Combi boiler pressure still going up after adding new expansion vessel

[belgianwaffle]

My Viessmann Vitopend 100 boiler has been struggling with high pressure (going above 3 bar when the heating's on) for some time now.

This morning, a repair guy installed a new expansion vessel. He did not replace the old one, just connected it between the two valves you use to refill the system. (Please see below.)

(Not the cleanest job, I know.) Here's a picture of the rest of the system for some more context.

Unfortunately, this had no effect as the pressure still goes above 3 bar when the heating is on.

He first left the two valves closed and left. I realized the moment I saw the pressure going up, so I switched off the heating and called him. He then told me to open the bottom one. After I told him my tap water turned yellow, he apologized and said I should close the bottom one and open the top one. Unfortunately, that didn't help either.

1) Is this setup correct?
2) Is it possible that I somehow affected the expansion vessel's own pressure when I opened the wrong valve so it now needs repressurizing?
3) I was told the boiler pressure should be 1.5 bar when the heating's off. However, Viessman's website says it should be "between 0.5 and 1.0 bar" and the boiler manual says it should be "at least 0.8 bar". Is 1.5 bar perhaps too much?
4) Our pressure problems started after we renovated the bathroom and moved one of the radiators to a different wall, then replaced it with a bigger one. Is it possible something went wrong there? (The apartment has a total of 7 radiators now.)

Many thanks.

 

[foxhole]

Drop pressure to 1bar .

 

[Madrab]

Oh my, that's a bit of a riot in there.

I don't care what country he's from, that's the most shocking excuse for an acceptable install of an external Expansion Vessel (EV) I've ever seen. I'd like to bet that the filling loop has a check valve in it (the connection just in front of the red lever valve that has the arrow and 1/2" written on it) and if it has then the system pressure will never get to the EV, hence why the problem still exists.

He needs dragged back and told to fit a proper external EV (below) on a bracket and mount it to the wall and then take a connection from the main system pipework to the vessel. It should never have been fitted to the filling loop circuit in the first place.

 

[polesapart]

^^ +1

Ludicrous

Fair chance that repressurising the old EV would been all that was needed.

 

[belgianwaffle]

Oh my, that's a bit of a riot in there.

I don't care what country he's from, that's the most shocking excuse for an acceptable install of an external Expansion Vessel (EV) I've ever seen. I'd like to bet that the filling loop has a check valve in it (the connection just in front of the red lever valve that has the arrow and 1/2" written on it) and if it has then the system pressure will never get to the EV, hence why the problem still exists.

He needs dragged back and told to fit a proper external EV (below) on a bracket and mount it to the wall and then take a connection from the main system pipework to the vessel. It should never have been fitted to the filling loop circuit in the first place.
View attachment 338311

Thanks. Yes, I am aware, but I'm in Brussels and most plumbers here don't speak English. (This one was sent by my insurance company.)

Here's a better picture of the valve:

Does that say anything to you?

Also, is there a big difference between a "proper external EV" and this one?

 

[Madrab]

Does that say anything to you?

Not really as it Belgian but given there is a flow arrow and the fitting is elongated, I would confirm if it was a check valve.

Also, is there a big difference between a "proper external EV" and this one?

No difference really as to how they work but the one that's been fitted it the type that comes internally to the boiler and would be fitted within the case as they don't come with external brackets or mountings - the one I pictured would come with a bracket and band to allow it to be fitted to the wall.

How the internal flat one has been left is just a problem waiting to happen. It's not designed to just be sat with it's corner on the ground like that and the flexi pipe supporting all the weight, its not ideal at all. I'd be complaining to the insurance company and let them deal with it.

 

[CBW]

Maybe try closing the valve that’s open, as loop could be letting by.

 

[Madrab]

Maybe try closing the valve that’s open, as loop could be letting by.

Fair shout but I think they were both closed to start with

He first left the two valves closed and left. I realized the moment I saw the pressure going up, so I switched off the heating and called him.

 

[belgianwaffle]

Maybe try closing the valve that’s open, as loop could be letting by.

I assumed that if both valves were closed, the new expansion vessel would be isolated from the rest of the system and, hence, have no effect.

Not really as it Belgian but given there is a flow arrow and the fitting is elongated, I would confirm if it was a check valve.

I gave him a heads-up. He will come back on Saturday to check. If that is indeed the case, he will have no other option but to get the EV off the ground and mount it to the wall.

To be fair, getting to the built-in EV is challenging as there isn't much room for maneuvering.

 

[CBW]

I assumed that if both valves were closed, the new expansion vessel would be isolated from the rest of the system and, hence, have no effect.


I gave him a heads-up. He will come back on Saturday to check. If that is indeed the case, he will have no other option but to get the EV off the ground and mount it to the wall.

To be fair, getting to the built-in EV is challenging as there isn't much room for maneuvering.

OMG! Please tell me that’s not hoe the boiler has been left to operate?

 

[DP]

red lever valve that has the arrow and 1/2" written on it)

Brilliant, you should change your handle to Hawkeye Jackflash

 

[Madrab]

To be fair, getting to the built-in EV is challenging as there isn't much room for maneuvering.

Don't get me wrong, there's nothing wrong with fitting an external EV if the internal EV isn't easy to replace but it certainly shouldn't be fitted like that and where connected it and he really needs to replace it for a correct external item in the correct position, nothing else is acceptable. Chances are they sent him out with the internal one for the boiler already in hand and he found it was going to be a PIA to fit (or he couldn't be bothered) So rather than return with a proper external one he just flung that one in like that and without looking for a check valve - A check valve would usually be fitted on the loop as the mains needs to be protected from backflow from the CH system water.