Range Tribune Combi Boiler Not Heating Water / Rads - HELP!

Alter_ego

Pump could be running but  the impeller not turning with the shaft - sheared key etc.

Sharons1987

Oh sugar sorry not sure why they wont open! Yes sorry i misnamed it! The 'plate' i meant the flat metal looking plate inside the white "box" on the top left of pic 1! In terms of valves they're def moving freely! One additional 'development' - there is an immersion switch on the wall, had it on for hot water for a bath, post bath and after it had been off for about an hour, i switch the heating on via the thermostat, immediately top corner of rads warmed up so thnking the water is getting too them, but within 2 minutes they'd all gone entirely cold again! baffled! presume i need a heat engineer to come (again)!

Sharons1987

Alter_ego said:

Pump could be running but  the impeller not turning with the shaft - sheared key etc.

Update - opened pump tested and the thing inside is moving freely 

Tallerdave

Sharons1987 said:

Alter_ego said:

Pump could be running but  the impeller not turning with the shaft - sheared key etc.

Update - opened pump tested and the thing inside is moving freely 

You mean you removed the pump and saw the impeller turning?

It's hard to diagnose other than being there.  When the programmer calls for heat from the boiler on the wall, one of the pipes from the boiler should get scalding hot and you should be able to trace that heat around pipes and through whichever valve is open for radiators or hot water. Ultimately the water returns to the boiler via the other pipe which will be scaldy hot but not quite as hot as the other pipe. Where the hot water does and doesn't go is your clue as to what's wrong.

tim_p

Sharons1987 said:

Alter_ego said:

Pump could be running but  the impeller not turning with the shaft - sheared key etc.

Update - opened pump tested and the thing inside is moving freely 

Something else to check for (from personal experience) is that the flutes and passages on the impeller are not blocked. We had a pump where the impeller was free to turn (and visibly turning behind a removable cap) but not moving water due to being blocked. Removed the pump and cleaned the impeller and all was well again for a few more years. 

Sharons1987

Thank you both!! @Tallerdave I’ll run the heat and try to trace and see abs @tim_p that could well be an issue - possibly beyond my skill level to get into any more tinkering but I’ll call in the professionals now I think! thank you so much for your guidance!

tim_p

I think the key thing to look at is to see where the point of failure is. If you’ve got hot water one side of a valve but not the other then that valve is suspect or the switching of it. It’s common for such valves to ‘fail’ after a summer of no use, as happens to me when I forget to run the system every few weeks, hence my earlier comment of giving it a clonk. A bit of detective works goes a long way in these sorts of problems. 

Sharons1987

Update on how this ended up: paid for a repair (408 pounds ouch) - turns out it was the heat exchanger that was completely blocked with dirt coming from the communal boiler / building side and no flow coming through - had it flushed, rads working as normal now) *not sure if i could try to get some of this back from building owner as fault on their side not mine but thats an aside. 

However while he was there i mentioned the boiler was firing up even when thermostat was on off - he checked and confirmed the 'water' motorised valve was moving freely on appearance but the signal was stuck on on to the system so was always calling for hot water. Have been quoted 380 pounds for parts and labour to replace (danfoss hpa2) - does that sounds reasonable?

Sharons1987

Sharons1987 said:

Update on how this ended up: paid for a repair (408 pounds ouch) - turns out it was the heat exchanger that was completely blocked with dirt coming from the communal boiler / building side and no flow coming through - had it flushed, rads working as normal now) *not sure if i could try to get some of this back from building owner as fault on their side not mine but thats an aside. 

However while he was there i mentioned the boiler was firing up even when thermostat was on off - he checked and confirmed the 'water' motorised valve was moving freely on appearance but the signal was stuck on on to the system so was always calling for hot water. Have been quoted 380 pounds for parts and labour to replace (danfoss hpa2) - does that sounds reasonable?

Just to add the valve itself seems fine to move but the actuator needs replacing maybe (microswitcher?) 2 hours work to replace the one valve is what’s quoted - appreciate any last thoughts before I add up to a 800 plus total spend on this damn boiler system 😭

Tallerdave

A quick Google shows the actuator is £30-£40, so it sounds pricey. Maybe phone around for a couple of quotes?