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Fan assisted radiators will extract a lot more heat without needing a bigger radiator. I fitted some 80mm computer fans under a radiator in my previous home and it dramatically speeded up heating the room.
 

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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.
.... 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.

I'd be open to new radiators ... it's been a discussion anyway over the years to do something cosmetically more interesting with them. And for a real solid, measurable reason .... even better again.

Insulation is probably my focus point. Half the house is tight as a drum. 30% remains to be done to a higher level. But we do also have a 20% that likely can never be done. It's original suspended wood floors then fitted (about 30 years back) with mega high quality and insane expensive hard wood flooring ... the real stuff, not that stuff from B&Q. I could never afford to pull that up and replace. Half of that is over suspended voids, the other half over concrete floors which were properly insulated in the build process.

The maths scares me some but I need man up to that very soon it sounds like.

Look forward to another installment soon Brian. Is proper good stuff for me.
 

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MG ZS EV
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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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Discussion Starter · #24 ·
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.
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. :)
 

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MG ZS EV
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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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Discussion Starter · #26 ·
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.
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.

And did you use a third party to co-ordinate and do the work Brian? No I certainly don't intend doing this one myself, not for a second. I'm just wandering where to go now to turn the knowledge you have kindly been sharing and turn it into something tangible.

And just doing the old consultancy thing for a second, what are the down sides of the Heat Pump installation? What has disappointed or not hit target so much as you'd hoped?
 

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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.
 

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Discussion Starter · #28 ·
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.
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.

Just to note we are in the part of the world (give or take 10 miles) as well so lead times will be pretty much the same I'd have thought.

The consistency of lead times / supply seems as consistent as Tesla destination chargers being usable by non-Tesla drivers :)

But if you need one and it's critical, I can confirm the OVO and to a lesser extent the Octopus routes work and in reasonable lead time.
 

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but so far my supplier (Utility Warehouse) have been unable to supply a 3-phase smart meter.
I wonder how much this is due to the difficulty of billing? For small domestic suppliers it may be a manual process.
 

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o_O

Presumably this is to allow you to export at something like 50kW?
Yes, but it was also to replace an ancient cable that the DNO just kept patching.
The old cable was a 1940’s paper and lead encased cable - originally three phase until one of the phases went poThen a two phase, a number of the prior customers were reduced to single phase and split across what remained.
There was a refusal to reinstate the three phase. After very frequent failures and power cuts, and getting nowhere with the DNO we decided to bite the bullet and get a new supply for ourselves. Unfortunately the DNO can dictate the size if the cable - so upsized it beyond our needs so the got us to renew and extend their network..
Just one of the issues with an abusive monopoly in charge of a region.
That cost certainly hurt, but yes we can now export up to 65kW out to the grid, although it’s highly unlikely we’d ever export much more than 40kW, and even that should be rare, since we aim to self consume most of what we generate using our large storage capacity.
 

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Ouch, doesn't it just! You in a different league altogether there Fordy.

Think I'm Renault Clio cup where you definitely F1! :)
Actually more like a 300hp Fendt Tractor rather than a ride on lawn mower!! 🤣
It’s all relative. The numbers are bigger but the challenges are just the same, actually it is sometimes harder going smaller.
We couldn’t really go much smaller with our storage, for example since then the scale of return wouldn’t make sense. We might actually add to the capacity later. Fortunately it’s a type of storage that allows “de-coupling” of power and capacity, so we can increase just capacity, just power or both.
 
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