A
angelf
I have a 3 bed property with 1 bathroom and one shower room. What size of indirect unvented cylinder & exp vessel would I need to fit please? I am replacing the boiler at the same time so advice on that wud be of use. Ta
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The rule of thumb is 50 li plus 50li per person who lives there.
In a practical situation because the future occupancy might be higher a minimum size of 210 li would be a sensible compromise.
You need to calculate the heating loss by the whole house method and add 2 kW as an allowance for heating the cylinder.
The cylinder nees to be fitted by somebody who holds the qualification and who has tested the mains supply first to ensure its adequate to operate an unvented cylinder.
Tony
In a practical situation because the future occupancy might be higher a minimum size of 210 li would be a sensible compromise.
You need to calculate the heating loss by the whole house method and add 2 kW as an allowance for heating the cylinder.
The cylinder nees to be fitted by somebody who holds the qualification and who has tested the mains supply first to ensure its adequate to operate an unvented cylinder.
Tony
Didn't know that! Presumably it apples to un-vented as well as vented cylinders?
If you use Boiler Size Calculator, it already includes the 2kw allowance in the answer.
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35-50lpp is a rough rule of thumb.
Proper calc would be using loading units against flow rate.worked out that way 210 is massively exccessive for your house.
I like the way people always quote 2kw,unless
you stagger heating hot water times or fit hot water priority it would take an age to warm that cylinder from cold after full use at the same time as the central heating was calling.
Try m=vt/(14.3p)
m is mins
v is volume
t is temp rise 10deg to 60deg would be a 50rise.
P is kw
Proper calc would be using loading units against flow rate.worked out that way 210 is massively exccessive for your house.
I like the way people always quote 2kw,unless
you stagger heating hot water times or fit hot water priority it would take an age to warm that cylinder from cold after full use at the same time as the central heating was calling.
Try m=vt/(14.3p)
m is mins
v is volume
t is temp rise 10deg to 60deg would be a 50rise.
P is kw
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A heating professional would set the HW to heat say 20-30 minutes before the CH.
The boiler is sized to heat the house when its -1° outside so for 98% of the year the boiler has a large overcapacity.
The cylinder is not just sized for one or two people who may live there now but for the number who COULD live there if it changed hands. Even that would be a British expectation of the occupancy and does not take account rates in other parts of the world which are often much higher.
Tony
The boiler is sized to heat the house when its -1° outside so for 98% of the year the boiler has a large overcapacity.
The cylinder is not just sized for one or two people who may live there now but for the number who COULD live there if it changed hands. Even that would be a British expectation of the occupancy and does not take account rates in other parts of the world which are often much higher.
Tony
Agre with Mr Agile, 170 - 210 if it was my house
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