navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Recommended Insulation layer to use under the underfloor pipes ?  (Read 4418 times)
bongoneil
Newbie
*
Offline Offline

Posts: 1


« on: August 20, 2006, 12:38:52 PM »

Hi All

I will be looking to install a Navitron 9kW unit later this year and am at the stage of digging up all of the floors in this old farmhouse, which were basically a mix of earth and rocks. Currently I am planning to lay concrete over the hardcore base, then a damp proof membrane, then some kind of insulation material, then more concrete and the underfloor pipes in screed. Is there any recommended thickness or type of insulating material that should be used with underfloof systems? I am guessing probably not, but as digging the floors is something I only want to do once in my lifetime, I just want to be sure.

Many thanks

Neil
Logged
Ian
installers
Sr. Member
*****
Offline Offline

Posts: 317


« Reply #1 on: August 20, 2006, 10:58:30 PM »

Hi Neil,

I think you will find that most UFH installers use a slab of 100mm EPS foam under the concrete slab and a minimum of 5mm EPE foam around the edges.

I could not find a way of improving on the 5mm foam around the edges (in my case - no skirting boards and tiled) but I used 200mm of EPS foam under my slab. I used a DPM under and over the foam just to make sure it does not get damp.

A couple of other points...

Concrete takes time to cure - it may appear to be solid after 24 hours but it does not get to full strength for up to 28 days. I would recommend that you leave your slab at least 3 weeks before you think of applying any heat from the UFH circuit. When you do apply heat, be VERY gentle in introducing heated water to avoid thermal shock; take your time and build up the heat slowly. This way you should avoid excessive cracking.

I hope your farmhouse is small or you have backup heating capability! Even if you make it a superb example of insulation, I cannot imagine that a 9 kW GSHP will do the business without some help on the coldest days.

Whilst others have reported no issues with cracking with a long slab without expansion joints - I would still recommend that you use them liberally.

I assume you will zone your system. Make sure that you do not pile too much energy into a small zone if that is the only one requiring heat at that time. The GSHP does not have anything between full on and full off. Some advocate the use of a buffer tank to allow for this situation but I am not 100% convinced.

I hope this helps.

Regards,
Ian
Logged
Amaterasu
Hero Member
*****
Offline Offline

Posts: 513



« Reply #2 on: August 22, 2006, 11:44:16 PM »

Additional to ians comments.
It is recommended that you pressure test before you lay the screed and when you do lay the screed apply pressure to the UFH pipework for the duration of the curing process, this will help prevent any squeezing of the pipework
Logged

Geoff.........
Douge
Newbie
*
Offline Offline

Posts: 2


« Reply #3 on: August 24, 2006, 03:26:36 PM »

Just my 2 pennyworth,
I stepped in to help a friend with his self-build when he had a serious stroke 2 years ago.
I remember crawling around on my hands and knees for days on end cleaning the concrete base before applying a liquid WPM and then the blue plastic (belt and braces). Then came 100mm of Kingspan with 25mm around edges all taped with metallic tape. The wet underfloor heating system was from Nu-Heat and with another friend we layed what seemed like miles of micro-bore 'pex'? pipe. The pattern provided by NuHeat was useless and my friend patterned on the fly ensuring that the length of each loop was within the parameters and the manifolds were best placed for the main feeds from the main manifold.
It was a seven zone system, 4 down, 3 up.
There was no intermediate membrane between pipes and insulation as keeping under control was almost impossible and there were various opinions as to whether it was needed. The system was pressurised and after a few days we watched with half closed eyes as the 65mm screed was laid. This was not good for the faint hearted as, although supported boards were supplied for barrows and workers the screeders were not always careful. The system is heated with Swedish groundsource heatpump of 7kw (I think) with vertical bored ground pipes.
The system heats the ground floor well (too hot for me) but is not so good on 1st floor with plywood subfloors and engineered wood flooring on underlay.
With 7 zones it may not be perfectly balanced but it is a long job to alter and then check the results.

During installation there was some conflict between the suppliers of the heatpump, which includes a tank for  DHW and the supply to the Underfloor heating, Nu-heat and the suppliers of a flat-plat Solar system. This is not yet connected as another tank is required (thermal-store) and a connection into the Heatpump tank.

If anyone is thinking of doing the whole ecoheating bit from scratch make sure all of the bits are compatible.
Hopefully this is what Navitron can provide.

My concern with all of this stuff is its longevity and replacement costs. How long does Underfloor heating pipe last.
Regards DougE
PS. Make sure that you emphasise to other trademans not to drill thru floors. The electrician at my friends house, despite being shown the pipework and given a severe warning, managed to drill thru a pipe within 10mins of starting work.
Logged
Amaterasu
Hero Member
*****
Offline Offline

Posts: 513



« Reply #4 on: August 24, 2006, 03:30:59 PM »

according to data I have seen (some) pipework is guaranteed for 50 years - which is many more years than i will probably need  Wink
Logged

Geoff.........
mtimm
Jr. Member
**
Offline Offline

Posts: 74


« Reply #5 on: August 25, 2006, 08:00:57 AM »


The system heats the ground floor well (too hot for me) but is not so good on 1st floor with plywood subfloors and engineered wood flooring on underlay.
With 7 zones it may not be perfectly balanced but it is a long job to alter and then check the results.
 

If itís the floor temp that is too hot the mixing valve needs to be turned down.
If itís the room temp that is too high I am guessing that there are not stats in each room and it will be very hard to do anything a bout it.

As far as I am concerned with UFH it has to be 1 room = 1 zone = 1 stat.

How can you have controlled heat in a house without stats in every room? All rooms have different heat requirements and heat losses.

Many suppliers are not specifying individual room control as a minimum standard I think is so the can SELL a cheaper system even if it is not an efficient one.
Logged
mtimm
Jr. Member
**
Offline Offline

Posts: 74


« Reply #6 on: August 25, 2006, 09:18:50 AM »

With suspended floors it is very hard to prevent air gaps and or drafts around the pipes add to this the plywood subfloors (12-19mm) the engineered wood flooring(12-14mm) and the underlay (all types provide insulation) the 1st floor is at best going to struggle without little that can be easily done.

With UFH 3/4" 22mm of wood is an absolute no exception maximum. Wood of any type provides excellent insulation which is the last thing you want on top of your UFH pipes.

Douge I know this not going to help you and I am not posting to get at anyone here. It might help someone in the future and it makes my blood boil that suppliers donít give out enough or some times any information that is essential for UFH systems to work properly.
Logged
Ork-NAK
Newbie
*
Offline Offline

Posts: 28


« Reply #7 on: September 08, 2006, 05:48:04 PM »

Douge,

Just to say 'thanks for the posting.' I am considering a UFH system, and your helpful and thorough posting has given me food for thought. I think this sort of contribution, and the debate it stimulates, is an excellent way of spreading ideas and learning.

Thanks for pointing out the land mines. All I have to do is avoid standing on any more!† Smiley

Neil
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!