How To Install A Central Heating Cylinder


You will almost certainly want to install a new hot water cylinder along with your central heating system. For one thing. You will need one with an indirect heating element in it, and if you don’t have central heating at present, your current water cylinder is likely to be of the direct type as these are very common. Although you can convert these, fitting a brandnew indirect cylinder is likely to be easier and more efficient.

It’s important to plan the changeover of cylinders carefully. So that you are not left without hot water for long periods. The night before, switch off any hot water heater — a solid fuel boiler should be raked out. There should be a draincock at the point where it enters the cylinder: if you already have a boiler of some sort, the drain cock may be at the lowest point of the boiler return pipe. You can drain the cylinder from either of these points. If there is a valve at the outlet of the cistern on the feed pipe. Turn this off to stop the cylinder refilling; if there is no valve here you will have to turn off the supply to the cistern, either at the main stopvalve on the rising main or by tying up the ballvalve, and drain the cistern as well.

how to install a central heating cylinder

After draining, undo all the fittings connecting the pipes to the cylinder (or cut the pipe if you have to). Disconnect any immersion heater at the nearest junction box — not at the heater itself — and be sure to switch off at the mains first.

Undo the immersion heater —you will need a special large spanner for this. Or a pair of slip joint pliers, which you can hire. If the heater is in good condition you can reuse it in the new cylinder — you may still want the ability to heat water separately with an immersion heater.

Try to do all this work early in the day, so that you can then try the new cylinder in place and decide what fittings you will need to connect it up — unless you are very lucky, you will have to move. Shorten, or extend atJ least some of the pipes and it’s unlikely that you will be able to plan this in advance.

At this stage, you need to connect up only the domestic water side of things — the inlet from the cold water cistern and the outlet to the hot taps.

As yet there is no need to to connect up the central heating.

Flow and return tappings; because these lead to an enclosed coil inside the cylinder, there is no possibility of the cylinder leaking when you fill it.

The inlet pipe should have a drain tap fitted to it, and accord ing to how your pipes are placed and the amount of space you have, this may have one screwed end, for screwing directly into the cylinder. Or two compression ends, for fitting a little way away from it. Either way. The drain tap may be a straight or elbow type of fitting. Make up the screwed ends of all fittings with hemp and paste.

With the cylinder connected, test this part of the circuit.

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