by Kenj »
Mon Feb 04, 2008 5:20 pm
Single pipe CH systems were fitted when Central Heating was first used. You are more likely to come accross this type of system in a National Trust property, than in a home.
Basically the water is fed from one radiator to another, so the first radiator draws heat from the hot water and passes it on to the next radiator. Each radiator in turn will draw heat from thw water, and the radiators at the end of the run barely get warm.
Modern systems are two pipe. The Feed and Return pipes go to each radiator in turn and are then teed off to that radiator. Effectively the radiators are connected in a Parallel arrangement, not in Series as with a one pipe system.
Each radiator gets its own hot water direct from the boiler, not from the previous radiator. However any radiator at the end of a pipe run or drop, does not need to pass the boiler's hot water on, so the pipework is not teed off but goes direct to that radiator.
This is what I think you are referring to, when you talk about single pipe systems. You usually cannot tell if a radiator is at the end of a pipe run, without taking floorboards up.
This is all very confusing without a picture. If there is a Wickes branch near you, go in and get one of their free leaflets about installing central heating. This shows you a layout of a fully pumped C/H system.