is my boiler thermostat faulty?

[hgee1205]

Hi
I have an ancient Ideal E type boiler which is primitive but works fine.
It has the original P0616 probe type stat ( Ranco?) which is probably nearly 40 years old and is the only
temp control for the hot water and radiators as I do not have TRVs fitted
So I have been turning the boiler stat control ( numbered 1 to 6) down as spring arrives and even at less than 1 the water seems quite hot.
I measured the boiler temp twice with the knob set to 1 ; the manual says this should give a temp of about 54C : the boiler switches on at 52C and burns until the temp gets to 67C , so a 15C switching range and an average of about 60C ; this seems a wide range to me?
Can someone tell me what the normal switching temp range should be for a boiler stat of this age?
I think a new stat may be needed?
Thanks

 

[Ric2013]

I have had a stat replaced on a boiler from 1978 (this was back in around 2010) and it did reduce hysterisis as well as keeping closer to the official setting. The old stat used to allow the boiler to run significantly above the correct setting, so i suspect it is a thing that happens with old thermostats.

My new house has a 1988 boiler that used to keep within 2 degrees. The flow temperature now fluctuates quite a bit (not as much as yours!) but I put that down to slower flow rates from the new pump and fewer radiators means the boiler is now oversized. If I rember rightly (be aware it's been a while since I took any notice of what my boiler is doing), the issue is that the flow minimum temperature is low, rather than the flow maximum is high though.

If you can find a spare it is unlikely to be especially expensive nor that difficult to fit. May be worth getting one for the next time you have the boiler serviced, if your registered gas installer hasn't the time of interest in sourcing the part for you. Note that some RGIs can be hesitant to fit a gas spare they didn't supply, so check with whoever you use first and keep all paperwork for the part, so they can know it is the correct part and that it came from a reputable source.