SteamyTea

If the sentence had been longer, then we could have had kw/h as well.

Materials have a number of 'strengths'. The main thing to consider is working at the lower end of the elastic limit (material can recover), and never getting close to the yield point (material cannot recover). One of the problems is that because strength of materials is a force, and a force has a time element (f = ma, where a is acceleration m.s-2), what initially seems fine can fail in the future.

They can in a controlled environment i.e. indoors. How long would it take to shoot 1000 rats on a 100 hectare farm? If we say a good shooter managed to kill 1 in ten, and each shot takes 1 minute, then that is 10 minutes per kill. 10,000 minutes. 167 hours. Or about 1 month for someone working a 40 hour week. The only reason that farmers claim to need a gun is to massage their fragile egos. Ban guns, then, in no time, much more effective controls will be in place.

Basically, the efficiency (CoP) of a heat pump increases the smaller the temperature difference between the outside air (OAT) and the delivered temperature. This is the power (W or kW). Depending on how long the heat pump is working, in hours, multiplied by the power it takes to run it, is the energy, the kWh. The problem is finding the right position under the curve (integral) that is most cost effective. This is especially hard if the outside temperature is variable i.e. the day starts cold then warms up, then gets cold again. The 'on' times need to coincide with this. This can be done manually i.e. switch the HP off for 6 hours during the warmer period of the day. The trouble with this is the efficiency of the HP may well be quite low as it tries to reheat everything up to operating temperature. This can cause icing up of the outside unit that takes energy out of the system to clear the frost off the fins. My view, and this is purely academic as I don't have a heat pump, is that, if you can run the unit for as long as possible, at the lowest output temperature possible, your increased CoP will counteract the longer running times. This may seem counter intuitive as the HP is using electric power for many hours. But ten hours at 1 kW is less than 4 hours at 3 kW, even if that 4 hours is spread across the day. The problems (calculations) gets compounded if, for tariff reasons, the amount of time the HP can be run on a cheaper tarif, especially if that tarif time is in the middle of the night. So summing up. Run the HP at the lowest output temperature you can get away with. Accept that the house temperature may vary during the day by 2 or 3⁰C. Learn how the weather compensation curves are set up, these are designed to deliver more power, but at a lower CoP when it is really needed then back off as the temperature increases. It is like driving up a hill, you have to put more pressure on the gas peddle, and sometimes change down a gear, then you can coast down the road for the next bit, as long as you did not loose too much speed on the up hill (or you just get in the way of everyone else).

Why should a pig farm not be able to control the distribution of animal feed. Do you really think that a gun is an effective manner to control vermin? Farmers tend to do what they have always done, look backwards to a time when there was less control on the food supply industry.

Would be easier to take away their food supply, they will soon move away. Always amazes me that farmers leave rat food all over the place. An oil storage depot would not be allowed the same tardiness. Guns, of any sort, should be banned.

@JohnMo You seem to be going down the same path that @Jeremy Harris went down a fair few years ago. Real shame that his blog is not about anymore (possible wayback machine has a copy). In the end he dumped it all and got a Sunamp for the DHW. No idea if that is still going well, he had trouble with one of them.

Building Merchant.

There is no one answer to that question. What are you trying to achieve, and what do you mean by efficiency?

Stops overheating. 300W is still pretty good.

Was wondering this. Can you tell how much power the unit is drawing when it is set to 15⁰C? Should not be as much as the proper inbuilt water heater.

I worked, briefly, for a small turbine manufacturer. They made a 5 kW turbine. It was a bit noisy if you were downwind of it. I did think up a way to significantly reduce and deflect the noise, but never got a chance to test it. Company ceased trading, then the design got bought off the receiver. Luckily I had not left my ideas with them.

That is interesting. I had a large garden to sort out when I was living in Hertfordshire. The small electric shredder (from B&Q) worked a treat on newly cut stuff, hopeless on week old stuff that had been left in the sun.

Could you do it with a Tyvek type material? It lets moisture out, but reduces air mass flow rate to virtually zero.

Would have to change my 3W Poundland bulb to a 5W one. I could live with 5W. 100W would not run the fridge. Would the kettle though, and that is important. May have to put the milk in first, then hope the fridge kicks in when the kettle is boiling. Second thoughts, that would make horrible tea, so happy to pay the import duty on 0.3 kWh a day.

Were you thinking that the Might James Dyson had fooled nature. Of cause it did nothing, the motor is tiny. There was a report about a new wind turbine on Moneybox the other day. Wind hits the vertical pipe, gets forced up to the turbine by vanes and generates power. Better than a traditional turbine. My arse it is. Why don't the BBC, who do reality checks, check with one of the many physicists they employ to show them the error of their ways.

That is really the over riding issue with storage. So half what is lost in cabling losses, and a lot less than inverter losses.

I did the same 17 years ago. Went from 4-8-4 (mm) to 4-16-4 (mm). Just had to make a new bit of trim. Some have now blown so will replace them in due course. No hurry as I don't sit looking out the windows. Shall do it next time I paint the frames. A quick job now I have my own scaffold tower.

Floors, walls, ceilings, rooms, roofs. With UFH, power delivery is a function of surface area and temperature. Eternal walls the heat losses are a function of area and temperature difference, same with windows and doors. Ceilings and roofs are a little difference a it depends on construction. But basically the same. Some rooms may be at a lower temperature than others, hence knowing the physical sizes helps with the heat emitter sizing. If the roof is suitable i.e. facing the right way, then PV is worth considering, especially if it needs reroofing. Put in PV modules rather than slates/tiles.

Right. Then just some accurate sketches. From them, heat losses can be calculated. Houses are basic things really. Insulated and airtight boxes, then control the ventilation and thermal inputs. I have had 5 terraced places, two which are end terraces. Was not until I moved to this place that I took much notice of energy usage, though I did appreciate the advantages of a better built place. But all that can wait until you own it. But in the meantime, read up about the physics of buildings on here, there is a lot of stuff.

Welcome. 2 things first. Wait until you own it. Then sketch up the place and take daily meter readings for gas and electricity. Then we can all chip in with conflicting advice and ideas.

It could be integrated into the MVHR. There is an argument to have the MVHR pipework double the usual diameter. I am not sure why it is so small really, probably ease of fitting/retrofitting. Larger pipework would reduce airflow speeds, and therefore noise, shift a lot more energy around the place, and possibly, due to lower back pressure, use not much more power. If you are fitting solar PV to the build (and you really should if you haven't already) then the A2A mini split already suggested is a no-brainer. The coincidence of powerful Sun and plenty of free electricity is a match made in heaven. Yes. But architects should not be designing in overheating. They are paid to be the experts, or at least be able to employ the experts to get the design right. My parents last house had a large, all glass, proboscis on it. Even though the glass was heavily blue tinted, the overheating was dreadful. Then freezing during the winter. Thinking about it, maybe the blue tint was not the best colour. Means it was absorbing the reds. They moved after 5 summers in it.

That is Essex for you, did they have primroses in the garden. (I spend some of my early years in Essex and still have the accent when I am tired).

Could you not have had the turbine (I assume it was small) dedicated to just heating water, then no need to control much at all, just maximum temperature.

Pretty good really. Makes me wonder why we don't fit a glass panel over 'daylight' walls and pump the thermal energy around the house. A posh trombe wall, but not using the wall as storage so much.