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MG ZS EV
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I had a discussion with a member of Octopus‘s people involved in heat pump research some weeks ago. There weren’t any 3 phase smart meters available at the time and no timescale for getting them. My discussion was about the total load with a heat pump and immersion heater running at the same time as 2 cars charging. It will be fine as long as I don’t boil the kettle!
 

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Glad to hear it has gone well. My quote for 3 phase was £750 plus VAT, but I had to provide the trench and draw rope! At 73 I became disinclined! However given that my heat pump can ramp up to 6 kW and we have a 7 kW hob thar does rake us up to the limit if the car charges at the same time. I suspect that a lot of folks in larger properties will need 3 phase before to long.
 

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Almost exactly the same Brian. And for me whilst not at your age, I smashed my ankle badly and like metal mickey below the knee at present. Otherwise would have done the ground work as well.

Price I thought was pretty good overall.

Heat pump will be my next project after the solar and batteries.
Heat pump needs to be done ASAP to get the RHI money which looks to be more generous than the new proposal of £5k if you have a larger property. My 14kw pump and controls were over £7k I believe.
 

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Thanks Brian. New area for me so not so knowledgable yet and keen to learn.

Could you explain what RHI is please? Our property is mid size .... 4 bed semi but extended twice. Insulation is 100% in some areas .... have done underfloor and over ceiling, room by room, cavity walls but roof area at top of house still needs improvement.

So you feel it's better to move before the new announcements by government today which I believe come into effect April 2022?

Do you have any links and resources that can educate a beginner in this area Brian? Very interested to start learning about the best options. And is your heat pump a horizontal solution or bore hole based? Which is the best way to go efficiency wise, budget aside?
The RHI grants are run by Ofgem. See this link for info.
Mine is an air source heat pump for a 5 bed house with a large kitchen extension. ASHP s need little maintenance and provided you keep it clean your installer can check for faults remotely. Ground source heat pumps are expensive to install and expensive to maintain with brine to replace every few years.
The RHI grant is payable over 7 years and is dependant on the heat requirement of your home per an EPC and the efficiency of the heat pump, the SCOP. There are cowboys in the trade upping the price because grants are available, if, as I did, you can find a local heating engineer then try for him. Installers have to be MCS certified and you can get a list of local people from their web site.
If you have 28mm piping to from your present boiler, installation will be a bit simpler, the ideal is for a lot of warm water at 35dec C or a bit less rushing around the system feeding big radiators. My house was built in 1984 and the insulation improvements meant that all but one radiator was big enough. The microprocessor controller needed a lot more wiring than I imagined and together with this we have 4 pumps on the system operating in 2 zones, one for radiators and the other for underfloor heating in the kitchen. It took 3 of them 3 days to remove the old oil system and get the new hot water tank with a large heat exchanger in place and the pipwork and pumps rejigged. Since then the boss has been back to continue the control wiring. That is awaiting completion with some bits on back order. We hope to finish this week, some 5/6 weeks after start. We also needed a new consumer unit for the extra power requirements, the additional immersion heater and the pump itself.
 

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Very interesting Brian .... thanks for taking the time with the explanation. Certainly ASHP would be miles easier and we have roof space right be the current boiler installation. And I am fairly sure we do indeed have 28mm pipes.

Our rads are very typical mid height old pressed steel ones. Do you mean larger would be better? And would an aluminium or higher efficiency rad help?

Didn't realise the GSHP's needed that level of maintenance. Good to understand that.

This is bad news .... you got me drafting out my next project Brian :) .... very interesting stuff. That me reading and investigating the right of this Wednesday evening
Ok, next instalment. Radiators are generally quoted as sized in btu or kW) 3400 btu equals 1 kW. That is the heat output from a radiator at average temperature of 70 deg C into a room of 20 deg C. Old systems pushed out water at approx 80 degrees and returned it to the boiler at 60. You size a radiator for a heat pump at 33 degrees into a room of 20 degrees, I.e. in at 35 degrees out at 31. Fifty degrees difference in the first instance 13 degrees in the second, so radiators need to be 4 times the size. Well you can have smaller radiators but your COP declines. The COP is higher the lower the difference between the air temperature outside and the heat of the water coming out the heat pump. Think of your fridge running hard on hot days, but in reverse.
If you can heat your home on the frost setting on your present boiler in cold weather, you may not need to change your radiators. You might get a chance to try that out in the next few days. Remember your heat pump runs long and low rather than high for short periods. High thermal mass, brick, block and concrete are good for holding heat. My 1984 house had single glazing and 2 inches of fibreglass in the loft when built. All my radiators bar one in a north facing room were good enough. They will all be turned on to gain from the whole radiator surface. If by chance you need to swap radiators look to swap single panel for double or double plus, type 21 or 22 to save moving pipes. The Screwfix/Toolstation catologues have radiator sizes and outputs.
You might want to work out some heat losses using u-values, that is another instalment.
 

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Next instalment….. well someone has done a good job of describing it for me, I think it is a good balance of straightforward and technical….


You can try and work out the heat loss for a couple of rooms and see how you get on. Heating engineers add for air changes so allow for about 10% and again another 10% for north facing or exposed rooms. Look at your radiators 60 cm single panel radiators emit 100 watts for every 10 cm length. A 60 x 60 double type 22 (2 sets of fins) emits just over 1 kWh at delta 50 (80/60 degrees into a room at 20 deg C) so divide by 4 for delta 13. If you have added a lot of insulation, double glazing and cavity insulation since the ch was installed you could be fine.
 

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A very useful read Brian. Many thanks for that. I'm going to take a little while to read again properly and not just pretend I understand it all.

Jumping off topic a little, I'm reminded how all this started with me breaking my ankle late May this year and spending 10 days in hospital! How so?

Well during the stay, I came under pressure from wife/daughters to stop doing all our work myself. And it is true I do, from house to car to computers to well near everything ... like some of you on here do. Not because I have to, because I had the choice to I suppose.

So after reading a pile of car mags, I quietly decided to order an Ioniq5 much to my wife's surprise and total agreement. Our local Hyundai dealership proved hopeless very quickly, so I moved to Audi (who have also been totally hopeless). And ordered an Etron GT with 22kw charge option. Bear in mind that I drive a 1995 base model diesel Peugeot 106 which is still doing near 60mpg :)

Then I looked at chargers .... which led to 3-phase, which led to batteries which led to solar and now here you and I are discussing what I am now certain 'WILL' be our next project! And ALL of those have either happened or are mid flight right now except the Heat Pump.

You sir are a bad influence .... a good salesman and very informative. :)
The RHI grants won’t last beyond March, by the sound of it you will need a fairly big system which you can’t install yourself to get the grant. It is paid over 7 years and might well be worth getting a loan if you need to to recoup much of the cost. My 14 kw heat pump, new high efficiency hot water cylinder and fitting wil come to over £13k. The RHI payments should come to over £12.5 k. I had a really efficient oil system but even so I expect to run my heating for about £650 compared to 2,500 litres of oil, so I should save £500 plus a year. My Octopus Go tariff is 5p / 15.59p fixed until next September. By then I think we will see power prices dropping, more so for electricity which I expect to see lose its carbon tax so as to encourage the switch away from gas, but also the new wind farms coming on stream will add 3 GW of generation by next summer and there will be a short lull before another 5 GW of offshore come on stream. Already this week the Agile tariff went negative on Tuesday at 2.5 p a kWh but only for half an hour, but this does show how finely balanced the supply is in getting back to cheap electricity. Last year we were averaging 8p a kWh on Agile.
Glad to see that you are embracing the green technologies, the naysayers are a pain in b**. They haven’t got the brains to look at it intelligently and take a punt.
 
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