Son in Law sent me on these photos ~ 10 years ago when the Ivar UFH system was being installed in a extension, its worked perfectly since with a oil fired boiler either on its own or with the existing Rads.

I only came across them recently and just drew a very rough schematic of what I think it looks like, the Pump is pumping downwards as shown and the TMV capillary is inserted in the lower manifold. It just doesn't look right to me if I have the direction of flows correct in the schematic, @JohnMo might comment since I believe he has this system or similar.

I’ve seen some odd UFH manifold arrangements, I’m adding this to the list. 
 

Technically it’s correct, pump sucking water through the TMV and taking cooler return water to blend it down, just odd to see it set up in this order of components. 
 

Is it still working? 

Perfectly Nick, but find it difficult to see why, forgot to mention that its set to 30C, I'd love to look at it but can't get the daughter to remove the cupboard full of stuff but I've no doubt its installed as shown.

If there was/is a blank before the T to the left of the flowmeters then it might make a bit of sense of if there was nothing on the bottom manifold apart from the hot flows?.

See attachment.

Edited September 20, 20251 yr by John Carroll

Sometimes it is best not to try and work out "how" it works, because you are never quite sure how the 3 port mixing valve in this case is actually ported.

 

If it ain't broke, don't try and fix it.

Amazing what you can find down a visual image search 

 

300125_01_17.pdf fifm_rev.3.0.pdf

7 hours ago, John Carroll said:

Perfectly Nick, but find it difficult to see why, forgot to mention that its set to 30C, I'd love to look at it but can't get the daughter to remove the cupboard full of stuff but I've no doubt its installed as shown.

Go to the pub. 
 

I’ll send you the money to buy the beer.

 

Go now  🍻

 

Hopefully, now, 443 viewers can sleep more soundly in their beds tonight, if, as I think the system works this way. It returns the mixed temperature to the boiler, maybe without any 65C hot bypass water or with some hot bypass water if its required to, in the case of a gas boiler, to reduce the dT below 30C and in the case of a condensing oil boiler to avoid low temperature corrosion, some/most oil boiler manufacturers recommend a boiler minimum return of 35C/40C. the TMV, I think is a FM 750 Flow Mix valve, I don't know know if its bypass can be regulated or not, @Nickfromwales or @JohnMo might be familiar with this valve. 

Ivar Flow Mix.pdf UFH with No TMV Bypass.pdf UFH with TMV Bypass.pdf

Someone else just pointed out that the bypass is upwards to the valve which does seem more correct as the TMV is close to the UFH manifold pump, anyway the "mystery" to me is solved as its mixed flow temperature water thats returning to the boiler and not the colder UFH return water.

Think we can finally put this to bed now as it must? operate like shown immediately below IMO, only difference is that the boiler return water temperature will be the UFH dT higher than the conventional setup plus the manifold circ pump will be circulating almost double the flow. I will post the actual numbers when I see this UFH system.

 

 

 

 

Conventional System