Oil combi not giving hot water

Matt789 · 15 Apr 2010

Hi all, I’ve been having to re-do the majority of the pipework to the upstairs of my house and most recently have had to cut the heating circuit pipes a couple of meters from the boiler. As I’m also having to live in the place while this goes on understandably hot water would be a bonus, so selected just hot water on the boiler and gave it a shot, on starting up the central heating pump kicks in regardless and so there was bit of a spillage – they’re now both capped with stop ends, pressure is good, no leaks, however the boiler isn’t firing up for hot water on demand. I did take advice from a boiler engineer before trying however he’s not an oil man.
Would it seem likely to have locked out? I remember my boiler serviceman saying there was a bleed valve on top of the boiler which I’m assuming I could use to release any air however I’m not now sure which section it was on!

Any help gratefully received, thanks

Boilerman2 · 17 Apr 2010

What make and Model Boiler is it, please reply so i can help

Matt789 · 17 Apr 2010

hey boilerman thanks for the reply
so happens im in tonight but had some wine so if i slip into incoherance you know why

its a worcester bosch heatslave 15/19 between 10 and 15 years old on a sealed system
I had brought it down to their being air it the heating circuit and it needing flushing out..would that seem along the right lines you think?

picasso · 17 Apr 2010

I havent any manuals on oil boilers but if you started the boiler with no water in it , the overheat stat has probably tripped, perhaps boilerman2 has the manual for your boiler.

tamz · 17 Apr 2010

You need to fill the heating side before you can get water.
Put 2 valves on the flow and returns then loop them together using a bit plastic if needbe.
This will let you pressurise the "heating" (loop of pipe) and let the boiler work for hot water.

Matt789 · 17 Apr 2010

so once the central heating feeds are in a loop all should be good again

tamz · 17 Apr 2010

picasso · 17 Apr 2010

I thought you had capped the flow and return and repressurised the system

as in "they’re now both capped with stop ends, pressure is good, no leaks".

Matt789 · 18 Apr 2010

yup correct picasso
whats more only flow and return to the upstairs is capped and the rest is as it was and in a loop so if it were the problem you'd expect it t be getting some draw from that

Boilerman2 · 18 Apr 2010

Underneath the Boiler Facia panel, you will see a dark red button - give it a press, this will reset the overheat, make sure the controls are set to Hot Water Only, as the heating pipes have been dissed and capped, however the hot water store and function should be un-effected by this

Matt789 · 19 Apr 2010

thanks boilerman i have tried, boiler fires up and all sounds well however on turning on the hot water there's no warmth there as you'd expect after a startup and it still doesn't fire up on requesting hot water..how does this work on a sealed system? because there has seemed to be a reduction in water pressure (despite it now being at 2 bar after heating on startup) so it seems like its not hitting its quotas which makes me wonder if something needs bleeding

thanks again people

Matt789 · 7 May 2010

I'm not sure if anyone will still be following this thread but I have all pipework back and have flushed the system - now leaving me with a kettling boiler! (although it did at times before)

From posts that i'm seeing i should be looking at getting a version of Fernox's treatment, F1, F2 or F3 does anyone have strong opinions?

Also when you flush your heating circuit people say do it till it runs clear should this also apply to any air bubbles? Thanks

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Oil combi not giving hot water

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