Combi Boiler - water heating then cuts out

My boiler will heat water, but if it has been running for a while (eg deep hot bath) then a minute or so after turning of the water there is a clicking noise from the boiler and the pilot light goes out. If you turn on the tap just after running a lot of hot water the water is very hot. Seems that something is overheating and causing a saftery mechanism to trip. However, I have had 4 visits from British Gas (I've paid for their insurance service!!) and each time they have failed to fix the problem. Any ideas?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Make and model would be useful.
Christian.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If I understand this correctly, it is after the boiler does a burn, that the system clicks and the pilot flame goes out ? Or does the pilot flame go out and then the clicking noise is heard.
I think the clicking sound is the gas safety valve closing off to stop the pilot flame injector from leaking gas into the body of the boiler. And this fault, if it is happening after the boiler does its burn, is more than likely to be the hot flue drawing air in and around the pilot flame and blowing it out.
To test this, get a piece of wooden board (plywood or hardboard is OK) and block off only the bottom half of the flue. Now if the flue is a balanced or not, it doesn't matter, and all you need is the bottom section of flue pipe to be slightly blocked. It also doesnt matter if the flue is of the type with pipe in front of the other, as slightly blocking either the intake or the outflow will tell you if the pilot flame is being drawn out by flue gasses after the boiler has heated.
If it shows that the pilot flame remains lit after doing a few burns and cools with the flue partly blocked, then call the gas company back and ask them to slightly increase the pressure of the gas supply to the pilot.
If it doesn't show any improvement with doing this test, then you'll need to have the engineer back to carry out other tests to find the real reason.
Remember not to block the whole flue, ONLY THE BOTTOM HALF OF IT. And keep the barrier there for any more than the length of this test. The test should only last for the time it take the boiler to cycle through two or three burn patterns and not to extinguish the pilot flame.
This is not a cure for the fault.
--
www.basecuritysystems.no-ip.com

Outgoing mail is certified Virus Free.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
depending on which boiler I would guess that the pump over run is not operating

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sorry for not including this info before. The make is Ocean model is Style FF . Its an old boiler but hardly used so in fairly good nick. Don't think the pilot is blowing out. It seems more like after the tap is turned of the water that remains in the boiler is continuing to get heated (although the flames are extinguished) - I can sometimes hear what sounds like water boiling inside the boiler. Perhaps there is a safty mechanism that cuts in due to the heating and boiling of the remaining water? If this is what is happening what is supposed to prevent it? What is "pump over-run"? Thanks
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The pump over run makes the pump circulate hot water out of the boiler for a short time thus not making it overheat and hiss slightly like a kettle, something like you are having. Check the manual ( if you have one ) and see if there is a pump over run on that boiler. I think you will find it is more likely to be the fault

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If it's the Ocean boiler I'm thinking about, there is a secondary heat exchanger in it aka calorifier. These are prone to scaling up, which would explain your problem. I used to descale them for Servowarm, but I no longer have any idea where the adapters are.
--
geoff

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
P Lavers Wrote:

I have exactly the same problem after running a bath. When the water i running the overheating light flashes, then when I turn the water off after a minute or so there is a click and the pilot goes out. Have you found and answer yet? Thank
-- Boiler
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
replying to Boiler, Paul Whitehouse wrote:

I sure hope it's all working, I know it's an old post - but the benefit of others on here who have the same problem - it's so hard to diagnose and even more hard to bear! My nextdoor neightbour had the very same problem it was driving him nuts, in the end I told him that STL Heating do a good job - and so he tried them (expecting a big bill). But, they were able to quote a price lower than others he'd had - but because they were'nt a one man band he knew they'd be good - and they were. after a visit and some work - all fixed (now he's happy as pie!)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.