Sime friendly format e Boiler short cycle?

[Kareng]

Hi

Not used to using forums so I'll try my best to give as much info as possible without waffling.

I have a Sime friendly format E boiler approx 10 years old.
Last week I had no DHW or CH. PCB and pressure swith? where replaced, and since then I have had both HW and CH 😀
A Diverter valve is due to be fitted next week as CH coming on when calling for DHW.

However I've recently had the CH on permanently, as I live a very cold 1900's terrace house. Since changing the PCB I notice the boiler firing up repeatedly. Flames for approx one minute, stops for approx one minute and keeps repeating.
Question is, should this be happening so frequently?? I assumed once the rads where up to temp the gas wouldn't keep firing up? Don't remember it cycling this often before.

My rads are old, no temp controls on them or thermostat in any room.
Hard water area and system hasn't been serviced for at least 3 years!
Other minor detail that might be of use, 2 x rads where removed for plastering purposes just prior to these problems arising

Many thanks in advance for any replies

Regards

Karen

 

[fixter1]

ch thermistor sounds like its not modulating

 

[Kareng]

Hi fixter1,

Thanks for taking the time to reply, any idea why the rgi Wouldn't have picked this up? I called him back this evening and he said he couldn't find a problem, but this may be because I've had the boiler turned off, (scared it might go bang!) so when he's turned it on the temp hasn't been that high. The short cycling does get worse the longer the heating is on.

Thanks again

 

[Kareng]

Ok things just get better!
Diverter valve was fitted yesterday, CH and DHW now fine, however noticed a puddle under the boiler this morning. Leaking from ball cock flow returns. (I believe!)
This seems to stop when the boiler is turned onto DHW , then continues when it cools down.
A-Expensive to fix?
B-Coincidence this has started leaking so much since new diverter fitted?
C-Will my boiler ever be ok?!!

Thanks

K