Air Sourced Heat Pump.

Thanks Z, but you don't need to "quote" the post above, not only you but is beginning to annoy me. Sorry!

I suspect you are still of the school of thought that you turn the heating off and back on again many times over a twenty four hour period, which is not the way to run a heat pump.

3 kW x 24 hours = 72 kWH


200% efficiency equates to 144 kWH.


500% efficiency equates to 360 kWH.


So with adequate insulation and correct design they will do the job, but they cannot just be retro fitted to existing heating systems in cold and draughty homes.

It does make the posts difficult to read on a phone, particularly when there are multiple quotes.

Back when I spent the day at  Mitsubishi, which was around fifteen years ago, they said they would only sell their products for their approved installers to install, otherwise they would get a dreadful reputation and they would not sell any.


So having taken the decision that installers had to be Gas Safe registered, despite there not being any gas involved, how does that decision stand up to scrutiny all these years later?

that has had a new build home which was required by building regs. to have an air sourced heat pump for heating and hot water


It could be a little unfair to blame Building Regs as I suspect there was a client or even architect concept idea of a design that was thermally inefficient, ie large areas of glass that in turn triggered a need for compensation elsewhere, ie the use of air source........


But easier to blame Building Regs rather than a poor, but "pretty" appearance for show.


Regards


BOD

I was listening to a discussion about air source heat pumps on the fix radio plumbing show and the speaker said that on the training course there was a lot of time wasted explaining how they work, but there was very little detail about the requirements for the wet heating system design, he went on to say that you don't really need to know how the air source heat pumps works and the focus of the training course was wrong.


Basically gas boilers, oil boilers, electric boilers and heat source pumps are just boxes with a flow and return pipe that connect to a wet heating system and all you really need to know is the volume, flow rate and temperature of the hot water available from the box, so that you can design the wet heating system accordingly, generally how the box works is irrelevant.


You don't need to know how electricity is generated to carry out electrical installation work, just the nature and capacity of the supply.

That may be true Andy, but I bet that he said nothing about the thermal mass of the building, or calculate heat-up times, or the other things I mentioned above. Most people do not know or understand that the COP (you called it efficiency above, but your term is seriously inaccurate) varies with the input and output temperatures very widely, or that wet heating with cooler water basically doesn't work, or that the radiator mainly transfers heat by convection or a myriad of other things. It would be nice to have wet heating with a small rad and a 25C water temperature, do you know why this will need rads the size of all the walls? Why does a house with 10kW of heat loss when outside is at zero, need more heat when it is -10C but not in proportion to the difference as the heat loss increases more than expected? Why is air to air transfer best? How much insulation do you really need to get heat loss in the low kW range, and how much energy do you need to make this compared with the heat loss it stops? Do you really want small portholes in place of windows? You know how much power in electrical form we have for each property and it is not a lot for space heating. Electrical energy transfer from fuels is about 30% efficient, but your gas boiler is 95% efficient (if modernish), so why change? Only if the electricity is essentially cheaper or free, but it is not! Even a combined cycle turbine is about 45% and then there are transmission losses, why go there? These are the really hard questions that politicians cannot answer because the answers are not sensible, particularly if every country changes to all electricity.


As a direct answer to your point, good electrical designers do understand the supply fully too, because they have many supply constraints to deal with. Domestics are usually fine, but bigger things get much more complex in concept, supply, and potential problems. You cannot design a hospital, school, or factory with the OSG or even just BS7671. You are just beginning to see supply constraints with car chargers and similar. It can only get more complex. Imagine a 500-bed hospital with 500 on-suite showers that are electric. What is the diversity to be applied?