Wet Underfloor Heating Query

russ9898

russ9898

russ9898

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Joined
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Location
Staffordshire
Hi,

I am currently in the process of an extensive refurbishment project to my soon to be new home and as part of the works, renewing the central heating system throughout the property. I would like to add UFH to the bathroom but would like to know whether any forum member would be able to share their expertise as to whether my proposed system is likely to work or whether I will need to reconfigure to avoid a poor performing heating system. A little information regarding my proposed heating system:

Boiler – Ideal Logic+ 35kw Combi Boiler
Zone Valve 1 – Downstairs Rads
Zone Valve 2 – Upstairs Rads (Inc UFH and towel radiator within the Bathroom)

The UFH will likely be the single zone kit linked below albeit with the included stat omitted/not used within my install and will instead rely on the programmer/smart stat controlling zone valve 2 to control the UFH and the upstairs rads as one.

https://pswtradesuppliers.co.uk/single-room-water-kit/141-10sqm-single-zone-water-kit.html

I would be interested to hear your thoughts on the above as to whether the 2 zones will work or whether I am likely to require a third independent zone solely for the UFH system to be controlled by the thermostat included with the UFH kit.

Thank you in advance for your assistance,

Russ
 
You'll need a third zone, or the under floor won't work as it's designed. They don't heat the same way a radiator circuit does. Just add a 2 port to that underfloor kit and it'll be fine. And it will need it's own thermostat also.
 
Underfloor heating has a blending valve, as it operates at a much lower temp than your radiators. The blending valve lowers the temperature of the water running through the underfloor heating circuit.
 
What did you mean by "won't work as it's designed"? If you were alluding to the flow temps, that's what I was referring to. If you were not, then it was just a general comment on how ufh works.

Having said that, I'd personally recommend a 2 port valve on any ufh circuit for simplicity and more control over the ufh zone.
 
It was regarding the fact that underfloor systems heat up and maintain room temperature in a different way to a radiator system and their controls/thermostat. Which is why you need the UFH on its own circuit and thermostat.

I've seen plenty of hashed together underfloor systems just like that described and proposed by the OP. And the biggest complaint is that it doesnt heat the room due to its heat/operation being dictated by the radiator circuit/control/stat. Which 9 times out of 10 isnt adequate to generate heat for the period of time required by the UF to heat the room to a comfortable level. The only way you might get away with it, is if the heating is on for lengthy periods (doubtful for upstairs) or the UF circuit is teeny tiny.

For the low cost of a valve and stat, its a no brainer really (the plumbing is the same) :D

Thats all ;)
 
FlyingFish said:
It was regarding the fact that underfloor systems heat up and maintain room temperature in a different way to a radiator system and their controls/thermostat. Which is why you need the UFH on its own circuit and thermostat.

I've seen plenty of hashed together underfloor systems just like that described and proposed by the OP. And the biggest complaint is that it doesnt heat the room due to its heat/operation being dictated by the radiator circuit/control/stat. Which 9 times out of 10 isnt adequate to generate heat for the period of time required by the UF to heat the room to a comfortable level. The only way you might get away with it, is if the heating is on for lengthy periods (doubtful for upstairs) or the UF circuit is teeny tiny.

For the low cost of a valve and stat, its a no brainer really (the plumbing is the same) :D

Thats all ;)
Click to expand...

Yeh, totally agree with you :)

Whilst it would technically work, you'd always have a compromise with either the radiators overheating their space or the UFH not adequately heating it's space.
 
Thank you for the answers guys, really appreciate the input and confirmation that a third zone valve is required. I suspected it would be the case and will order accordingly now, I'm investing quite significantly in the property and don't want to compromise the installation for the sake of £50 on a two port valve.
 
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