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Heating help


Active Member
Hi All,

Can you recommend something before I call out an authorised engineer - hopefully it's something simple that won't cost me a penny!?

I moved out last week to have my flooring done, and the contractors decided to play with my boiler, and leave the heating on all night to dry out the concrete I presume?

Anyway, when I moved back - I can still get heating, but no longer hot water?

It's a combi boiler, with 2 dials - one for the temperate of the taps (currently set to midway), and the 2nd dial for the radiators - there's 2 symbols, one being a snow flake, and the other which looks like a sun...this dial also has the temperate gauge.

When reading the instructions, it tells me to put it to the sun like symbol, and the thermo stat set to on (I've set it to auto) and the flame lights up on my thermo stat, but when I run the hot water tap nothing.

The only way I can get my radiators to run is to set the dial to the temperate gauge.

Also, not sure if it matters, but my temp gauge is about midway (I can't remember the exact figure) but the pressure is zero!

What am I missing? Sorry I don't know the make of my boiler at the mo...


Distinguished Member
Had they turned off the tap at the tank upstairs as well as the main inlet possibly?

Have you bled the radiators?


Distinguished Member
Doesn't sound right that the pressure is at zero. Would normally expect a boiler to be operating around 1-1.5 bar. having said this, yours may be some kind of special boiler...

I have a mate who's a gas engineer - will be seeing him tonight. Presuming you haven't had a response before then, I'll ask him later.


Distinguished Member
It's that zero pressure reading which is doing it. To give instant hot water at the taps, a combi boiler feeds them from a small internal pressurised tank, which is kept hot.

Without being able to see the actual boiler, I can't advise exactly, but the pressure gauge should have green and red sectors; the needle should be in the green.

There should be something like a tap near the gauges which you hold on to pressurise the system.

Do you have the instruction manual? It should tell you what to do. What make & model is the boiler?


Active Member
Thanks for the replies - I thought it might have something to do with the pressure.

I don't have the manual, but i'll have a look online tonight to see if it's simple to re-pressurise, and give it a go...if i don't reply, i've blown myself up :D


Active Member
My boiler has 2 valves underneath it (looking up underneath the boiler). If I open both, the pressure level goes up...see if you have these. My vales are two small grey taps.


Well-known Member
As said, look for the filling loop (two check valves or little taps) under/near/next to the boiler. When cold pressure is usually 1bar. One questions is why is it at zero as it's a sealed system. This could mean a leak in the central heating system. Just be on the look out for a wet patch somewhere ;)


Distinguished Member
Probably a radiator that needs bleeding, put some extra pressure in it with the taps and it will probably sort itself out.


On some systems the filling loop is not left permanently in place, so if you find those little taps, make sure there is a small hose running between them.

A photo of the underside of your boiler showing the pipework would be of great help.

It's possible that after cranking up the system to help dry out the flat that the builders turned something off that they shouldn't have.


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