Underfloor Heating Question...

Underfloor Heating Question...

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Discussion

HDog

Original Poster:

90 posts

188 months

Tuesday 16th December 2014
quotequote all
Hi

I've recently had wet underfloor heating fitted to my new extension, a largish L-shaped open plan room which circa 7m long by 5m.

How can i tell if it is working correctly? It seems to take a long time to heat up, e.g the return pipes on the manifold remain cold for circa 2 hours when then heating is constantly on. As a result you get a warm floor in half the room and it will still be cold on the other half?.

Anyone have an idea how long it should take to get warm water circulating around the whole system and hence have an even heat throughout the whole room?


silversurfer1

918 posts

135 months

Tuesday 16th December 2014
quotequote all
HDog said:
Hi

I've recently had wet underfloor heating fitted to my new extension, a largish L-shaped open plan room which circa 7m long by 5m.

How can i tell if it is working correctly? It seems to take a long time to heat up, e.g the return pipes on the manifold remain cold for circa 2 hours when then heating is constantly on. As a result you get a warm floor in half the room and it will still be cold on the other half?.

Anyone have an idea how long it should take to get warm water circulating around the whole system and hence have an even heat throughout the whole room?
You should have actuators on the manifold controlling the flow to each area these open and allow mixed water to flow around each circuit. Each circuit also usually has an flow restrictor so you can set the flow in ltrs per min so make sure they are open.

post a pic of your manifold if you can

ss



loughran

2,731 posts

135 months

Tuesday 16th December 2014
quotequote all
Also you will have flow meters on top of the manifolds possibly looking like this....



The red collar pops off and by twisting the base of the meter you can control the flow through the circuits. There is a float in the glass vial that rises and falls as the flow increases and decreases.


caziques

2,567 posts

167 months

Tuesday 16th December 2014
quotequote all
Just wondering if the pipes have even been laid correctly.

All underfloor pipes should be laid in a spiral pattern and not a snake.

With a snake layout someone starts at one end of the room and snakes backwards and forwards - the result is a warm end and a cold end.

Also how many runs of pipe? Should be 2 or possibly 3.

Pictures would be good. - Must dash, got 5 pipe lays to do by the weekend.

loughran

2,731 posts

135 months

Tuesday 16th December 2014
quotequote all
caziques said:
All underfloor pipes should be laid in a spiral pattern and not a snake.
This is gospel is it ?

HDog

Original Poster:

90 posts

188 months

Tuesday 16th December 2014
quotequote all
Thanks for the responses chaps, i've attached some pics which may help to clarify.





I do have the flow meters on top of the manifold, if i play with the black collar will this adjust the flow rate? It never seems to change currently, always sits at the top of the meter reading circa 0. What should this be showing?

caziques

2,567 posts

167 months

Tuesday 16th December 2014
quotequote all
loughran said:
This is gospel is it ?
Think about it.

The "hot end, cold end" problem is an issue made worse when using gas or oil for underfloor heating.

Water is tempered to 45 for going into the floor, and would return at say 20 - alleviate the problem with a spiral pattern as then you have hot/cold next to each other - and the whole floor is fairly even.

Put it another way - there are no downsides to a spiral pattern, and with fewer sharp corners it's easier to install.

Muncher

12,219 posts

248 months

Tuesday 16th December 2014
quotequote all
loughran said:
This is gospel is it ?
Sometimes that isn't always practical and after a little while the flow and return temperatures even up so it doesn't make much difference.

silversurfer1

918 posts

135 months

Tuesday 16th December 2014
quotequote all
You have two circuits a flow and return one above the other

Make sure the white caps below are not screwed right down this is where an actuator would sit and open and close the valve if they were connected to thermostats it would operate a pin. If the pin is fully down then there won't be any flow.

The black rings may just be locking rings but yes that is where you can set the flow if the actuator side is open usually you will be twisting the ring or flow meter to adjust the flow your just have to fiddle.

Ss

Also check the zone valve feeding the manifold is open the lever will be floppy and that the pump is running id be setting the flow at about 4 litres per min each circuit and see how that goes

Edited by silversurfer1 on Tuesday 16th December 22:48

HDog

Original Poster:

90 posts

188 months

Wednesday 17th December 2014
quotequote all
Thanks for the help SS

Bit of a lamens question this, but how can I tell if the pump is actually working correctly without taking it all apart?

Also, the white caps on the return pipework (actuators?) seem to be just plastic caps which you can tighten or loosen. Currently they are fully open so I would imagine this would facilitate a maximum flow rate? I'm still getting no movement on the flow gauges from the 0 reading they currently show.



worsy

5,776 posts

174 months

Wednesday 17th December 2014
quotequote all
HDog said:
Thanks for the responses chaps, i've attached some pics which may help to clarify.





I do have the flow meters on top of the manifold, if i play with the black collar will this adjust the flow rate? It never seems to change currently, always sits at the top of the meter reading circa 0. What should this be showing?
Do you have the design? The flow will be on that. Make sure the pump is running to adjust as it will say 0 when no call for heat.

loughran

2,731 posts

135 months

Wednesday 17th December 2014
quotequote all
Looking at the photos I would say the black collars around the base of the flow meters are the locking rings. These should prize easily up and off the flow meters so you can twists the glass phials and adjust the flow.

If twisting them has no effect you may have air in the system.

silversurfer1

918 posts

135 months

Wednesday 17th December 2014
quotequote all
HDog said:
Thanks for the help SS

Bit of a lamens question this, but how can I tell if the pump is actually working correctly without taking it all apart?

Also, the white caps on the return pipework (actuators?) seem to be just plastic caps which you can tighten or loosen. Currently they are fully open so I would imagine this would facilitate a maximum flow rate? I'm still getting no movement on the flow gauges from the 0 reading they currently show.

Keep the white caps loose, no the flow rate will be set at the other end of the circuit on the glass flow meters.

Id start by just putting my hand on the pump you should be able to feel it running. Failing that you can remove the cap on the front and push a small screwdriver into the spindle your know if its running.

Its a small manifold and quite simply the pump should running sending return water from the UFH circuit to mix with flow water from the boiler then this is sent around the the UFH circuit as a mixed water that can be set by the thermostatic valve on the top left (id set 40 - 50 c depending on floor covering)

One thing to note is what brings the pump on? some of those small manifolds are temperature operated so the zone valve opens and sends hot water through the manifold this is sensed by a thermostat which turns on the UFH pump, so if the zone valve was closed or that part air locked there would be no flow around the manifold thus pump will not run.

So really get and have a feel is the zone open (lever will freely move from one side to the other) if so is the pump running ? if so move the locking rings up and set up some flow rates. If the zone is closed open the lever manually and see what happens might just be the zone valve is not getting a signal to open (demand is off or incorrectly wired)the heating will need to be on if your opening the valve manually to get hot water to flow around it.

SS

caziques

2,567 posts

167 months

Wednesday 17th December 2014
quotequote all
Just check the flow valves on the top manifold are open.

Most manifolds come with the valves screwed shut - pop the clip off and physically unscrew the flow valve, should be about five threads showing when fully open.

Cap on the front of the pump can also be taken off (as others have said), a few drips of water will probably come out as well. With the cap off you can see if the pump is rotating (goes clockwise).

HDog

Original Poster:

90 posts

188 months

Thursday 18th December 2014
quotequote all
Okay so last night I had a play with the flow valves, turns out they are fully open (as i managed to completely unscrew one of them and it popped out!)

It looks like the main valve is opening when heat is called for so there is hot water coming from the boiler to the top manifold and into the pump. I unscrewed the bleed screw on the pump and water flowed out so i guess there is no air lock in there.

Any other suggestions? the flow readings are still not changing from 0 when have the UFH switched on or off.

TheTardis

214 posts

189 months

Thursday 18th December 2014
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Have you spoken to the installer?
Surely they can give advice over the phone or pop round and diagnose

loughran

2,731 posts

135 months

Thursday 18th December 2014
quotequote all
Does the installer live in a large house just down the road from you ?

Woody3

748 posts

203 months

Thursday 18th December 2014
quotequote all
No idea if this applies to you, just going on experience of our new UFH which we got commissioned over the last couple of days.

We've got thermostats so have the actuators as opposed to caps like yours.

Even though the actuators were warm and open the water wasn't flowing through the pipes. Turned out that the electrician hadn't put in a switched live to the pump, meaning the pump wouldn't turn on.

There's a light on our pump when it's on. Is there one on yours?

Muncher

12,219 posts

248 months

Thursday 18th December 2014
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I suspect the pump isn't working (wired properly) but that's just my educated guess.

RedLeicester

6,869 posts

244 months

Thursday 18th December 2014
quotequote all
Even with a silent, or nearly silent pump you should still be able to tell it's running simply by putting your fingers on it - you'll feel it vibrate.