Wet underfloor heating mixing valve settings

[dazzler9000]

Hi, another question about my UFH. I've discussed previously on this forum about my poor UFH insulation -
https://www.diynot.com/diy/threads/spray-foam-underfloor-insulation.602155/#post-5375045

Due to the poor installation/insulation, my UFH doesn't heat the house very well at all. I understand this is down to the above-mentioned insulation, but when my heating was on today, I thought I'd check the temp of the underfloor pipes with my thermal camera, in the hope of maybe turning up the heat. I have a mixed floor covering, tile and engineered oak, both tile and wood floor was around 25c. I then looked at the input temp (I have no temperature gauge), so again, used the thermal camera. The input pipes after the pump read 58c and the return pipes were 48c.

The wife is always asking me why we can't turn up the temperature of the UFH. Is this possible? By the looks of it, the flow input is pretty hot, considering my boiler is set to 67c. I understand the mixer valve cools down the input and I can see mine is set to 4 in the photo below. I did try twisting it but it didn't move? Any ideas?

 

[Rodders53]

Is there a screw in the centre of the mixing/blending valve cap?
If so unscrew and lift off the cap then replace 90 degrees out on the spindle to adjust it.

The Reliance (RWC) one on my UFH has this 'lock' as a feature to prevent accidental/unauthorised user adjustment. It's a small allen socket head screw in my case.

However 25C floor surface temperature is good and much higher could damage the wooden flooring..
58 flow and 48 return are both quite high, I think, for UFH generally as well?

So you possibly need to adjust the loop circulating water flow rates and / or have the heating on for longer rather than making the water hotter?

 

[dazzler9000]

Ignore, messed up the quote.

 

[dazzler9000]

Thanks, I will take a look. As you said, it looks like the flow temp is probably okay, it's a shame I'm trying to heat under my house due to my poor install .

I'm going to have to rip up my floor at some point and will be replacing the UFH with a load of radiators.

 

[Diver Fred]

What is the UFH pipework in?
Looking at the picture in your previous post it looks like the floor is timber on joists with the pipework hanging below the floorboards. Every UFH installation I've seen the heating pipework has been set in concrete.

 

[dazzler9000]

What is the UFH pipework in?
Looking at the picture in your previous post it looks like the floor is timber on joists with the pipework hanging below the floorboards. Every UFH installation I've seen the heating pipework has been set in concrete.

It's hard to say, as I don't have much access. The first photos in my other thread are a bit misleading, the pipes must go back up soon after that hole and I believe they sit on some board that sits over the joists, and the floor covering on top. The key thing is, no, or very little insulation.

 

[Madrab]

No, if the input temp is 58deg and output is 48deg then you need to reset the flow meters and the pump setting to slow things down to allow the UFH pipework enough time to release its heat.

If your wooden floor is 25deg, then you're probably getting near to the max that the wooden floor can safely take (~27deg), not so much for the tiles of course.

 

[dazzler9000]

No, if the input temp is 58deg and output is 48deg then you need to reset the flow meters and the pump setting to slow things down to allow the UFH pipework enough time to release its heat.

If your wooden floor is 25deg, then you're probably getting near to the max that the wooden floor can safely take (~27deg), not so much for the tiles of course.

Thanks, yeah as much as I hate my current install as I'm bleeding heat through the floor, I should probably get somebody in to see if anything can be done to improve anything in its current state. It will be a while before the other half lets me rip up the downstairs floor.

Out of curiosity, what would you expect the return temp to be? Is adjusting the flow meeters and pump a DIY job or best done by a pro?

 

[Madrab]

Well, there wouldn't be anything wrong with having the system reset and set back up by someone that is experienced I wouldn't think.

Not having gauges on the manifold is a missed trick too but they could be added.

The return temp needs to be what it needs to be to obtain the correct output per M2 over the floor, to replace the amount of the heat the room looses, if that makes sense. Slowing down the flow will allow the floor to absorb and then release more heat, you may actually find that you need to drop the input temp.

 

[dazzler9000]

Well, there wouldn't be anything wrong with having the system reset and set back up by someone that is experienced I wouldn't think.

Not having gauges on the manifold is a missed trick too but they could be added.

View attachment 330217

The return temp needs to be what it needs to be to obtain the correct output per M2 over the floor, to replace the amount of the heat the room looses, if that makes sense. Slowing down the flow will allow the floor to absorb and then release more heat, you may actually find that you need to drop the input temp.

Thanks, I will get it sorted in the summer, I've got other fires to put out at the moment. I know my boiler is constantly running when the UFH is on which is annoying, perhaps this is why?

 

[Madrab]

Thanks, I will get it sorted in the summer, I've got other fires to put out at the moment. I know my boiler is constantly running when the UFH is on which is annoying, perhaps this is why?

The boiler will certainly run constantly if it never gets up to temp.

 

[Johntheo5]

Thanks, I will get it sorted in the summer, I've got other fires to put out at the moment. I know my boiler is constantly running when the UFH is on which is annoying, perhaps this is why?

Can you post what the flow meters are reading, its quite easy then to calculate the UFH output knowing the manifold flow & return temperatures.

 

[dazzler9000]

Can you post what the flow meters are reading, its quite easy then to calculate the UFH output knowing the manifold flow & return temperatures.

Sure, how do I do that? I'm new to UFH

 

[Johntheo5]

Where you have 1,2,3,4 etc written, the flow meters are right underneath, glass meters with 0 to 5 or so LPM, when the UFH is on you can read off the flowrates, normally ~ 1.0 to 3.0LPM.

 

[dazzler9000]

Where you have 1,2,3,4 etc written, the flow meters are right underneath, glass meters with 0 to 5 or so LPM, when the UFH is on you can read off the flowrates, normally ~ 1.0 to 3.0LPM.

The UFH isn't on at the moment and it's hard to read as there are no easily visible indicators on the glass. I think I can just about make out some numbers though, so I will take a look next time it's running.

In its current off state, the flow indicators look to be at the top. Is that expected in an off state?