Boiler Pressure

[Bashy]

Hi peeps

Our combi boiler has an adjustable red mark for the presure, this red mark is set to 1bar but when the heating ion the gauge goes to 2bar, is this right?

[tango232]

you will need to check the manual for your boiler as it should be left with the boiler so anyone that comes to your house can service it corectly, it may be that it is set to high but without the book you can not tell, if there is no book have a look on the manufactures web site for the details as it should give you it

[Bashy]

Cheers Tango...

Just checked the manual and it says MAX 2.5 so it's within parameters..
Phew....

[baztheman]

hi m8 my combi chaffatoe (celtic FF) has a pressure range od 1 bar to 3 and my pressure drops now and again which causes the combi to go on strike if it drops below 1 bar,all i do is give it a shot of water to 1.5 bar as the fill loop is still connected ....baz

[Bashy]

I think mine is now just under 2 bar....red lines at 2 lol

[nik0038]

Just moved in a newly built property and my combi boiler pressure reads just under 2 bar and i think it should be between 2.5 bar and 1 bar, but should never drop below 0.5 bar. If it does, your boiler will stop working and you will have to reset it. Refer to your boiler manual for resetting the boiler.

[shilusat]

hi m8 my combi chaffatoe (celtic FF) has a pressure range od 1 bar to 3 and my pressure drops now and again which causes the combi to go on strike if it drops below 1 bar,all i do is give it a shot of water to 1.5 bar as the fill loop is still connected ....baz

Ah!ha! This seems to be as a result of a leakage in your radiator pipes. Check the ceiling for staining. If there is no staining you may have a leak on the underfloor pipes.
Before you go removing the floor boards, check the radiators... there may be a leakage at the valves or at the vents.

Hope this helps

[timeless]

Hi Bashy it is normal for the sealed loop pressure to rise when the boiler is active. when the boiler is inactive ie when it is cooled down the water pressure should drop down to 1to 1.5bar approx. if it is below that you need to top it up via your filling loop. if you regularly need to keep topping it up the expansion vessel may need replacing....hope this helps mate

[dolly]

I think the red bar will be adjustable, this is just used as a guide, if you set it at what the preassure is then you will be able to tell if you are loosing preasure or not

[theater]

A little explaination just to give people who don't know, a little insight into the function of an expansion vessel (pressure vessel) these are not used solely in combi boilers but that is where must people will come across them.

In a traditional heating system you would have had a small tank probably in the attic which took up the expansion of water within the system when the water was heated and allowed water to flow back into the system as the water cooled (feed and expansion tank more commonly called the F and E tank).

One of the advantages of a comi boiler is to do away with the need for tanks in the attic and the subsequent pipework by feeding cold water direct from the mains rather than via a cold water storage tank and a hot water cylinder (calorifier) and use of an expansion vessel instead of the F&E tank.

Inside the expansion vessel is something similar to a balloon which is pressurised with air (should have been checked for pressure at the time of installation and you should never have to touch this) when the system is filled with water (system cold) the water pressure is usually set to between 1 - 1.5 bar though this can also vary depending on the type of property eg single story 2 story, 3 story.

As the system heats up the water expands and this expansion is taken up within the expansion vessel by compressing the "balloon" within, and an increase in pressure will be noted on the dial. There is a pressure relief valve fitted to the system usually set to 3 bar which protects the system from over pressurisation should a fault occure you will usually be able to see the pipe for this going from the boiler direct to outside.

The most usual faults leading to pressure loss are a leak somewhere on the system on a joint, radiator etc.........
the pressure relief valve passing this can usually be seen by water dripping from the pipe outside.
Failure of the expansion vessel where the "balloon" inside has burst and there is therefore nowhere for the expanding water to go. this will usually cause your system pressure to go over 3 bar when it is hot and the pressure relief valve will then operate to let out the extra pressure, but then when the system cools there is a shortage of water within the system which results in a low pressure reading. If you feel confident enough you can test this. You will need to locate the schrader valve (looks like the valve on a car tyre) on the expansion vessel. If you very very briefly depress this you should get air out (don't let out too much pressure) if you get water then it has failed and requires replacing.

There are other things which may cause loss of pressure or over pressure but the above are the simplest and most common.

Hope this is of some assistance to people but remember if you don't feel 100% confident or competent get an engineer to look at it for you, may cost you a few quid but could be a lot less expensive than messing something up yourself.

[ponyness]

combi and condensing as a rule have the safety valve set at 3bar presure fluctuates with temp as long as its around 1 bar cold and doesnt get up to 3 when hot it should be ok obvoiusly if the safety valve lifts you will lose some pressure and will have to keep topping up until you find the problem.:jiggy: