I hope the STW can help once again. Pregnant wife and facing the second night without hot water or heating. I have tried everything I can. Too poor for a plumber 🙁

System was working fine, now boiler fires, quickly reaches temp and cuts off.

Both on CH and HW, both have separate motorised vales which both work so not the issue. Pump works and spins fine.

Full system has been bled including boiler (worcester greenstar ri open vented system).

I thought it may be an airlock hence full drain down and refill. No luck
Bled boiler no luck
Bled pimp no luck
All radiators bled no luck

Gah!

Both on CH and HW, both have separate motorised vales which both work so not the issue

you have checked that you get hot water on the outbound side of each valve when you expect to?

Have you tried the manual lever on the valve if not?

Sign up for the British Gas service plan. At least you can spread the cost & get it fixed. I was in the same situation once.

Boiler fan maybe on its way out,i.e stopping and causing the cutout.

1st thing i would check is condense pipe is not frozen

Stoner, yep both get hot just after the valves but there doesn’t seem to be any flow boiler only works for 30 seconds or so, doesn’t give it much chance to heat up. ( worked fine yesterday eve). Both manual levers work and I took the actuators off to see if I could turn the valves by hand and could.

Peasant, checked the condenser pipe all clear but it got a kettle full earlier just in case.

Seems there is a lack if flow on the return. Thought it may be an airlock but if it is, I can’t clear it!

Anyone know how to bleed a will-smart pump? I’ve lost the instructions and it had all sorts about shutting the valves on one side for a bit…

1st thing i would check is condense pipe is not frozen

Very common on WB boilers so I would also check that first.

Seems there is a lack if flow on the return. Thought it may be an airlock but if it is, I can’t clear it!

when you bleed an upper rad is it pressurised?

Stoner, the air rushed out of every one of them beautifully. I hope I understood the question properly!

OK. And (sorry if stating the bleedin* obvious) after bleeding, you recharged the circuit so that the pressure gauge at the boiler is in the “green” zone?

*bdumtish.

Stoner, my system is open vented not a closed system. Unless I have got the wrong end of the stick? Truly thanks for the help BTW!

ahh, sorry. had assumed combi boiler/unvented.

so…..

Header tank full of water?
When boiler running header tank doesnt get hot?
If you just run DHW or CH independently of the other does the same problem occur?

Im afraid I dont know enough about the boilers themselves to help there, only a bit about the system. Tootall knows this stuff IIRC and may be along.

Stoner, thanks, yep header tank full, same issue if run together or separately. Hence my thoughts it may be at the pump or at least the return part of the pipe work. New pump fitted last year.

does the pump sound like it’s cavitating (slurshy noises)?

Hmm what do you think, I read elsewhere that closing the valve under the pump should change its sound proving it works. There is no difference if I do that with mine.. Dead pump? I can hear it whirring but maybe the impeller is knackerd ?

Have you tried turning up the water temperature up and down to see if that reduces or prolongs the firing time?

How old is the system
Are the radiators full of rust ?

Large screwdriver to ear + metal tip touching pump. Should hear it spinning away.

If not

Undo the cap in the centre of the pump (2p size) & you’ll either see the impeller spinning or you’ll need to stick a flat blade screwdriver in to spin it. Should just be a dribble of water that you catch with a rag.

If it spins, great. If not….. Repost

Had a similar thing a couple of years ago in an older house. Took a rad off, refitted it, bled it, then suddenly the boiler kept cutting out – overheating.

Turns out, there was that much gunge in the header tank, that when the rad was refitted and bled, the gunge went down the pipe, choked up the boiler, and forced the flow to stop. First blockage was at the badly sited air separator, the 2nd at the entrance to the heat exchanger. It was the worst blockage we had seen, and taught us a lesson to always check the header tank before refilling a rad.

A clean up sorted it, but a right pain of a job to do.

Worth trying the thermal cut out, check it hasn’t pooped, usually a quick press to reset…

if you’re anywhere near hereford I’d be happy to come have a look, not a pro but spend lots of time replumbing ch systems and fault finding rented property stuff 😀

If there’s a pressure guage you should see the guage dip or rise when the pump starts.

WB low voltage fan relays fail on some models

Although if it runs for more or less 30 sec each time then cuts out it wont be that

Flame fail device cutting out? although 30 secs is too long for that
Ionisation probe wonky or thermocouple going south?

have you tired full speed ahead #3 on the pump? assuming its a variable speed motor?

Had same thing a couple of years ago. Reckon the pipework has a bit of crap blocking it. Try tapping the pipes(not too hard), mainly near the pump or boiler

Could be a faulty pump, and just because they spin at the front end doesn’t meant the impeller is spinning the other end as the shafts sometimes shear.

Also as you have vented it, you could have a blocked cold feed from the cistern, therefore the cistern would remain full but you have moved water from high spots to fill rads thus potentially starving the system of water. The cold feed will normally choke where it joins the system and can sometimes be checked with a magnet.

http://www.home-heating-systems-and-solutions.com/hydronic-heating-system-expansion-tank.html

shows correct orientation of close coupled cold feed and vent pipework arrangement. Most are not done like this and can cause problems.

Always vent off a horizontal section too, not off the vertical legs as is common practice.

Right, I’m stuck again. Pump seems to be working fine and I’ve bled it again.

Water just doesn’t seem to flow around either the HW or CH

Time to bleed the boiler again just in case

Update

Plumber came round, we pulled a load of pipes out and they were all solid with crap. Looks like years of neglect from before we bought the house. Hope my nice new boiler isn’t getting killed by it.

Learnt a new trick. Copper not being magnetic but rust from dead radiators is, a magnet soon pinpointed the problem.

Time for a power flush which is rather pricy

On a related note, anyone any experience with those in-line CH filters?
Worth it or not?

We’ve got an in-line magnetic filter on our system.
It was a joy, recently, seeing the grey sludge around the core of the filter that could have collected in the boiler’s heat exchanger.

I dread to think of the damage caused to our boiler by the sheer amount of crap in my system….

Update to finish this thread off. Had the system power flushed with no luck. Plumber cut out all the pipes and valves in the airing cupboard and put them where they were meant to be (it has a horror story in there) now boiling hot radiators and as much hot water as we needed.

Looks like a case of bad plumbing so preggo with happy now.

so preggo with happy now.

Pregnant with happiness? What a delightful phrase!

Whoops, wife that should say! But that is a nice phrase I may use at some point…

Double post!