Crazy boiler - off on off on ALL THE TIME!

[ponymath]

Hi guys,

I just wondered if someone could help me.

I moved house in summer - and therefore didn't really do much with the boiler - however have begun to turn it on more and more as the tepertautr drops. However, when on it appears to go in 3 minute cycles, each on comprising of:
Complete silence, nothing running

Boiler turns on
Gas on and flame lights
Flames goes out (and gas stops)
Boiler off again

It is driving us mad! All we can hear is it turning on and off all the time! The boiler its self (not a combi) is set to medium, and the thermostat to about 24....

I don't fully understand the workings, I know the temperature gauge on the boiler is the radiator water temp - but not sure what the low and high are equivalent of. I also don't know what part may be doing this! Surely the room should hit the temperature and shut off for more that 5 seconds? I doubt it is actually reaching the temperature and the thermostat connection is this issue?

Any ideas?
Thanks in advance

[markiii]

That aside is the house getting warm?

Is the pump running?

[ponymath]

Yes! (Sorry, should have stated that!)

Radiators get nice and hot (eventually) but I doubt they heat the room to the set thermostat temp!

[littlebasher]

My boiler did that when the pump was fked. I guess the thermal cutout kept switching off the boiler.

[gobstopper]

I had the same problem after moving into our present house. It turned out to be the flow and return pipes into the boiler partially blocked with sludge and the reduced flow meant that the heated water would not flow away quickly enough from the boiler so the boiler stat. shut down the boiler.

[KTF]

What make/model is the boiler? Are there any error codes/lights on the display when it does this?

[Rickyy]

Sounds like a circulation issue or possibly a sensor fault.

[pharmvrs]

As above check the flow, some radiators may be turned off, air-locked or blocked. We had the same issue (its likely the internal boiler thermostat overheating and shutting down as it is heating a small volume of water) till i discovered the previous owner had partially closed off a lock-shield valve next to the pump severely restricting the flow!

If the boiler operates normally whilst heating the water then the boiler "should" be ok and the issue is elsewhere with the radiators and associated pipework.

[silversurfer1]

Measure the flow temp of the boiler if its hot 60c plus then as ricky says circulation issue boiler is shutting down because its hot enough.


ss

[dtmpower]

My mother-in-law's boiler did this when the fan motor and bearings were getting old and seizing up. The fan would run for a short time before locking up and then the boiler killed the flame.

[ponymath]

Hi all,

Thank you for your replied

It is a Suprima 60L boiler and there are no error lights coming on. It starts with a solid green during the air proving and ignition phase, and then after 5 minutes it begins flashing which indicates "Boiler temperature control satisfied", its quiet at this point for about a minute; it then goes solid orange for "mains on and no external call for heat", before flashing orange/green for the air proving and ignition phase again...So I guess it is getting hot enough...the bit its heating anyway!!

One other problem is that I don't know how to test anything! So I don't know how to know if the pump is actually working (other than hearing it) or how to measure the flow temp or check for blockages!

I will try just heating the water now and see if it goes on and off still.

Thank you again!!




http://www.diynot.com/forums/viewtopic.php?t=24843...

[ponymath]

(the link at the bottom of that was a similar thread i came across by accident when trying to find the user manual online!!!

[Busterbulldog]

faulty air pressure switch or flue issue

[Hilts]

My boiler does this.

I thought it was maybe just because of its age, 21 years old.

I have a new pump installed and everything appears to work ie. I have hot water and all the radiators work.

It's an Ideal Classic NF 40. Would a boiler service work or am I looking at some sort of repair?

[Rickyy]

ponymath said:

Hi all,

Thank you for your replied

It is a Suprima 60L boiler and there are no error lights coming on. It starts with a solid green during the air proving and ignition phase, and then after 5 minutes it begins flashing which indicates "Boiler temperature control satisfied", its quiet at this point for about a minute; it then goes solid orange for "mains on and no external call for heat", before flashing orange/green for the air proving and ignition phase again...So I guess it is getting hot enough...the bit its heating anyway!!

One other problem is that I don't know how to test anything! So I don't know how to know if the pump is actually working (other than hearing it) or how to measure the flow temp or check for blockages!

I will try just heating the water now and see if it goes on and off still.

Thank you again!!




http://www.diynot.com/forums/viewtopic.php?t=24843...

PCBs are a very common failure on these. They will run for a few minutes, cut out and SOMETIMES reset themselves, other times they won't play ball for a while.

[ponymath]

Called the plumber - who is saying I need to pay £50 for diagnosis (if he can fix it within the hour with no parts needed, then that's included in the £50) and then I will be given an estimate for the repair (on top of the £50)....does this sound right?

[rfisher]

Is it in the garage or in the house?

If it's in the garage it could be the frost protection cycle kicking in.

There should be a second adjustable thermostat near the boiler that may need to be turned down to around 2-4oC.

Sometimes owners think this should be at 19oC like the house stat so turn it right up!

[Fastpedeller]

ponymath said:

Called the plumber - who is saying I need to pay £50 for diagnosis (if he can fix it within the hour with no parts needed, then that's included in the £50) and then I will be given an estimate for the repair (on top of the £50)....does this sound right?

Depends whether you think it is or not! I always think if I'm paying the guy more than I earn it's because I can't do it.....
Sounds reasonable for a heating guy (make sure gas safe ID)

[ponymath]

No - it's in the house, I haven't found any more thermostats...yet!!!

[ponymath]

It's just depressing...mostly because I am an engineer!! I should be able to fix it (or at least diagnose it!) embarrassing!