Ravenheat RSF82ET (groan...) - please can you advise..

[GH blackpool]

Hi there

I've the above combi boiler, had some issues with it December that resulted in the heat exchanger being replaced (HW flitting from hot to cold constantly).

All well since then, nice hot water, heating fine, but tonight, the hot water has just gone. It's there when you first turn the tap (I guess from residual heat in the boiler), but after a matter of seconds it goes and runs cold constantly. The boiler does fire up (though rather than instantly, it takes about 10-15secs), and stays fired up, but this isn't heating the water.

Any ideas? ALL ADVICE GRATEFULLY RECEIVED.

Many thanks

 

[gas4you]

Sounds like a diaphragm problem

 

[kevplumb]

but after a matter of seconds it goes and runs cold constantly. The boiler does fire up (though rather than instantly, it takes about 10-15secs), and stays fired up, but this isn't heating the water.

if it aint heating the water where is the heat going (clue ) white things hanging on walls

 

[GH blackpool]

Thanks guys:

2 Questions

1) What is a diaphragm problem? Other than a faulty ladies contraception...

2) Kev, are you suggesting it might be the DV? I wondered this, but the little thing inside is moving position when the hot water tap is turned, and changes back when turned off. Would a knackered DV still move the little thing inside (sorry for lack of technical terms, I've not proficient in this kind of thing really)

Thanks for the quick replies folks!

 

[gas4you]

Diaphragm in big round metal thingy with loads of screws holding together on front of DV. Does ch flow get hot when running hot tap? if so this will prove kevs diagnosis. If taking dv out might as well replace diaphragm at same time. From memory they are a bit awkward to get at in situ.

 

[GH blackpool]

I see that big round thing - is this actually part of the DV then? I've just turned off the heating to get the heating supply pipe to cool, then I'll attempt to prove Kev's theory

 

[gas4you]

it is part of it but usually it is held onto dv with grub screws or the like

 

[GH blackpool]

Right then = tested and...well...not sure.

System turned off for about 10mins, heating supply warm (not hot as before).

Hot water tap on: Boiler fires up. Heating supply pipe stays warm, but is slowly cooling still. Hot water supply pipe - cold.

Where's the heat going? It's not kettling or anything, the only pipe hot is the one to the right of the combustion chamber which bends and feeds into the top of the DV (or does it feed out into the CC? dunno how these things work...). Saying that though, it was hot but no where near as hot as it is now i've switched the heating back on.

 

[GH blackpool]

sorry guys - any ideas re the above?

 

[GH blackpool]

It was the thermistor!

 

[dan the man]

It was the thermistor!

im glad u have said this..ive just bought two thermistors as had a quick look at a ravenheat other day that had a mind of its own.. heating on when it wnats..HW intermittant..

The technical helpline- what an arsehole..so ignorant and downright rude..everytime he would say its the board..

well ill be damned if i fit the dearest part and it dosent work