Testing underfloor heating

[Milleniumaire]

They are reading 0

I guess this is bad? (excuse my ignorance, but I'm new to UFH and manifolds).

Try unscrewing the white caps for a start.

The three white caps are unscrewed and are just "sitting" in position. This is how the plumber left them.

How are you balancing the flows between the rads and the UFH?

For the purpose of testing the UHF I've had to turn off pretty much every radiator in the house by closing each of the thermostatic valves. Only the hall radiator has been left on, which is where the thermostat lives. 48 hours at 27 degrees was just too hot with the radiators on!!!! So, I guess this should allow all the hot water to be fed to the UFH.

Is there just the boiler pump or do you have a manifold (eg a low loss header) and separate pump for the rads in addition to that for the UFH manifolds?

There is a boiler pump and the one you see on the manifold.

 

[Dan Robinson]

The black rings around the base of the flow gauges can be lifted up/off - then you can unscrew the gauges a couple of turns.

With the system on you should see the gauges move.

Guessing - but you want them to be at around 1.5.

 

[Milleniumaire]

Are there any flow meters on the manifold? What do they read?

Aren't the flow meters the same as the flow gauges that I took a photo of? What you can see in the photo is all there is!

The photo was taken without the boiler running for the CH as it's currently too warm for it to kick in. When it was running earlier today the only difference was the two round gauges showed higher figures. I assume these are the supply and return temperature gauges. Also, there's a small green light when the manifold pump is working, but that isn't on in the photo.

 

[Dan Robinson]

I'm feeling generous - bear with me and I will video me adjusting my manifolds flow gauges and put it up in a few minutes.

 

[Milleniumaire]

Hi Dan, that sounds like it should be useful, but I'm not exactly sure what the flow gauges are meant to do. I assumed they simply showed the water pressure for each loop and that when the red bit was at the top of the gauge, this showed there was water pressure.

I guess this is complete rubbish, if they can/should be adjusted.

Can you please enlighten me as to what the flow gauges do and what they are used for (by adjusting them)?

 

[Dan Robinson]

They indicate flow... funnily enough.

A pressure gauge indicates pressure.

I have the same kind of manifold, and although in need of a clean, you will be able to see what i am referring to.

Should take long just uploading a video from my mobile.

 

[MJGas]

When the red is at the top its reading 0. The further down the scale it goes the faster the water flows through the system. Depending how your system has been desgined ( pffff) sorry. Depends on the flow rate you need to set.

 

[Dan Robinson]

You shouldn't need the pliers either.

 

[Milleniumaire]

Okay, so unlike a pressure gauge, which may increase as the water temperature increases (due to expansion), a flow gauge will show when the water is moving through the pipes. I guess therefore the gauge would look different when the pump is on (pushing water through the manifold), than when it was off. By look different, I mean the red marker would be in a different position.

I thought they were in the same position tonight (while the CH is off), than when it was on earlier today, but now I'm not so sure and may need to crank it up again.

I've just looked at a diagram on a website and realised the top part of the manifold (with the flow gauges) is actually the supply and the bottom part (with the valves) is the return. I was thinking it was the other way around, which confuses me as I'm sure the pipes from the lower part of the manifold (the return) where hotter than the top pipes (the supply) when it was on earlier today!

 

[Milleniumaire]

Hi Dan, I'm getting a little excited now as I've just followed your video and as I turned the flow gauge, the red marker moved down and I heard the trickle of water. I quickly reversed this so that the marker went to the top.

What exactly is this doing?

Also, I've turned up the thermostat and the boiler and manifold pump are now working, but I've noticed the bottom part of the manifold (with the white "lockshield type" valves is very hot, but the top part (with the flow gauges) is still cold. Why is this, if the diagram I looked at http://www.thefloorheatingwarehouse.co.uk/acatalog/TFHW_UHeating_Installation_guide.pdf is correct and the top is the supply. Surely this should get hot first?

Why are the flow gauges at the top (zero?). Is this likely to be how the plumber set them up? Should I now turn each one until it's about half way down?

 

[Dan Robinson]

Turn each one so that the gauges settle with the red marker at around 1.5 to 2.

Leave them there - although you might need to tweak them a little as air pushes through the system.


If the return manifold is getting hot first then they have plumbed it the wrong way round.


Like I said - builder's in house plumbers are usually ********s of the highest order.

 

[Dan Robinson]

Having said that my manifold is the same as yours - I have looked at your pictures properly and it is not the same at all.


Are you sure they have plumbed that correctly?

What brand UFH did you get?

 

[Milleniumaire]

I guess if they have connected it up the wrong way round I should wait for them to rectify this before I change the flow gauges?

 

[Dan Robinson]

The gauges look okay (I think):

View media item 80579
View media item 80581

This looks totally weird to me but then I have had a long day.

 

[Milleniumaire]

Having turned each of the flow gauges and set them to 1.5, I noticed after about 4 minutes they all set back to 0 i.e. the red marker moved back upto the top. After this, no amount of turning could move the marker!!!

I did notice one of the lower pipes got hot, but the other two were only warm.

I'm totally confused and have screwed them back down again and will wait for the plumber