Well, we decided to go with the heat pump and blown insulation of the roof space in the old part of the house.
The job is all done now and I am more than pleased with it. The temperature is set at 20C and it maintains it throughout the house. The outside unit (fan) is so silent that, even though it is directly underneath my ground floor open bedroom window, I can't hear it in the room.
After first setting it to switch off at midnight and then back on at 7am I realised my mistake. The temperature dropped to 14C and took all morning to get back up to 20 again.
Since then I have left it on all the time.
Trialling over 2 5-day periods the total daily electricity used by the house (not just the heat pump) has been an average of 22kwh. I reckon this works out at a very rough calculation at €871 a year, bearing in mind it will be unlikely to be running in summer, and our normal leccy bill is around €500, that seems pretty reasonable to me. Especially in view of the fact that we spend around €450 a year on wood. It does act as a cooler in summer but it would have to be a real canicule for that as we prefer doors open for the dog and the living room is rarely too hot.
The joy of not having to daily cut and stack logs or worry that, while in another room I have let the fire go out, makes it worth every penny.
Getting up to a nice warm house isn't bad either.
Oh, the cost for both the pump and the insulation was just over € 8,000 which we decided was better paid out straight away by stealing from the savings account. We were offered finance, 6 months free, then 4 monthly payments followed by an immediate settling of the debt without cost. I decided against that for 2 reasons. When I heard the name of the finance house and realised that it was the same outfit that diddled me on my health insurance last year, so didn't trust them to stick to the bargain, and remembering a similar scheme in England many years ago when 4 different firms, seller, bank, finance, another bank, got in a mix up and started to charge me £2 a day interest for a bill I had paid. It took months of letters and phone calls, the last directly to the CEO of RBS personally, before it was settled.
Actually, a third reason, the loss of one year's interest on our LEP was way less than the interest, charges and insurance of the never-never route.
Forgot to mention, the heat pump does not qualify for a grant but the €900 insulation bill does, of 30%. So we will get around €300 back next year.