combi boiler - hot water pressure

Combi boilers do come is a range of power outputs. How much water makes a good shower is very much a matter of opinion. However a 35Kw boiler will be noticeable better than a 23kW unit.

Might an alternative to a boiler upgrade be a heat recovery device in the shower output?

Best install another combi and join the DHW outlets using check valves and a shock arrestor downstream of the check valves. Why thrown the combi out? It works.

And spend money heating water, rather than heating it free...

Heat recovery drainpipes in showers are very useful. But few people can fit them in typical modern British homes.

It is possible to use the heating system, the rads and pipework, as a thermal store. When the combi calls for DHW the cold mains passes through a plate heat exchanger pre-heating it from water store in the radiators. In summer the water in the rads maybe 20C, in winter 70C. This will fill a bath very quickly.

I'm surprised nobody does a shower tray with one integrated.

The cost of recovery would greatly exceed any savings. It's a concept as unviable as replacing an old reliable boiler with a modern less reliable unit. On paper the cost saving is say £100/yr, but with only a 10 year life, it's more cost effective to keep the old unit and pay more for fuel. (but spend more on insulation)

Regards Capitol

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