Boiler pressure drops but no adverse effects.

Joined
10 Dec 2005
Messages
16
Reaction score
0
Location
Leeds
Country
United Kingdom
Hello,

I noticed last week that the pressure on my combi was at zero.

I topped it up and left it.

This morning I noticed it at zero again, so I topped it up.

This afternoon its on zero, which makes me think its been on zero for some time.

The strange thing is, the thing seems to operate just fine, plenty of hot water and heat.

Should I be concerned?[/b]
 
Sponsored Links
Joined
22 Jan 2007
Messages
7,086
Reaction score
1,229
Country
United Kingdom
Best get it sorted, not a good idea to keep topping it up. Probably just enough pressure to keep the boiler going.
 
Joined
8 Sep 2011
Messages
125
Reaction score
12
Location
Nottinghamshire
Country
United Kingdom
you've either got a leak or a busted expansion vessel.

refill to your 1 / 1.5 bar, leave the heating & hot water off (give it an hour), if it steadily declines while cold then you've got a leak somewhere, fix this first!

if it stays put, get the heating on , keep an eye on the pressure,
if it goes up to about 2.5 / 3 bar then the boilers expansion vessel will need recharging or replacing.
(the excess pressure will be let off by the pressure relief valve, and you should have water exiting the building, normally a copper run outside that could be tee'd into the wall)
 
Joined
10 Dec 2005
Messages
16
Reaction score
0
Location
Leeds
Country
United Kingdom
you've either got a leak or a busted expansion vessel.

refill to your 1 / 1.5 bar, leave the heating & hot water off (give it an hour), if it steadily declines while cold then you've got a leak somewhere, fix this first!

if it stays put, get the heating on , keep an eye on the pressure,
if it goes up to about 2.5 / 3 bar then the boilers expansion vessel will need recharging or replacing.
(the excess pressure will be let off by the pressure relief valve, and you should have water exiting the building, normally a copper run outside that could be tee'd into the wall)


Thanks very much for this.

I did notice the pressure on 3 bar today when the heating was on.

I'll try your procedure tomorrow and let you know.
 
Joined
10 Dec 2005
Messages
16
Reaction score
0
Location
Leeds
Country
United Kingdom
I followed the above procedure,

Went up to 3 bar with heating on with water dripping from the copper pipe outside.

So i'm looking to recharge my expansion vessel?
 
Sponsored Links
Joined
7 Feb 2008
Messages
23,730
Reaction score
4,738
Location
Northumberland
Country
United Kingdom
As a general test, if the air inlet valve on the EV sprays water when you press it (car schrader valve type) the EV is goosed.
With the boiler pressure at zero, pump air into the EV to around 10 psi or whatever the manual says. Its a good idea to disconnect the flexible water pipe to the EV when you do this.
When reconnected, use the filling loop to bring the boiler pressure up to about 1 bar - turn the heating on, and the pressure should rise to 1 1/3 bar, and then back down again with the heating off.
John :)
 
Joined
6 Mar 2003
Messages
2,328
Reaction score
134
Location
Manchester
Country
United Kingdom
Yes and make sure there is no water in the vessel.
A vessel half full with water having the correct pressure 0.8bar still can't do what's it's supposed to do.
You'll may also find after fixing the vessel problem that the PRV does not seal properly and that also needs replacing or cleaning (if you can get it apart)
 
Joined
10 Dec 2005
Messages
16
Reaction score
0
Location
Leeds
Country
United Kingdom
ok,

If the boiler carries on giving out heat and hot water, do i need replace the vessel (if its broken)?
 
Joined
7 Feb 2008
Messages
23,730
Reaction score
4,738
Location
Northumberland
Country
United Kingdom
Yes for two reasons really - its a safety device as yours is a sealed system, and you don't want to be introducing fresh water at all - it will start corrosion.
John :)
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top