SteamyTea

Then that 415 kWh seems plausible, especially as the ASHP, at 13 kW (not kw) is well sized to supply that. For a laugh, try and take daily readings, and if you can get the outside and inside temperatures as well, all the better.

If you take away 2 kWh a day for cooking, and assume a CoP of 3.5 if an ASHP was installed, and the gas boiler has a true efficiency of 85%. True gas usage for water heating: 28 [kWh.day-1] x 0.85 [eff] = 24 kWh.day-1 Now a 3.5 CoP ASHP: 24 [kWh.day-1] / 3.5 [CoP] = 7 kWh.day-1 Half a year is 182 days. 182 [days] x 7 kWh.day-1 = 1724 kWh So something does seem amiss. 2, 5 minute showers, at 10 lt.min-1.day-1 would be around 3 kWh.day-1, or 540 kWh, which seems plausible. If that was heated at CoP of 3.5, then 154 kWh over 6 months, which is a third of the meter reading.

What is the EPC Score, and I suspect you mean the maximum heat load is 7.49 kW. What size is your ASHP?

Depends on what the overall heat losses are, and the peak load is. Have you had a heat loss calculation done?

well it does depend on how sweaty they are, and for how long they are kept like that.

If it is a HP that is heating the water, then that will be 3 to 4 times larger, with only a small proportion of it going to space heating.

No. Saying you need to calculate the floor losses as a fraction of all losses. You could fit a combination of traditional double radiators and skirting radiators, and possibly plinth, fan assisted ones.

So you saying that climate sensitivity models have never existed? Or that if they do, they are just work of imagination? Or maybe they are tackling the problem from the wrong angle, maybe these corrupt climate scientists should only look at the social impact that that their reports have, even if they have been asked to report on something else As I have said before, in science, it is best to answer the question asked, not one you wish to answer. Not answering the question is what politicians, pub bores and wankers do. And if the person asking the question does not understand the answer, that is not the problem of the person answering it. It is wrong to put all the onus on the person that has done what was asked if then. This is not a communication failure on behalf if the science community, it is a failure of education at a lot if different levels. Only hearing what you want to hear, and dismissing, in general or unrelated, terms, any answer you personally dislike, just makes one look uneducated.

Not really, in my opinion. It is not the intrinsic properties of the materials used, it it the floor losses, as a percentage of your house losses. This is caused by the greater temperature differences that the floor is heated to, compared to an unheated floor. So as an example, if your house needs 10 W/m² at a temperature differences of 10⁰C, you may find that 3 of those watts are going through the floor when it is at 18⁰C. But 7 are going through if you raise the temperature of the floor to 30⁰C. It is just a case of doing the numbers and seeing how they compare. 0.15 W/m².K will be 3 W when the slab is around 28⁰C. 3 W does not sound much, but that is for every m², and all the time the heating is on, plus a bit when it is cooling down. So if your slab is 100m², and the heating time is 1000 hours, that is 300 kWh.

That is a very valid point.

God, I wish I had never mentioned signing off others work. But I have had no abuse on this topic, must be loosing my antagonist mannerism. Can't be that hard to run a bit of unjointed pipe though a house wall. Larger buildings maybe a problem. Or just fit a heat pump. If fitting solar thermal, you use compression joints.

When a heat pump is running at full power, it is because the temperature difference between inside and outside the house is at maximum. This will affect the coefficient of performance, especially true for ASHPs. It is usual to size a heating system to cover 99% of the time heating is needed. This does not mean that during that 1% it supplies no heat, just that the CoP drops to parity i.e. you may as well have used a fan heater, or the internal temperature may be lower than the ideal temperature. The trouble with with methodology is that there is no scale, so you may be 0.1°C below the ideal temperature, or 15°C below it. So take where I live in Cornwall, I could set a minimum external temperature to -5°C and be fine. Up on the East Coast of Scotland, probably have to set that minimum temperature to -12°C (bit of a guess there as I have no idea what the temperature profile actually is). So apart from taking the possibility of frosting, in the case of ASHPs, into account, yes, set the size for the maximum load, or to the next available size up. It is possible to model the expected temperatures if you already know the external temperature profile. There are only two number that are needed, the mean temperature and the standard deviation (the spread of the temperature range). Then it is just a matter of creating a dataset of the temperature range and plotting it. This will create a chart similar to this: From that, you can add up all the percentages below the whatever temperature you turn your heating on from. These percentages are for the time the heating is on, not of total time i.e. 8760 hours in a year. So taking 12°C as the temperature you need to start the heating season, this gives a total percentage of 93% of the time for the real data and 91% for the modelled. Pretty close to the 99%. So probably going up to the next size HP will cover it, especially as my data is using the min real temperatures, not the mean, which is higher at 9.2°C and a SD of 5.4°C. The big frosting risk for an ASHP is between 0°C and 4°C, this is when water is most dense, so there is more to freeze. Summing up the percentage of time for those ranges give: Real 31% and Modelled 29%. By oversizing an ASHP (as opposed to a GSHP or EAHP), you get more running time before the defrost cycle needs to start. This is worth bearing in mind when heating DHW because that is for a shorter time and at a greater temperature (generally close to the units maximum). DHW is another reason to oversize a HP. The most important thing to do though is a proper heat loss calculation for your house, that will establish the power needed at any external temperature, the W.ΔK-1. Without that calculation being done, it becomes guesswork, and that is never good.

Got my hard hat there

Ok from now on I will assume this audience is scientifically illiterate. Should be fun. That Radio 4 program about copper pots and leeches is about 20 years too late. It is all old research. Was even taught to some undergraduate nursing students in the late 90s (where I heard about popping maggots in ears.

When I bought my house, my solicitor got very hung up on the replacement front door not having a FENSA certificate. It had been in 8 years. I went and found, for a few quid, an indemnity policy to cover it. This was not good enough for my solicitor. So to move things on I bought through them at over twice the price. Now, 16 years later, and that one door, is 24 years old. Would I need, or whoever wants to buy the house, a certificate or indemnity insurance?

Karl Popper would have liked that response.

You see what you are doing here is using something that is now accepted, but ignoring all the other ideas, some may have been better.

Yes.

Only come from the days when blasphemy was an offence. Just means "God blind me".

Not when it is opinion.

That is because it was never there. You still believe that don't you. Just go an read up about it, I have posted up enough links about it. Just saying what you want to believe is happening does not make it true. The CET data was not collected by climate scientists. You really have a personal problem with people that are educated and study their chosen field.

Just washed my hair, will it dry it for me?

The enthalpy H of a thermodynamic system is defined as the sum of its internal energy and the product of its pressure and volume:[1] H = U + pV, where U is the internal energy, p is pressure, and V is the volume of the system. As you are trying to change H, but do not know U, and cannot control p, the only thing you can change is V, by putting more air though the system.

I remember that there was a guy on eBuild that that had trouble getting his RH down. He kept opening windows putting the MVHR on and off, heated etc. Don't think there was an outcome. Have you got any lime in your build?

I was always told that if you draw a line from Bristol down to Weymouth, then anything west of that is the South West. I once heard a radio program where they referred to Oxford as in the South West. When I lived in Bournemouth (west of Salisbury), it was always refereed to as Southern England, and was on the South Coast. Much of this is to do with how the UK is orientated on a map. It is easy to assume that where I am, 5°W is above France, but it is actually more than halfway across Spain.