Boiler keeps tripping

[hillbillies]

Hi, I have a boulter camray5 bonus 65/90a , it works fine as long as i don't set the control stat any higher then 3, anything above that and after a couple of hrs it trips out and i have to reset the limit switch, I've changed the two stats that go into the top of the boiler but the problrm stii persists, any advice would be greatly appreciated. cheers

 

[hillbillies]

Spoke to a few plumbers but still no further on .

 

[cso30]

It could either be a lazy pump or the ch system might need flushing.

The easiest way to test a pump is to elctrically isolate the ch pump, use a multimeter to measure resistance over the live and neutral terminals.

If the readings are,

150 - 200 ohs the pump is ok

Any other reading or an unstable reading the pump needs replacing.

 

[Agile]

presumably you mean its tripping the over temperature switch?

You should measure the flow temperature and see exactly what it really is.

Does it trip when the boiler is burning or AFTER the burner shuts down?

Tony

 

[hillbillies]

I think it's tripping after the burner shuts down, it's been like this for about 3 years now , did have a plumber look at it when it started playing up and he came and put a cleaning agent in the system but it still tripped , he never mentioned a lazy pump , i'm working abroad at the moment but i'll check the resistence on the pump when i get home in april.Thanks very much for the replies.

 

[kevindgas]

have you contacted Boulters? i have only every contacted them once but their tech guy was excellent gave me a ten minute lesson over the phone and i got the job done really quick

 

[Agile]

If its tripping AFTER the boiler shuts down thats a classic case of lime scale in the main heat exchanger.

The treatment would be to close all rads and run the boiler after introducing about 60 grams of Sulphamic acid ( sold as Fernox DS3 ) into the boiler.

Assuming its not a combi then run the boiler for about 15 minutes on water heating only. Then drain most of the boiler water and repeat with the same dose.

Repeat the DS3 two or three times until it drains out less cloudy.

Lastly repeat with about 25 grams of citric acid ( sold by Fernox as DS40 )

Then drain out and refill and drain a few rtimes and then reconnect to the radiators and test.

These are acid and messy chemicals and only do this if you can safely handle acids.

Tony

 

[Jezclayton]

You say you have already had a plumber out who has cleaned the system and that the problem has persisted for about three years. Blimey.

Have you ever had a competent oil engineer (OFTEC registered) out to give this oil boiler a proper service. Don't bother with the ones provided by your fuel supplier. There are loads of independent OFTEC engineers in your area. OFTEC isn't necessarily a sign of competence, so ask people you know for a recommendation.

Assuming the boiler is/has been PROPERLY serviced, get the control thermostat checked again. I'm not convinced this is functioning correctly and suspect the boiler may be working off the limit stat. The other possibility is that the flue is too restricted.

 

[Agile]

To give him his due, he only said the "plumber" put some cleaning agent in the system.

That defines him as a plumber with little knowledge of boilers as he was unable to diagnose and treat the problem.

If he just put a sludge remover in the system that would not have dealt with the lime scale I suspect may be causing the problem IF as stated it trips when the burner goes off.

Anyone know if these have a pump overun?

Tony

 

[Jezclayton]

No pump overrun on these boilers. The OP says that the boiler runs for about two hours before it trips. What is not clear is if the limit stat is tripping and causing the burner to shut down or if the limit stat is tripping after the burner has shut down.

Not enough information unfortunately.

 

[Agile]

Thanks, I thought non.

That adds to the likelyhood of the boiler being lime scaled and overheating after the burner goes off.

A further confirmation could be provided by running the boiler and then cutting the power.

Tony

 

[Dick Puller]

Sounds like a faulty boiler thermostat or Hi limit stat, every chance it's the former.
Also a ARGI RGI, but a time-served one!!

 

[Agile]

I did not know you were an ARGI member Dick !

Are you sure you are not Pullin the other one?

Tony

 

[hillbillies]

still doing it, spoke to a heating engineer who told me that i dont get lime scale where i live(scottish highlands). has anybody got a wiring diagram for this type of boiler

 

[kevplumb]

look here