UFH some zones not so hot/possible not working

[Adam2]

I have a gas boiler running DHW and UFH. In room thermostats seem to be ok in that the red light comes on as expected. The house is 3 floors with boiler and hot tank on top floor. UFH on ground floor seems Ok in 1 zone but not in others.

Pic is the ground floor manifold, bedroom is OK others are not.

 

I removed actuators and pins seem OK beneath but have some lube anyway.

 

With actuators off, the bottom manifold goes cold top one stays warm so actuators are on the flow which I understand is not so common. Though other floors seem ok and the other manifold is also configured like this.

 

Any suggestions on what steps to troubleshoot further appreciated.

 

Will try the working zone actuator on another zone.

[Adam2]

When I hold in the pin below actuator the flow drops to 0. When released it varies across the zones from about 1 to 2.5.

 

I  find this pretty confusing - I expected the actuator being removed to open the circuit so provide heat but the return is then cold yet the flow indicates some hot water movement. Surely it should be more logical than this seems ?

 

[ProDave]

That is correct behaviour.  With the actuators off, all loops will be at full flow, set by adjusting the flow meters.

 

An actuator pushes down on the pin to stop the flow.  When it is energised it releases that pressure to allow the water to flow.

 

If all zones flow okay with the actuators removed, there are no blockages. So if a zone is not opening when energised the actuator head has probably failed.  They are easy to get and can be had for mot much more than £10 each.

[Adam2]

OK cheers @ProDave- will leave actuators off overnight and see if any difference.

 

Some of the flow valves look a bit dirty and opening them up a bit and some are cold even with actuators off which I find very strange

 

[Adam2]

Ok so still issues here. I have a manifold with actuators removed from 2 zones  one has a cold return (which in this setup is the flow control) the other is hot. Seems to imply a blockage?

 

The pins are up from beneath where the actuators would normally be and both have good spring pressure so think OK.

 

To troubleshoot, should I lock down all zones with the actuator and the flow control then connect a tube to one end into a drain and run water through the other? Or should I use the drain valve on manifold, or call a plumber???

 

Another question, the Grundfoss pump feels pretty hot, is that normal?

 

 

[Nickfromwales]

They’re not blocked, they’re air-locked.  
You need to use cold mains to force water through the loops, come off the cold feed to the boiler for that, and then a hosepipe to outdoors for draining. You connect the hoses to the valves at the end of the manifold rails. And make sure the manifold isolation valves are shut first. 
The UFH needs to be commissioned properly, and very few installers bother, instead assuming that the manifold pump will circulate the water and bleed all the air out. Wrong !  The water flows very slowly through the loops, and air remains in the pipe and eventually causes an airlock. That what your issue is here.
Do you tinker, or do you need / can you get the installer back to commission it properly? Anything else is a waste of time and effort, and I’d recommend doing every loop to be sure this issue goes away and stays away. 

Edited December 11, 2020 by Nickfromwales

[Nickfromwales]

Which of those is flow? Eg which rail gets hot first? The rails are reversed, and flow gauges should be on the flow. 

[PeterW]

8 hours ago, Adam2 said:

Another question, the Grundfoss pump feels pretty hot, is that normal?

Assuming it’s the pump below the blending valve then it could be getting hot as it’s fighting the flow valves - those manifolds are back to front. 

[Adam2]

35 minutes ago, Nickfromwales said:

Which of those is flow? Eg which rail gets hot first? The rails are reversed, and flow gauges should be on the flow. 

The manifold with the actuators gets hot first

 

14 minutes ago, PeterW said:

Assuming it’s the pump below the blending valve then it could be getting hot as it’s fighting the flow valves - those manifolds are back to front. 

It's been this way since built about 15 years now. 

 

[PeterW]

Ok so this may be your issue. Those flow meters have been working the wrong way for all this time and may be jammed, causing your flow failure, or the actuator valves may have failed. 
 

These units are designed for a particular direction of flow, which you don’t appear to have with this set up. I would be considering switching the manifold out - you’re talking change of  £100 for a new 4 port manifold and a pair of isolators to redo that. Just reverse the rails so the correct one becomes flow - actuators should be on the return. 

[Adam2]

thanks @PeterW so weird that someone did that. We're moving out real soon so didn't anticipate this in our plans! 

 

Seeing as the flow meters worked badly but still worked for 15 years - is it worth just swapping in a new one to test that? If I unscrew the old one I guess I'm going to get wet - so presumably turn off system first and isolate?

 

Am a bit concerned seeing as we're near Christmas that I embark on something that may have a further surprise and we have no heating!!

 

[Adam2]

I found this which assumes eurocones which seem to be reusable- 

 

 

 

 

[JamesP]

I would just swop over the manifolds as Peter and Nick have suggested. Isolate the two manifolds.

You will have to top up the loops and purge the air, Wunda has all the details.

[Adam2]

2 hours ago, JamesP said:

I would just swop over the manifolds as Peter and Nick have suggested. Isolate the two manifolds.

You will have to top up the loops and purge the air, Wunda has all the details.

 

Yes would be nice to do that - we have 2 of these manifolds. They don't seem to have an air-vent so maybe I could get new ones that do to make installation easier.

 

My query re the flow valve replacement is that this is £10 and maybe 10 mins vs £200 and some hours and maybe a risk of prolonged period of no heating if there are any surprises that need parts.

[JamesP]

2 hours ago, Adam2 said:

 

Yes would be nice to do that - we have 2 of these manifolds. They don't seem to have an air-vent so maybe I could get new ones that do to make installation easier.

 

My query re the flow valve replacement is that this is £10 and maybe 10 mins vs £200 and some hours and maybe a risk of prolonged period of no heating if there are any surprises that need parts.

Sorry I meant just change the existing  flow and return manifold first before spending money.

[ProDave]

How do you know the manifolds are the wrong way round?

 

Yes normally the flow manifold is on the top, but that is usually dictated by the porting on the blending valve so you don't get a choice.  But you have no blending valve so there is nothing stopping them being fitted any way round.

 

I would have thought if they were the wrong way round, backwards flow through the flow meter would try to push the plunger up, not down, and you would see no flow reading.  The fact you do see a flow reading on some of them suggests the water is going the right way.

 

Or have I missed something?

 

I subscribe to the air block theory to explain no flow on a couple of loops.

[Gav_P]

1 hour ago, ProDave said:

How do you know the manifolds are the wrong way round?

This...

 

which is flow and which is return?? Probably the right way round as it’s been working for 15 years. 
 

Definitely sounds like an airlock. 

[Adam2]

On 11/12/2020 at 22:00, Gav_P said:

which is flow and which is return??

 

The flow is the manifold with the actuators on.

 

I've fiddled with some of the valves and open/closed isolators, restarted boiler/pump, turned up and down the flow on the pump.....now we have heat again! 

 

thanks for all suggestions

[Nickfromwales]

On 11/12/2020 at 20:32, ProDave said:

I would have thought if they were the wrong way round, backwards flow through the flow meter would try to push the plunger up, not down, and you would see no flow reading.  The fact you do see a flow reading on some of them suggests the water is going the right way.

The OP states the actuator rail gets hot first ergo they’re the wrong way around. The flow meters are like a flap / paddle over a tube end, so correct direction of flow promotes that paddle being pulled away to make way for the unhindered flow of water. Reverse flow actually pushes those paddles against the tube end and the higher the flow potential, the firmer they get shut.

Things will improve when the manifolds are in the correct positions, and the loops have been purged. 
Get those done and order the eggnog  

[ProDave]

12 minutes ago, Nickfromwales said:

The OP states the actuator rail gets hot first ergo they’re the wrong way around. The flow meters are like a flap / paddle over a tube end, so correct direction of flow promotes that paddle being pulled away to make way for the unhindered flow of water. Reverse flow actually pushes those paddles against the tube end and the higher the flow potential, the firmer they get shut.

 

Yes but with the paddle going the wrong way you would not get a flow reading?  So the flow cannot have been going the wrong way all this time because some were showing correct flow.

 

I take what we have been told so far with a pinch of salt.

[Nickfromwales]

4 hours ago, ProDave said:

 

I take what we have been told so far with a pinch of salt.

I have re-read, and yes, confusion reigns.......

[Adam2]

14 hours ago, ProDave said:

I take what we have been told so far with a pinch of salt.

Not sure if you mean my description but if so - I even had a digital thermometer on the two manifolds to confirm different temps so I assure you of the fact that the actuators are on the flow. On some of the loops this wasn't even necessary as the pipe connected to the flow meter was cold (only heat seemed to be by virtue of minor heat transfer from adjacent loop) whereas the manifold with the actuators was hot.

It is a mystery but one which I won't investigate any more unless we get more issues as we've sold this house and we now have some heating on all loops so although maybe not correctly installed it seems OK for now - time to crack open the Christmas brandy and enjoy the warmth 

[ProDave]

So now it has started "working" do you see readings on the flow meters, because I cannot see how they possibly give a reading with the flow going backwards through them?

[Adam2]

Yes. I agree is odd but also please believe me when I tell you I can tell the difference between the hot pipe feeding one manifold and the much less hot one connected to the other.