How to Install Your Own Central Heating System
Your 20-Point Plan
Installing a central-heating system is a job which can cause major domestic upheaval if not tackled carefully and systematically. Work to a definite plan, have everything to hand, and complete each stage before proceeding to the next. Provided you work to these ‘rules’, you should quickly have a more comfortable-and valuable-home.
Installation of central heating means following the rules of good basic plumbing-but with a few small differences. The first rule is to assemble everything you need, for at some stage you will be interrupting the domestic water system to make connections.
Fit as much as possible before you shut off the, to minimize dislocation, and work in easy stages-then things will not tend to get out of control!
Tools and equipment
These are broadly those used for general plumbing. You need a pipe cutter or, with a fine-toothed high-tensile blade; bending springs (probably both 15mm and 22mm); two spanners, either 200mm or 305mm; a hammer; a cold chisel; a blow torch; a case opener, for lifting floorboards; a handbrace and 19mm auger bit; 38mm No. 12 and when hanging radiators; an Allen-key set, to fit stems of ; a power saw; a spirit level, used to align boilers and radiators; and a lead light, for use in dark corners.
Among materials you may need are solder or solder paste; flux; non-toxic plumbing compound; PTFE pipe-thread jointing tape or hemp and jointing compound; fine wire wool for protecting behind fittings when using a blow torch.
You only need solder or solder paste where you use capillary fittings.
It is best to avoid using standard 15mm fittings, of either compression or capillary type, for bends unless a tight bend is necessary, since this may lead to water turbulence and frictional loss. Use a ‘slow’ bend-either a fitting or a bend made using a bending spring.
Fittings are largely the same as those used in general plumbing. Boiler fittings, radiator valves and manifolds, on micro-bore systems, require similar fitting techniques to other plumbing components.
Capillary fittings are neater and cheaper than compression fittings-but need a little more skill to make the joints. If one leaks, it is not so easily patched up as a compression fitting, which usually only needs tightening. The system, or part of it, may have to be drained down to repair a leaky capillary joint, since the presence of water prevents solder from taking.
It is best to work to a systematic plan. This is a suggested 20-point programme of work:
1. Assemble all the materials and fittings needed;
2. Plan all pipe runs so that there is the minimum domestic dislocation; lift floorboards and fit them back loosely, so that you can work quickly and without impedance;
3. Thoroughly flush out radiators;
4. Fit all radiator and lockshield valves, plugs and air vents;
5. Hang all radiators or fit convectors;
6. Connect up the radiator pipework and put in heating pipe runs;
7. Install the expansion cistern (where fitted), together with the pipework of the ball valve to the mains supply, and connect the overflow pipe;
8. Install the cylinder and pipework for the domestic hot-water supply and any immersion heater. The latter allows for hot water while the boiler is being installed. It is only likely that you will install an immersion heater permanently with some solid-fuel systems.
9. Where a self-priming cylinder is fitted an immersion heater cannot be used, for design reasons;
10. Install the boiler and the flue pipe, where the latter is required;
11. Fit theor oil line, where appropriate. The supply can usually be taken from a branch fitting, made on the outlet side of the meter-but check with the gas authority that the supply is adequate to meet heating needs;
12. Connect up any primary (hot-water) circuit;
13. Connect up the pipework circuitry to the boiler;
14. Fill the system and check for leaks. Vent the radiators, making sure that all the lockshield valves are fully open;
15. Flush out the system completely-at least twice:
16. Fit the pump into circuit and circulate hot water, again checking for leaks;
17. Wire in all thermostats and other electrical equipment;
18. Switch on the heating and balance the system. Use clip-on thermostats to adjust lockshields or other balancing valves;
19. Check that the control system is working satisfactorily;
20. After the system has operated for about two weeks, disconnect the pump and flush out again;
21. Check finally for leaks and loss of pressure, particularly with sealed systems operating at elevated or higher temperatures. As air is expelled from the system, water levels have to be topped up.
The pump is not fitted initially and is removed when the circuit is flushed out so that it does not collect harmful sediment.
Slight variations in technique are needed for microbore installation. This may involve fitting pressurised equipment and manifold distributors. Microbore piping is usually easier to run than small bore, because it is more malleable and can often just be threaded beneath floorboards.
Take account of the line of your joists when installing pipe runs. Joists run at right angles below floorboards. If it is necessary to run pipework across the joists, these must be notched to accept the pipes.
Pipes must have sufficient clearance to allow for thermal expansion, otherwise odd creaks may occur. Pipes of 15mm, 22mm and 28mm are usually fixed at intervals with pipe clips.
Never build pipes in or allow them to be gripped between floorboards or joists in such a way that movement, caused by the expansion and contraction of the pipe, produces noise.
A power saw can be used in lifting tongued-and-grooved floorboards, by running the saw along the tongue of one board, allowing the remaining boards to be simply lifted out.
Special floorboard saws are made which enable individual boards to be cut. If you have to cut through a floorboard, go through it at an angle, or directly across it, beside the joist. In the latter case, a timber noggin can be nailed to the joist to support the board.
Floorboarding over pipe circuitry should, if possible, be screwed back and not nailed. This provides for ease of access.