Expansion Vessel Underfloor Heating - Advice

[kozmian]

Hi everyone,

This is my first post - so glad to find somewhere that i will get good advice.

I am about to order an UFH system that I will install myself. I am told by the company selling the components that there will be 60L of water in the pipework and to run it at 60 degrees C. The boiler that i am having fitted has a 7 litre expansion vessel - is this sufficient to cope with the expansion and if not how big does the expansion vessel need to be?

Thanks for your help / advice

Ralph

 

[tamz]

For 60 litres of water @1.5 bar the vessel size works out at 5.1 litre. @1 bar it would need 3.88 litre. You should be ok.

 

[kozmian]

Thanks for that - couldn't find a calculator online anywhere!

Had that confirmed by the UFH company as well.

cheers

 

[heinz57]

For 60 litres of water @1.5 bar the vessel size works out at 5.1 litre. @1 bar it would need 3.88 litre. You should be ok.

Hi Tamz, would love to know the formula for working this out myself, is there an online calc. or do you think you could post the formula, cheers matey!!!

 

[ecowarm]

V= eC
______
1-p1
__
p2

V The total volume or nominal size of the expansion vessel.
C The total volume of water in system (60l)
p1 The fill pressure in Bar (1.5Bar) + 1 bar
p2 The setting of the expansion/pressure relief valve in Bar absolute amospheric. (Gauge pressure plus 1 bar)
e The expansion factor (0.03) approx

V= 0.03x60 V =1.8 V= 1.8 V= 4.8
_________ ______ ________
p1= 1.5+1 1- 0.625 0.375
__
p2= 3+1 4


4.8l expansion vessel

 

[tamz]

Worked out same as Eco. Slightly different result as different expansion factor used.

V=__eC__
1-P1/P2

=0.0324 x 60
1 - 2.5/4.5

=1.944
1-0.625

=1.944
0.375

=5.184 litres @ 1.5 bar fill pressure