SITE TOOLS // PLUMBING QUANTITIES
Plumbing Quantities Calculator
System volume, cylinder capacity and underfloor pipe runs – the numbers you need before ordering.
ABOUT THESE CALCULATORS
Knowing how many litres are actually in a heating system decides how much inhibitor it needs, and underdosing is one of the most common reasons a system sludges up again a year after a powerflush.
These three calculators cover the quantities that come up most on heating and hot water work: total system volume and the inhibitor dose that follows from it, nominal cylinder or tank capacity from its dimensions, and the length of pipe an underfloor loop needs at a given spacing. Pipe volumes are worked out from the actual internal bore of standard copper, not a rounded rule of thumb.
#
L
Around 5-6L for a single panel and 10-12L for a double is typical, so 8L is a reasonable mixed average. Use the manufacturer figure if you have it.
M
M
L
L
Dose rates differ between products – always check the bottle rather than assuming 100L.
Total System Volume
0 litres
approximate, filled and vented
MM
MM
Nominal Capacity
0 litres
straight-sided volume from dimensions
This is the geometric volume of a plain cylinder. Real capacity is usually a little lower once dished ends, the immersion boss and any internal coil are accounted for, so treat it as an upper figure rather than a badged capacity.
M2
%
Covers the tails back to the manifold and the turns at each end of a loop.
Pipe Required
0 m
including allowance
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These are estimates for planning and ordering, based on standard copper bores and straight-sided geometry. Confirm against manufacturer data and product instructions before dosing chemicals or committing to an order.