Wet ufh issues. Any advice?

[Dirty tree]

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?

 

[jase158]

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?

 

[Aquazone]

220m? Jesus no wonder it doesn't work. I have used Nuheat for years and I think the longest I have ever done in one loop is 110-120m, however most are 70-90.

 

[Neil K]

Picture of the manifold please, there may be a way or two out of this

 

[lame plumber]

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

 

[dirtytree]

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.

 

[erpkid]

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.

 

[Badboy plumber]

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

 

[jase158]

do you have one of these?

 

[jase158]

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?

 

[Worcester]

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.

 

[Ermintrude]

150 centers with floor temp of 63c be ok in the nursery boss?

 

[Worcester]

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.

 

[Ermintrude]

Or fit Myson mptrf and have a few hundred permutations