Anyone know anything about combi boilers?

We have a combi in the loft at home which was fitted feb last year by British Gas (previous owners removed night storage and had gas c/h fitted). We're having some issues with it now though - hot taps on their own are fine but if you also turn on cold, the hot tap pressure drops and the water goes stone cold. And the boiler makes some nasty sounding noises lol

I thought it might be pressure related, possibly the cold forcing its way back through the hot pipes somewhere so will check the gauge later tonight. Any other things i should check as well?

annoyingly and very unsurprisingly the BG 5yr warranty isn't worth the paper its written on as they say thats only valid with the people who lived here before :roll:

We had a similair problem. Couldn't tell you exactly what it was. But something to do with a pcb board inside that they replaced. Probably no help but worth an investigate.

Check the water pressure Guage. Believe it could be as simple as that. Needs to be around 2psi I think from last checking mine. I have a loop on mine so the system can be topped up if I bleed the rads etc and that raises the pressure.

1.6- NO more than 2bar
turbojolts ya man for this though

He really isn't lol

Does sound like a water supply issue anytime a boilers pressure runs low you get that grumbling noise! Is it shitting water out of the overflow?

Just had a quick look yesterday. Soooo if the pressure gauge reads 0 then I guess thats a bad thing? lol

I've just read mine and I'm on 1 bar psi. I said max 2 bar but now believe it should be 1.5 really. I'm running an ideal logic combi. Sounds like you need to ad pressure to it. Must be a pipe linked to the system to do this?

Yer 0 isn't ideal lol

There should be a procedure for pressurising the system

Different models vary, Google your model, normally easy to do
Mines done by opening a valve with a flat blade screwdriver
Any fault codes on the display?

Ok. There is always a pressure boost tap. But it sounds like your supply pressure is too low.

Mines is in the attic too 1.5 is good. There should be a filling loop. With it being in the attic I have to top up every 3 to 6 months. Just with it having to travel so far. But TJ will beable to confirm. Mine was fitted last January and toppex it up twice.

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Originally Posted by Shamish82

Mines is in the attic too 1.5 is good. There should be a filling loop. With it being in the attic I have to top up every 3 to 6 months. Just with it having to travel so far. But TJ will beable to confirm. Mine was fitted last January and toppex it up twice.

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That isnt right....
I know my boiler is limping along and I have to fill that twice a year.
A nice new one shouldnt need touching for atleast a year at a time.

The things I've changed on mine to slowly get it back to health:
Expansion vessel - replacement for it = £150 + time to tear the whole thing apart... OR fitted £20 external expansiono kit and plumbed it to the original locaion :D
Divertor valve service kit
divertor valve actuator

IT does need a new pump, new heat exchanger and new pressure relief valve as once those go off they leak.

Jack you'd probably want a new PRV as a matter of course and then keep an eye on things

My 'new' (probably 6 years old lol) combi boiler needs a slight pressure top up every 12-18months. And by slight I mean 0.1-0.2.

Doesn't sound right to need to top it up every 3-6 months.

It's a Worcester, they have a handy troubleshooting thing on their site which shows how to re-pressurize various models, so managed that quite easily and set it to just over 1.5bar. Will check it again in a week or so to see if its holding Ok but its certainly fixed the heat and noise problems for now

Regular falls can indicate a weep somewhere

And or a shagged expansion vessel leading to the pressure relief valve blowing it's guts out

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Originally Posted by Stuart

And or a shagged expansion vessel leading to the pressure relief valve blowing it's guts out

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This. You can normally see if it's been happening especially on a regular badis as it leaves marks on the wall and ground

Get an engineer out to give it a once over, you don't want pressure in the system or a lack in your case or it might cost more, might just need a decent service and flushing through as well.