Fitting a reflex expansion vessel
Discussion
I'm a reasonably competent DIYer, I don't touch gas but I'm happy doing general plumbing repairs and changes.
Our Worcester combi boiler has for some time suffered from gradual pressure loss and a BG engineer previously advised that an external expansion vessel would probably sort this and enable the boiler to survive a few more years. It's got to the stage now where we have to re-pressurise every time we want a shower, otherwise there's a load of banging and clanking and the water goes cold. Raising the pressure in advance prevents this.
So, my questions are:
- is it a reasonable and feasible job for a DIYer to fit such a vessel?
- how do I know what size I need?
- diagrammatically, into which water circuit does the expansion vessel fit? I believe it goes into the return of the relevant circuit?
- if it's the house water circuit then I need a potable type of vessel?
- is there just one feed into the vessel (and an air valve the other side to pressurise it?)
- what else do I need to know?
- am I ridiculous for even considering doing it myself? And should just get a plumber in?
TIA.
Our Worcester combi boiler has for some time suffered from gradual pressure loss and a BG engineer previously advised that an external expansion vessel would probably sort this and enable the boiler to survive a few more years. It's got to the stage now where we have to re-pressurise every time we want a shower, otherwise there's a load of banging and clanking and the water goes cold. Raising the pressure in advance prevents this.
So, my questions are:
- is it a reasonable and feasible job for a DIYer to fit such a vessel?
- how do I know what size I need?
- diagrammatically, into which water circuit does the expansion vessel fit? I believe it goes into the return of the relevant circuit?
- if it's the house water circuit then I need a potable type of vessel?
- is there just one feed into the vessel (and an air valve the other side to pressurise it?)
- what else do I need to know?
- am I ridiculous for even considering doing it myself? And should just get a plumber in?
TIA.
It’s quite easy to find details of what to do on google. Size of vessel will be a function of overall system volume. The ones inside the boilers tend to be very small. A lot of manufacturers list the Max system volume - mine is 100l, and find out the size of your current one then over size it a bit.
https://m.youtube.com/watch?v=EozGdz1Pd3I
https://m.youtube.com/watch?v=EozGdz1Pd3I
CAPP0 said:
I'm a reasonably competent DIYer, I don't touch gas but I'm happy doing general plumbing repairs and changes.
Our Worcester combi boiler has for some time suffered from gradual pressure loss and a BG engineer previously advised that an external expansion vessel would probably sort this and enable the boiler to survive a few more years. It's got to the stage now where we have to re-pressurise every time we want a shower, otherwise there's a load of banging and clanking and the water goes cold. Raising the pressure in advance prevents this.
So, my questions are:
- is it a reasonable and feasible job for a DIYer to fit such a vessel?
- how do I know what size I need?
- diagrammatically, into which water circuit does the expansion vessel fit? I believe it goes into the return of the relevant circuit?
- if it's the house water circuit then I need a potable type of vessel?
- is there just one feed into the vessel (and an air valve the other side to pressurise it?)
- what else do I need to know?
- am I ridiculous for even considering doing it myself? And should just get a plumber in?
TIA.
Why the BG engineering didn’t fix the problem is the answer I’d like to know?Our Worcester combi boiler has for some time suffered from gradual pressure loss and a BG engineer previously advised that an external expansion vessel would probably sort this and enable the boiler to survive a few more years. It's got to the stage now where we have to re-pressurise every time we want a shower, otherwise there's a load of banging and clanking and the water goes cold. Raising the pressure in advance prevents this.
So, my questions are:
- is it a reasonable and feasible job for a DIYer to fit such a vessel?
- how do I know what size I need?
- diagrammatically, into which water circuit does the expansion vessel fit? I believe it goes into the return of the relevant circuit?
- if it's the house water circuit then I need a potable type of vessel?
- is there just one feed into the vessel (and an air valve the other side to pressurise it?)
- what else do I need to know?
- am I ridiculous for even considering doing it myself? And should just get a plumber in?
TIA.
Having to re-pressurise everyday is an issue that sounds very much like more than just fitting an additional expansion vessel. However, you asked so I’ll answer.
- Yes, it is DIYable (with lots that you could get wrong).
- to get the ‘right’ one you need to do some calculations. Having said that the general rule is that you can never have an expansion vessel that is too big.
- it should be located on the heating return, as close to the boiler you can get it so as to give it the best chance of lower water temperatures.
- it doesn’t go on the potable side (cold or hot water)
- single feed, usually 22mm compression or 3/4” BSP.
- yes, there is a lot more you need to know (see below post).
- it’s not ridiculous to consider doing it yourself.
How to fit an additional expansion vessel.
1) Isolate the power to the boiler.
2) Drain the heating system (depending on the location of the expansion vessel you might be able to get away with only draining part of the system).
3) Cut in a tee into the heating return pipe work (closer to the boiler the better). It will most likely be 22mm.
4) Fit an isolating valve. This will enable you to isolate the vessel from the system for future maintenance/replacement.
5) Fit a drain off valve between the isolating valve and the expansion vessel. Again, for future maintenance/replacement. Plus, you cannot measure the pressure of the vessel whilst it is under load from the system and full of water.
6) Fit the expansion vessel, making sure it is secure (most will hook onto a bracket although larger ones will be floor standing).
7) Set the pressure of the expansion vessel to around 0.2bar BELOW the COLD fill pressure of the system.
8) Fill system. Vent System.
9) Turn the power back on.
10) High five yourself and have a tea.
1) Isolate the power to the boiler.
2) Drain the heating system (depending on the location of the expansion vessel you might be able to get away with only draining part of the system).
3) Cut in a tee into the heating return pipe work (closer to the boiler the better). It will most likely be 22mm.
4) Fit an isolating valve. This will enable you to isolate the vessel from the system for future maintenance/replacement.
5) Fit a drain off valve between the isolating valve and the expansion vessel. Again, for future maintenance/replacement. Plus, you cannot measure the pressure of the vessel whilst it is under load from the system and full of water.
6) Fit the expansion vessel, making sure it is secure (most will hook onto a bracket although larger ones will be floor standing).
7) Set the pressure of the expansion vessel to around 0.2bar BELOW the COLD fill pressure of the system.
8) Fill system. Vent System.
9) Turn the power back on.
10) High five yourself and have a tea.
Thanks for the replies.
ST12AT said:
Why the BG engineering didn’t fix the problem is the answer I’d like to know?
It was a quite a while back, maybe a couple of years, he mentioned it as we were having to depressurise the boiler maybe once every couple of months, but it's gradually got worse and is now a twice-daily thingST12AT said:
Having to re-pressurise everyday is an issue that sounds very much like more than just fitting an additional expansion vessel. However, you asked so I’ll answer.
Are you able to elaborate more on that? I understand it's entirely possible we just need to replace the boiler, but my thinking was that if I can get a bit longer out of it for the sake of £50 then why not.ST12AT said:
How to fit an additional expansion vessel.
1) Isolate the power to the boiler.
2) Drain the heating system (depending on the location of the expansion vessel you might be able to get away with only draining part of the system).
3) Cut in a tee into the heating return pipe work (closer to the boiler the better). It will most likely be 22mm.
4) Fit an isolating valve. This will enable you to isolate the vessel from the system for future maintenance/replacement.
5) Fit a drain off valve between the isolating valve and the expansion vessel. Again, for future maintenance/replacement. Plus, you cannot measure the pressure of the vessel whilst it is under load from the system and full of water.
6) Fit the expansion vessel, making sure it is secure (most will hook onto a bracket although larger ones will be floor standing).
7) Set the pressure of the expansion vessel to around 0.2bar BELOW the COLD fill pressure of the system.
8) Fill system. Vent System.
9) Turn the power back on.
10) High five yourself and have a tea.
That doesn't sounds too disastrous, although I'd have to cut the pipe with a saw as they are all located up close to a wall (I prefer to use an automatic cutter, to get the cut square). Thanks for this.1) Isolate the power to the boiler.
2) Drain the heating system (depending on the location of the expansion vessel you might be able to get away with only draining part of the system).
3) Cut in a tee into the heating return pipe work (closer to the boiler the better). It will most likely be 22mm.
4) Fit an isolating valve. This will enable you to isolate the vessel from the system for future maintenance/replacement.
5) Fit a drain off valve between the isolating valve and the expansion vessel. Again, for future maintenance/replacement. Plus, you cannot measure the pressure of the vessel whilst it is under load from the system and full of water.
6) Fit the expansion vessel, making sure it is secure (most will hook onto a bracket although larger ones will be floor standing).
7) Set the pressure of the expansion vessel to around 0.2bar BELOW the COLD fill pressure of the system.
8) Fill system. Vent System.
9) Turn the power back on.
10) High five yourself and have a tea.
CAPP0 said:
Are you able to elaborate more on that? I understand it's entirely possible we just need to replace the boiler, but my thinking was that if I can get a bit longer out of it for the sake of £50 then why not.
You’re losing water so you either have a leak or a passing pressure relief valve. Fitting an additional expansion won’t help if either of those are the case. It will help, however, if you resolve the losing water issue and your existing expansion is knackered. Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff