Insulation & Underfloor heating Qs

Meclor

We are currently at planning stages of our self build. We are keen to get UFH but don’t know much about it. We have been recommended by our architect to get UFH downstairs and rads upstairs and basically insulate the hell out of the house!!! Just wondering if anyone can answer these questions for me.

At what stage should we start meeting with UFH suppliers?
What pump works best with UFH?
What would the average costs be for 126 m2 (2155ft) and how much extra would this be than putting in radiators?
What kind of insulation should we look at?

muffler

There's been a couple of recent threads about this so have a wee trawl back through the topics and you should find some info

Edit: I was looking for something in the older threads and found this which might be of help

anon1

You will have to allow for the thickness of the insulation under the concrete slab (or screed) containing your UFH pipes at an early stage so that your finished floor level is correct.

I would go with the thickest single board of insulation for underfloor I could find, I think it is 125mm at the moment. Putting in two smaller boards on top of each other under the slab is messy. It could lead to a bouncy floor.

Put in perimeter insulation at the edge of the screed as alot of heat is lost here. I'd put it along all walls to prevent cold bridges.

Screed depth is usually 65-75mm. Decide on the depth of your floor covering asap.

Consider thermostat location, see manufacturers recommendations.

Consider the location of the heat pump to prevent noise pollution in beedrooms at night.

Consider going with borehole vs Horizontal collector.

tribesman

anon1 wrote:

Putting in two smaller boards on top of each other under the slab is messy. It could lead to a bouncy floor.

One thick layer is handier but two layers can be useful to bridge over other services unders the screed. Say central vacuum pipes or waste pipes from sinks or baths. With two layers, the first layer can be cut to fit around the pipes and the second can be run unbroken right over the top.

The other advantage of two layers is that you can stagger the joints so there are no gaps down to the slab.

Qwerty?

tribesman wrote:

One thick layer is handier but two layers can be useful to bridge over other services unders the screed. Say central vacuum pipes or waste pipes from sinks or baths. With two layers, the first layer can be cut to fit around the pipes and the second can be run unbroken right over the top.

The other advantage of two layers is that you can stagger the joints so there are no gaps down to the slab.

Thats the way I've done it it rooms with services I used 40mm and 60mm layers. With 75mm of screed on top, I don't notice any bounce in it.

Qwerty?

Qwerty? wrote:

Thats the way I've done it it rooms with services I used 40mm and 60mm layers. With 75mm of screed on top, I don't notice any bounce in it.

Same here but with 100 + 100 EPS & 100 reinforced screed, but if something VERY heavy is dropped you can just feel a small bounce, much less than the equivalent on a suspended timber floor though, tbh.

Viking House

The average new house in Sweden has 300mm of EPS insulation under the foundations with 100mm under the footings, even then 35% of the heat from the UF heating is still lost to the ground. The Supergrund system cuts the UF heating heat loss to 15%.
This page http://www.supergrund.se/Uvarden.htm describes the U-values that can be achieved with both systems, the Finja system L element system achieves .05 worse U-values than the Supergrund system for the same thicknesses of insulation.

Viking House

Viking House wrote:

even then 35% of the heat from the UF heating is still lost to the ground. The Supergrund system cuts the UF heating heat loss to 15%.
.

It just goes to show that there is a pratical limit as to how much insulation can be used. It also comes down to temperature difference between floor slab & subground, in Ireland that difference could be 20C (slab 30C & subground 10C) in sweden the subground could easily be several deg below freezing!

With my UFH I intend to run it at as low a temperature as possible to minimize this loss, it is likely that during cold periods it will be running 24/7.

galwaytt

fwiw it's worth, I have ufh downstairs and rads upstairs in my existing house, since 1997. Never again. The rads, I mean........!!

Nope, our new house, nearing finish, is UFH upstairs and down. I wouldn't advise rads upstairs again, and for a geothermal system ufh on both floors would suit much better - rads upstairs will have to be 'oversize' if not boosted with another source (boiler) or you'll have to boost the water temps with a boiler/etc for rads. With ufh, you can eliminate that whole issue, and makes plumbing and controls much simpler.....

Insulation? - we've put 2 x 50mm Dow Floormate downstairs, and 30mm Dow Floormate upstairs. 65-70 screed on both floors. Upstairs is conc screed in a TF house.

anon1

Are you putting reinforcing steel under your ufh pipes?
Ducts are a good idea for services.
Leave expansion gaps in screed if using concrete.

Viking House

What is Dow Floormate?

Mellor

its a rigid EPS (or maybe XPS) insulation. There are a number of different one available, but they are very standard, even below standard.


Viking House, is that the insulated ring beam you showed at the RDS. Looks good. I could be wrong but I imagine it is used in conjunction with concrete piles. So the beam is fully supported, but with minimal thermal breaks.

Viking House

Hi Mellor

Piles are only used in swampy ground.
The house sits on a bed of structural polysterene, Aerobord can produce polysterene that takes 12 tonnes/m2, they use it under a lot of new roads in Sweden. There are now 800,000 houses built on polysterene in Sweden with a 0% failure rate.

galwaytt

Mellor wrote:

even below standard.

I think you need to explain that sweeping statement.

Kayaker

If i were to build again i would spend more on insulation, that said i was talking to a geo installer and it was said that he saw a timber frame house which was spray foamed through out and the geo-heating only comes on for less than a hour a day in winter. My timber frame house has both UFH upstairs and down with a concrete first floor, as i was doing some research there is a company that supply UFH and Floor board combined, the down side is that there is no heat retaintion by the floor. Me I am bit of a nerd and i've made a few mods to my own to my Thermia heat pump to make it run better. the house is 2200 Sq/ft and total energy cost(light,cooking,heat and hot water)for the year was 10,000 units- 1400 euro. best tip is install night saver meter, and get a elec. meter (meters.co.uk) and install it on the heat pump so you can see exactly what your heat costs versus total energy used.

L8r
Robbie

lfcjfc

What insulation would people recommend for under floor heating on the first floor of a dormer with hollowcore floor - on insulation at all, minimal insulation eg 30mm Xtratherm, or go the whole hog again with 100 - 125mm?

Go for more... you only buy insulation once, but you will save on your fuel bills every year.

I went for 200mm EPS.

Edit: just seen you are referring to first floor - just go for the minimum, any heat leaking down will remain within the house anyway.

I have heard several self builders say that they have NEVER used their 1st floor UFH as the warmth from downstairs (& extremly good insulation in the roof) is sufficient to keep the space warm
i.e. the thermostat never comes on!

lfcjfc

Thanks Dolanbaker
I was thinking along the lines of 25 - 30mm of Xtratherm for the first floor. With reference to your original comment on the ground floor and the recommendation of 200mm of EPS, is there a "denser" insulation that could provide the same thermal resistance but with a thinner layer? - I dont think I will have 200mm to spare in my floor level!

ardara1

lfcjfc wrote:

Thanks Dolanbaker
I was thinking along the lines of 25 - 30mm of Xtratherm for the first floor. With reference to your original comment on the ground floor and the recommendation of 200mm of EPS, is there a "denser" insulation that could provide the same thermal resistance but with a thinner layer? - I dont think I will have 200mm to spare in my floor level!

120mm of Xtratherm/Kingspan is the same as 200mm EPS or 180mm of HD EPS or 160mm of Grey EPs - but it is not a dense as the white stuff I'm not sure about it in floors at that depth - the performance of a floor is based on the Area and the exposed perimter of the ground floor the bigger a floor is the less insulation is required to achieve the same U-value.

MGal

I am just at the plastering stage of my new build. Its nearly time for the insulation for the underfloor heating but the floor level is the perfect height as it is for the velux windows! Is there any thinner insulation as effective as the regulation so I don't have to increase my floor level too much? I know should have thought of this earlier!!:( I have a concrete slab for the upstairs.

sinnerboy

for upper level - min 40mm pir ( kingspan/xtratherm/quinn therm/ballytherm)

you can save some mm's by using an easi screed - 35mm thick - ( it is more expensive than 75mm cement screed )

anon1

Make sure your architect specs the house to be able to support the additional weight of screed upstairs.

RKQ

It is possible to use a thin pipe in a thin rubber screed, used in Sweden.
PM for details of 10mm screed including pipe!

No real heat retention in screed but pipe is so thin it takes very little water to heat room!

Works well with heat pump or ice stick.

wallt

Meclor wrote: »

We are currently at planning stages of our self build. We are keen to get UFH but don’t know much about it. We have been recommended by our architect to get UFH downstairs and rads upstairs and basically insulate the hell out of the house!!! Just wondering if anyone can answer these questions for me.

At what stage should we start meeting with UFH suppliers?
What pump works best with UFH?
What would the average costs be for 126 m2 (2155ft) and how much extra would this be than putting in radiators?
What kind of insulation should we look at?

get in touch with ufh company before you break ground as ideally you should be putting in 150 mm of ridgid board insulation so your foundation levels will have to allow for this as most builders will only allow for 50 mm insulation as for cost just contact a plumber and he will point you in the right direction or failing that we got lots of ref,s on boards here . any of the newer systems work well with ufh but after a lot of searching we are going for air to water system

yop

wallt wrote: »

get in touch with ufh company before you break ground as ideally you should be putting in 150 mm of ridgid board insulation so your foundation levels will have to allow for this as most builders will only allow for 50 mm insulation as for cost just contact a plumber and he will point you in the right direction or failing that we got lots of ref,s on boards here . any of the newer systems work well with ufh but after a lot of searching we are going for air to water system

Have you no other alternative that air to water? You are probably going to be using the least efficent alternative heat source out there. So if you have the room and the funds I would go for borehole before geo and geo before air sourced heatpumps.

wallt

cheers yop
from what i,m hearing the older versions were not the most efficient but have been researching this for a while now and have two different companies willing to put me in touch with customers who have this product and are very satisfied with it . one of the companies in mayo are doing a housing estate in boyle and said that one woman can even show me her esb bills for heating her 2400 sq ft house . i also got the spec of insulation for her house and while well insulated i will be using the passive houses u-value for my 2000 sq ft . i asked the companies for there thoughts on my best option and both recommended the air to water units even though they sell all the three types

yop

wallt wrote: »

cheers yop
from what i,m hearing the older versions were not the most efficient but have been researching this for a while now and have two different companies willing to put me in touch with customers who have this product and are very satisfied with it . one of the companies in mayo are doing a housing estate in boyle and said that one woman can even show me her esb bills for heating her 2400 sq ft house . i also got the spec of insulation for her house and while well insulated i will be using the passive houses u-value for my 2000 sq ft . i asked the companies for there thoughts on my best option and both recommended the air to water units even though they sell all the three types

The crowd who showed you the ASHP in Boyle, by any chance are they based in the South East of the country?.

Maybe they have but I would definately do more investigation, I know of 2 installations and both are using twice as much electricity as we are with our heating system.
Out of interest what was the woman heating bill per month our year?

Personally I would not take a lot of heed of a company who is telling you that they have improved, if you google Air sourced heat pumps or ASHP and see the COP values of borehole V ashp V gshp then you will see the differences and the sliding scale from borehole to gshp to ashp.
The main time you need your heat is when its cold outside, when its cold outside the air is cold, so where is your heating going to come from... the immersions which are built into heat pump.
If you can afford it and have the area to it, I would put ashp at the bottom of the queue, even try for a passive house with an air recirculation system.

I dont want to seem like a ranter, but I spent a long time getting independent research from universities and off websites without any connections. I have one mate imparticular who installed an ASHP, the crowd who sold this nearly had me convinced, this guy is now spending 1000 euro per year to heat his house with this system and this is a direct expansion (DX) system, which is one of the newest types out there as opposed to the water based versions.

But if you have your mind made up, you have it made up.