Ballynoes

Sorry I meant my electricity usage drop by half as soon as the heating goes off. I use roughly 30Kw/Day during winter and once the heating is off I use around 15Kw/Day, This might be high compared to some but there are multiple other factors in my daily Kw usage not just home heating and DHW. Still working on the heating demands bit, hence the question, and still getting used to the ASHP, just had 1 winter with it . But compared to £2000 each year to heat the old (now demolished cottage) I can't complain too much.

Thanks all, just had the one winter with the ASHP so still getting to grips with it. Might not plunge into the Economy 7 tariff just yet then. as SteamyTea says the heating is off now and only DHW which is timed the same every day all year, so I can get good base figures to start. I do know from my electricity readings my usage drops by half or so as soon as the heating goes off. Always learning..

Interesting JohnMo, thanks for taking the time to answer. Still getting used to an ASHP, but would flow temps in the 20's actually produce "noticeable" heating. Might try that as well. The house is well insulated so it doesn't need much to keep it warm, I guess I am still in the oil boiler mind set, where the radiators had to be in the 60 degree range to heat the old house. Trial and error I guess. Many Thanks.

ASHP, what’s the best way. I guess this is the question most asked about ASHP’s how and when to have it on. So the house is built and we have been in just over 12 months now. So far the ASHP seams like a good choice. However I was just wondering if anyone on here can shed light on my question. Do I leave it on all the time or switch it on and off. I have A Mitsubishi Ecodan 8Kw heat pump, with a storage cylinder for DHW and UFH throughout, all floors are tiled. The house is really well insulated, and very air tight, no drafts, like the old cottage. Last year the heating was on from say October till April, we don’t need any heating out with that usually, as the glass wall lets in lots of thermal heat as soon as the sun shines. My rooms are controlled by thermostats in each zone, no timers built in, it’s either calling for heat or not. Played around with-it last year and the option I ended up using was to have the flow temperature of the UFH set at 45 degrees. Heating came on at say 3am till 9am. This put heat into the floors and it radiated up during the day, house was fine no issues. Same thing the next day. Then thought about an Economy 7 tariff as I have my heating is on during the night. Hot water is not an issue. To keep the cylinder full of hot water when the heating is off, the ASHP is only working about 5% of the week. Hot water on from say 7am until 10pm. Obviously the hotter the flow temperature the more the pump is working and the more KW’s I use. I have been investigating the best way to get the most out of the ASHP, and most sites I look at say to set the flow temp to 38 degrees, but leave it on all the time. That’s my conundrum. Obviously not having tried that I have no stats for electricity usage, and it’s all about the KW now the prices have gone through the roof. Most of the recommendations to leave it on all the time suggest turning the temp down at night, but I can’t do that with my thermostats. Is it just a matter of trying it on 24/7 at the lower temperature, but I have no need for rooms temps of 22 through the night. ?? So I was just wondering if the collective geniuses on here could shed any light as to options worth investigating. Many Thanks in advance.

Just as a side question, how noisy are ASHP's, as I was hoping to site it outside the house, on the south side, as this gets most of the sun and warmth. Any thoughts. Edited, sorry should have said directly outside the house.

Thanks, much appreciated.

I'm interested ProDave how you're 4Kw solar system only cost £1500, I have been quoted close to £6500, which makes it un-viable, At £1500, I would jump at it, did you do it yourself. If I can get the equipment and get the builder to install it whilst he is building the house it might be an option. So far a 500w panel comes in at £400 and I need 8, pus the inventor.

Hi, thanks for the replies, I suspect ScottishJohn has hit the nail on the head, with people fed up paying for Oil heating and persuaded to fit an ASHP by a salesman, then being surprised that it costs a fortune to heat their still old drafty house. Our new build will be well insulated draft free and have good insulation figures, so I suspect it won't use £1250 per year to heat, as that is what I pay on Oil for my old drafty soon to be demolished house.... can't wait. But I'm still struggling to justify solar panels, so far it will take me 23 years to get a return for a 4Kwh array fitted. No wonder no one fits them any more.

Hi, just looking for some real advice. We are soon to start our build, and I hear horror stories, from those who have not built, about Air Source heat pumps, running away with electricity use. Is this real life or scare mongering, most of those who say this do not have a heat pump, but " know someone who knew someone", you get the drift. So my question is, for those who have fitted an Air Source heat pump, did it run away with electricity or not. I know we will have additional electricity costs, because of the heat pump but we are currently using oil, and I calculate we would need to use an additional 9500KWh each year to be "out of pocket", that's roughly an additional £103 per month of electricity, on top of our current use. Bearing in mind our new house will have an Air Source heat pump, underfloor heating, and will have U-values of 0.17 W/m2K, according to the spec. I have tried to justify solar panels as well but the sums just don't add up either, taking roughly 23 years to get my investment back. Thanks in advance.

This looks promising. http://www.chelmerheating.co.uk/self-build/thermal-store-and-buffer-cylinders/thermal-store-heat-bank-cylinders.html

I wish we had gas, but live in the country, so don't even have sewage, or decent broadband, but that's the price you pay for piece and quiet surrounded by your own fields... not complaining though. ? I still find it difficult to comprehend that you cant "feed" a hot water cylinder with two different form of heating, after all I was under the impression that you had to occasionally heat the hot water tank to a certain temperature, to make sure certain bacteria don't thrive... or is that another myth. ?

Hi ProDave, I was thinking that in the summer months, with a fully insulated house, the ASHP would provide sufficient hot water, and only be running at a small percentage of its capacity, as it will probably not be heating the UFH, I just thought that in the winter when UFH demands are higher, I can supplement the DHW, with the log Burner. After all, if I am building from scratch now is the time to install it all, even if it only gets used occasionally, as the Log Burner will essential be fed by free timber. Just my thoughts.

I was think along the lines of ProDave's answer, in that why pay for electricity to run the ASHP, to heat a tank of hot water in the winter, when I can get free wood to run a Log Burner, which will heat the hot water and throw out extra heat into the whole house. I am surrounded by woods and live opposite a sawmill, and each year I burn excess wood in the open just to get rid of it. Yes the ASHP will come on automatically, like "central heating", when we need it, but I can "turn it off" when the log burner is producing what will effectively be free heat. Very interesting replies all the same.

I'm slightly disappointed that you can’t simply connect a wood burning stove, to the hot water cylinder which the ASHP will also heat. Back when I was a lad, we had an immersion heated water cylinder ALSO connected to the coal fire back boiler, so when the fire was lit, no need for the electric immersion heater. This sounds like a step backwards ?? To answer the points above, this is a new build, fully insulated with an ASHP and underfloor heating. I was only looking to fit a log burner for those long cold evenings. Also during these times in winter the ASHP would have to work overtime to heat the water as well, when it is least efficient, due to the ambient temperature. The log burner I hoped would supplement the water heating during these times, and just leave the ASHP to deal with the UFH. Am I missing something…. probably.

As the house is being built from scratch, I can have as much space as I need, insulation levels will be "over the top", as I have spent 30 years in a cold drafty 200 year old house, hence the new build. I checked and there are no smoke control zones anywhere near us, thankfully.