Roca Combi boiler. When heating is on, which includes the hot water, the pressure in the boiler will go over the 3 bar mark and shut the boiler off. I have to drain least 2 .5 litres.

Combi-boiler-turn hot water tap on/off and the heating stops for ...

singletrackworld.com/.../combi-boiler-turn-hot-water-tap-onoff-and-the-...

Combi-boiler-turn hot water tap on/off and the heating stops for 20secs ... hot watertakes priority over central heating so when you run the hot tap, heating is ... Yeah onmy worcester combi there is a diverter valve - it feeds either the heating or ...

My central heating works but I have no hot water - 24'7 ...

https://www.247homerescue.co.uk/my-central-heating-works-but-i-have-...

Diverter valves switch heat between the hot water and the central heating. When youturn your hot tap on, the diverter valve temporarily shuts off the water supply ...

Does your boiler keep switching itself off? Here's why ...

www.dhs-uk.com/does-your-boiler-keep-switching-itself-off-heres-why/

Jul 7, 2015 - ... Bathroom Suites, - Showers, - Wet Rooms, - Taps and Accessories, Information and ... Low water pressure can cause your boiler to turn itself off. ... boiler is not turning off, you aren't getting the amount of hot water you require. ... If there is air in your central heating system, then your boiler may shut down.

The water isn't maintained hot (unless the central heating is on) in a combi boiler. you will, therefore have to turn the water on, which activates the burner. The burner will then have to heat up the heat-exchanger which then supplies the hot water through cold pipes. Once the pipes are warm, you will receive hot water.

Your boiler has an expansion vessel that is like a bladder full of air. Yours has lost it's air pressure. Check your manual for this vessel and where the valve is to re-inflate it and what pressure to inflate to. It should have a simple tyre valve, pump it back up (usually to about 1 bar after releasing the water pressure) and should be all fixed. If you can't re-inflate the bladder is holed and the expansion vessel will need replacing.

check tops of spindles at radiator valves for leaks easy repaired set pressure to .8bar setting at 1.5 may be make overpressure and blow off through high/pressure releasese valve

if your boiler is a combi re-pressurise locate filling loop and refere to manual

on the pipework below there may be a silver braided hose with one or two valves on the end. turn the valve(s) so the handle is inline with the pipe this will allow water from the mains supply into the heating circuit , remember to keep an eye on the pressure gauge. fill the system to 1bar cold then shut down the valve(s). turn on the boiler and it should be ok, if you lose pressure again then you may have a leak somewhere which needs to be found.

The first thing you need to do is to put some more water into your heating system. This is usually done by allowing water from your (pressurised) domestic cold water supply to flow into the system: On older boilers, this is done with a connection (often made with a removable hose) on the pipework just outside the boiler. Newer boilers may have a built-in connection with some sort of removable link (sometimes looks like a plastic key).

Once you've got the boiler up to working pressure (typically about 1 bar - 15 psi), you should be able to bleed your upstairs radiator properly.

This may be all it takes, though the pressure excursions you're getting when you run the hot tap suggest there may be another problem. See what happens to the pressure as the boiler heats up and cools down. There really ought to be very little pressure difference between the two conditions. If you see significant changes, this usually means that the "pressure vessel" (or in hydraulic terms, system accumulaor) has lost its air charge.

The pressure vessel is a metal container inside the boiler, usually painted in red enamel. Somewhere near the top, you will find a schrader valve (like the one on a car tyre), and you can use this along with a tyre pump to replenish the air in the top of the vessel. This will reduce your pressure transients for a while, but you need to keep an eye on it. If the problem returns, you probably need to replace the pressure vessel (or clag another one into the plumbing alongside the boiler).

A.

Hi Leehardcast,

Yes the problems are related. The system is low on water. So now instead of water you have air in radiators which is easily compressed when it heats up. Then pressure loss when it cools down.

Add some water to your system until you have 15lb pressure and bleed out upstairs radiators at the same time.

Please rate this response and Good luck, Phil

replace pressure release valve

is this a baxi 105? chances are you diaphragm has gone on your diverter valve. Or your diverter valve.
Do you will initially get a liitle hot water if your heating is on?