MJNewton

That's a good point, and I think mine does the same.

I don't - yet - as I haven't finished the installation (still have a few runs to add) and so haven't done any balancing. All I've done is set the flow and extract to be similar (based on power consumption rather than flow rates) and made sure they're sufficient to convince me it's working. 'Heat transfer' as in efficiency? If so, that seems to be pretty good at an average of between 80% and nearly 100% depending on the two methods described at the Paul Heat Recovery page on the subject: The negative 'blips' appear to align with going into boost as the humidity and power graphs demonstrate, and I guess would make sense as the air is moving faster hence less time for transfer: (I have to laugh: when zoomed in you can even distinguish between my wife taking a shower and I! ) In terms of heat rise between intake and supply temperatures I am therefore seeing pretty much all of what I'm extracting out: We don't tend to have the heating massively high (lounge stat set to 20C but bedroom TRVs tweaked down a little), and this is a retrofit to a 2007-built Persimmon house so far from a perfect environment I'm sure. The pipes are running within the ceilings so whilst they are within the heated envelope of the house I doubt the temperatures there are the same as the rooms and will be being cooled by air leaks here and there. The unit itself, manifolds and termination of all the pipework is in the cold loft so there must be losses there too. Still getting air delivered 17C when it's 0C outside so perfectly acceptable I think - even without a heater as I say, and particularly when compared to what would've been coming through the window trickle vents which I have not foamed up!

Yes, we do - intake, exhaust, supply and extract. There's also a humidity sensor in the extract to trigger boost for cooking/showering. Regarding heaters, we don't have one - and I don't think we really need one either. Even if the supplied air is a little cooler than the room temperature I haven't noticed it cooling the room down, perhaps due to the relatively low air volume and limited heat capacity of air. I'm also mindful of the higher cost of electricity compared to the mains gas we've got - perhaps if we were all-electric I'd be more open about using an electric inline heater more as a case of 'why not?'.

I must admit I've moved on myself a couple of times but have always returned as I'm interested in the subject, can always learn more from others and, more to the point, don't like to think of anyone being persistently cold as that's no fun at all. Very frustrating though.

'It' = your ASHP, and the flow temperature you've set it to in particular.

No, it really is *balancing* radiators. The aim of the adjustments is to make the temperature drop across each radiator the same. If the radiators are correctly sized then this will *in turn* lead to the rooms being heated at the same rate. There is nothing wrong with the term. Please stop with the arguing as it is not helping get your house warmer (quite the opposite in fact - it is putting people off helping).

No problem, and I'm glad you read it - I'm typing on a phone and might've exploded if you'd just dismissed it and kept on going about dictionary definitions of the word 'balance'. For what it's worth, radiator balancing can be mind bending even when you understand it - particularly if you overthink it rather than just go through the right process (which is iterative and can take a while). It is really important though - or at least highly desirable - but often isn't done, properly at least. Many just twiddle a few knobs until everything feels hot and leave it at that. That's fine; they get away with it but this is largely due to the nuclear reactor they've got burning away at the front. You haven't got that luxury (I say luxury; they are unnecessarily overpaying due to the inefficiencies running like this) and so you need to get the most out of that heat pump you've got and be able to quantifiably determine whether you are getting it or not. Even just simply confirming that whilst you've set it to 55C is that what you're getting?

Whilst there is indeed no cold water introduced you must remember/realise that the radiator is extracting heat from the water and transferring that heat to the room. If you throttle the lockshield (which is usually on the return) then the flow through the radiator decreases and allows more time for extraction to take place. Too slow and it'll fail to deliver its full output. If you open it up then the amount of heat extractable increases but do it too far and it'll exceed the radiators capacity and that heated water will return to the heat pump. This 'wasted' flow could've been of more use elsewhere ie run through radiators that are getting insufficient flow to them. That's where balancing comes in - tweaking the flows through each radiator so they get the right amount of flow for their size/capacity/location, ensuring there's enough to go round, helping rooms heat up at the same rate and (for boilers at least - don't know anything about ASHPs) increasing efficiency by minimising short circuits and enabling condensing boilers to extract even more heat from their condensating ability. A thermometer on the flow and return will enable you to observe the effect of adjusting the lockshield, and the former will also tell you if you really are getting water at 55C to all your radiators.

It is so much easier balancing radiators if you can actually measure the flow and return temperatures, indeed I probably wouldn't bother trying if I couldn't unless it was purely to get a radiator working that wasn't receiving any flow at all. But if you know best then crack on and let us know when it's done. We can then rule out lack of balance and inadequate flow temperature from the list of possible causes.

You need one.

Quite an impressive achievement Zoot - you've gone from not understanding the term (perhaps not even hearing of it before either?) to saying the entire heating industry is wrong for using it in, what, a few days?

Yes, I have had *exactly* that with Blauberg. Their website was saying things like (literally, actually): Low stock: 8,957 remaining Turns out it was exactly like you describe and they had loads (somewhere) but none in the UK.

I didn't even know they had prices on the shelves! You must have nice ones round your way. That said, nothing I want is ever out on a shelf anyway as if it was I could work out for myself if it was the right thing and then run the risk of sounding confident at the till - could probably game the system if I remembered to go in my scruffs at the crack of dawn. Ah, yes, the discount. Forgot about that. I think it goes something like: Discount (didn't ask for one: x1, asked for one: x2 then /2)

There's still the 18% of the time when it is in stock though and then you've got the amazing Seemingly-Random Price Calculator that comes out. Turns out it's not random through; I caught a glimpse of the algorithm once and it had various multiplication factors such as: Customer's clothing (ripped/painted clothing: x1, clean jeans: x5, suit with shoes and an office pass around the neck: x10) Desperation level (just passing so thought I'd pop in: x1, clearly desperate and it's getting late: x5, clearly desperate, it's getting late and it involves water: x10) Repeat custom (in here every day at 7am: x1, only here because online delivery not quick enough: x10) Product knowledge (asked for it by name: x1, described it with hand movements and comparison with household objects: x10) Gullibility (didn't ask if the price included VAT: x1, asked if the price included VAT: add an amount equivalent to VAT on top) Duress (no queue behind: x1, queue of real tradesmen behind: x10) Mystery adjustment (x random) (This is just to ensure you never pay same amount twice otherwise you could reverse engineer the algorithm) I'm sure there are others - the list was a fair bit longer.

It's not even that - it's the difference between the *average* radiator temperature (thus (flow-return)/2) and room temperature which therefore drops the actual output even further. It doesn't change the rest of your point though so don't anyone let my pedantry get in the way!