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Dirty tree

Hi,
our plumbers installed a john guest water underfloor heating system in our kitchen extension.
The pipes were laid and slab poured and all was good.It was connected up correctly to the manifold and is powered by a worcester Greenstar 37kw boiler which is overkill for our small house.Everything is working fine except......
We now have one area of hot floor and large areas of cold or luke warm floor. Approximately half the tiled floor is cold and return pipe going to manifold is luke warm at very best.It has been flushed through and there are no air blocks or blockages at all.
The floor space of entire kitchen is 32m2 but actual floor space for UFH is around 25m2.
Our plumbers tell us that this is how UFH systems work and that the entire slab/floor does not have to be uniformly heated and that cold patches are normal. It is our suspicion that they should have installed a dual system so that each pipe run had half the kitchen floor to heat and thus eliminating the cold areas and making the system more efficient.
The pipe was also run in one direction so to speak without the flow and return being always side by side.
The UFH system actually does heat up the room but it is annoying that half the kitchen still has a cold floor to touch and i can't help but think that the whole system would heat quicker and be more efficient if the whole slab was warm and not only 50% of it.
Your thoughts please and any advice.
Is this normal?
Should the entire slab be warm or are cold areas acceptable?
Is our system in some way worse off for the way it has been installed?
Is there a widely accepted correct/standard way of laying pipes so that the entire slab warms up evenly?
Should we have had a dual two pipe system for our floor space of 25m2?

looking forward to some advice.

thanks.
 
UFH is only one loop of pipe laid down in a particular pattern according to a design usually supplied by the manufacturer as a free service.

The temperature should be fairly uniform across the screed.

Sounds to me like they've made an expensive cock up but one of the lads more conversant with UFH will be along shortly to confirm this or give me a slap....
 
I don't use jg put polyplumb and for that size area you would be using a three port manifol, so you have 3 separate loops to heat your floor space. From what you are describing sounds as if they may have just gone in one side of the room and out the other did you take any pictures?
 
How many loop in the floor?
it will be either air locked, not balanced, kinked, or too long?
 
I don't use jg put polyplumb and for that size area you would be using a three port manifol, so you have 3 separate loops to heat your floor space. From what you are describing sounds as if they may have just gone in one side of the room and out the other did you take any pictures?


Thanks for your opinion.

yes i do have photos.
they went onto the floor with the pipe from the manifold, snaked all around the room and then came back to the manifold.
Have i been left with a bad ufh system then?

anymore opinions gladly welcomed.
 
Might be something as simple as flow and returns mixed up at manifold aswell. If that's all it is then it's not too bad
Hi guys,
everything is connected perfectly and everything is working as it should.
there are no blocks or kinks in pipe.
i would like your opinions regarding size of room and length of pipe used.
they used one pipe on 25m2 of floor.
is this why the floor is hot where the pipe comes onto the floor from the manifold but by the time it has reached the second half of our kitchen floor which is further away from the manifold the water had cooled down and the slab is cold.
will our system work properly if only half the slab heats up?

thanks
 
Only one loop.
spaced at around 100 mm apart laid in serpentine fashion and around 220 metres long.
 
We have 220 metres of one single pipe at 100-150 ish spacings in a serpentine layout.
 
What diameter pipe did they use?

25 m2 could be pushing it on one circuit, but not overly.

What are the distances between the pipes?

Post a couple of pics.. it will be easier to see what has been done
 
Did you have a pump for the UFH at thye manifold or is it simply off the boiler, i know its only 1 room but better ,
 
Just done a quick dork out o. My ufh app.
Recommends 3 loops, with a total length of 205m at an average of 159mm centres.

you will need massive water velocity to get any heat.

balls up by installer, the stupid thing is that splitting it up into 3 loops uses no more pipe.
 

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I would say it's the size of run . What insulation was under the slab?

You could fix it mechanically by installing a massive pump and blending valve set. Must have joined pipe or they spaced pipes too far apart. U could get it more uniform by running pump constantly even when rooms warm enough. - need extra controls but running the pumps would even out flow.


Really sorry to hear that this had happened. Were they the only quote u got? Really not done properly. Take them to the wall and have it all redone ?
 
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Hi Guys,
thanks for your opinions. Just spoke to John Guest technical. They recommend a maximum 100m run per loop.Our installer has given us 225m of a single loop.Over double the recommended run.
Chalked, you are right. John Guest also advised a 2 or 3 loop system. This is why half the floor is cold.Our installer clearly did not check manufacturers recommendations .
We do have a pump attached to the manifold.
Ermintrude, what size pump would we need to get a better performance from the UFH system?
 
As said before, 120 metres is maximum with jg speedfit so minimum of 2 loops.
Yes you will notice cold spots on warm up, but after 2-3 hours it should be warm all over
What you need to know is
1. Concrete depth
2. Pipe lengths
3. Pipe pattern
4. flow rates

Then ring JGspeedfit UFH department:
Speedfit Underfloor Heating with warm water | The Speedfit Underfloor Heating System

Explain the problems and ask if there is anything you can do.

1. The problem is that they may not guarantee the pipe or anything else as not done properly
2. you may never get a good heat from the pipe

Can you do me a favour and turn the underfloor heating on, wait 10 minutes and take a picture of the flow meters please?

Finally it sounds like he has bought a single room kit instead of the proper kit, find out how much he has charged and investigate what it would of cost?

A single room kit is a lot cheaper then the proper kit.

Was he a plumber or a builder?
 
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interesting to fond out if this was price orientated or done to a manufacturers spec and how much input the customer had on the final plan
 
Sorry.Forum will not allow me to upload links to photos.
Slight correction on our specs having looked into it.
We have around 165m of 15mm JG pipe on one single serpentine loop at around 150mm/200mm spacings. Still 65m over maximum recommended length by JG. It should have been installed as a 2 loop system.
Jase158 - Screed depth is 80mm. I do not know where/what the flow metres are.
We do have a pump attached to manifold.
Neil K - what is the way out of this?
Ermintrude- how big a pump would help?
Lame plumber- this was not price orientated. We chose the installer because they fitted our CH system three years ago.The total price came in at around 1800 to supply and fit.We did not have
input into the design.we left it up to them.
 
100 metres for any loop should be a max although it will work at greater lengths but due to the lower temp will perform poorly. If it has been plumbed direct as say a rad then you have the answer.
 
Hi,
our plumbers installed a john guest water underfloor heating system in our kitchen extension.
The pipes were laid and slab poured and all was good.It was connected up correctly to the manifold and is powered by a worcester Greenstar 37kw boiler which is overkill for our small house.Everything is working fine except......
We now have one area of hot floor and large areas of cold or luke warm floor. Approximately half the tiled floor is cold and return pipe going to manifold is luke warm at very best.It has been flushed through and there are no air blocks or blockages at all.
The floor space of entire kitchen is 32m2 but actual floor space for UFH is around 25m2.
Our plumbers tell us that this is how UFH systems work and that the entire slab/floor does not have to be uniformly heated and that cold patches are normal. It is our suspicion that they should have installed a dual system so that each pipe run had half the kitchen floor to heat and thus eliminating the cold areas and making the system more efficient.
The pipe was also run in one direction so to speak without the flow and return being always side by side.
The UFH system actually does heat up the room but it is annoying that half the kitchen still has a cold floor to touch and i can't help but think that the whole system would heat quicker and be more efficient if the whole slab was warm and not only 50% of it.
Your thoughts please and any advice.
Is this normal?
Should the entire slab be warm or are cold areas acceptable?
Is our system in some way worse off for the way it has been installed?
Is there a widely accepted correct/standard way of laying pipes so that the entire slab warms up evenly?
Should we have had a dual two pipe system for our floor space of 25m2?

looking forward to some advice.

thanks.

i used to to fit wet UHF daily but never to a drawing or plan, we had to follow known limitations like pipes should be 200mm apart meaning 5 linear meters of pipe per 1M squared, if you have 25m squared floor space that single pipe must be a minimum of 5x25 = 125m pipe length not including tails back to flow and return pipes, the maximum length of a single piece of UHF pipe is 100m, so yes in my opinion it was installed very wrong indeed. However it isn't unusual to only heat the usable parts of the floor/slab, we wouldn't run heat under work surfaces, fridges and cupboards ect so to not lay pipes through the whole screed isn't unusual but any visible part of the floor shouldn't have cold spots!! True story!!!!
hope this all gets fixed for you. P
 
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if so, on the top is the temperature control, let us know the maximum temperature and what temperature it is currently on

Also on the black case where the cable goes into, there should be a light, let us know which light is on, is it 1,2 or 3?
 
1800 to supply and fit

Ouch. Very expensive mistake. Get the "plumber" back he is the only one that can fix it. And your floor will have to come up

It should be designed with no cold spots, a good layout will eliminate these. John Guest would have even done a detailed design for free.

Under floor heating is best left on 24x7 with a set back temperature at night.

At first start up, the heat will work it's way along the pipe runs, however designed properly you wouldn't notice it.

Retrofit we budget around £20/m2 for 100m2 plus .....

see this document http://www.jhplumb.com/system/brand...dfit_underfloor_heating_details_and_notes.pdf

Page 4 - the Pipe Layout Detail 1 - Counterflow Pattern is what they should have done to eliminate cold spots. A single serpentine is the worst of the lot, though easy for an untrained person to install....

The pipe spacing SHOULD have been design based on flow temperature, designed room temperature and heat loss for the room.
 
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That'll be the plant nursery for some suspect green hemp I guess 🙂

Meantime, as Ermi and the others have pointed out, if you can get the system to blast water round at a moderated temperature of say 50°, on it's own circulation pump, independent of the rest of the central heating system, then, apart form the high energy costs of running the pump, it MAY work....

Take a photo of the manifold, thermostat and underfloor heating controls and post them up on somewhere like dropbox.com so we can all see it, and we'll see if we can give you some solid pointers on what workarounds you can do = #1 is make sure it isn't on the same controls as the normal heating circuit so that you can run it 24x7 with set back at night - the JohnGuest Controls (aka heatmiser) allow you to set up to 4 different temperature/time combinations per day.
 

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