Great video again this week @editor, I am very interested in the FRV valves referenced in the part about balancing. I had a disastrous attempt at balancing my rads last time around and basically gave up and just opened them all up again. I got the rads to all be about DT5 but the next day after I headed of to work the system went crazy and sounded like it was going to explode, leading to a severe bollocking from the missus who had to deal with it. Note self never ever tinker with the system unless you are around to fix it lol!

Are these the magic bullet I need? And do I need them on every radiator?

FIREPOWERHEATING.CO.UK "https://www.firepowerheating.co.uk/frv"

FRV Flow Regulating Valves | Firepower Heating

@grantmethestrength, the podcast episode you mentioned (link below for others) was one of the most interesting and eye-opening we’ve done. It was a real lightbulb moment in understanding how much efficiency and comfort can be lost through poor system balancing. Despite the episode title focusing on pipe sizing, we actually spent a lot of time discussing radiator balancing and its impact.

The FRV you’ve mentioned sounds like a really promising bit of kit. We’re finally getting around to re-piping our frankly bodged system (it’s going to be quite the overhaul) and we’ll be fitting FRVs on all radiators as part of that work. 

To answer your question: yes, they need to be fitted on all rads to allow for full balancing. The only downside is that you’ll need to drain your system to install them. I can’t yet say whether they’re a silver bullet, and people have only just started fitting them, so this winter will be the first real-world test. But on paper and in theory, they sound like they could sort out a lot of the issues in a poorly balanced system like ours (and the sound of things, yours).

If you decide to go for it, drop me a DM or email… I’ve got a 10% voucher code I can send you.

Posted by: @grantmethestrength

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Great video again this week @editor, I am very interested in the FRV valves referenced in the part about balancing. I had a disastrous attempt at balancing my rads last time around and basically gave up and just opened them all up again. I got the rads to all be about DT5 but the next day after I headed of to work the system went crazy and sounded like it was going to explode, leading to a severe bollocking from the missus who had to deal with it. Note self never ever tinker with the system unless you are around to fix it lol!

@grantmethestrength

There are a couple of subtle points to make here which might explain the noise you experienced:

1: did you ensure that, when you balanced them, the LSV on at least one radiator (normally the one furthest from the heat source, but maybe also a couple of adjacent ones) was fully open (and yet still in balance).  

2: Balancing for DT5 is a mistake unless the design is perfect (which it almost certainly isnt) and the OAT is the design OAT and has been for at least 24 hrs (which is rarely if ever the case). 

Getting wither of these wrong will lead, in most cases, to turning the LSVs down too far and thus throttling the flow unnecessarily, increasing noise and wear on the water pump and increasing running costs.  

The objective is just to achieve 'balance' ie either the same DT (not necessarily 5, in many cases it will be less) across each radiator or the same room temperature (or the desired difference in room temperature) in each room, whilst keeping the valves as open as possible so as not to restrict flow more than is necessary.  Hence why you should start with and maintain at least one LSV fully open and not worry about adjusting the LSVs for DT5 (if, for some reason, you want to adjust for DT5 then its the water pump speed that should be changed).

@jamespa You are right I must have cranked them down too much. I am struggling to get my noodle around what balancing is I thought it was getting the DT the same on each radiator so I am obvs not grasping the fundamentals of it. But thanks for the explanation. I think I am falling into most of the categories you mention incorrect design, not at design OAT etc. As was said in the video balancing a radiator is a simple task in principle 😝

Posted by: @grantmethestrength

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I am struggling to get my noodle around what balancing is I thought it was getting the DT the same on each radiator

My understanding (someone may correct me) it that it is this, but not a specific DT for the reasons outlined above.  Alternatively its getting the same flow rate. In a system where the radiators are precisely sized to match the load, they will occur at the same point.  In both cases, however, the aim is to do so without restricting flow more than you absolutely need to.

A refinement is is getting the same room temperature (or the desired differences in room temperature).  This 'takes out' the inevitable variations in radiator sizing from the ideal.  Heat Geek says something about this in their videos on balancing.

In reality any of these may be good enough (because rooms share heat) unless you have gross imbalances in radiator sizing in which case the last is what you really want, but its much more time consuming.  

If you are going to balance for same DT then it needs to be large enough to be measurable.  Some heat pumps turn their water pump speed up or down to maintain eg DT5 at the heat pump, but many don't and so DT is going to be <5 most of the time.  If yours doesn't then, at this time of year, the DT wont be large enough to measure unless you whack the flow temperature up well above the target so the house overheats, and then allow it to stabilise for a while.   Similar considerations apply to balancing for same room temp.    It may be that professional installers (which I am not) have some other tricks to deal with this.

FWIW I found balancing my house, at least to a 'comfort' point, quite easy.  After doing a very rough balance for DT (really no more than the 'feel' test plumbers reputedly use - effectively making sure all rads are getting a reasonable flow and at least one is fully open), I simply turned down a couple where the room overheated, and turned up a couple where the room underheated.  Fortunately it was cold outside so it was relatively easy.  Perhaps I could do better with a more precise/scientific balancing, but its comfortable, I get a COP I'm happy with and I have other things to do in life!

Posted by: @jamespa

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Posted by: @grantmethestrength

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I am struggling to get my noodle around what balancing is I thought it was getting the DT the same on each radiator

I get a COP I'm happy with and I have other things to do in life!

I may need to adopt this technique lol!

When adjusting the FRV you need to use the area of the radiator. Does the radiator type (K1, K2, K3 etc) need to be taken into account?

Posted by: @fred-gray

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When adjusting the FRV you need to use the area of the radiator. Does the radiator type (K1, K2, K3 etc) need to be taken into account?

Good question.  Based on physics I think the short answer is yes.

I have actually been thinking about this area since I posted above with the comment that balancing for DT and balancing for equal flow rate will achieve the same result. 

I now think I was wrong and your question has cemented my belief that Im wrong.  If you balance flow rate per unit output it will result in equal deltaT.  The output for any particular rad type is proportional to area, but the proportionality constant is different depending on the radiator type (K1, K2, K3, K+)

I just looked at the FRV data sheet and it says to multiply by the area, but doesn't specify the radiator type.  Something isn't right! 

@editor  I think you are in contact with these guys, maybe you know?

@jamespa that is quite important. It would be good if they had a video tutorial on how to set them up, with some examples of the maths for us dummies! I wonder if you would put one on the rad that is supposed to be fully open?

Posted by: @grantmethestrength

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I wonder if you would put one on the rad that is supposed to be fully open?

With their balancing process Im pretty sure all rads could end up being restricted at least a bit.  Its unlikely however that the restriction would be so great as to cause a problem.  Personally I would probably adopt a slightly different process but the difference would be marginal.

Doing some maths on their figures 1.3l/min/sqm at DT5 is 1.3*5*4200/60 = 455W/sq m (assuming water not glycol). 

At room DeltaT of 20 thats equivalent to (20/50)^1.3 =1496W/sqm at room DeltaT of 50 (which is how rads are normally quoted). 

Stelrad Type 11 500mm high rads are quoted as 1548W/sq m at room DeltaT50, so it seems that the figures in the FRV leaflet are for Type 11.   

The Stelrad figures for other variants, and the ratio relative to type 11, are

Type - W/sqm - ratio relative to Type 11

11-1548-1

21-2106-1.4

22-2666-1.7

33-3786-2.44

Assuming my logic is right that enables the calculation to be done for other rad types. 

So, for example, a 0.5m*1.2m (0.6sqm) type 22 needs a flow rate of 0.6*1.3 * 1.7 =1.33l/min to get DT5 at 20C room to rad deltaT.

Watched the latest homeowners qa and they mentioned some easy to balance lock shield valves. It’s something I need to look at in the winter as not had the HP that long. Or if they are not an option is there a reasonably accurate, or one I can calibrate, temp meter I can use to balance them.