I have:

A house with 3 small floors and a very small garden. A non-condensing/non-combi gas boiler with a hot water tank and a single radiator "heating zone". In part due to a conservatory style living room extension, it is hard to control the temperature on the middle floor with the thermostat on the ground floor.

The house is built early 2000s, so has cavity wall insulation and very basic double glazing. I have topped up the minimal loft insulation.


I would like:

Two heating zones:
Ground floor
First floor (effectively "the rest", as top floor is usually OK without additional heating).

This would also make sense as I am considering letting out the ground floor while living on the top two floors (or vice versa if I hit hard times!).

I am considering keeping the gas system, but then using an air to air heat pump for space heating on the top two floors. I have had a good experience with one of these in the past and I think, considering the layout (plus small upstairs heating requirement), that a single ceiling mounted fan unit could cover top the two floors.

I would then just have to work out a sensible way of working out a contribution towards the "downstairs" gas bill for hot water.

I could upgrade the boiler when required and any sceptic/conservative future buyers could ignore the heat pump and fall back on standard gas heating.



That is probably the simplest and cheapest. I think that would be an improvement on energy efficiency/environmental costs, but if I wanted to go slightly more green, what do people think are good options?

For example, to exploit the water tank, which I expect is less efficient with a gas boiler than a combi boiler (like a storage heater it is not only hot when I need it, so some heat is wasted and it takes adjusting etc.), I could imagine:


* Using an ASHP for DHW and delivering space heating to air (is such a split possible?)

(All bathrooms are due updating or moving, so I could add the smallest wattage electric showers also to try to run the ASHP at a more efficient temperature - and if the tank emptied of hot water, the electric showers would still cope. The existing tank immersion heater could satisfy the Legionella pasteurisation legislation.)


* Using an ASHP for DHW and wet heating, splitting into two radiator loops.

(Would pobably require upgrading 4 of the radiators to minimise water temperature.)
This would need a controller with two room thermostats - don't know if this is common for ASHP systems.


* Adding solar panels to boost hot water.

This could be done in combination with one of the other 3 options - although I guess I need a water tank with two inputs. If used with the previous option I guess the controller would get quite exotic(?).


Any comments/ideas? Thank you!

When you say split heat pump, you mean two fan units? I prefer wall ones, but a ceiling one would mean I could do with just one unit for the two floors (if it was at a particular end of the room over the window).

I could go instant electric, if you can get such things for kitchen taps, which are practical, ie. not too costly to service?