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The Importance of Radiator Balancing for Efficient Heating: Introducing the Flow Regulating Valve

Mars · 2025-07-05T13:16:23Z

It’s fascinating to watch how low-temperature heating is evolving in the UK. For decades, domestic heating has largely been defined by the simplicity and forgiving nature of fossil fuel boilers. Stick a gas or oil boiler in a home with any radiators and it’ll usually cope, no matter how slapdash the system design might be. But heat pumps have changed the game. Unlike boilers, heat pumps demand finesse, care and a touch of engineering discipline to deliver their best. They reward good design and punish lazy shortcuts. And one area that’s gaining more attention (but still doesn’t get the headlines it deserves) is radiator balancing. In traditional boiler systems running at higher flow temperatures (70C+) you can get away with poor balancing. One radiator might boil you out of the living room while the spare bedroom stays stubbornly chilly, but the boiler just keeps pumping out heat, masking the imbalance with brute force. With heat pumps, it’s different. Because they run at lower flow temperatures (typically 35-50C) you don’t have that huge headroom to paper over design flaws. Every degree counts. If the flow rates through your radiators aren’t right, you’re more likely to find cold spots, inconsistent room temperatures and higher running costs. A well-balanced system ensures the right amount of heated water reaches every radiator. That means each room warms up as it should, the heat pump operates more efficiently, and you enjoy steady, comfortable warmth without some rooms feeling like saunas while others never get warm enough. The Balancing Act: Easier Said Than Done Traditionally, balancing means tweaking each radiator’s lockshield valve to control how much water flows through it. It sounds simple on paper but in reality, it’s a fiddly, time-consuming process that few installers do well, and even fewer homeowners attempt at all. Ask any heat pump installer what’s involved and you’ll probably get a wry smile. It’s a painstaking cycle of adjusting one radiator, then another, then another, then going back to check the first one because your previous tweak has thrown it out of balance again. So for years, balancing has been a best practice that’s often neglected or done half-heartedly. But when you’re spending £10,000-£20,000 on a heat pump system that could cost you thousands to run over its lifetime, it really shouldn’t be optional. Enter the Flow Regulating Valve This is where a new product comes in that’s turning heads among heating pros: the Flow Regulating Valve, or FRV for short. At first glance, the FRV is deceptively simple. It replaces your radiator’s standard lockshield valve, but unlike the old-school version, it lets you quickly and precisely set and check the exact flow rate for each radiator. No more guesswork with screwdrivers and temperature probes. No more vague instructions about “turning it a quarter turn and hoping for the best.” With the FRV, you fit the valve, consult the simple flow rate chart to find the right setting for that radiator, adjust the dial to the correct flow rate, and you’re done. The clear visual indicator shows you exactly what’s happening inside. Once set, the valve holds the flow steady, ensuring each radiator gets exactly the right share of heat, all the time. You can still use TRVs (thermostatic radiator valves) at the other end if you want extra room-by-room control which is handy in rooms with big windows or unpredictable heat gains. But the real magic is that the balancing is now built into the system by design, not left to chance. Perfect for Heat Pumps... and Boilers Too While the Flow Regulating Valve is a game-changer for low-temperature heat pump systems, it’s just as useful on conventional gas, oil and biomass boilers. After all, any hydronic system benefits from better flow balance, whether you’re running weather compensation, open loops or good old on/off boiler control. The FRV is also a retrofit dream. Just swap out the old lockshield valve for the FRV, set it up and forget about it. No massive system overhaul, no smart gadgets that break or need an app... just simple, robust engineering that does what it says on the tin. A Little Bonus for RHH Readers We’re excited to share that the team at Firepower, who distribute and sell the Flow Regulating Valve, have given us an exclusive 10% discount code for our community. If you’d like to get the discount, just email us (editor@renewableheatinghub.co.uk) and we’ll send the code straight to your inbox. Balancing radiators might not be glamorous, but it’s one of the most impactful things you can do to make your heating system, especially a heat pump, perform to its full potential. On the surface of it, the Flow Regulating Valve makes that job easier, quicker and more accurate than ever before. If you’re serious about comfort and keeping running costs down, this is one piece of kit worth looking into.

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Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls

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Mars

(@editor)

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Topic starter 01/08/2025 7:25 am

@adamk what I like about these valves is that once set, your rads for rooms are set and shouldn’t get “unbalanced”.

For those interested, in these valves, if you decide to go ahead, DM or email me, editor@renewableheatinghub.co.uk and I’ll send you a code for a 10% discount.

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JamesPa

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01/08/2025 7:53 am

Posted by: @adamk

↑

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.

If you don't need your trvs (and you shouldnt) you can repurpose them as lsvs by removing the heads and replacing with decorators caps. Trvs generally have better 'valve authority' than old lsvs, ie the response to turning them occurs over a wider range of positions. Old lsvs (and many new ones) are basically shut off valves so difficult to set precisely. There is a heat geek video on valve authority.

This doesn't have the easy set, calibrated, advantage of the frvs but may be easier than using your lsvs and avoids replumbing.

In addition its worth noting that some trv bodies have an adjustable flow rate restriction built in, eg Drayton ones, which you need a tool to set. Again thus doesn't have the calibrated self maintaining functionality of the frvs, but may be useful in some cases.

That said I managed to balance my rads on the lsvs even though the adjustment on some of them was only in the last half turn.

This post was modified 2 months ago 3 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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Toodles

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01/08/2025 10:27 am

@jamespa I found the same about the last half turn being the only effective part of the mechanism. Some chap called Toodles wrote an article for RHH and he found the same too!😉 Regards, Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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JamesPa

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01/08/2025 10:31 am

Posted by: @toodles

↑

Some chap called Toodles wrote an article for RHH and he found the same too!

I know.

Sadly many dont read articles, I keep referring people to the ABC guide that cathoderay wrote! I must add yours to my list of referrals.

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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Grantmethestrength

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01/08/2025 10:35 am

Posted by: @toodles

↑

@jamespa I found the same about the last half turn being the only effective part of the mechanism. Some chap called Toodles wrote an article for RHH and he found the same too!😉 Regards, Toodles.

It is deffo a me thing as it was your guide I was trying to follow lol! 2/10 go see the headmaster and try harder!!!!

Kind Regards
Si
——————————————————————————
Grant Aerona3 13kW
13 x 435w + 13x 480w Solar Panels
Sigenergy 10kW Inverter
16kW Sigenstor battery

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Toodles

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01/08/2025 10:36 am

@jamespa Thank you!😊 Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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Toodles

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01/08/2025 10:38 am

@grantmethestrength Sorry! I must try harder then! Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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Grantmethestrength

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01/08/2025 2:05 pm

Posted by: @toodles

↑

@grantmethestrength Sorry! I must try harder then! Toodles.

I think it is very much me that is sitting outside the headmasters office for being unable to follow instructions lol!

Kind Regards
Si
——————————————————————————
Grant Aerona3 13kW
13 x 435w + 13x 480w Solar Panels
Sigenergy 10kW Inverter
16kW Sigenstor battery

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