Which UFH mixing valve brand?

[sharpener]

 

I need a replacement 22mm mixing valve, they seem to vary in price from about £50 to over £100. Is there anything to choose between brands? Like compactness, ease of fitting, reliability...

 

Inta and Reliance seem to be widely available. Some of the cheaper own-brands e.g. this one specify mixed temp down to 35C and an incoming hot range of 60 - 85C which if true is not low enough for use with a heat pump.

 

OTOH  this one from RWC has a setpoint for the mixed output which will go as low as 25C which might be useful.

 

Ideally I would like to find one with the cold opposite the outlet with the incoming hot at right angles (as per this thread) but that seems to be a forlorn hope!

[JohnMo]

Ivar Unimix. Way better than most tat on the market. Has adjustable primary by pass to ensure heat pump min flow is always achievable, plus a secondary one to adjust how much mixing occurs between incoming water and return water. 

 

 

[sharpener]

  On 23/03/2025 at 22:28, JohnMo said:

Ivar Unimix. Way better than most tat on the market.

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Yes, obviously the Rolls-Royce of mixing valves. But is designed to plug straight into an Ivar manifold and not mine (make unknown).

 

Have now taken the original valve off and all three ports communicate whatever the knob setting! Taking it apart, it clearly has a thermostatic capsule but the internals are all seized solid.

 

Simplest(!) is to re-do some of the pipework to suit a modern valve, they all seem to have the inlets at the two sides and outlet opposite the knob. Choice seems to be between the Inta or RWC or the cheaper plumbing/UFH outlets' own brands at about half the price.

 

Maybe @Nickfromwales has some advice?

 

Current thinking is that with the valve to set to say 37C then with the flow at correct temp for the rads it will close down to admit the right (small) proportion of hot and mainly recirculate. OTOH without any call for heat for the rads the HP will provide flow ~35C, so the valve will open right up and present no restriction to its full output going into the UFH. 

 

So the switch between modes should be automatic. But the catch is at startup, I think I will need to ensure the rads circuit gets up to temp for say 30mins before the UFH is switched on to ensure there is a store of water at ~45C to make sure the valve closes correctly. If not it will remain fully open, the return flow will be diluted by cold return from the UFH and the HP will never get hot enough for the rads. As long as the UFH remains energised this will be a stable latch-up situation.

 

 

Edited March 24 by sharpener

[Nickfromwales]

Most manifolds are 1” BSP threads so a lot of these are interchangeable, just a matter of sometimes having to remove the isolation tails to take you from male > female to whichever option you need (some TMVs have a pair of male unions, some female, where’s these have been supplied as a paired setup / are OEM).

 

Easily doable, and if the centres are measured you will know if that’s an issue or not, but usually, again, any decent plumber will swap this all out and ‘make it work’ in one day. 

[sharpener]

  On 25/03/2025 at 08:56, Nickfromwales said:

Easily doable, and if the centres are measured you will know if that’s an issue or not

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Thanks @Nickfromwales. The TMV isn't mounted on the manifold (there isn't room) but beneath the pump (as in the pic in this thread) so to shoehorn it into the same space I want to replace it with one with 22mm compression fittings like this own-brand. 

 

Or this RWC or this Inta, is it worth paying the extra money?

 

Thanks for all your help on this forum!

 

 

Edited March 25 by sharpener

[Nickfromwales]

Yes, understood, but as said any decent plumber will

just shoot off and buy some unions and make it up according to what / where / how. It’s just like playing with LEGO tbh, just just use the bits you need, click them together, fill and test, go to pub. Very simple job tbh. 
 

Mounting the pump and mixing set away from the manifold is easy, your only difficulty will be finding a good plumber who won’t instantly shit the bed when you ask them to switch on the gray matter.

 

Are you looking to keep that manifold? Chain being as strong as the weakest link etc etc. 

[sharpener]

  On 25/03/2025 at 09:48, Nickfromwales said:

Are you looking to keep that manifold? Chain being as strong as the weakest link etc etc.

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Yes, it does not look brilliant but all is operational so a lot more work to replace it esp if I have to move/extend the loop tails. Have currently got the sight glasses soaking in de-scaler, do you know of a better way of cleaning them?

 

  On 25/03/2025 at 09:48, Nickfromwales said:

your only difficulty will be finding a good plumber

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Sorry to disappoint but I won't be employing a plumber for this! 

 

In addition to the new mixing valve it will as you say need a couple of elbows as the cold inlet will be where the control knob is and v-v. But a small DIY job compared with fitting 3 extra rads which is what I did before the HP was contemplated.

 

  On 25/03/2025 at 09:20, sharpener said:

like this own-brand. 

 

Or this RWC or this Inta, is it worth paying the extra money?

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Has no-one got any views on the relative merits of these various valves or do they all come from the same Chinese factory anyway?

[JohnMo]

Why do an ESBE? They seem well engineered quality valves

 

https://esbe.eu/group/applications/underfloor-heating#underfloorheating

[Nickfromwales]

  On 25/03/2025 at 13:41, sharpener said:

Has no-one got any views on the relative merits of these various valves or do they all come from the same Chinese factory anyway?

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Apologies, I’ve not answered that and you did ask 

 

They’re all much of a muchness, but Reliance and Esbe are the industry leaders. Inta and Caleffi are #2, then after that it’s Russian roulette.

 

The scale is ferrous oxide, so see what the good old internet says about getting it shifted.

 

If you’re a competent plumber then crack on, we can help out by drawing some pics to guide you along 👍

[sharpener]

  On 25/03/2025 at 14:52, Nickfromwales said:

They’re all much of a muchness, but Reliance and Esbe are the industry leaders.

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Job hasn't turned out quite as I expected. Ordered a Reliance online, was sent old water-damaged stock with a date of manufacture 2010 so I asked for and got a full refund. Had noted the locking ring requires you to take the entire knob off so losing any relationship with the calibration markings (current model may of course be different). Also the bumf says all ends are compression but this is not true, the outlet is a union fitting that needs soldering to the pipe.

 

  On 25/03/2025 at 14:52, Nickfromwales said:

Inta and Caleffi are #2, then after that it’s Russian roulette.

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Then ordered a 22mm Inta. More compact and seems better designed, though instructions are pretty sketchy. Regulates to 35C quite closely. Quite heavy and bulky bc (I think) the casting is the same as for the 28mm model, ports are just drilled smaller. Seems more flow resistance than the unknown old one, loop flow rates are about 1/2 what they were.

 

  On 25/03/2025 at 14:52, Nickfromwales said:

If you’re a competent plumber then crack on

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Well 11 compression joints and 5 capillary ones later it is all in place with a few mm to spare and does not leak. But weather now too warm to evaluate properly. (Original pic is here, the scorch marks are not mine!)

 

  On 25/03/2025 at 13:41, sharpener said:

Have currently got the sight glasses soaking in de-scaler

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This softened the black magnetite(?) deposits sufficiently that I could carefully scrape the inside of the sight glasses clean using the threads of a 2 in woodscrew.

[Nickfromwales]

  On 21/04/2025 at 16:50, sharpener said:

Well 11 compression joints and 5 capillary ones later it is all in place with a few mm to spare and does not leak

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I find that using compression for these things offers a far better opportunity for removing / servicing these things downstream, so no probs there at all. Happy days.

[sharpener]

  On 21/04/2025 at 20:24, Nickfromwales said:

I find that using compression for these things offers a far better opportunity for removing / servicing these things downstream, so no probs there at all. Happy days.

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Needed one capillary coupling bc there is no room for a compression one under the TMV, and took the opportuity to move the drain cock round a bit so I can now get a hose on it out through the cupboard door. 

 

Otherwise it is all easily dismantlable for access. A lucky bonus was that where the new T is there was a (redundant) isolating valve, and its end cap thread was the same so I didn't have to get the nut and olive off the pipe. Bizarrely the top joint on the T (which was all new) was the only one I had trouble getting to seal, all the re-used old olives sealed first time with a smear of Hawk White.

 

As you say, happy days when it goes well but I am glad I did something else for a living.