UFH Conundrum - No flow through manifold. Please Help!

[RichardB]

Hello, I have a polypipe UFH system which has been recently installed, and there seems to be little to no flow going through the manifold. I'm not sure that it has ever worked properly.

Bizarrely, the only time I get any flow at all is when the mixing valve is closed off - this is when all the flow meters drop in height. This presumably means there is no air lock in any of the UFH loops, otherwise they would presumably still not flow? (Please correct me if I'm wrong!) It also means that the UFH pump is working.

I have just taken the mixing valve apart, and there did appear to be half of a broken thin washer stuck in there (presumably debris and not from the valve itself? Again, please correct as necessary). I've removed it and flushed the valve through with water (checking that it wasn't clogged). I've successfully reinstalled everything, repressurised the heating loop to about 1.75bar and switched the UFH back on again, yet still the same issue.

To me this suggests that there just isn't enough flow coming from the boiler, but it is only one year old and has hardly been used, and still seems to heat the hot water for the taps fine.

Has anyone got any ideas as it's driving me crazy, and we're also living in a fridge at the moment.

Thanks in advance!

Richard

 

[ShaunCorbs]

Was it set up / commissioned?

 

[king of pipes]

Can you post some pictures of your boiler conections and how the uhf manifold is connected ? Cheers kop

 

[RichardB]

Was it set up / commissioned?

Bit of a long story - the job quoted for included installing the UFH, but also installing a bathroom and a few other bits. We're live-in renovators and as such the job is bits and pieces by nature (probably a tradesperson's nightmare). We're yet to have the bathroom installed, so you could argue we're mid-job, and as such, I don't think anything has been/is officially commissioned. We've certainly had no paperwork to say as such anyway.

Richard

 

[ShaunCorbs]

Best option is to Get them back then and commission it

 

[RichardB]

Can you post some pictures of your boiler conections and how the uhf manifold is connected ? Cheers kop

Best option is to Get them back then and commission it

In an ideal world, yes, but he won't be available until new year, and it's pretty cold at the moment! I just fear that I'm missing something obvious that doesn't require someone to come in. Also, having taken apart that valve today, I'm happy to have a go myself. 🙂

 

[Chalked]

Are the main pipes to the manifold warm?

 

[RichardB]

Can you post some pictures of your boiler conections and how the uhf manifold is connected ? Cheers kop

Photos attached. Please ignore the left-most flow meter as it is stuck - I don't believe there is actually any flow.

 

[RichardB]

Are the main pipes to the manifold warm?

Main pipe is warm, suggesting there might be a small amount of flow. The flow manifold is also slightly warm, but the return is pretty cold.

 

[sparkie30]

Looking at your manifold 3 loops 2,3 and 4 looks to me that they havent not been set. Basically need to know the length of the pipe to calculate the flow rate. Length divede be 40= flow rate
Say 80:40=2 so 2litres of water per minute so you set that to 2.

 

[ShaunCorbs]

thats in a shocking state and needs to be changed

 

[sparkie30]

Just noticed loop 2 has a T. That cant be be right.
Think you might need a 5 port manifold and a decent plumber.

 

[RichardB]

Looking at your manifold 3 loops 2,3 and 4 looks to me that they havent not been set. Basically need to know the length of the pipe to calculate the flow rate. Length divede be 40= flow rate
Say 80:40=2 so 2litres of water per minute so you set that to 2.

Thanks for the info, but the photo is misleading - the first flow meter is stuck (it doesn't return to zero when the system is switched off). I've tried adjusting the flow rates, but nothing makes the flow meters drop apart from closing the mixing valve.

 

[RichardB]

thats in a shocking state and needs to be changed

If you have the time/patience/energy, I'd love to hear why. (Don't worry, you won't be offending me - it's not my work).

 

[RichardB]

Just noticed loop 2 has a T. That cant be be right.
Think you might need a 5 port manifold and a decent plumber.

This may all be true, but I don't think it explains why I cant get any flow.

 

[ShaunCorbs]

state of the pipework eg the flux hasnt been cleaned off / unnecessary elbows been used

no port valves on the system (best to have underfloor systems on an splan/s+plan)

no auto bypass

looks like a system boiler so wheres the prv pipe

i would say expansion vessel is undersized

condense pipe too small as its going through the wall (white pipe)

 

[king of pipes]

Not the best install I've seen but one thing you could try is disconnect each actuator individually and with the system calling for heat, push the pin in on manifold to make sure its free see if you get any flow through the loop with the head removed, kop

 

[sparkie30]

Dont think anyone will be able to tell you just by looking at those pics and description you given as it could be a number of things.

 

[Chester]

Thats... new?

 

[SimonG]

What boiler?

 

[ShaunCorbs]

What boiler?

Worcester 27 system compact

 

[Chalked]

Hi
System should have a zone valve fitted the the heating side and the underfloor. Otherwise, ether the radiators or the underfloor will bring everything on.
But none of that will be causing your problem. It’s probably never been filled correctly. Follow the instructions on this video and it should work ( apart from the one that’s teed off!)

It’s basically the same as yours, except upside down

 

[Darren Jackson]

It looks like the 22mm pipe coming out of the top of your blending valve is connected to the flow and not to the return pipe, And the 22mm pipe going into the right hand connection of the blending valve is connected to the return pipe of the boiler instead of the flow pipe. If this is so it would explain why it only works when it is closed off as it is doing the opposite of what it should be doing. It is hard to tell from the pics but it needs checking that the flow and return are piped up correctly, and a auto or manual bypass and motorised valve should be installed as it does not appear to have them looking at the pictures. Hope this helps.

 

[Chalked]

It looks like the 22mm pipe coming out of the top of your blending valve is connected to the flow and not to the return pipe, And the 22mm pipe going into the right hand connection of the blending valve is connected to the return pipe of the boiler instead of the flow pipe. If this is so it would explain why it only works when it is closed off as it is doing the opposite of what it should be doing. It is hard to tell from the pics but it needs checking that the flow and return are piped up correctly, and a auto or manual bypass and motorised valve should be installed as it does not appear to have them looking at the pictures. Hope this helps.

Good spot mate.
It does look like it’s piped up backwards.

 

[Murdoch]

Bear with me , as I'm a spark ..........

How many room stats do you have controlling the UFH/ zones?

What happens if you turn the room stats up and down when the boiler is on? Give the actuators a minute or 2 to respond!