Pressure at 0 on Worcester 28i Junior Combi Boiler

[toshtastic]

Hi, I have recently moved into a house with the above mentioned combi boiler. My central heating and hot water all seem to run as expected, but I have recently noticed that when my central heating is off that my pressure gauge is at 0!

When I turn the heating on it goes to about 1.25.

Is this correct? I thought the heating was all in a closed loop and that the pressure should stay constant whether the heating is on or off.

Ive tried a google search to see if this is expected, everything I find makes me think its not, but the fact my heating etc all works ok makes me wonder.

Thanks in advance

PS Im a total novice with these things, but I will try and answer all replies as best I can

 

[toshtastic]

sorry, the model number is actually the 30si

told you I was a novice

 

[Agile]

The pressure should be about 1.5 cold but this will increase a litle to perhaps about 1.7 when its hot.

Assuming its the dial gauge you are reading then it implies that the expansion vessel may be at fault.

See the FAQ to read more about it if you are the owner or call landlord if you are a tennant.

In either case it might be better to call a competent boiler engineer.

Tony

 

[toshtastic]

Thanks for your reply, I have been looking online for a manual and I found a technical spec here : http://www.worcester-bosch.co.uk/ho...boilers-and-systems/greenstar-30si/literature

Way down on p.27 it talks about the cold water pressure operating at 0.2, does this mean that when its not in use then the pressure will naturally be low?

Thanks again

 

[Agile]

You are reading too much!

Thats just the minimum incoming pressure for the mains cold supply.

Tony

 

[toshtastic]

yeah, I probably am, but I just dont want to call someone out when its just something daft.

plus I am new to this kind of thing so im trying to find out as much as possible.

Sorry to keep being a pain, but I have a few pipes going to the boiler, 2 of these have an on/off valve on them and one of those is off.

From what I understand, I turn one of these on to pressurise the system - do you know what the other is for?

They both look very similar and they both have a sort of flexible silver piping on them too.

I dont have a manual for this boiler - hence my dumb questions

Thanks

 

[Agile]

I dont want to make any wrong guesses.

If you can take and post a picture of your pipework we can tell you.

Tony

 

[CrazyAMonkey]

My boiler is the 28i Junior and it too runs low on pressure. When it is operating constantly it runs around 1.5 - 2Bar but when it turns off the pressure reduces too 0. I have topped the system up twice, bleed the radiators and examined for leaks but i cant find any. I called a boiler tech out to take a look as the house is only 6 months old and he said 'if it works just live with it'. That's not my philosophy as 1 week after the warranty runs out it will blow up. Does anyone know if it is a quirk of these boilers or something more sinister?

Cheers,
Ewan

P.S. Tosh I assume those valves/braided metal hose assembly is your boiler filling mechanism. You need to open one valve then open then second whilst watching your pressure gauge. Stop when needle hits one bar. Don't forget to close both valves.
**** I am not a plumber - its just my opinion! ****

 

[toshtastic]

CrazyAMonkey,

I got someone out who works for british gas to look at my boiler and he couldnt find anything wrong with it either. He did get me to test the boiler though by turning off two feeds and the heating for 24 hours, but to still use the hot water during that time.

I did that and the pressure didnt drop, so that basically indicates a leak - which I cannot find anywhere.

I have one other possible place to check for leaks as my pipes upstairs look as if they run directly under some screws - there could be a problem there, but I see nothing on the ceiling underneath

At the minute im the same as you, everything works fine, but the pressure drops and I cant find a leak!

PS to turn off the feeds I was talking about you simply use a flat head screw driver to turn the two screws at the top of your furthest apart pipes (i.e. far left & right). they only turn about 90 degrees - I assume your boiler is the same

 

[Agile]

Have you put something over the pressure relief valve vent to see if thats leaking?

To me it sounds as if the expansion vessel may be failed or need recharging.

Tony

 

[toshtastic]

is the pressure release valve the pipe that feeds outside? If so then I havent put anything over it - the weather has been nuts and wasnt much point. Although when I did inspect it, it was bone dry

If the valve is under the boiler then I have towels and stuff there and they are all dry, so I dont think there is a leak there either

 

[Agile]

is the pressure release valve the pipe that feeds outside? If so then I havent put anything over it - the weather has been nuts and wasnt much point. Although when I did inspect it, it was bone dry

Thats why you have to put a baloon over it and inspect after a full day or so of boiler operation.

Tony

 

[toshtastic]

ok thanks, Ill give that a try

Thanks