UFH not reaching temps over 15degrees.

[MrPlumbician]

Recently installed Underfloor heating. in a renovated Timber clad building with suspended floors.
The walls are all filled with 100mm insulation in between and 50mm over studs.
Floors are 50mm celotex overboarded, with aluminium spreader plates and 18mm t+g flooring on top. 15mm engineered oak finish floor.

Boiler is a Worcester Bosch 27i system condensing boiler.

6 zones (on an 8 zone manifold) largest being 100m, smallest zone 50m. Digital programmable room stats for each zone. Actuators all working.

All air purged from system at start up. Flow rates attempted to be adjusted (cannot quite get the 2 large zones showing as fully open, they currently sit at 4 on flow meters)

Only one Zone reaches 18 degrees, all other zones, even the small ones struggle to reach temps of 15+ degrees

Any help would be super appreciated!

Kris

 

[Dan Robinson]

100m and 50m.... Square or linear?

blending valve setting?

Flow temp from boiler?

Manifold flow and return temps?

Loop flow and return temps?

Pipe centres/diameters?

33mm of wood on top is a lot, but should work.

 

[MrPlumbician]

All measurements of zones linear.

Flow temp from boiler 65 degrees
Blend valve set at 60 at manifold.
Flow and return 22mm copper.
Manifold temp showing at 60degrees on return.

 

[Dan Robinson]

Loop temps/centres/diameters?

 

[MrPlumbician]

Not sure of loop temps except what stats show. Which are generally all around 14/15 degrees.
Centres 200mm
Diameter 15mm

 

[Dan Robinson]

Need to know what the loop temps are really.

Manifold could be fed backwards and the blender not working properly?

Wouldn't be the first time its happened.

Never like to see loops over 80 metres personally.

 

[MrPlumbician]

Yeah unfortunately couldn't get away from it
What's best way to get a reading on loop temps? A handheld thermometer? Hehe.
So if flow and return were wrong way round, wouldn't it just shut off the boiler?
If the mixer was faulty, I wouldn't see a temp of 60degrees at the manifold right?

 

[Dan Robinson]

Clamp on thermometers or K-Type thermocouples
Boiler F&R may be right, but the manifold might be connected wrong.
You might.

 

[roguetrader]

What method was used to get rid of the air?

 

[Groovejet]

Roguetrader made a very valid point.
Best to stick with manufactures instructions on best way to remove air from u.f heating circuit.

Its a case of filling system through the drain off valve on manifold, isolating valves on part of the circuit and opening a valve to release the water until no air is present.

Unfortunately its not a case of filling and bleeding the manifold as 9 times out of 10 there will be air still present. (From my experience anyway!)

Hope that helps but M.I is best way forward , they'll tell you everything you need to know about venting U.F heating.

 

[MrPlumbician]

Ah yes. Well that's where we didn't follow the exact manufacturers instructions.. As I've now read after searching fault finding online. As the rennovation is still ongoing, the UFH is the only circuit fed off the boiler.
So we filled from filling loop, one zone at a time, releasing the blue caps but by bit. Bleeding 2 buckets of water from each zone. Until water ran uninterrupted.

Our very experienced heating engineer (he's been in the business all his life! And hes 60+) recommended this way. I don't know if it was coz it was 5pm on day after boxing day. And it was just a quicker way or if he was right. But can it be remedied if wrong?

 

[roguetrader]

You need to connect a drain hose to one manifold rail and a mains water hose to the other manifold rail. Close the flow and return ISO valves so you are dealing solely with the UFH manifold.
Turn the water on and run each loop through individually until it runs clear and uninterrupted by air. Close down that loop and do the next one.
Two buckets per loop isn't enough.
Does your manifold have a temp sensing phial?

 

[MrPlumbician]

Yeah it has a dial that connects to various parts of the manifold.
It's always indicated 60degrees.

 

[roguetrader]

No, the head that you turn to vary the temperature, does it have a thin wire attached to a phial? Maybe attached to the pipework somewhere.

Air is the most common thing.

 

[MrPlumbician]

No it doesn't have one :-s I'll try starting again from beginning filling mains. And take it from there. It's gotta be that! I'm sure! It's the only thing that differed from manufacturers instructions.