UFH - zone not heating up. No flow...

[Newbuildnewbie]

Hi, 

 

A bit if a novice at this but trying to work it out. We've been in our self build a couple of months now and heating has gone on, but one of the zones doesn't seem to be heating at all. The thermostat calls for heat and actuator pops up to open for water to flow, but there is no flow at all showing in the flow meter - it simply doesn't move. I've got a nu heat UFH system and gave them a call they suggested it might be a fault with the flow meter and to screw the flow meter out and swap it with another that I know works, but I simply can't screw it out, it just screws out a bit and never seems to actually pop out. I'm a bit out of my depth to be honest but can't seem to get a plumber to look at it before Christmas! Any thoughts greatly appreciated 

[Alan Ambrose]

Maybe check that the actuator is clipped on properly. We had one that wasn't - in our Uponor system that meant the flow was always on 100%. They are a bit hard to clip on properly.

 

Alan

[ProDave]

Usual question, has it ever worked?

 

Probably an air lock in that loop, i.e. it wasn't bled properly.

[Newbuildnewbie]

51 minutes ago, ProDave said:

Usual question, has it ever worked?

 

Probably an air lock in that loop, i.e. it wasn't bled properly.

Thanks it has never worked. I thought it was an air lock and tried to vent it myself but the hose got to bar pressure 3 and then popped off. Couldn't imagine an air lock could cause that sort of pressure issue but perhaps it could? Sounds love it is a plumber job, will just have to wait until after Xmas! 

[ProDave]

If you can't force water through that loop with 3 bar pressure, then there is a serious blockage.  Pipe kinked flat at a bend perhaps?

[newhouse87]

Can i still have flow showing on manifold but airlock on loop down along it. Left sitting room heating on all night and no heat increase and floor v cold to touch. Thought maybe stats wired wrong but that doesn't seem to be the case.

[PeterW]

7 minutes ago, newhouse87 said:

Can i still have flow showing on manifold but airlock on loop down along it. Left sitting room heating on all night and no heat increase and floor v cold to touch. Thought maybe stats wired wrong but that doesn't seem to be the case.

take the actuator off and put the commissioning cap on and open it all the way then check for pump flow etc - pipes will be warm if it’s working 

[newhouse87]

the actuator heads are warm and flow meter on that loop is showing 2.5l. Would that mean no possible airlock down the loop?

[Temp]

On most systems the actuator heads press down on a pin to turn off the flow. Removing the actuatorcallows the pin to come up/on. This pin can get stuck down/off. Perhaps remove the actuators on that one and another to compare it with. Eg both/all pins come up to the same height? Does the flow increase with the actuator removed?

 

If that all checks out I would try turning off the three good loops and turn on the problem loop. Does that cause the flow rate on the problem loop to go right up? If so sounds like balancing issue. Partial blockage?

 

When you check for a blockage with a hose make sure you put the supply hose on the flow manifold and hose to drain on the return manifold. Make sure the actuator is open (pin up).

Edited March 2, 2023 by Temp

[newhouse87]

ill do it when i get home after tonights shift. Thanks. I wont go near it with hose as im not most diy savvy. Could flow meter read ok on manifold yet still have air in the loop? Are actuator heads meant to be hot? Return pipes dont feel warm however.

Edited March 2, 2023 by newhouse87

[newhouse87]

Edited March 2, 2023 by newhouse87

[newhouse87]

bloody painters painter over plumbers writing if whats what but have most of it figured out.

[PeterW]

No circulation pumps on the manifold - there is your issue.

 

[newhouse87]

What? Im quite cluelss and my plumbers not the best. Most zones work ok. Bit slow to heat up but ok.

[newhouse87]

Can this pump be added now? juts thinking its the rooms farthest away are slowing /not heating at all.

[Temp]

Yes they can be added. There would normally be a pump and mixer on each manifold.  

 

The manifold pump sends the same water round and round the floor loops. 

The mixer injects new hot water into the floor loops to maintain them it at a set temperature.

 

Typically looks something like this (see photo). The pump is obvious. The mixer is at bottom left near the flow and return valves.

 

You might also need a bypass added to the system to deal with a situation where the mixer on both manifolds is closed. 

 

We have seen all sorts of problems on here. Manifold pumps and mixers are normally fitted on the left of the manifold. We've seen problems where they have tried to fit them on the right due to a lack of space and they have ended up being fitted upside down or with the pump pointing in wrong direction.  If your plumber doesnt know about UFH I would find another that does. 

 

I note a distinct lack of insulation on all your main flow and return pipes as well.

 

 

[Temp]

PS: The absence of a mixer probably explains why your actuators feel pretty hot when it is working. UFH temperatures are normally 30-50C eg  lower than boiler/rad temperatures 60-80C. If you have any solid wood flooring this can be damaged by too high a floor temperature. Ditto some lino like products have a max floor temperature. Sometimes as low as 38C. 

[newhouse87]

Thanks so much for the info, before i go asking my plumber who probably never heard of most of this a few more pics to see if any pump anywhere. would the fact my flows all seem ok not indicate my pump function is ok?

[newhouse87]

it does seem be my sun and sitting room which are farthest away dont seem to get up to temp. Last few months i have been thinking maybe its loops wired to wrong stats. Would lack of circulation pump explain this?

[JohnMo]

Was the system ever commissioned by the plumber - or did he just install and walk away?

 

First set all the thermostats so they are calling for heat.  Check all actuators are open.  Then reduce thermostat temp (one at a time) and which actuators close (after about 5 to 10 mins) mark the room on the actuator (s).  Once you have rooms for each actuator, check if they match where you think they should be.

 

Your pump from the heat pump/boiler may be just too small to cope with the flow to all your loops.  Go through each loop and record the flow being recorded on the flow meter.  Does your paperwork contain a pump curve?  It will be a graph m3/h or litres/min on the bottom and pressure or m head on the vertical axis.

 

You have a short run of pipe to the manifolds, but a lot of loops in the floor.  The issue could be the amount of flow required?

[newhouse87]

Plumber set up pipes and another guy came and commissioned the daikin unit, didnt leave any paperwork. Im doing it sunday. I know most of what turns on what just loops1-5 for sun/sitting room im not sure of. All flows get up to 2.5 so would that suggest i have circulation pump somewhere?

All actuators do open fine.

Edited March 3, 2023 by newhouse87

[newhouse87]

Just reading about my dakin unit, it has circulator pump in unit and says no third party components needed. Was thinking because flows are all ok so must be just stats wired to wrong loops.

[PeterW]

On 04/03/2023 at 04:04, newhouse87 said:

Just reading about my dakin unit, it has circulator pump in unit and says no third party components needed. Was thinking because flows are all ok so must be just stats wired to wrong loops.

Yep that’s fine for Rads but not for UFH - the manifold flow is finding it’s own shortest and least resistant route.

 

I’m losing count of the amount of crap UFH installs I’ve seen or had to fix where pumps have been ignored to save £200 and then it’s a £4-500 job to fix retrospectively.

 

On 03/03/2023 at 22:33, newhouse87 said:

another guy came and commissioned the daikin unit, didnt leave any paperwork.

So where is the G3 sign off for the pressure tank..?? Building regs/Manufacturer requirement 

[JohnMo]

1 hour ago, PeterW said:

the manifold flow is finding it’s own shortest and least resistant route

 

 

Understand if the pump cannot supply enough flow to manage the flow requirements it will supply the lowest head loss loops and ignore the high loss loops.  Which maybe the case here.

 

But a conflicting statement is

On 03/03/2023 at 22:33, newhouse87 said:

All flows get up to 2.5

And

On 03/12/2022 at 20:58, Newbuildnewbie said:

but there is no flow at all showing in the flow meter

 

Also if all flows show 2.5 l/min, would suggest zero commissioning has taken place and the flow are not balanced.

 

Big pump or 2 maybe needed for 16 x 2.5l/min

[newhouse87]

7 hours ago, PeterW said:

Yep that’s fine for Rads but not for UFH - the manifold flow is finding it’s own shortest and least resistant route.

 

I’m losing count of the amount of crap UFH installs I’ve seen or had to fix where pumps have been ignored to save £200 and then it’s a £4-500 job to fix retrospectively.

 

So where is the G3 sign off for the pressure tank..?? Building regs/Manufacturer requirement 

BUt if the manifold finding flows that are heating rooms is that not ok?  Dunno where any of that stuff is but he was daikin engineer.