Calculating the water volume of a heating system

[ConorM8350]

Can anyone give me a specific way to calculate the water volume within a heating system? I'm trying to work out if an existing installation would benefit from an expansion vessel.

 

[SafeGasInstall]

my dad told me 1l for each rad will be ok plus 5 on top to back up your self !

 

[mutley racers]

is that including pipework?

 

[FD Powerflow]

Heating load wise on domestic its 6 litres per KW heat load so 18kw heat only would be 12kw x 6l = 72L in commecial its 10-12 litres per kw of heat depending on the type of output, ie underfloor or steel panel rads.

 

[SafeGasInstall]

Heating load wise on domestic its 6 litres per KW heat load so 18kw heat only would be 12kw x 6l = 72L in commecial its 10-12 litres per kw of heat depending on the type of output, ie underfloor or steel panel rads.

72L expansion vesel for a 18kw on the heating ???

 

[SafeGasInstall]

hope some one will come with the right formula

 

[sheff paul]

hope some one will come with the right formula

Bang in a 12 litre for a normal house,if the prv starts discharging,look em in the eye and tell a lie...... ''Must be due to Hard water guvoner''

 

[mountainman]

I'm not sure that that there will be an accurate formula because the length and diameter of pipe runs would be an unknown.
If in fact you did know the true volume of a system then you could work out the size of vessel required but you would always add on a bit for luck.

 

[SafeGasInstall]

if it starts discharging just stick a 6 bar one ( from another post leaking prv)🙂lol

 

[mountainman]

Bang in a 12 litre for a normal house,if the prv starts discharging,look em in the eye and tell a lie...... ''Must be due to Hard water guvoner''

And by the way, the system now needs a powerflush lol

 

[sheff paul]

if it starts discharging just stick a 6 bar one ( from another post leaking prv)🙂lol

When i first saw the discharge pipe on a logic i thought it had been capped off by a DIYer,i was going to knock on the door and warn them of impending doom.... when i fitted my first a week later i was so glad i didnt

 

[mutley racers]

so what your basically saying is, a 3 bed house just stick in a 12 litre expansion vessel?

 

[sheff paul]

so what your basically saying is, a 3 bed house just stick in a 12 litre expansion vessel?

if its a small 3 bedder i bang in a 8,if its larger i normally go for a 12.

 

[Nostrum]

If the existing vessel is sound and the pressure is rising excessively when heating up whack another one in? an Additional 8 litres should suit most applications?

Or do you want water content per metre info?

 

[sheff paul]

if its a small 3 bedder i bang in a 8,if its larger i normally go for a 12.

think of it as not an exact science as many combi's only have 8 litre fitted,this will do most homes,but sometimes on a big house you have to fit additional expansion vessel,have seen the maths to work out vessel size,but on housing you dont have to be spot on,as combi,s are an example,but as said before on a big commercial job you would have to work it out

 

[sheff paul]

If the existing vessel is sound and the pressure is rising excessively when heating up whack another one in? an Additional 8 litres should suit most applications?

Or do you want water content per metre info?

spot on ,normally if space is tight a pull out the old vessel and bang in a 12 on sealed symstems,did water content years at college ago ,never remembered it.

 

[ManchesterGas]

Attach a hose and drain it into a bucket and see show many time you have to empty the bucket. Add a bit on if the drain is higher than the lowest point and have fun if it's a drop system!

 

[SafeGasInstall]

Attach a hose and drain it into a bucket and see show many time you have to empty the bucket. Add a bit on if the drain is higher than the lowest point and have fun if it's a drop system!

cleaver idea I will just add 5 or 10% to this volume as you will have water left in the pipe work and bottom of rads

 

[tamz]

Raise the pre-charge pressure if it is near the limit for the vessel size.

 

[sheff paul]

Raise the pre-charge pressure if it is near the limit for the vessel size.

that will put the system under higher pressure and activate prv on full load usage

 

[doitmyself]

Heating load wise on domestic its 6 litres per KW heat load so 18kw heat only would be 12kw x 6l = 72L

Really?? Shouldn't it be 18 x 6 = 108 litres??

 

[sheff paul]

Really?? Shouldn't it be 18 x 6 = 108 litres??

ive got a 18 kw system boiler in my gaff,its fitted with 8 litre vessel g/worm flexicom

 

[tamz]

that will put the system under higher pressure and activate prv on full load usage

No it won't

 

[sheff paul]

No it won't

less flex on diaphramn due to more charge pressure=more system pressure......

 

[sheff paul]

less flex on diaphramn due to more charge pressure=more system pressure......

i will take some of this back you can increase the pressure to suit static head..