A Worcester Bosch combi in Livingston, fitted and piped properly

Why the condensate pipe went underground

A condensing boiler produces a steady trickle of slightly acidic water that has to drain away. The lazy way is a plastic pipe clipped down the outside wall to a gully. The trouble is that on the first properly cold night that pipe freezes, the boiler locks out, and you have no heating on the morning you most want it. It is one of the most common winter call-outs there is.

Here the pipe leaves the wall and drops straight into a trench, running underground to the drain, so the run exposed to the air is a few inches of insulated pipe rather than a whole wall's worth. Digging the trench is an extra hour on the job and saves a cold morning every winter for the life of the boiler.

The magnetic filter

The black cylinder on the pipework under the boiler is a magnetic filter. It sits on the return, so water coming back from the radiators passes through it before it reaches the boiler, and it pulls out the iron oxide sludge that builds up in any heating system over time.

Without one, that sludge ends up in the heat exchanger, which is the most expensive part of the boiler to replace. With one, it ends up in a canister we empty at the annual service. Worcester Bosch, like most manufacturers, expect a filter to be fitted for the warranty to hold.

Bonding, labelling and the bits nobody photographs

Every copper pipe under the boiler has a green-and-yellow earth bond clamped to it and a label saying what it is. The bonding is a safety requirement; the labels are for whoever services the boiler next, so they are not guessing which pipe is flow and which is return.

It costs nothing extra to do and is a decent tell, when you look at any boiler installation, of whether the rest of the job was done with the same care.

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