How to choose an expansion vessel

[James Dyson]

Hello! I have a cold water plumbing system which leads to a paloma boiler, a few taps and a shower. I currently have a 500l water tank which leads to a jabsco 12v 25psi pump and an 18L expansion vessel. The expansion vessel is bust and leaking. So I need a new one.

 

There's a whole range of prices and sizes available online. Does anyone have any tips on buying a new one? Size guides suggest I could go for a smaller size than 18L. Is there any point in spending more money on a more expensive one?

 

Currently looking at this: https://www.mrcentralheating.co.uk/heatwave-12-litre-heating-expansion-vessel

 

Thanks,

 

James

Edited March 20, 2023 by James Dyson

[Tracy D'arth]

Practically every boat I have seen uses an expansion vessel of around 5 litres on the hot water pipes..  Unusual on a system with no storage  though i.e. a Morco or Paloma, 

BUT  did you mean an accumulator for the potable cold water?  Again 5 litres to 8 litres seems to be enough to stop the pump hunting on and off too much. Bigger will give you chance to wash your hands in the dead of night without the pump coming on.

Edited March 20, 2023 by Tracy D'arth

[James Dyson]

1 minute ago, Tracy D'arth said:

Practically every boat I have seen uses an expansion vessel of around 5 litres on the hot water pipes.. BUT  did you mean an accumulator for the cold water?  Again 5 litres to 8 litres seems to be enough to stop the pump hunting on and off too much. Bigger will give you chance to wash your hands in the dead of night without the pump coming on.

Hi Tracy! Thank you. Yes, an accumulator for cold water, to smooth out the water supply and avoid using the pump in the dead of night. Okay! Yes avoiding the pump coming on when I don't have daylight for solar is useful.

[BEngo]

Make sure you buy one that is rated as suitable for potable water.  They all look similar, but some are for pressurised central heating systems and rely on there being corrosion inhibitor in the water.

 

N

[GUMPY]

We have a 20L one.

Great for long delays between pump runs and silence during the night.

Couldn't be dealing with anything smaller.

 

[James Dyson]

Thanks, do you know what brand your 20L one is? 

[GUMPY]

27 minutes ago, James Dyson said:

Thanks, do you know what brand your 20L one is? 

Afraid not, it was fitted in the boat when I bought it. Boat us the other side if the country so cant look

 

[James Dyson]

3 minutes ago, Loddon said:

Afraid not, it was fitted in the boat when I bought it. Boat us the other side if the country so cant look

 

Ah no worries, hope you get back soon!

[GUMPY]

3 hours ago, James Dyson said:

Ah no worries, hope you get back soon!

Next time I visit I will be preparing the boat for sale ☹️

[ditchcrawler]

On 20/03/2023 at 11:27, Loddon said:

We have a 20L one.

Great for long delays between pump runs and silence during the night.

Couldn't be dealing with anything smaller.

 

I go along with that , the bigger the better, you could use more than one.