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Discuss Should UFH be nearly scalding at floor with Vinyl (LVT)? in the Water Underfloor Heating Installations area at PlumbersForums.net

Hi All.

I'm pretty sure the answer to the above is "no".

I've recently had UFH installed, with a mixture of porcelain (kitchen) and LVT (lounge). I have a mixture of neoStat wall stats but no floor probes. (I was never advised to get such). The UFH in lounge is sitting in Polypipe Boards and in scree in kitchen.

Now that we actually (post-heatwave) need the UFH, we've noticed that the LVT is "spongy" and almost too hot to stand on.

I assume this means the temperature is way too high? That, or there isn't enough substrate between pipes and LVT.

What's the best way to address this while ensuring performance (i.e. that it's still hot enough to warm the tiled areas). Should I ask the installer to reduce the temperature? Should I insist on lifting things up and fitting floor probes (which sounds painful)?

Many thanks in advance.
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
There should be a temp gauge on the manifold what's this set at also any pics of the manifold
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
Yes that's running way to hot 65 dc through the under floor way way too hot can cause problems for your floor

Get the people back who installed it

@Uheat – Jake
 
Yes that's running way to hot 65 dc through the under floor way way too hot can cause problems for your floor

Get the people back who installed it

@Uheat – Jake
Thank you. One quick thing. Isn't 65 dc the input temperature (from the boiler) and 53 the temp going into the floor? Am I mis-reading things? (Of course, 53 dc may well still be too hot). Thanks again!
 

Chalked

Esteemed
Plumber
Gas Engineer
Turn the thermostat ( black knob that’s upside down) slowly, while the heating is on, until you get a constant 40 degrees. On the top dial. Then adjust each flow restrictor, until the return temp gauge reads around 7 degrees lower.
Takes a bit of time to do, but will work correctly.
 

Chalked

Esteemed
Plumber
Gas Engineer
A
So looks like the actuators are on manual. They should face the other way. Turn clockwise to put onto auto.
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
A
So looks like the actuators are on manual. They should face the other way. Turn clockwise to put onto auto.
Also doesn't look balanced
 
A
So looks like the actuators are on manual. They should face the other way. Turn clockwise to put onto auto.
Hi. Just so I'm clear, because the heating is responding to the neoStats. What do the actuators do? Are they not being controlled by the wiring attached to the neoStats? Thanks
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
Apologies for not knowing the terms. "Balanced" how?

Thank you for your continued help.
Clear flow dials haven't been set either I think
 
Clear flow dials haven't been set either I think
Are these the flow guages at the top? The red discs are dropping a few minutes after the heating comes on in each room, except for the third guage (which I think has problems). Thanks.
 

Chalked

Esteemed
Plumber
Gas Engineer
Hi. Just so I'm clear, because the heating is responding to the neoStats. What do the actuators do? Are they not being controlled by the wiring attached to the neoStats? Thanks
Yes they are individually controlled by your stats. But they look like they are on manual. So will be on all the time any other room is on. Plus it’s set too hot.
 

Chalked

Esteemed
Plumber
Gas Engineer
Are these the flow guages at the top? The red discs are dropping a few minutes after the heating comes on in each room, except for the third guage (which I think has problems). Thanks.
Without knowing the loop sizes, adjust the restrictors to give 1-2 litres a min. That should give you a starting point.
Did you install yourself, or get a contractor in?
 
Last edited:
Without knowing the loop sizes, adjust the restrictors to give 1-2 litres a min. That should give you a starting point.
Did you install yourself, or get a contractor in?
It was installed as part of a building project we've only just (so we thought) seen the back of. The builder's sub-contracted plumber did the job.
 

Chalked

Esteemed
Plumber
Gas Engineer
I would be getting them back in. You don’t just switch this stuff on. Needs commissioning properly.
 
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Gasmk1

Gas Engineer
Advent Win
Thank you. One quick thing. Isn't 65 dc the input temperature (from the boiler) and 53 the temp going into the floor? Am I mis-reading things? (Of course, 53 dc may well still be too hot). Thanks again!
65 dgrees C is the input temp 53 degrees is the return temp afte rgiving heat up so its way too hot on th e flow as mentioned to you, all needs setting up properly
 
All.

Thank you for your recent advice re the temperature of my UFH; it was invaluable.

Hoping for a second go.

Our plumber returned the other day and finally - so he assured us - properly commissioned the UFH. We have noticed on more than one occasion that when we try to run UFH to multiple rooms the Manifold makes a VERY loud singing noise. (I say "singing" as it's quite a high pitched hum, more like an old-school kettle boiling).

What can be causing this and what is the best way to stop this happening? Is this related to the flow rates not being properly set (despite assurances related to this)?

Many thanks (again), Steve.
 

Chalked

Esteemed
Plumber
Gas Engineer
All.

Thank you for your recent advice re the temperature of my UFH; it was invaluable.

Hoping for a second go.

Our plumber returned the other day and finally - so he assured us - properly commissioned the UFH. We have noticed on more than one occasion that when we try to run UFH to multiple rooms the Manifold makes a VERY loud singing noise. (I say "singing" as it's quite a high pitched hum, more like an old-school kettle boiling).

What can be causing this and what is the best way to stop this happening? Is this related to the flow rates not being properly set (despite assurances related to this)?

Many thanks (again), Steve.
Hi yes that is down to a incorrectly set up system . The noise is the mixer valove struggling to control temps when the flow rate and return temp is too high.
Needs setting at 47 degrees and then each loop needs to have a 7 degree differce.
I’ve also had the same noise on a faulty mixer too.

Can you post a pic of the manifold as it is set right now?
 
Hi yes that is down to a incorrectly set up system . The noise is the mixer valove struggling to control temps when the flow rate and return temp is too high.
Needs setting at 47 degrees and then each loop needs to have a 7 degree differce.
I’ve also had the same noise on a faulty mixer too.

Can you post a pic of the manifold as it is set right now?
Hi. Thanks for your help. Sorry - I didn't see you reply until now.

After speaking with the manufacturer - Wunda - last week I managed to make some progress with the noise by reducing the pump speed to setting "2" (the recommended speed for 7-port manifolds).

However. There is still some occasional noise and I suspect it's down to what you say. I also reduced the outlet temperature down to the minimum (40 deg) in order not to damage the LVT even further, so it's interesting you're suggesting 47 deg. I know the loop temperature can be reduced further by changing the flow rates, but I didn't think it was so significant.

Any advice is very welcome. Thank you.

IMG_2763 (1).jpg

IMG_2762 (1).jpg

IMG_2765 (1).jpg

IMG_2764 (1).jpg
 
Hi yes that is down to a incorrectly set up system . The noise is the mixer valove struggling to control temps when the flow rate and return temp is too high.
Needs setting at 47 degrees and then each loop needs to have a 7 degree differce.
I’ve also had the same noise on a faulty mixer too.

Can you post a pic of the manifold as it is set right now?
Hi. Further to the above.

I should add that we have two separate flooring types - porcelain tiles (with scree) plus LVT (overfloor with s/l compound). Unsurprisingly I'm having trouble getting the temps in the rooms with porcelain times sufficiently warm given I need to keep the temp low for the LVT.

I'm beginning to think I need two separate manifolds, given the need for a 10 degree difference in outlet temp? I wondered if you agree?

Many thanks again, Steve.
 

Ric2013

Plumber
Thank you. One quick thing. Isn't 65 dc the input temperature (from the boiler) and 53 the temp going into the floor? Am I mis-reading things? (Of course, 53 dc may well still be too hot). Thanks again!
No. That's the temperature of the water from the pump, which should be a mixture of hot boiler water and cooler water that has already made a circuit of the UFH.
 

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