next week. All was well until this weekend.

On Saturday I noticed that the CH had fired up early morning but then shut down and not restarting until the rads have virtually gone cold. The system was not maintaining a constant firing cycle and temperature. The same was happening in the evenings.

Today I again noticed the same problem so I tried to force the CH to start up by switching to manual. The boiler would not fire -up (maybe because the rads had not cooled down to a level it deemed appropriate). I left it on manual, then 45 minutes later it fired up and has maintained heat ever since.

Things I have noticed:

This morning the PSI had fallen below 1.4 PSI. I tried to top-up but no water entered the system. When it did fire up some 45 minutes later the PSI have shot back up to around 1.5 PSI.
There is no Room Stat on the system, only thermostatic valves on the rads
The system is a conventional glow Worm Micron 120 FF
Having bought the house recently with no installation certificate I have an ideminity for the installation, which maybe I could use?

I'll try to answer any further questions you may need to make a intelligent assessment. Thanks in advance

 

[Agile]

What exactly is this indemnity?

Have you been turning many radiators off on their valves or just turning them down very low?

Can you turn a couply to maximum an dtell me if it makes any difference?

Tony

 

[krupatel]

The indemnity is for the correct (as by regs) installation of the boiler system. Essentially an insurance policy in case the system is inspected and found to be incorrectly installed. From reading a couple of other threads the fact my system does not have a Room Stat is against regs, so I could use the policy.

Incidently I've taken out a maintenance plan from Cover Heat, who are due to make a initial inspection. I would imagine the Corgi guy will point out any non compliance, which I can take up with the underwriters.

On your question about the valves. All are more or less on 4 (scale is 0-5, plus Max). None are low or off.