Low pressure reading on combi boiler

Bogof_Babe

I have a Worcester Greenstar 24i Junior condensing combi boiler in my flat, almost four years since it was installed. It has been serviced annually and I've had no trouble with it.

However I noticed just now that the water from the kitchen tap wasn't as hot as it should be, and on checking, the pressure needle is just into the (low) warning area on the dial.

On reading the leaflet that came with the boiler it says:-

"This appliance is fitted to a sealed heating system which is pre-pressurised. Your installer will advise you of the minimum and maximum pressure which should be indicated on the pressure gauge.

Check regularly that the pressure is maintained and contact your installer or maintenance engineer if a permanent significant drop in pressure is indicated on the pressure gauge. If the system loses pressure it should be re-pressurised and the cause of the fall investigated."

Does this mean I shouldn't top it up myself? I can just about access the pipework and tap although it means removing a false wall panel, and used to have to do it regularly with my old boiler, but as this is a "sealed system" should I leave it to an expert? My annual service isn't due for a couple of months so I didn't want to pay for an unnecessary call-out if avoidable.

Yorksboy

Hi

I think that Greenstars have a built I filling loop. Have a check I the manual, if you don't have it you an download from the Worchester Bosch website.

Low pressure In the heating system doesn't usually mean low pressure in the domestic hot water, but in the first instance I would top up the system and see. If you are not confident with these sort of things get. Your service engineer in, ask. Them to show you how to top up etc

andygb

Our Worcester Bosch combi works best off about 2 Bar pressure, and if it drops below 1 Bar then the water takes a while to heat. I find it quite simple to pressurise (every year, just needs a little bit added), but others may be intimidated. For those who are unsure, then it may be worthwhile looking for a local, reliable plumber.

keystone

The pressure reading on the pressure guage has absolutely nothing, zero, zilch to do with the DHW. Its the pressure of the heating side.

For the DHW water is drawn directly from the main, heated and delivered to your taps.

If the hot water temperature has gone down that implies some sort blockage in the HW heat exchanger.

I'd bring the service forward and get both sorted.

Cheers

Bogof_Babe

Thanks everyone. The heating seems to be working fine, although I've only had it on for half an hour a day at the moment.

Checked again this morning and the reading is still just below 1, when I believe it should be around 2. I'll give my usual guy a call, don't want problems when the cold weather really kicks in.

I'd hoped for a few more years of good service from this boiler as it's still comparatively new.

gas4you

Just because the pressure has dropped slightly doesn't necessarily mean there is a fault with the boiler.

It is quite common to have to top up sealed systems 2 or 3 times a year.
If it was monthly or weekly then you would have a problem somewhere.

Check your instructions as said, because you don't want to pay a call out for a simple topping up. Top it up to about 1.5 Bar.

Keystone, as per usual you are correct, but if the system pressure drops, it can cause problems with the boiler operating for DHW due to it affecting the pressure sensor.

I think the junior will have an external filling loop IIRC.

Norman_Castle

When you have it serviced ask for instruction on how to top it up.