It’s actually Mitsubishi and I have a double setup because of the area it has to cover.
Thanks. I’ve already looked at Mitsubishi and already have Mitsubishi clim for the summer. My installation is just for underfloor heating, so will be much simpler than yours, needing just a single exterior monoblock unit. had no issues with the clim and Mitsubishi do seem quite competitive.
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A word about Mitsubishi, they have a habit of updating their kit and not always holding or making service parts available after a few years. I had to rely on my contractor and his stock of old units for spares on several ocassions. Not had that problem with other companies like Daikin.
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This is exactly what we were told by the people that installed our heat pump system. In fact they originally presented us with a Mitsubishi set up, but then had to roll back on that and switch to Saunier Duval, because they couldn’t get all of the major elements they needed for the installation from Mitsubishi due to supply issues. Worthwhile at least checking to see if that issue has resolved itself.
I have had the oportunity to look at some output figures for our curent Broseley evo 26 woodburner which provides 10kw heat output to the room in which it stands and a further 16 kw to domestic hot water and heating.
looking at the cost of our current electricity consumption all in it costs about .254 cents per Kwh including all the add ons.
Using the figure of 16kw for heat and water over a 7 month period (October to April) at 12 hours each day on a sliding scale starting and ending at 3 hrs per day and building up to a full 12 hours during december, January and February I estimate around 7900kwh is required.
Assuming an air to water heat pump is 300% efficient then to generate 7900kwh of power I would need 2633kwh of electricity at a cost of .254 cents per kwh costing 2006.60 euros.
This winters supply of oak cost about 700 euros so on face value the euro cost to run our log burning system compared to an air to water system is 1300 euros cheaper.
I would of course save on the physical energy of stacking, cutting and loading the fire although there would still be that to do in part when using the woodburner as a room heater at focal point. We would also have a warm house 12 hours a day without relying on me stoking the fire every hour or so.
Obviously there is the cost of installsation of a water to heat pump but I see this as a seperate cost and not to be included in my calculation.
Unless my calcs are wrong to incur an additional 1300 euros per year running costs is a no no. Please prove me wrong as I do like the idea of heat on tap rather than stacking cutting and fueling the wood burner but will comtinue if my cals are correct.
As in my post above we came to the conclusion it was not justified us making the change over at the moment.
Can you not get the wood pre cut to 35 or 50cm lengths as our wood guy does that at no extra cost, I just then have to wheelbarrow it across to the house and take it in, I very rarely cut timber now unless I am taking trees down to store due to disease or wind damage/area clearing.
Dont forget, those figures are generally the maximum heat tolerance of the woodburner, not the actual output which very much depends on the type and condition of what’s being burnt
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Your calculations are way out somewhere. If you have the full 16Kw going into your hot water tank for 12 hours then that is enough heat energy to raise 200l of water by over 800 degrees Celsius. That’s assuming no losses between buring and heating water, which of course there would be but not that much.
Edit: Less than 10% of that heat should be going into the water which leaves 90% of it going into heating your house. That’s still a lot of heat energy, unless you have a very large house that is very badly insulated. I recon at the coldest time of year, we use less than 10% of that figure although we do have a well insulated house.
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They may well be. I have started to look at the various calculation formula on line of which there are many. I am not a mathematician and some of the calculations seem very complicated but I will persevere. It seems that a very general rule of thumb is that 1kwh is needed for every 10m2 of floor space which of course can vary widely depending on local conditions.
As I have previously stated the house is very well insulated and the current hot water/heating system works well however as it is wood fired my idea is to reduce my labour involvement if possible, hence introducing an air to water heat pump.
My electricity consumption forcast for the next 12 months is 1200 euros, add to this 700 euros for the seasoned oak already purchased for the same period then the cost of providing all the heat and hot water we need will be 1900 euros. This cost also includes running the piscine filtration in the summer (piscine not heated) and our cooking needs. Our cooking range is dual fuel (electric and bottled gas) so add 100 euros for gas.
I see our total cost for electricity, firewood and gas at around 2000 euros for the next 12 months. Putting aside any cost for installation of an air to water heat pump it seems to me that its running costs will have to be pretty impressive to justify the installation.
I will be obtaining quotes in any event which will perhaps prove that it is worth the switch.
I would be interested to know what other SF members total heat/fuel costs compare.
Our house is 101m2 and we use a ground source heat pump split into three zones that uses 2.1Kw peak. Just looked at our last 12 months consumption and it’s just over 5,000 Kwh per year for everything. All our energy needs are met with electricity. That should be a total of less than €1300 per year. I’m not sure what proportion of that goes on heating in winter, cooling in summer and hot water but I’ll bet it’s not far from half.
If you’re using €1200 per year minus heating and hot water and some cooking, that’s around 13Kwh per day on average, which is quite a lot and not far from what we use in total.
The 1200 euros includes water heating when wood burner not running for some 6/7 months of the year, cooking (hob is gas and 2 ovens electric), pool filtration and workshop which I use quite often.
Edit
Your situation having ground source heat pump proves all the reports that such a system is the best. At best we can install and aur source heat pump which will be subjected to air temperatures ie low temperature equals less efficiency.
Very true but offset against the far higher installation costs of ground source you should win financially for a few years. Also newer units are better, variable speed makes a considerable saving over single speed units. Just make sure its a cold climate unit unlike some of the low cost Brico versions which really cannot cope well with colder temperatures.
Yes, air source is much cheaper than ground source,and not just because of the groundworks, the heat pump units for GSHP seem to be double what they are for ASHP. I bought the house when it was 7 years old and it already had the ground source heat pump. In a few years the heat pump unit will need replacing and then I’ll convert it to air source which I’m led to believe won’t be a problem. Yes, ground pumps are more efficient as the underground temperature is steady and higher in winter but we rarely get frosts here in the winter, and you can get air source units that work better at lower temperatures. The ones I’ve been researching give a COP of about 5.0 at 14C and 3.8 at 2C (I think but would have to check exact figures).
Edit: The COP figures I quoted are for an outlet temperature suitable for underfloor heating, about 30 or 35C. If you want to drive radiators then it gets more complicated as the higher the outlet temperature, the lower the COP and for standard radiators you need a much higher outlet temperature. I believe you can get radiators suitable for lower water temperatures but then things get more expensive 
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@hairbear I am encouraged by the statistics for your ‘all electric’ 7 year old 101m2 house and its ground source heat pump in that our 200 year old house is performing very well. I mentioned earlier that our house is effectively an 11 year old renovated pod sat within its original structure. We have 91m2 of habital/ heatable space on the ground floor and a furtrher 46m2 on the first floor. Your all electric running costs of 1300 euros per year actually compare quite well to my mixed electric, wood and gas costs of 2000 euros per year. The two principal downsides for me is (a) my physical energy input to keep the fire burning and (b) when we go out for a few hours the heat drops as no one is stoking the fire.
I get the feeling that installing an air to water pump may well not save me any money but will help in removing (a) + (b).
Yes, once you’ve totted up the cost of installation and possibly new radiators it will get very expensive and the payoff time will be quite long. If you say that the temperature drops in winter in a few hours if the stove goes out, is it really that well insulated ?. We only have the heating on for a maximum of 5-6 hours out of 24 in the winter and that keeps us going all day. We do have a large thermal mass in the floor due to the underfloor heating, which means it releases heat gently for a long period and we never have it too hot anyway. We also benefit from large south facing patio doors that create quite a lot of heat gain inside the house when it’s sunny in winter.
I think the thermal mass in your floor is the answer to maintaining the heat for you. We have an insulated floor but it isnt heated. The inside air temperature of our house never drops below 15 degrees in any weather if the fire isn’t in but even that feels cool in winter when you return from a dayout.
Might have to rethink the idea of a air to water pump after firing up the wood burner today.
When they look like this I will be convinced.
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Just put a video of a wood fire on the telly.
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This is essentially what you will be paying for - convenience. No cold starting the fire in the morning, been there, done that, as a kid (coal) and an adult (wood), fewer occasions for chafed, frostbitten, chillblained hands/fingers, etc. We use our wood fire insert as a complement to the air source heat pump, or as a tide-over between seasons, but once you get used to the extremely controllable comfort of a heat pump, it is difficult to go back 
I can see ourselves just using the fire for those “hygge” moments in the future.
We basically will run our fire 24/7 untill the end of February, because of the thick walls and very thick ceiling’s the fire is only topping up the heat, it is basically in chunter mode all the time so we get 4-5 hours between having to put wood in as it never really needs to be blazing.
During the night at some point either my wife or myself will be up to the toilet so we have a big dice sitting at the side of the fire and when we put wood on we set the time face up on the dice, 2/3/4 etc so the other knows when wood was last put on and doesn’t need to open up the fire so no smoke, so you are luck if it ever needs relit, it only needs cleaned out once a week and I sweep the chimney in February and the chimney sweep does it in September.