Baxi 105e - I need a new expansion vessel

gas4you

grumpycrab wrote: »

Hi - been told that our "expansion vessel" needs replacing (don't understand the technicalites but its full of water? should have some air in it?).

As above quote. Membrane will have perished. Very common fault.

ariba10

gas4you wrote: »

As above quote. Membrane will have perished. Very common fault.

Have re pressurised three (Successfully) in the past, and still recommend a second opinion.

grumpycrab

1. Had a separate expansion vessel fitted. Pressure rose overnight and water leaks out pressure relief valve.
2. Had new plate heat exchanger fitted and new PRV. Pressure rose overnight and water leaks out pressure relief valve. (about 3bar)

!!!!!!. Engineer is now scratching head and talking to Baxi. We don't think the fill loop is leaking mains (although I haven't taken that off to prove it).

Cliffh_2

If pressure rose overnight I would have def been checking the filling loop early on especially if no heating or hot water are being used. I had a head scratcher similar to this on a Glowworm, turned out to be the diverter valve, very rare fault but can happen.

Lgas

ariba10 wrote: »

Where does it say the water was comming out of it?

I still recomend a second opinion.

Here:

Hi - been told that our "expansion vessel" needs replacing (don't understand the technicalites but its full of water? should have some air in it?).

Normally you can repressurise them, but if the expansion vessel if full of water, and/or there's water coming out of the schraeder valve, then the diaphragm's split. Ridiculous quote for repair though!

Further to the last posts, I would agree it's most likely the filling loop letting by. Shame that wasn't checked earlier by the engineer.

grumpycrab

Anybody know what this valve is? I thought it was an isolating valve - turned the screw anti-clockwise and water started coming out from the screw - clockwise tightens. What's the point of it?

Canucklehead

Hi.

It's a check valve.

It will prevent the backflow of heating water into the mains water supply.

The other end of the filling loop is the isolator which you fill the system with.

The flexible hose should be disconnected from the valve after filling, then fit the cap that's on the other end of the black plastic strap.

GSR.

grumpycrab

Ahhh - I see. I'll pluck up courage to disconnect the hose on Monday and see if the isolating valve is leaking any water. (And it explains what the cap is for).

EDIT. This is why I went into computers - you seldom get wet and/or electrocuted (I'm talking about modern times of-course...)

1. turned water off to boiler (and electrics)
2. tried to unscrew end of hose attached to check valve; ended up unscrewing check valve - got a little wet (but not too much); found another wrench (or watever they're called) and did it properly the second time.
3. put screw cap on check valve (it was certainly doing its job!)
4. turned water back on slowly
5. there's a slow drip coming from the end of the fill hose
6. temp capped the hose off by screwing it to an isolating ball valve (all I could find) which may or may not work - put end in an ice-cream carton if it doesn't
7. ran some water off from the boiler(?) drain !!!!

So pressure is now at 2bar (was at 3bar with water coming out of PRV); guess I just have to wait 24h to see if this is now fixed. £400 for nothing if it is (apart from new external pressure vessel and plate heat exchanger and PRV, although I probably need another one of those now).

The fill hose loop was always connected. In the boiler's early days I think we used to top-up quite often. Bit surprised that 2 separate engineers didn't check this first (don't blame me).

Cliffh_2

As I said its one of the first things that should have been checked.
If it has cured the fault you could still do with lowering the pressure a bit. At cold it should be between 1 to 1.25 bar.

grumpycrab

Thanks. One (possible) effect of the new plate heat exchanger is that we can run HW to the bath at a much higher flow rate than before.