.... another installment, made me laugh Brian. But hey this is genuinely interesting stuff to the uninitiated .... is quite amazing just how much you can learn in a few posts from someone who has gone through the hard work for real.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.
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.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….
U values in building construction - introduction
Explains simply how U values are derived from components: R value resistance; Lambda (λ) or k value and the thickness of the material product.www.greenspec.co.uk
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.
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.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.![]()
Again, genuinely thought provoking stuff. I'm definitely getting pulled into this as well as all the others I have circulating to land like planes on the westerly approach at LHR.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.
Is probably the wrong time to move, but what I've found is that Octopus officially quote 3 months lead time but in reality (when they trust you after a little discussion) are saying 6 weeks. And OVO (current supplier) was just over 3 weeks and no charge. Booked and in process.To get back to the start of this thread, I have a 3-phase supply (dating back to MEB days) because I have a large off-peak heating load, but so far my supplier (Utility Warehouse) have been unable to supply a 3-phase smart meter.
I would have thought that as users with 3-phase supplies would have the larger loads, it would be important to get the half-hour data for those loads, but that appears not to be the case.
I wonder how much this is due to the difficulty of billing? For small domestic suppliers it may be a manual process.but so far my supplier (Utility Warehouse) have been unable to supply a 3-phase smart meter.
Yes, but it was also to replace an ancient cable that the DNO just kept patching.
Presumably this is to allow you to export at something like 50kW?
Actually more like a 300hp Fendt Tractor rather than a ride on lawn mower!! 🤣Ouch, doesn't it just! You in a different league altogether there Fordy.
Think I'm Renault Clio cup where you definitely F1!![]()