expansion vessel needed or not

JohnNightmare

Hi how is everyone?
I recently changed my hot water tank from the old copper one that needed a lagging jacket to the new one that has the blue insulation around it, perfect job, question is there was an expansion vessel installed on top of the old copper one but the plumber said I didn't need it when he was changing the tank so he left it off, now he did say if there was a problem give him a bell and he'd be straight over to put it back on but he didn't see that happening, so far so good anyway the heating is perfect touch wood, , any idea why it was there in the first place and why it's not needed now? We used to have to heat the water to have a shower but we got an electric shower installed last year would that have anything to do with it??? We have gas heating with a baxi solo boiler. I should of asked him to explain more but I was on the night shift and knackered and was just glad to have it done. Thanks for any help or explanation.

John.G

Is the new cylinder made of copper.?
Is there a pipe coming off the top of the cylinder going up to and bent over the top of a cold water storage tank in the attic.?

JohnNightmare

John.G wrote: »

Is the new cylinder made of copper.?
Is there a pipe coming off the top of the cylinder going up to and bent over the top of a cold water storage tank in the attic.?

Hi john.g,
yes the pipe is as you described, I don't know about the new tank , it's well insulted with that blue foam stuff so I can't see.

John.G

That's good news as it means you have a vented hot water cylinder, strange that you had a expansion vessel on the old copper cylinder as these must be vented.

JohnNightmare

John.G wrote: »

That's good news as it means you have a vented hot water cylinder, strange that you had a expansion vessel on the old copper cylinder as these must be vented.

It might of been there as a extra precaution you think, or just a waste? But it's not needed anyway, that's grand, thanks,

Wearb

What colour was the vessel that was removed?
Do you have 2 tanks in the attic?

JohnNightmare

Wearb wrote: »

What colour was the vessel that was removed?
Do you have 2 tanks in the attic?

Red vessel removed and 2 tanks in attic, one big and one small.

Wearb

JohnNightmare wrote: »

Red vessel removed and 2 tanks in attic, one big and one small.

Seems all good then.

John.G

The only "other" reason for the expansion vessel is that the open vented Central heating system was converted to a semi sealed system, a lot of houses near me, on converting from oil fired to gas fired had a expansion vessel fitted and a swing check non return valve installed in the cold water fill from that small (feed&expansion) tank but the boiler safety (PRV) valve would now be lifting if the expansion vessel was removed without also removing that non return valve.

JohnNightmare

John.G wrote: »

The only "other" reason for the expansion vessel is that the open vented Central heating system was converted to a semi sealed system, a lot of houses near me, on converting from oil fired to gas fired had a expansion vessel fitted and a swing check non return valve installed in the cold water fill from that small (feed&expansion) tank but the boiler safety (PRV) valve would now be lifting if the expansion vessel was removed without also removing that non return valve.

We upgraded and moved the boiler about 5 years ago , the boiler was in the back of the fireplace ( that's how old it was ) I remember him calling the system a ' closed system ' regarding the non return valve, that is still there I can see it in the hot press, ( I know what it is as I had to replace it ) and the automatic air valve/vent is there obviously, unfortunately I used a different plumber for this as my usual plumber had no van and tools due to the covid virus so be interesting when I have him back to service the gas boiler if he asks to have a look,.
If the vessel should be installed and is not what's the worst that will / could happen and in what time frame? Will the gas boiler just knock off ( has it had previously done when the automatic air vent was leaking and drawing air into the system ) or is it something more dangerous eg the tank or pipes can burst?

What / where is the ' prv ' that could be lifting? It's something I could be looking out for, thanks

John.G

IF the PRV is lifting then every time the boiler heats up you should see a sign of water somewhere close to the boiler, normally its piped outside and you should see it easily enough, eventually it would cause corrosion/sludge build up.

Why did you have to replace the NRV?.
Was the E.vessel part of the original installation or was it installed when the boiler was shifted?
Do you have a pressure gauge on the boiler or system and readings cold/hot.
I would certainly try and see if that NRV is now still part of the "new" system.

The boiler may have its own internally mounted E.vessel.

JohnNightmare

John.G wrote: »

IF the PRV is lifting then every time the boiler heats up you should see a sign of water somewhere close to the boiler, normally its piped outside and you should see it easily enough, eventually it would cause corrosion/sludge build up.

Why did you have to replace the NRV?.
Was the E.vessel part of the original installation or was it installed when the boiler was shifted?
Do you have a pressure gauge on the boiler or system and readings cold/hot.
I would certainly try and see if that NRV is now still part of the "new" system.

The boiler may have its own internally mounted E.vessel.

The boiler kept knockng off about a year and a half ago so the plumber was trouble shooting he knew air was getting in somewhere, the nrv was letting water through both ways so that was replaced, the vessel also burst so we replaced that but it was still knockng off a couple weeks later than I notice water coming out of the air vent value but chance when I was at the hot press, a chain reaction of sorts, I can't remember 100% if there was a vessel in the hot press when we moved in ie. with the original system but if I really had to guess I would say there wasn't, if there is an internal vessel in the boiler you would think he wouldn't have replaced the vessel in the hot press and just took it off like it is now. But I really don't know, it's just a pressure guage on the boiler, 0.5 when not running and between 0.5 and 1 when running as of now. Incidentally before I got the new tank the boiler was 0.5 when not running and between 1 and 1.5 whilst running. Is that something of note?

John.G

If you post the exact gas boiler model some one here will know if it has a internal E.vessel the 0.5/1 bar might indicate a system without a NRV and 0.5/1.5 would indicate a system with E.vessel (external) with a functioning NRV, both not a problem as the PRV doesn't lift until 3 bar.
The whole idea of having a semi sealed system is that it helps to prevent any air entering the system and stops any pump over/back to the F&E tank which can occur in some systems, you might have a look into the F&E tank sometime, preferably with boiler firing and see if any sign of water coming from the vent and check that the tank is clean.

DGOBS

No, Baxi Solo is a 'heat only' boiler, no internal vessel