Combination boiler question

[MartinP]

Hi Everyone I'm installing a new CH system in a barn conversion to supply both the arn and the house; the two are connected via a conservatory. I'd like to use a combi boiler to supply the radiators and DHW in the barn. The house is too far away to sensibly supplt DHW but there is a hot water tank there from the existing, ancient system. Can I use a combi boiler to supply a hot feed to an indirect cylinder via a three way valve along with hot water directly to some taps and the rads. One question, does a combi work directly off mains water or do I need a cold water tank?

Martin E Yorks

[Set Square]

Yes. You simply treat the CH side like a conventional boiler, and split it into CH (proper) and HW circuits.

The HW side of a combi heats mains-pressure cold water as it passes through its heat exchanger.

You will still need a cold header tank for the old indirect hot water system.

The primary CH circuit (feeding the radiators and - in your case - the indirect coil) will almost certainly be unvented - and will have a filling loop and pressure vessel rather than a feed & expansion tank.

Does that answer the question?

[MartinP]

To explain further

Thanks. Yes it does although I'm unfamiliar with pressure vessels so need to look further.

Thanks anyway I'll post again (probably when I've done more research :-)

[Set Square]

To aid your research, have a look at Ed's Sealed System FAQ at