Worcester Bosch 24 cdi DHW fault. (still)

[ukdan]

Hi fellas.
I had a problem a while ago with the flame for the DHW going out and coming back on again. The advice i was given was that the plate h/e could be blocked. I eventually got a new h/e and fitted it today. However, the problem is still there. Where would i go next? Just to add, i changed the diverter valve about 3 years ago du e to the diaphragm breaking up.

Many thanks in advance

Neill

 

[OLLIE20]

Who told you to replace the plate heat exchanger, do you get any flasjing lights when hot water going on/ off if not i would guess your diaphragm has gone again, 3 years isnt uncommon, when its going on/off does the hw demand light (red) stay on, by the way you can get the diaphragm seperate which i a hell of a lot cheaper than complete div valve

 

[ukdan]

Hi Ollie

i was advised to try cleaning out the old h/e but when that didn't work i bought a new one. When the DHW is on it runs fine for a few minutes then the flame and the flame light go out and come back on in about 10 seconds. The pressure gauge on the front flicks down by about 0.2 of a bar when the flame comes back on then settles back to its original spot. the demand light stays on all the time. it's just the flame light that goes out. You think its worth getting a new diaphragm then? I need to get this sorted cos i've got a housefull of women over the weekend and i don't need the hassle.

Cheers again

neill

 

[OLLIE20]

If demand ligh is staying on i wouldnt bother to be honest pal, that would suggest diaphragm and micrswitch working as it should, it does sound as if its getting to temp and shutting down, hard to say without being infront of it, could do with taking some temp readings and b.p. to see modulation etc etc , is the CH ok

 

[ukdan]

Central heating seems fine. Not had it on too much but when we have it seems to be working properly.

 

[OLLIE20]

Like i said pal would prob need to be stood in front of this myself, not allowed to advise to do the checks on this site as its d.i.y. gas, but i would tale front pff see if it makes any differance, if it did i would clean fan and venturi, as if it stayed on without it would indicate an airflow fault, but they usually lockout for that fault, and flash 5 times a sec i think

Does sound like its getting to temp and shutting down, is the water hot when it shuts down and then runs cold before it comes back on

Did you get rid of the air when you replaced the plate he

 

[ukdan]

it feels like the water heats up more before it goes cold, when the flame goes out.

So, when you say get rid of the air, i didn't do that. Is there a way to bleed the air out of the DHW? How would i go about that?

Thanks for your time, Ollie.

 

[Agile]

The pressure gauge movement implies the pump is being deactivated.

That gives me a clue but I could only mention that to registered gas engineer.

As far as I recall there is no DHW temperature dial but if there is one then try turning it down a bit.

Tony

 

[ukdan]

I've got the DHW temperature dial set at about 1 and a half and the CH dial set about the same. Although it doesn't seem to have any effect wherever i put the dial. I'm going to get a service engineer out to have a look and give it a clean out. I think i need the gas pressure coming out of the gas valve looking at too.

 

[OLLIE20]

If there is air in, the auto vent is on top left of boiler (on top) has a black cap amkesure its loose or just take it right off and give the valve a poke with a screwdriver to makesure its shot its air

 

[boilerdoktor]

sounds to me like your g/v isn't modulating down if you have put a new plate h/ex on it! you need someone qualified to do this>

 

[ukdan]

thanks for all the help fellas. But what is a g/v when its at home?

 

[boilerdoktor]

gas valve

 

[ukdan]

Ahh, right. The gas valve is only about a year old. I've got someone coming on Saturday to check all my pressures and to service the boiler. We'll see what happens then.

Thanks again, fellas

Neill