Posted by: @editor

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@andrewj, you’re absolutely right that these systems work best when the house is well balanced and properly designed from the outset

This is so important.  For my money householders need to know how to balance radiators using the lsv.  Why? Because, given that its unlikely that radiators are perfectly sized, you really need to balance for room temperature not deltaT.  That takes longer to get right and so it's unlikely an installer will do it.

The good thing is that in many cases it won't have to be particularly accurate, because rooms share heat.  It's also fairly intuitive.  However there is a pitfall namely a householder turning down the lsvs on all radiators potentially restricting flow.  How to get that over?  Possibly something like 'if one or two rooms are too hot (absenting disturbing factors like solar gain) turn down the lsvs.  If the house as a whole is too hot/cold think about whether you need to adjust the wc curve?

@jamespa hi James, yep in deed you can and thet would be my 1st solution rather than change a rad but it does effect the overall flow of the system slightly which is ok with one or 2, I was not offering solutions just pointing out the likely causes and so on. Otherwise I would have to write 5000 word response to every question 🙂

Posted by: @jamespa

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However there is a pitfall namely a householder turning down the lsvs on all radiators potentially restricting flow.

You may recall that this is what I did, without realising I had done it. The problem is this: you balance the radiators on a normal day or over a period of normal days. Without realising it, you have turned some or all the lock shield valves down to the point where the flow is severely restricted, but you don't realise this, because, being normal conditions, the heat demand is low, and the restricted flow, despite being restricted, is sufficient for the current lower demand.

I think the only practical way for the average occupier to spot they have throttled the system is to wait until they have design conditions outside, and then check the heat pump's output, to see if it matches the design output. This assumes you have a way of knowing what the current output is, which not everyone has. That just leaves the room temperature: the house gets cold on cold days. But the causes for that are legion...

I am not sure how much of a problem over-balancing radiators is in the real world. Any thoughts anyone?    

@cathoderay Unfortunately, you are correct and although there are many sound ways to work this out manually and roughly, to balance systems correctly need's tools to measure DT on every flow and return at every emitter and a correct design with correct emitter selection.

If a customer wants the best COP with the best comfort and the best efficiency it all starts with design and ends with commissioning. 

I think eventually there will be a service like you could get on your car to tune it, there will be companies offering an ASHP heating tune up / blancing and the cost will probably be covered by the savings on the worst set up systems.  

Posted by: @cathoderay

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I am not sure how much of a problem over-balancing radiators is in the real world. Any thoughts anyone? 

In addition to Adia, I know of two other auto rad balancing valves that will be hitting the market imminently. I might actually write about one this week. The other is still under NDA. 

Posted by: @ashp-bobba

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@jamespa hi James, yep in deed you can and thet would be my 1st solution rather than change a rad but it does effect the overall flow of the system slightly which is ok with one or 2, I was not offering solutions just pointing out the likely causes and so on. Otherwise I would have to write 5000 word response to every question 🙂

 

 

Fair enough, I was just checking I hadn't missed something!  Thanks for replying.

@jamespa anytime. you would not believe how many times I have had to stop myself going so far as to write a complete document to a solution, I keep reminding myself to respond in chunks but each time I do, in my mind I am thinking this answer will lead people to ask about another answer and so on.

You have great and quite tech knowledge of these systems and I enjoy reading many of your responses so thank you too.     

Posted by: @editor

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Posted by: @cathoderay

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I am not sure how much of a problem over-balancing radiators is in the real world. Any thoughts anyone? 

In addition to Adia, I know of two other auto rad balancing valves that will be hitting the market imminently. I might actually write about one this week. The other is still under NDA. 

Very interested in this!

Aren't self balancing valves really designed for multiple zoned houses. So as one or more zones open or close the flow rate through other radiators adjusted. I know Salus self balancing actuators for UFH are for that very reason.

So with above, and running single zone open system - what value do they add to you - not the sales man?

@editor there seems to be a fair bit of interest in this area, I reckon it would make a good podcast to talk in more detail about the ins-and-outs of load compensation, details about setting it up and making sure it works successfully, how to recognise and resolve problems, perhaps how to balance the system with and without auto-balancing valves.  It could be done just in time for the next heating season perhaps?  I know some of this will be manufacture specific, e.g Samsung will be different to Vaillant but puking a couple as examples would work and pointing to a forum post to cover other manufacturers could work.

Posted by: @Anonymous

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Aren't self balancing valves really designed for multiple zoned houses. So as one or more zones open or close the flow rate through other radiators adjusted. I know Salus self balancing actuators for UFH are for that very reason.

So with above, and running single zone open system - what value do they add to you - not the sales man?

In the context of a single zone heat pump system a valve that self balances very slowly for equal (or set) temperature would avoid the need to adjust using lsvs.  Given that this is a very slow process that might take many hours or even a day or two to get right (in contrast to balancing for deltaT) I can't personally believe many installers do it, and I am certain that many householders wouldn't dare.  This may be why some people resort to using trvs instead of operating open loop.

Essentially what is needed I think is an automated lsv.  The challenge in my mind is to develop one that fits on an existing trv body and has the right time constant, then to stop people fiddling with them in the first few days of operation while they settle down.  I am not sure if they all need to communicate or whether a bit of randomisation of the time constants will stop them fighting each other.  It also needs to be decorator proof!

Cost needs to be sufficiently low that they can be fitted to all or most rads.  Alternatively it needs to be a system that the installer fits and then removes a couple of weeks later.  Not sure if the latter would make commercial sense though.

The starting point is probably a smart trv mechanism with different firmware.  

Well that's my take anyway.  It will be interesting to see what the industry comes up with!

Posted by: @jamespa

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Posted by: @Anonymous

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Aren't self balancing valves really designed for multiple zoned houses. So as one or more zones open or close the flow rate through other radiators adjusted. I know Salus self balancing actuators for UFH are for that very reason.

So with above, and running single zone open system - what value do they add to you - not the sales man?

In the context of a single zone heat pump system a valve that self balances very slowly for equal (or set) temperature would avoid the need to adjust using lsvs.  Given that this is a very slow process that might take many hours or even a day or two to get right (in contrast to balancing for deltaT) I can't personally believe many installers do it, and I am certain that many householders wouldn't dare.  This may be why some people resort to using trvs instead of operating open loop.

Essentially what is needed I think is an automated lsv.  The challenge in my mind is to develop one that fits on an existing trv body and has the right time constant, then to stop people fiddling with them in the first few days of operation while they settle down.  I am not sure if they all need to communicate or whether a bit of randomisation of the time constants will stop them fighting each other.  It also needs to be decorator proof!

Cost needs to be sufficiently low that they can be fitted to all or most rads.  Alternatively it needs to be a system that the installer fits and then removes a couple of weeks later.  Not sure if the latter would make commercial sense though.

The starting point is probably a smart trv mechanism with different firmware.  

Well that's my take anyway.  It will be interesting to see what the industry comes up with!

Morning, could this not be achieved with “regular” smart valves?
Never looked into them but if they could be controlled by say Home Assistant they could be programmed to go into balancing mode untill they are done then switched into sensor mode to provide room by room temperature data.
You could also have some tht are set for solar gain mode. You could add guardrails such as input system volume to prevent choking off the flow too much.

Obviously this would be for a very niche audience and not everyones cup of tea but it is doable I reckon.