Expansion vessel or accumulator

dcawkwell · 17 Jun 2011

For an unvented hot water cylinder is there any difference between
an expansion vessel and an accumulator tank when
used to improve flow?

My house has good pressure but lacks a bit of flow.
I was thinking all I need to do is place a check valve
after the stop cock and a large expansion vessel will
give me a improved flow for hot and cold water.

John506 · 18 Jun 2011

An expansion vessel isn't for improving flow or pressure, it just takes up the water when it heats up as water expands when heated. Generally an unvented cylinder wouldn't be put in with poor pressure, are you sure no stop taps are slightly shut anywhere? Putting a check valve on won't improve anything, but you should already have a check valve on there anyway, but it is purely to stop any cross contamination.

Accumulator tanks are generally only used in large commercial buildings or high rise flats etc..

wetshoes · 18 Jun 2011

An accumulator is just a large expansion tank.
Seen a few of these fitted with unvented cylinders and they work well.

there's some good installation diagrams at www.gah.co.uk

hope this helps

simond · 18 Jun 2011

gAH are not allowed to sell accumulators, they no longer have rights to the uk patent.

You must fit a check valve or the accumulator wont build up a proper charge.

You could fit a large expansion vessel and a check valve BUT

- the expansion vessel would have to made for potable water
- a standard exp vessel does not have a diffuser, so the stagnation of water cannot be avoided

wetshoes · 18 Jun 2011

simond said:
gAH are not allowed to sell accumulators, they no longer have rights to the uk patent.

I didn't know that - not sure how you could patent one anyway as similar set ups have been around for years.

maybe it's to do with the diffuser design ?

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Expansion vessel or accumulator

dcawkwell

John506

wetshoes

simond

wetshoes

DIYnot Local

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