P/N 10460 Imperial model (for outside wall U values 0.1 to 0.37 Btu/ft²/h/°F).
P/N 10461 Metric model (for outside wall U values 0.6 to 2.1 W/m²K).
Size: 7.5/8" dia.
Engraved in four colours. Complete in case with instruction booklet.

Simply set two dials to: length, width, height of room, temperature required and type of construction and the calculator gives immediately an assessment of the total heat required. Radiator, boiler and pipe sizes including smallbore and microbore are quickly obtained from the reverse side.

A preliminary pipe size for each circuit is indicated from the heat requirements and enables pipe layouts to be readily arranged.
Alternative sizes are shown for small bore and microbore.