Energy efficient heating/DHW

brig001

We are looking to replace our 13 year old boiler with something more efficient. Our current system has a Albion Mainsflow thermal store which is directly heated by a conventional boiler (Baxi Solo). Rads and UFH are fed directly from the bottom 1/3 of the store and there is an internal coil for the DHW. We pre-heat the DHW to the coil with a separate store fed from a solar panel.

1, Is it possible to connect all this lot to a combi?
2, Would a combi be more energy efficient than the store?
3, Is there a more energy efficient way of doing this?

Thanks,
Bri.

silvercar

I'm not sure that a combi can be combined with a stored hot water system.

robv_3

Why move to a combi?

A combi when supply significantly lower water flow rate than your current system. If you want to go all eco, install more insulation in the house.

brig001

Silvercar, yes it is possible, but there are complications.
robv, I have checked our flow requirements and worst case is about 20 l/min, so quite a big combi, although low flow shower heads would help. The house is already insulated about as far as it will go, but there's still one or two air-tightness issues to sort when re-decorating etc.

I was really interested in saving money/the environment, so was curious to know which combination is the most energy efficient. So far:

Solar compatible combi: probably greenest, but most expensive.
Non solar compatible combi: would have to reduce the temperature of the solar down to 25 degrees C or so so it doesn't get upset, so not making full use of the solar.
New system boiler: cheapest by a long way since the boiler is very simple and no plumbing to change. Makes full use of solar.

I think the new system boiler has it, as a combi would cost about £300 more (even to get a reduced flow rate) and plumbing would run to a few days work. This could easily add up to £1000 which would never be paid back by any (small) gain in efficiency if there was one.

Thanks all,
Bri.