When to read the dial??

[Aquaman]

Excuse me for not knowing what it is called but the dial on the central heating boiler that shows when you should top up the system with water when should you read this???

when the boiler was first fitted the engineer said it should always be at about 1.5. Now when the heating is on the needle goes past 2, but when it is off it nearly goes to 0 sometimes. I'm topping up the system (to 1.5) about once a month from the reading when the system is off and just wondering if this is right, and if I should have to fill this often??? It seems I having to do this more regularly that when the system was new (its about 4 yrs old)

Any help appreciated!

 

[D_Hailsham]

That's the pressure gauge.

It should read between 1 and 1.5 when the system is cold. The pressure will go up when the water is hot.

If you are having to top up the pressure, there is a leak somewhere in the system. Check the boiler connections and all rad valves for any signs of water seeping out.

 

[Aquaman]

Thanks for your speedy response and help. I will check about for leaks as well on your advice!

 

[Charnwood]

when should you read this???

Regularly.
I check mine about every 14 to 21 days in winter, less frequently the rest of the year.

 

[Aquaman]

OK......so when the heating is on the pressure gauge goes to MAX and into the red, and when the heating is off the pressure gauge goes below 0 and looks empty. If I top up the system this starts happening within a couple of days again.

Now I've found no leaks anywhere in the system, the only thing is it is dripping from one of the pipes outside (the leak off pipe, not the condensate)

Is there something wrong with the system?

It very frustrating

 

[Aquaman]

bump

 

[ChrisR]

Is there something wrong with the system?

Yes, there is.
It needs attention. See "boiler pressure problems" in the FAQ, wherever they buried it here.
You will quite likely need a boiler geezer.
Or a geyser geezer...

 

[MANDATE]

I reckon you have two problems to deal with.
First it appears the expansion vessel has lost some of its 'air' charge, meaning that it's partly filled with water, leaving little air for compression because of this the water pressure goes far too high and operates the 'pressure relief valve'. So you got to get rid of the water in vessel and charge vessel to 0.8 to 1bar. You will also need to pressurise water to 1bar.
When heating is on, the water expands and compresses the air. pressure should increase by about 1bar. 1 rising to 2bar or 1.5 rising to 2.5bar is ok but it should not reach 3bar, because 3bar operates the PRV.
It would appear this has already happened, but the PRV has not fully sealed when it has closed again. Cleaning the PRV is time consuming and easier to fit new.
With a leaking PRV water will be lost and pressure reduced slowly overnight and the rate of loss and pressure reduction will increase when heating is on.

 

[Aquaman]

I have monitored the pressure gauge for last two days. It is now staying at about 1.5bar when heating is on, and when the heating has been off for a few hours it is just under 1 bar (in the gap between the red and green on pressure gauge)

If I leave it till next payday and it loses all pressure while I'm out would the boiler just turn off or would it cause more expensive damage to the boiler?

 

[onlyfitidealboilers]

That's the pressure gauge.

It should read between 1 and 1.5 when the system is cold. The pressure will go up when the water is hot.

If you are having to top up the pressure, there is a leak somewhere in the system. Check the boiler connections and all rad valves for any signs of water seeping out.

Don't jump to conclusions, it may be gasing up?! Hydrogen

 

[Aquaman]

Sorry to bring this thread back to life but my problems continue.

I had someone to look at the problem. They said the Pressure vessel is OK and at the recommended pressure and that the system has no leaks. But the PRV is still leaking, but they were confused as to why the boiler is having the problems? They have gone away to speak to Worcester Tech line on Monday and report back.

The only thing they thought was they were unsure as to if a switch on the prv valve had been removed and not replaced during the last service....could this be possible??

 

[Phill Peck]

A prv doesn't have a switch on it but if it is passing(dripping) it should be replaced

When the guy checked the expansion vessel do he drain the boiler to check the pressure? I would be pretty certain that the EV has failed.

Drain the water out of a radiator but don't refil it. The air trapped in this one radiator will then work in the same way as the expansion vessel proving it has failed

 

[MANDATE]

The boiler will have problems if water leaks out of the system. the pressure will reduce and will have adverse effect any pressure switch that is needed to operate boiler.
The PRV is leaking so it needs replacing (or cleaning) The slow leak is due to sediment trapped between washer and valve seat.
But the PRV must have been opened at some stage for the above to happen.
It could have been intentional when boiler was serviced or it could have been due to an incorrectly operating expansion vessel which allowed the pressure to rise to 3bar (due to reduced volume of air in vessel)
If your happy pressure does not reach 3bar when heating is on then it would suggest expansion vessel is operating ok, but the fact is the PRV has at some time been opened and has not sealed fully on reclosing

 

[Aquaman]

Is changing the PRV an easy job?

 

[libby lou lou]

yes!