advice needed with expansion vessel

[mark_mc]

have a sealed system with a exposed vessel, brand new. the incoming mains pressure is only 0.5bar so will only charge the vessel/heating to 0.5bar. can i pump air into the vessel to increase the pressure in the vessel to the recommended pressure of 1bar?
all radiators are full of water and working but is 0.5bar ok?

 

[tackleburger]

.5 bar it has to be mate it should be equal to the heating system pressure or it wont be as effective.

 

[migoplumber]

the size of the expansion vessel, depends totally on the closed circuit it is connected to, with respect to water volume. need more information.

 

[mark_mc]

its a 18litre expansion vessel, connected to a grant 70-90,000btu condensing boiler. can i put more air into the expansion vessel to increase the pre-charge?

 

[tackleburger]

I am assuming the vessel is the correct size.

 

[migoplumber]

is it connected to your primary circuit ? - it should be.
how many rads ? is it a standard house installation ??

tackleburger - your totally right, however nothing was stated, so i assumed the worst.

 

[mark_mc]

yes the vessel is correct, can someone just tell me can you put more air in the vessel to increase the pressure????

there is 8-9 rads. its on my primary circuit. please can someone tell me can i pump more air the vessel to increase the pressure/charge in the vessel, cause i cant fill more water in as the mains pressure is only 0.5bar

sorry and its a standard house installation 2 storey

 

[migoplumber]

if you simply want to pressurise your expansion vessel, then find the nipple on it, connect a bicycle foot pump and pump away

 

[jono44]

Hi Mate, If i'm reading this right and you want to increase the pressure within the circuit to a boiler manufacturer specification and your incoming pressure is inadequate to raise it above 0.5 bar then you can't just add more pressure to expansin vessel (you need to keep it at specified pressure) The only suggestion I could make would be to pump the pressure via the filling loop with a hydraulic test pump (not air) and then close off the isolation valves and "Hey presto" If you're the installer and have access to a pump its easy if not then you may need to create a head of pressure and fill it some other way.
Jon.

 

[migoplumber]

well done jono for picking that one up. easy when you re-read the question and thanks to you know the answer !!
cheers

 

[mark_mc]

thanks lad, done that already with the test pump when i installed the boiler. its just the customer rang me up the other day saying he took of a rad to decorate and cant it back up to pressure 1.5bar only can get it to 0.5bar, was just wondering can you put more air into the vessel but i cant, great to know. will go someday this week and pump with test pump again.

 

[Plucky]

You dont need more air in you need more water