white expansion vessel pressure

Trapeze

I have an unvented cylinder. Domestic hot and cold are pumped from a pump and tank in the attic. Vessel looses pressure over 9 or 10 months. Plumber showed me how to take pressure of the vessel and how to pump it up.

What I've forgotten is what air pressure I should put in it. Anyone know the answer to this?

BTW it's a 3 bar pump in the attic.

Kencollins

I have a similar setup and have the pressure vessel set to 2.7 bar, with the pump pressure valve set at 3 bar.

make sure the pressure vessel is disconnected from the pipe to set the pressure, if the water resists the air behind the diaphragm then the pressure will be wrong.

yannakis

Would you pump it up with a standard kind of bike pump?

By the way, do you have to drain the pressure vessel before checking the pressure?

embracingLife

https://www.boards.ie/discussion/comment/119752021#Comment_119752021

But if you disconnect the vessel from the pipe - water will come out of the pipe - unless there's a valve on pipe where it connects to the vessel - but on lots of vessels there's no valve between it and the pipe.

So it's a big job to do what you suggest.

I've come across several plumbers who pump the vessel up as its fitted, never disconnected it from the pipe. The same on boilers with the built in vessel, by plumbers and by plumbers who do service warranty work they pump the vessel as its in place.

embracingLife

https://www.boards.ie/discussion/comment/119761359#Comment_119761359

Yes bicycle pump would do but the handiest is a pump with a pressure gauge attached so you can see the pressure you putting in.

If you don't have a pump with a pressure gauge attached, an ordinary bicycle pump is not ideal as you are guessing what pressure you are putting into the vessel. (if you have strong arms like Popeye or Arnie you can use the bike pump).

Some bicycle pumps have the guage attached or a better type is the car tyre foot pump. Mostly the bike pump - provided it has a pressure gauge attached - is used on the very small vessels on shower pumps which service repairmen use.

2nd) Drain it how? Do you know what you are doing?

The "pressure" being referred to here - is air- and the vessel internally consists of two parts. One half of the vessel where its attached to the pipe is filled with water and the opposite side of the vessel is filled with air-(the two parts are separated internally by a sheet of rubber preventing both from mixing and allowing the air to be pressurised against the water) and you check the part that the air is in through the bicycle valve sticking out of the surface of the vessel.

You should have/buy an external pressure gauge (same type as you can use for car tyres) or if you have a pump with the above described valve you can check the pressure using it, by putting it on the air valve on the outside of the vessel to measure the air pressure.

Wearb

https://www.boards.ie/discussion/comment/119771498#Comment_119771498

It doesn't have to be disconnected. You just need to make sure there is no pressure at the water side.

embracingLife

Grand 👍

yannakis

Much appreciated guys. I've got a bike pump with the gauge so I'll give it a go one of these days. How can I check the pump pressure? Can't see dials or anything on my pump. It's a Walrus if that helps.

https://www.boards.ie/discussion/comment/119771533#Comment_119771533

Just to confirm I'm understanding this correctly.. Drop the fuse for the pump, turn on a tap or two to let the pressure out, and then pump the pressure vessel?

Wearb

https://www.boards.ie/discussion/comment/119777878#Comment_119777878

Probably yes. So long as no water pressure on vessel.