Expansion vessel pressure?

Eireann81

I recently moved into a house, and the water for the house is heated by an oil boiler and solar panels. When the water is heated, the pressure increases, and water flows out the discharge pipe. I think this is an issue with the expansion vessel.

The water from the mains is supplied at approx 3 bar. Is this an indication of what the air pressure inside the expansion vessel should be charged to? From looking at the sticker on the vessel, it seems that the vessel should be charged to 1.5 bar. Is that enough considering the water pressure is 3 bar? Or, maybe I need a different expansion vessel? When I press the button in the schrader valve on top of the vessel, nothing comes out (no air or water). When the water temp exceeds about 50-55'C, water starts dripping from the discharge pipe.

I've attached photos of the system and the sticker on the expansion vessel. I've done a lot of googling and have found conflicting info. Any help is appreciated.

Wearb

Do you have a red tank anywhere? From which vessel (circulation system) is the water discharging?

Wearb

Just noticed that it’s the blue vessel that you posted a pic of. I presume this is your mains water vessel. What is the source of you mains?

Eireann81

Wearb wrote: »

Just noticed that it’s the blue vessel that you posted a pic of. I presume this is your mains water vessel. What is the source of you mains?

Yes, it's the mains vessel. The mains is fed directly from a group water scheme. There is a mains water tank but it is not used at the moment (pump is broken). I get about 3 bar pressure from the group water scheme. I've attached another photo outlining the mains water (in blue), and the discharge (in red).

Eireann81

Forgot to attach photo in previous post

Wearb

You seem to have a pressurised hotwater system. I expect that your vessel should be just under the water pressure and that the water pressure is controlled by a pressure valve. HOWEVER, this is beyond my certified ability (such pressurized hot water systems need certain qualifications afik), so wait for someone else to comment or have a plumber look at it. its too dangerous to interfere with it if you are not certain.

dathi

Eireann81 wrote: »

? O When I press the button in the schrader valve on top of the vessel, nothing comes out (no air or water).
.

the label on the blue vessel says 2006 thats 11 years old chances are that there is no air left in the expansion vessel and it needs recharging

Ajsoprano

Does your safety valve blow at 3 bar?
Is your water feed nearly 3 bar?
Does water expand when heated. Is your system working perfectly but you are feeding it 3 bar of water?

Eireann81

dathi wrote: »

the label on the blue vessel says 2006 thats 11 years old chances are that there is no air left in the expansion vessel and it needs recharging

That's what I was thinking, but wondering what pressure to charge it to.

Eireann81

Ajsoprano wrote: »

Does your safety valve blow at 3 bar?
Is your water feed nearly 3 bar?
Does water expand when heated. Is your system working perfectly but you are feeding it 3 bar of water?

Very good point. If that valve below the vessel blows at 3 bar, then that's where my problem is... feeding it too much pressure in the first place.

Its hard to tell what pressure that valve is at because its wedged in against the wall. I'd say I'll have to get a plumber in. Thanks everyone for the replies.

Ajsoprano

Eireann81 wrote: »

Very good point. If that valve below the vessel blows at 3 bar, then that's where my problem is... feeding it too much pressure in the first place.

Its hard to tell what pressure that valve is at because its wedged in against the wall. I'd say I'll have to get a plumber in. Thanks everyone for the replies.

Reach your phone in and take a picture.

K.Flyer

Your pressure reducing valve appears to be reading 3 bar, which is usually how they come preset.
On a multiblock inlet valve the pressure reducer is preset at 3 Bar, the safety valve is usually 6 bar and the T and P valve on the unvented cylinder is usually 7 Bar.
Typically on a 200 L unvented cylinder the pre charge air pressure would be, atmospheric pressure plus approx 2.7 Bar.
Strictly speaking this is not a DIY job. You should get a competent person familiar with unvented cylinders to correctly pre-charge the vessel and check that everything else on the cylinder is in order.

Eireann81

K.Flyer wrote: »

Your pressure reducing valve appears to be reading 3 bar, which is usually how they come preset.
On a multiblock inlet valve the pressure reducer is preset at 3 Bar, the safety valve is usually 6 bar and the T and P valve on the unvented cylinder is usually 7 Bar.
Typically on a 200 L unvented cylinder the pre charge air pressure would be, atmospheric pressure plus approx 2.7 Bar.
Strictly speaking this is not a DIY job. You should get a competent person familiar with unvented cylinders to correctly pre-charge the vessel and check that everything else on the cylinder is in order.

You're right, it's a 7 bar T and P valve on the unvented cylinder. Thanks for the advice - definitely sounds like time to get in someone who knows what they're doing.