Heating manifold - one circuit not working.

[reb78]

To solve a radiator issue on out system (lots of 8mm and 10mm micobore) we have fitted a pumped underfloor heating manifold to five rads upstairs that werent working properly.

Flow and returns are all plum ed in correctly but one circuit has no flow. We have bled it, check as best we can for air locks, got the system hot and tried just that one circuit but all to no avail. There was some flow on the old system it just wasnt very good. Now there is none on this circuit. The other four rads are working really well amd a lot better than before so it should work perfectly.

Pic of the manifold below. Its a JG speedfit from screwfix. What are the chances either the flow or return pins are faulty and are they simple to check? This is brand new so i dont want to invalidate any warranty.

Interestingly there is no flow to what I think is the flow to the rad. If the return is turned off at the rad I get nothing from the bleed screw, which makes me wonder if the flow at the manifold is faulty?

Any thoughts?

Pic

 

[gaz1]

swap the pipes around so you get a back flow of water in the system redo the one system on its own so it gets full pressure from the pump into it

you maybe lucky and you can flow it back dislodging the dirt thats there

the alternative is messy and will have issues to deal with using that method but it may just clean your pipes and rads enough to get working again

 

[brightspark]

failing all that take pipes of the manifold and fix a hosepipe to one end and other in a bucket and blast it through with mains water from the tap and reconnect while the pipes are full . any airlock will be blasted through

 

[reb78]

Thanks chaps. Just seems weird the pump on just that one circuit cant force it through. Those pipes were all clear two days ago.

 

[reb78]

Could the valves be stuck from new?

 

[Smallfry]

The pump moves water, but they are NOT pressure pumps as such.

Have you tried a system cleaner ?

 

[reb78]

The pump moves water, but they are NOT pressure pumps as such.

Have you tried a system cleaner ?

No, I get that, but they will create some pressure, i take your point though but its effectively dead heading without any of the other circuits turned on.

We haven't put a cleaner through but its relatively clean and a lot of it was redone when we added the Rayburn and thermal store about 18 months ago. Like I say, these two pipes - the flow and return to this rad - were working two days ago so were clear... this was supposed to make them work better! We know they were clear as to double check we were pairing the right flow and returns we put gentle pressure down the flow to find the return - none were blocked.

 

[addjunkie]

Connect them up to the spare pair….see if the issue is the manifold valves or the loop. The manifold valves can stick.

 

[Smallfry]

When we did the shop, with the manifold they supplied screw on caps that could replace the gauge thingy, and you screwed them down to oven the valves manually.

 

[gaz1]

No, I get that, but they will create some pressure, i take your point though but its effectively dead heading without any of the other circuits turned on.

We haven't put a cleaner through but its relatively clean and a lot of it was redone when we added the Rayburn and thermal store about 18 months ago. Like I say, these two pipes - the flow and return to this rad - were working two days ago so were clear... this was supposed to make them work better! We know they were clear as to double check we were pairing the right flow and returns we put gentle pressure down the flow to find the return - none were blocked.

if was working other day you can try a backflow using the pressure of the system

first drain rad reconnect or retighten again
pressure the system up higher than normal 1.5 or even 2 bar
remove the bleedvalve ( not always the bleedvalve its the whole nut on newer rads ) turn on the valve where no water was coming through the back presure should dislodge any crap but not always

it will gurgle like crazy and flow into the rad ( if it backflows ) either shut the valve off fast or get that nut back on if your not fast enough you will get a wet area
either reinsert that bleed valve back in
open other side and bleed that side a bit then lower the pressure to working pressure then run it

its naughty but it does work sometimes on shifting some much or dirt that does get into the system

 

[DickyDoDah]

The flow restrictor valves are actually very restrictive even when fully open. I have fitted two systems using UFH manifolds to radiators and I removed the flow valves and replaced them with 1/2" BSP radiator blanking plugs. You get a much better flow rate and heatup time.
My reason for using manifolds is that it's easier with pex pipe and you can have each room as a seperate zone if you fit the electric valve heads. Also there is no need for balancing.

 

[reb78]

if was working other day you can try a backflow using the pressure of the system

first drain rad reconnect or retighten again
pressure the system up higher than normal 1.5 or even 2 bar
remove the bleedvalve ( not always the bleedvalve its the whole nut on newer rads ) turn on the valve where no water was coming through the back presure should dislodge any crap but not always

it will gurgle like crazy and flow into the rad ( if it backflows ) either shut the valve off fast or get that nut back on if your not fast enough you will get a wet area
either reinsert that bleed valve back in
open other side and bleed that side a bit then lower the pressure to working pressure then run it

its naughty but it does work sometimes on shifting some much or dirt that does get into the system

Its a vented system Gaz due to the Rayburn in the system. This might be part of the problem as the pressure is only what the header tank provides.

 

[reb78]

The flow restrictor valves are actually very restrictive even when fully open. I have fitted two systems using UFH manifolds to radiators and I removed the flow valves and replaced them with 1/2" BSP radiator blanking plugs. You get a much better flow rate and heatup time.
My reason for using manifolds is that it's easier with pex pipe and you can have each room as a seperate zone if you fit the electric valve heads. Also there is no need for balancing.

Interesting.

If i whip that flow valve out is it likely to go back in and seal ok? Like I say the thing is brand new so dont want to invalidate any warranty.

 

[reb78]

Connect them up to the spare pair….see if the issue is the manifold valves or the loop. The manifold valves can stick.

This might be the easiest thing for now.

 

[DickyDoDah]

The flow valves come out in one piece quite easily as they seal on an O ring. Just use a ring spanner or deep socket.

 

[DickyDoDah]

On my first install I left the flow valves in but after only a year they were blocking up and that was with brand new rads and full pex piping. They are designed for only Pex underfloor pipe and low/slow flowrates so it doesn't take much to block them. Not had any issues since I took them out.

 

[DickyDoDah]

https://www.bes.co.uk/1-2in-bsp-radiator-plug-21369/
These will do it

 

[dobbslc]

The flow restrictor valves are actually very restrictive even when fully open. I have fitted two systems using UFH manifolds to radiators and I removed the flow valves and replaced them with 1/2" BSP radiator blanking plugs. You get a much better flow rate and heatup time.
My reason for using manifolds is that it's easier with pex pipe and you can have each room as a seperate zone if you fit the electric valve heads. Also there is no need for balancing.

I used these to supply my rads, no valves just a manifold to connect up the pipes, it works very well.

Another advantage is I can add to the system as I want which is very useful when I'm doing a full house restoration.

 

[reb78]

All sorted. It was an air lock. Plumber friend came back this morning and we isolated the manifold, turned off all but the affected circuit, connected the flow to the mains and return to a bucket and then turned on the tap. Got a bit of crud out and then a glug of air. Disconnected and turned the pump on and its all flowing now. Will get it hot later and then see how it is working. Seems like you can kind of powerflush the rads on this manifold in this way...