Variotherm

[Barnboy]

Has anyone any experience or comments on the Variotherm Varicomp ufh system ?

I've priced up a couple of different systems, Nuheat, Wunda, Robbens, Minitec and Variotherm.

The Variotherm uses a Gypsum panel with 100mm centres and claims to give out 155w/m² @ 50⁰C flow temp which is the highest I've seen but is it true in real life and worth the extra cost ? My house faces east, west with 2 big glass doors facing east so I'm looking for a decent retrofit system that can be off when the sun's coming up 1st thing but then keep the place warm later in the day.

[SteamyTea]

50°C for UFH is very hot, too hot to walk on.

[PeterW]

It’s based on the Fermacell floor panel system - nothing new. Uses 12mm pipe from memory and needs either self levelling or tile over it as a finished surface. Wouldn’t want to be running it at 50°C though ..!!

[Barnboy]

So 50⁰ is a bit hot, that's obviously how they get their specs up to give a high w/m². 

So if that was ignored and ran at a more reasonable temp, closer to other systems and maybe then giving out a lower but more realistic w/m²  would you say the Gypsum panels have any advantage over the eps systems ? Would they act any more like an in screed system, slightly absorbing the heat and holding it longer rather than reflecting it all up to the surface ?

I've got about 40/45mm of build up before tiling as my door manufacturer gave me the wrong dimensions for thresholds, so self levelling etc as required for the Variotherm system isn't an issue, apart from the extra cost 😥

[Barnboy]

I'm down to the choice of 2, Variotherm Gypsum panel at 100mm pipe spacing or Continal tile fix, composite panels at 150mm centres.

Can anyone give me an independent view of the benefits or disadvantages of either please as I can't decide on which is best. 

[JohnMo]

How many W/m2 output do you need? Do you have insulation below the UFH pipes.

 

I am in the process of putting UFH in a summer house, I went EPS on 125mm centres, with timber bearers on 400mm centres between the EPS panels and with a 2 layer (glued and screwed) OSB on top.  Not sure how it will perform, but don't see any problems.

[embra]

On 07/01/2023 at 21:27, Barnboy said:

Has anyone any experience or comments on the Variotherm Varicomp ufh system ?

I've priced up a couple of different systems, Nuheat, Wunda, Robbens, Minitec and Variotherm.

The Variotherm uses a Gypsum panel with 100mm centres and claims to give out 155w/m² @ 50⁰C flow temp which is thebhoghest I've seen but is it true in real life and worth the extra cost ? My house faces east, west with 2 big glass doors facing east so I'm looking for a decent retrofit system that can be off whe the sun's coming up 1st thing but then keep the place warm later in the day.

 

On 29/03/2023 at 05:49, Barnboy said:

I'm down to the choice of 2, Variotherm Gypsum panel at 100mm pipe spacing or Continal tile fix, composite panels at 150mm centres.

Can anyone give me an independent view of the benefits or disadvantages of either please as I can't decide on which is best. 

 

I'm also looking for a high output (need 90 to 100 w/m2), low profile system for a renovation project. Did you make a decision on which system you're going for?

 

Which companies supply Variotherm in the UK? I'd be interested to take a look.

 

I'd also had a look into Continal tilefix, seems to be quite expensive though!

[SteamyTea]

28 minutes ago, embra said:

I'd also had a look into Continal tilefix, seems to be quite expensive though!

Not as expensive as running UFH at 100 W.m^-2.

 

There was a tale about a dancing chicken that did the rounds at freak shows.

A Victorian entertainer was so impressed that he bought the chicken and cage it came in.

The cage was a fancy affair, deep base, gilt on the bars and a red ruby on the top.

The entertainer took it along with his travelling freak show.  After a week though, he was getting concerned as the chicken just seemed to love dancing all the time.  After 10 days the entertainer decided to track down the fellow that sold it to him and seek his advice on how to stop the chicken dancing.

"Blow the candle in the base out" was the reply.

[embra]

18 minutes ago, SteamyTea said:

Not as expensive as running UFH at 100 W.m^-2.

 

There was a tale about a dancing chicken that did the rounds at freak shows.

A Victorian entertainer was so impressed that he bought the chicken and cage it came in.

The cage was a fancy affair, deep base, gilt on the bars and a red ruby on the top.

The entertainer took it along with his travelling freak show.  After a week though, he was getting concerned as the chicken just seemed to love dancing all the time.  After 10 days the entertainer decided to track down the fellow that sold it to him and seek his advice on how to stop the chicken dancing.

"Blow the candle in the base out" was the reply.

 

I'm sorry, I don't follow. Why is it expensive to run underfloor heating at 100 W/m2? 

[JohnMo]

Do the maths, 100W X m2 of UFH X hours run X number of days.

[SteamyTea]

7 hours ago, JohnMo said:

Do the maths, 100W X m2 of UFH X hours run X number of days.

Thanks, I had gone to bed.

 

[embra]

Still not following... 100 W/m2 is not the heat loss of the house, if that's what you're implying.

 

I'll need the same heat energy input to the house no matter the specific output per unit area of the UFH system.

 

What's important to me is that I can achieve the right absolute energy output from the UFH in areas where it's not practical to cover the entire floor area with UFH.

Edited April 21, 2023 by embra

[JohnMo]

16 minutes ago, embra said:

I'll need the same heat energy input to the house no matter the specific output per unit area of the UFH system.

That isn't exactly true. A 100W/m2 UFH system, will require 100mm centres and a mean flow temp of around 45 (or higher) degrees, irrespective of system you use. If the system is particularly inefficient your mean flow temps will be higher. So the downward heat losses will pretty high, the higher the flow temp and the less well insulated the floor, the higher the downward heat loss will be.

 

The downward heat loss is a product of U value, area and delta T (difference between floor temp and ground temp).

 

In a radiator house, floor temp will be 19 to 20 degrees, ground temp around 6 (unless your floor is ventilated then it could be -2 or less), so the delta T is, let say 14

 

In a your UFH, system, with a flow temp 45 (mean flow temp) - 6 (ground temp) is 39 delta T .  So downward heat loss for the same U value floor is nearly 3x as much.

 

Depending on floor U value a bigger proportion of heat will be travelling downwards instead of upwards.

 

Low energy input homes UFH is good, but still more costly to run than big oversized radiators, but high heating energy use home UFH, can be very costly to run, due the the losses downwards. 

[Barnboy]

On 20/04/2023 at 21:12, embra said:

 

 

I'm also looking for a high output (need 90 to 100 w/m2), low profile system for a renovation project. Did you make a decision on which system you're going for?

 

Which companies supply Variotherm in the UK? I'd be interested to take a look.

 

I'd also had a look into Continal tilefix, seems to be quite expensive though!

UFH1 Supply the Variotherm in the UK, they've been very helpful, and the only company that I've contacted who haven't then called me every week to "see how I'm doing and if I'm ready to order".

I have also been looking at Contnal lately, as I'm on a 2 steps forward, 10 steps backwards project so I'm not a stage to order anything yet. Continal didn't seem that much different in price, I think that they were about £400 more than the Variotherm, which the other quotes that I've had have been about that one way or the other. 

Please let me know your thoughts on either as it may help.me decide when I eventually get there.

 

Re the W/m²,

I haven't had the time to sit down and look at how these figures work into everything. My simple thought was that the higher the number, the higher the output. Yes maybe by putting the pipes closer, or running a higher temp, but does this not correspond in simples term to, the higher the output, the quicker that you get heat ? I've got the same insulation levels whichever system I use, apart from any difference in the panels themselves, so surely the same heat loss too. 

Please explain in simple terms, my brain is fried at the moment.

[JohnMo]

You are over thinking it. Reading to much promotional clap trap and believing it.

 

At the same flow temp and area, the only really thing that changes anything with respect to the output of the panels is pipe spacing and foil thickness.  Pipe spacing and temperature sets the output, foil thickness has a small difference on how the temp is distributed across the floor.

 

There is a third thing that being floor coverings, but that's a different discussion.

 

UFH isn't a radiator system, if you want quick response, use radiators. UFH is a low flow temperature, high surface area heating system for comfortable background heating.

[Barnboy]

On 22/04/2023 at 08:57, JohnMo said:

You are over thinking it. Reading to much promotional clap trap and believing it.

 

At the same flow temp and area, the only really thing that changes anything with respect to the output of the panels is pipe spacing and foil thickness.  Pipe spacing and temperature sets the output, foil thickness has a small difference on how the temp is distributed across the floor.

So if I've got a narrower pupe spacing then I'll have a better output ?

What about the difference between the Variotherm gypsum panel and Continal insulative composite ? Am.i thing along the right lines that the Continal will reflect the heat more than the Vaiotherm which will act more like an inscreed and heat itself up, dissipating it more evenly ? I've got 90mm of kingspan, and 50mm of Newton fibran below my screed and it looks like I'll have 20mm of Jackon board or similar below the ufh, as the external door manufacturer gave me the wrong dimensions for my sills, so I need to bring the internal levels up.

[JohnMo]

10 minutes ago, Barnboy said:

narrower pupe spacing then I'll have a better output

Yes for the the same mean flow temperature.

11 minutes ago, Barnboy said:

right lines that the Continal will reflect the heat more

Unless there is an air space, reflection does not occur.  The aluminium use in these systems are conductors so act as a heat spreader, the thickness affects the heat up time slightly.

 

How these perform will be different, but generally not that different. Insulation and floor buildup probably have a bigger impact. As well as overall insulation standards of the whole house.

 

 

 

[dw_young]

Hi - picking up on this old thread as it seems to be the only one about Variotherm. I installed this wall-panel heating in 2007, perhaps one of the first in a residential property in the UK. I'm really please with it but after so many years I can no longer dredge up the technical details that led us to the specifications we installed. But I do have one question: can anyone recommend a competent heating engineer (for north London area) to service the system. We've had some real issues with finding someone who understands the manifold, electrics etc. Thanks.

[JohnMo]

Wouldn't servicing be just the same as UFH?

[Barnboy]

I still haven't managed to get to the stage of ordering anything UFH wise yet but have been going over and over this in my head.

I've got 140mm of Insulation below my already laid 65mm screed,  this gives me a u value of 0.18W/m²k. Using Jeremy's heat loss calculator and some off the top of my head figures I get a total heat loss of 3268W with a floor area of 90m². If I understand this correctly and have filled everything in correctly I work it to equate to about 36w/m² of ufh being required???

If I was to opt for the Variotherm gypsum panel, this in my thoughts would basically act as part of the screed but with the pipes 65mm upwards of the insulation and about 45/63mm below my ffl.

Would the insulation u value and depth compared to the pipework allow this system to work to  a decent standard or would there

(A) not be enough insulation

(B) the height of the pipes in the build up not allow the slab to work as a thermal mass well enough ? I've read on here of people having their pipework midway up there slab and also having 100 -120mm of slab with ufh. 

Any inputs to help my understanding before I loose anymore sleep and hair over this.

Thanks

[JohnMo]

Are you certain you have filled the spreadsheet in correctly? Sound a huge heat loss for 90m2.

 

What air change figure have you use?

[SteamyTea]

4 hours ago, Barnboy said:

u value of 0.18W/m²k. Using Jeremy's heat loss calculator and some off the top of my head figures I get a total heat loss of 3268W with a floor area of 90m²

0.18 [W.m^-2.K^-1] x 90 [m²] x 20 [ΔT] = 324 W

 

Have you got a factor of ten error somewhere?

 

(I know that is just the floor, but it is to highlight the possibility of an error)

[Barnboy]

These are my inputs, I need to measure the walls and windows etc accurately and just went from memory last night, but I don't think that I'm far out with those.

I can't find anything relating to air changes in any of the architects paperwork ( He pretty much abandoned me when I said I was going to self build) everything is taped and sealed as best as I can do it so I'm pretty sure it's well done, a sparky mate who's on sites everyday keeps telling me that I've gone ott with my membranes and taping.

[JohnMo]

It's unlikely you will have 0.5 ACH unless you are running MVHR, if that's the case add 90% in MVHR efficiency.

 

If not MVHR how are you ventilating? What is your target airtightness?

[Nickfromwales]

1 hour ago, Barnboy said:

a sparky mate who's on sites everyday keeps telling me that I've gone ott with my membranes and taping.

This will be the best time, expense and effort you can possibly invest in. Tell sparky boy to just stick to sparking   
 

6 minutes ago, JohnMo said:

It's unlikely you will have 0.5 ACH unless you are running MVHR, if that's the case add 90% in MVHR efficiency.

 

If not MVHR how are you ventilating? What is your target airtightness?

What he said. 
 

Is the entire house airtight by design, and you’ve integrated this from day 1? Or have you taped and membraned where you think it’s needed? 
You defo need an AT test asap before doing anything else regarding calculations for heat loss and then deciding how you will achieve that energy input.
 

@Barnboy I am assuming you’ve not done an AT test yet? If not, why? If AT you will need MVHR and the MVHR design should have demanded this result to be a known also?! Or at least target.