Wet underfloor heating questions

[ARWadworth]

My brother will be starting an extension soon and he is considering underfloor CH? Is it really as good as it claims to be?

I see various problems. The extension will be a bedroom with an ensuite over his attatched garage.

1. He will be heating up the floorboards and probably a carpet before he gets any heat, that must be a massive waste of energy. Would a good quality wooden floor be better than a carpet?

1. Would I need to zone off the bedroom and ensuite seperately? I will zone them off from the rest of the house regardless.

2. One thing we have considered is making the ensuite floor lower than the bedroom floor so that UFH could be laid in a tiled screed above the floorboards and it's finished level would be the same as the bedroom. Is that feasible?

Adam

[John Stumbles]

How is the energy wasted? Where does it go? Does it somehow get out of the house?

[The Natural Philosopher]

It not a waste of energy, it is just a time delay. Conversely the heat in these will stay there after the heating goes off. A massive saving in energy :-)

The key is to make the path to the cold places a lot better insulated than the path to the places you want to heat! I.e. LOTS of insulation under the pipes.

Maybe. One tends to have sones anyway as all [pipes should be laid back to a manifold. Its possible to e.g. put a TRV on a small zone.

definitely.

But beware of massive screeds on a suspended wooden structure. I would rather go for a very stiff wood structure, with kingspan under the floor and pipes just laid on top of that, and ply over. Then tile the ply. Make that floor a lot stiffer than you would for carpet or laminate..maybe 7" deep with herringbone braces..then there is plenty of room for insulation and pipes as well.

[ARWadworth]

I think it might be worth doing. Especially as we can put all the needed bit in in as we build.

So masses of kingspan then between the badroom floor and the garage.

Room for thought. It should not be massive amounts of screed as this would only be in the ensuite area.

Adam

[ARWadworth]

Eventually it will leave the house. But I am with you now.

Adam

[John Stumbles]

Have a look at the wiki article on UFH - I put in several links to manufacturers' sites with some how-tos in there.

[Doctor Drivel]

A waste of time. He will be heating up a garage as well. Best he heavily insulates the floor between bedroom and garage and make sure is it air-tight.

Myson Kickspaces can fit under baths thyat heat your feet - towel rails too.

Yes, zone off the new extension.

[ARWadworth]

Will do. Time is on our side still as work will not start for a few months.

Cheers.

Adam

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember The Natural Philosopher saying something like:

The above would work ok, but with the addition of heat spreader ally plates would work better.

[The Natural Philosopher]

Kingspan has ally foil on it. Its a moot point as to whether the cost of adding more is worth the benefit. At this point I have no opinion.

[John Stumbles]

Question is whether you can get a significant amount of heat into the kingspan foil by just laying the pipes on top of them. Otherwise you're likely to have hotspots (or hot lines) in the floor.

I've been minded to try making grooves in the top surface of kingspan, laying bacofoil over it and pressing 10mm pipe into it to warm the floor of my loo. Will brag about it when/if I get Round Tuit and if it works.

[The Natural Philosopher]

I definitely get hot spots even buried in 4" of screed.

Actually having pipes in an air mass under a suspended floor is probably better to spread the heat,as micro convection will circulate the air around.

[John Stumbles]

What's the spacing?

[The Natural Philosopher]

Two squares on a rebar grid.

Its not noticeable in use, but it sure showed up when I was putting levelling compound down.

The hot spots you can feel now are under the sofa :-)

[John Stumbles]

I notice the hot spots in our kitchen floor if I'm walking in bare feet. Otherwise it just tends to feel comfortable in there most of the time, unless it's really brass monkeys outside.