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expansion vessel

An expansion tank or expansion vessel is a small tank used to protect closed (not open to atmospheric pressure) water heating systems and domestic hot water systems from excessive pressure. The tank is partially filled with air, whose compressibility cushions shock caused by water hammer and absorbs excess water pressure caused by thermal expansion.

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  1. D

    Expansion vessel issue possibly?

    Hi I have a baxi duotec combi boiler that every day or other day needs topping up as pressure drops below 0.5bar. When fired up it can reach OVER 2.5bar also whilst running CH. Is this more than likely a flat Expansion Vessel that needs inflating or could there be other possible causes if...
  2. M

    Worcester 28i expansion vessel hose??

    Hi guys. Can this hose be removed without taking the vessel out? Is there a specific tool that makes it doable?? Cheers
  3. R

    Need to replace expansion vessel (oil fired boiler)

    Looking for someone that can replace the expansion vessel on an old heating system that is losing pressure every day and needs topping up at least three times a day. Trying to eliminate what the cause could be. Appreciate that it could be a leak somewhere, but looking to tackle one issue at a...
  4. W

    Taking forever to pressurise gravity fed system. Why is this?

    Hello, I live in a two floor semi with a gravity fed conventional gas fired boiler (Potterton Kingfisher MF). The boiler is fed cold water from the loft water reservoir tank (which also feeds the cold water taps in the bathroom & the WC cistern). There is an expansion vessel attached to this...
  5. S

    hot water not staying hot in an unvented system

    hello we have an unvented system. we have an issue where the hot water is hot for 10 seconds and then luke warm, turn off taps / wait and turn back and it repeats itself. had boiler checked and told it was the expansion vessel. Had the expansion vessel drained and recharged. plumber told me...
  6. RenzoPan

    Leak in the expansion vessel - can I keep the heating on?

    Hi, We have a leak in the expansion vessel, which is on the first floor, above the hot water cylinder. As we wait for a plumber, can we keep the heating on?
  7. RenzoPan

    What is the pressure in this cylinder expansion vessel?

    I was told by the plumber to keep an eye on the pressure, to ensure it stays above 1.0. The red one is… but the black one is not…. What do the two mean?
  8. Crossfingers

    Expansion Vessel Hose Change

    Hi How simple is it to replace the expansion vessel hose? Do I simply turn the boiler off, drain the boiler and swap hoses, using some PTFE tape?
  9. T

    Expansion Vessel Questions

    Just some questions re Expansion Vessels: Q1 when system boiler water is cold, how full should the Expansion vessel be Q2 18L Expansion vessel - does this mean the whole volume of the vessel is 18L
  10. T

    Unvented Expansion Vessel Replacement - what else needs changing

    Potable water unvented expansion vessel needs replacing - water is coming down the tundish. What else needs to be replaced. Does the enginneer need a G3 unvented certificate to do this work and what are the consequences if he does not have one
  11. L

    What threads for flexi pope to expansion vessel?

    Hi all, I need to order a flexible pipe to connect this vessel up with. The pressure vessel instructions don't mention the thread size? A 22mm pipe almost fits over the threads so I assume it's 3/4 BSP? Does that sound right? The other end goes to the valve, will a flexi like this...
  12. S

    Changing expansion vessel?

    After the plumber changed the expansion vessel, the boiler was leaking even worse leading it to being condemned. It is quite old, so I suspect it was on its last legs anyway. Still, he was banging it quite a lot, and I just wanted to check there was a good reason for him to do so. Thanks.
    • Salchi
    • Thread
    • banging boiler expansion vessel
    • Replies: 2
    • Forum: Plumbing Tools
  13. M

    Expansion vessel position

    I see a lot of small 2l expansion vessels fitted horizontally and a few with the water connection at the top, in the legionella advice it mentions having water connections at the base for draining and flushing, also so no debris falls into vessel. From a practical view if the membrane breaks...
  14. M

    Expansion Vessel leaking water - no air or water from Schrader valve?

    Hey, I've got a Grant Vortex that's leaking water from the seal around the expansion vessel - it's the round type about 50cm wide. The system is at 1.5 - 2 bar, but the expansion vessel has no air in it, and it's leaking water. No water is coming out of the Schrader valve either. The system...
  15. ollie74

    Boiler Expansion Vessel Question

    Hi, I have a Glow-Worm Easicom 28 boiler and i had to get a new 8 litre EV (expansion vessel) for it, which has arrived. i did check with the seller to ensure the new EV was correct for my boiler and he said it was. the query i have though is, on the original faulty EV, on the sticker, it says...
  16. Crossfingers

    Can a DIYer replace an expansion vessel

    Hi Is it possible for a DIYer to replace an expansion vessel and hose? It's an external grant vortex boiler and from what I've seen online it looks simple enough
  17. P

    URGENT Do I need a expansion vessel fitted to my system

    I have just had a water meter fitted and since been told I need a small expansion vessel fitted to my domestic hot water system as the meter will have a NRV in. I have also been told no I don't as my boiler is over 10meters away from the meter and any expansion will be taken up within the...
  18. R

    Why do I have 2 Expansion Vessel

    I have Gledhill 300L unvented water cylinder storage system with Vaillant Boiler. We are using it for UFH and radiators. My plumber has fitted 2 expansion vessels 1) Zilmet - 18 Litre Red Heating Expansion Vessel & Sealed System 2) MULTIFUNCTIONAL TANKS WITH REPLACEABLE MEMBRANE Why has he...
    • Rahul Sood
    • Thread
    • expansion expansion vessel vessel
    • Replies: 3
    • Forum: Central Heating Forum
  19. M

    Expansion vessel hose

    Do many merchants sell 1 meter long 3/4 male to 3/4 female. The 3/4 male screws in to the composite valve and the other end the expansion vessel. I presume came supplied with the composite valve. The flexi is leaking.
  20. S

    Closed loop pressure increasing

    Just wondering if anyone has even seen an issue with the pressure gradually increasing on a closed loop system where there is no fill loop attached. I'm seeing this issue on a gshp and whats more unusual is its on the cooling side. If it was on the heating side you could put it down to expansion...
    • Shifters
    • Thread
    • closed expansion vessel pressure
    • Replies: 5
    • Forum: Renewables
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