Hello,
Our heating at the moment is a large woodburner which sits in the middle of the house so the heat gets to most of our rooms. For a couple of bedrooms we have a couple of mobile electric heaters. The house is quite sheltered allthough we have found that woodburners are difficult to -regulate’ their heat.
We have found that we really need cooling almost more than the heating. So looking around we found this…
This system appears to run off an air/air or air/water. The only thing we know about this is that they do not work if the temperature drops below a certain level about 5C??? So it does not work when its cold!
We are not DIYers so just looking for advise if anyone gone down this route ? I may have asked before but this is becoming more of a priority.
Thanks in advance to all you clever people out there
regards
They certainly work! Who tells you that they do not?
OK, there is not as much heat in the air at 5 degrees as there is at 35, but enough. It will not be instant heat - you need to plan a day ahead and leave the pump on to do its job, but they are affordable.
While you are correct in that there is not as much heat energy in a unit volume of air at 5°C than there is 5°C it is not true to say that you can’t extract the same heat from the two volumes because it is the temperature change which is important.
You get just as much heat by dropping air at 5°C to -5°C as you do from dropping air at 35°C to 25°C
In fact slightly more as air starting at 5°C will be denser.
That said it is, indeed, harder in practice to get the heat out of cooler air, especially when it starts above zero but below about 10°C - water vapour in the air will freeze on the heat exchanger and reduce efficiency. Indeed it’s probably easier to start with air that’s -25°C and drop it to -35°C because the input air will have very little humidity. However very low temperature input air has the additional problem that it is difficult for a single stage to get the output temperature high enough. AFAIK 2-stage pumps exist for very cold climates.
Our heat pump falls firmly into the category of “the less you need it, the better it works”
We’ve got four reversible AC units that were already in when we bought the house eleven years ago. We found them found them inadequate during the first (and only) cold winter we’ve known (2012 - -C10°), but at the time we had no other heat source. However I believe you can get ones which continue to work well at lower tempsremain relatively
Ours have four modes heating, ac, dehumidifier and fan only. These days usually use the fan or the dehumidifier if its really hot outside 40+ (less intrusive and chilling than ac) . We no longer use the pumps for heating because six years ago we installed a wood burner on the ground floor of our three storey house and added a pellet burner on the middle floor last autumn. We don’t need to directly heat the top floor, as convection from the lower floors works remarkably well.
Obviously the above is a very different layout to chez vous also we’re a lot further south and much more inland (12) but with elec going up by 10% next month, maybe you’re better off with your log burner remaining the primary heat source and looking at other ways of keeping the temp down on hot days - closed shutters and fans or an air mover
Lastly, have you considered roof space ducting from your log burner’s chimney to the colder rooms that could obviate their need for electric heating? there’s usually a box around the chimney pipe with ducts going off it and a fan to draw the air - simple and cheap to install
We have air source heat pump for heat and for hot water. We live in the mountains where it gets cold, Above -5 or so it is efficient. Once the temp drops below that you start to loose efficiency and eventually it is similar to electric heating. But it works, and keeps our house at a steady 19 degrees. We have underfloor heating which is the most efficient, but I guess that doesn’t work for cooling!
But the water one is great in summer as just unhook outflow and get a stream of cooled air.
I have never tried this but if you had an internal fan core unit on a valved arrangement and diverted the underfloor to the fan core you could get air to air possibly?
Must be a warm climate or old tech unit, modern units built for colder climates regularly work to minus 15c and I saw a unit in Canada rated to minus 25c. Some of the models sold in bricos or other box shifting arrangements are low cost warmer climate units. Buyer beware.
In winter our total electricity cost runs at around €30 to €33 per week, that includes 2 air to air heaters running all day but shut down at night. House similar to yours and prefabricated, not brick or block, but around 100m2.
In summer much less unless we use the air to airs as climas, so far this year not needed. But last year the total when used hovered around € 11 or €12 per week.
I have a new air heat pump split invertor system which feeds both the air con and heating in winter and also to the hotwater system via a huge 270L tank. This has been my first full year of using both and the cost electric-wise has beenhalf of what I was paying monthly back in the north using a standard chauffe-eau and pre-set convector heaters plus a log burner if I needed it, I am therefore rather more than content plus no more buying wood, stacking and having the house subject to fire risk and soot.The equipment is Mitsubishi and Atlantic for the tank and actually have seen it advertised on TV recently. I pay €60/monthto the electric company and than also includes all electric machines such as hob,oven,dishwasher,washing machine and very large fridge/freezer etc
Yippee! This year our Reine Claude tree has prospered and will give forth fruits! I reckon it’s 10 years since it did that. A decade of frosts, intense heat, drought, fungus and aphids. The fruit is not quite ripe but I am planning to harvest the plums before the wasps do…
Oops! I thought I posted this in the cheerful news thread. Tant pis.
Do you need ducting through the house for that? Any pictures of setup? We are looking at changing our heating/cooling and are interested in a similar setup. Thanks in advance.
Just seen this. The two big very stiff cables with thick copper inside for the AC/Heating control unit were sticking out when I bought the house, they come in from the two exterior fan boxes on the rear house wall about 5m away. My new house is 1.5m above ground level as they all have to be in this region now so the vide sanitaire space underneath the house provided the ideal way of getting all the piping inside and the big cumulus in the kitchen utility comes up from underneath as well. The Atlantic tank is the Calypso split inverter thermodynamique chauffe-eau vertical 270L powered by a Fujitsu box outside and the split aircon/heater unit is Mitsubishi MSZ-HR50VF.
Have you installed one for yourself and have you any negative feedback to give.
I’m going to have to change my HW tank one day and think this would be a good thing to look at. Would it be more efficient than a conventional 32g / 150l HW tank using mains electricity. When I have to change my HW tank I’ll replace with a smaller 100l
