Underfloor heating

FaceHead

Hi. 

I'm going to have a kitchen fitted in an 18msq space in 8 or so weeks time. I'm considering water underfloor heating. I was thinking about doing most of it myself - I'm quite handy with tiling and electrics, but have never been that good with plumbing. 

The builder doing the extension and kitchen is expecting to fit a radiator, so I thought I might ask if I laid out the mats and pipes, he could connect up the motor/manifold bit instead of fitting the radiator.

Some questions: 

1. It looks like I can pick up what i need for about £700 (insulation boards, adhesive/primer, the heating pipe, manifold/motor and thermostat). Am i missing anything big?

2. Does it go under my kitchen units or do I fit it and tile after the kitchen is fitted? I'm really tight for ceiling height on the kitchen units, so I'd prefer to put the kitchen units on the concrete floor, and then put heating and tiles around them. In that case, will it make getting the appliances out impossible? And will if look wierd as the tiles will then be a long way up the plinths. 

3. Any brand recommendations?

Thanks for any advice or experinces people want to share,

ComicGeek

What are you proposing that the pipe sits in? Normally that would be a routed chipboard (or similar) for a dry system, or screed poured over. Both adds significant height to the existing floor if you're not digging down to compensate, plus your tiles. You have to think about floor levels across any door thresholds as well.

You wouldn't run the heating pipe under the kitchen units as they don't cope well with the trapped heat, but the floor level should be the same otherwise you won't be able to get appliances in/out.

Kitchens are difficult to heat with underfloor heating, as once you remove all of the area under the cabinets you're not left with much area for the heating pipe. You don't want to do all that work and find you can't get enough heat from it - get some proper heat loss calculations undertaken.

In terms of brands, look at Robbens first as they have good info on their website and good technical support - https://www.underfloorheating.co.uk/

And I guarantee that the builder won't see this as comparable to fitting a radiator, as it will affect a lot of their sequencing - the whole of the floor works will need to be complete before they can start fitting the kitchen.

You're probably looking at underfloor heating because the tiles will be cold - simpler to just change the floor finish to something less cold.

daveyjp

Well worth doing, but far more involved than simply deciding to have UFH instead of a radiator.  As above prep is required.

If you have a suspended timber floor it needs removing then a sub base, damp proof membrane, mats, pipework and screed need installing.

If you have a solid floor it will need digging out.

fenwick458

theres 2 different ways to do wet UFH

1st one would be how it's built in a new build, you have to break up and remove the concrete floor, and then remove another 150mm which will normally be hardcore. then get a 100mm slab poured, then lay down visqueen, 100mm celotex and insulation around the perimeter, more visqueen, and then clip the pipes onto the top. and then get the finished screed put on top of that, 65mm thick but can be thinner or thicker lots of options. this method all the materials are cheap, UFH pipe is dirt cheap, insulation is never cheap but at least you are getting a lot of it in there, it'll help with running costs

that does not sound like something you can DIY if you are having to ask the question

so there are other kits designed to go on top of the floor and only raise it up 50mm or so, but you'll loose headroom, and have to figure out what to do with the steps in/out of the room and doors. these kits cost a lot more that the first method, and as there is no physics defying technology yet the insulation is thinner so it's not as economical. also heats up and cools down very fast

also the argument about whether or not you should run the heating pipes under the kitchen units, I bet theres someone here who will disagree but I say just do the full floor. I have a 600mm dead zone on the back wall of my kitchen and when I stand at the sink in winter I get cold feet, theres a 300mm strip that is only 2 degrees cooler, but it's enough to notice and is annoying.
I also have another part of the kitchen cupboards that has the heating pipes underneath it (I did this as at the floor design stage I didn't know what to do with the kitchen plan) and if I put food in that cupboard, surprise surprise it doesn't cook itself or go off! this is one of the stupid reasons why people are scared of putting the pipes under a cupboard. 
last xmas I got 2 crates of beer delivered, left one crate on the kitchen floor for a few days and put other crate into one of those cupboards. a few days later decided to have one later on that day and went to put some in the fridge; the ones on the floor were above 20 degrees and I realised my mistake, so got a few out of the cupboard and they were still cool. so the fact that theres an air gap between the floor and the cupboard bottom is enough to stop the heat transferring through to the food

FaceHead

Thanks for the thoughts so far.

I watched the prowarm installation video, where you stick down mats and then you slot the heating pipe into routing in the mats. I saw a kit on offer for £600, and I think you need a c.£100 pump too.

Installing this feels entirely do-able to me, but breaking up/pouring concrete etc seems like a bit much. 

With the adhesive and the mat this option does probably raise the floor by c.50mm as Fenwick says - I'm ok with that where you stand in the kitchen, but not under the units, as then the full height units won't fit once the floor is raised

Part of me thinks that this a a 5-10 year home, so locking the appliances in place won't be my problem when a new e.g. dishwasher is needed in 10 years. Or it's have a bit of a chilly kitchen in what is again, not a forever home. 

ComicGeek said:

You're probably looking at underfloor heating because the tiles will be cold - simpler to just change the floor finish to something less cold.

True, and a realistic option, but I'm still holding out hope for the practicality of warmth and the floor finish I want. 

grumbler

FaceHead said:

With the adhesive and the mat this option does probably raise the floor by c.50mm as Fenwick says - I'm ok with that where you stand in the kitchen, but not under the units, as then the full height units won't fit once the floor is raised

Part of me thinks that this a a 5-10 year home, so locking the appliances in place won't be my problem when a new e.g. dishwasher is needed in 10 years.

IMHO, it's a botch. All appliances have to be easy to remove, replace, repair.

Jeepers_Creepers

FaceHead said:

Part of me thinks that this a a 5-10 year home, so locking the appliances in place won't be my problem when a new e.g. dishwasher is needed in 10 years. Or it's have a bit of a chilly kitchen in what is again, not a forever home. 

It'll be your problem if the buyer expects you remove all your 10-year old appliances to make way for their spanking new ones. What are you going to rip up - the floor or the worktops?

"With the adhesive and the mat this option does probably raise the floor by c.50mm as Fenwick says - I'm ok with that where you stand in the kitchen, but not under the units, as then the full height units won't fit once the floor is raised"

Why won't your full-height units (larder? tall oven housing?) fit if you raise the floor by 50mm? The tallest units tend to be around 1970 high, so adding 50mm to this would only make it 2020mm. If that'll make it 'not fit', then you must have very low ceilings, in which case raising the floor even by a gnat's crochet would be a silly thing to do.

UFH is great, but really comes into its own in particular areas of the house; sitting rooms, where its gentle and even way of heating is very pleasant, and bathrooms where you tend to be bare-footed.

Kitchens? Very much a luxury, I'd say, and hard to justify unless done from the off. Whatever floor finish you were after, you can almost certainly get it in a 'warmer' material. To lose 50mm height is a biggie - you have all sorts of threshold and doorway issues to take care of, and to entertain doing this for only part of the kitchen is, well, nuts.

TELLIT01

FaceHead said:

With the adhesive and the mat this option does probably raise the floor by c.50mm as Fenwick says - I'm ok with that where you stand in the kitchen, but not under the units, as then the full height units won't fit once the floor is raised

You are in effect lowering the worktop height by 50mm which will make it an awkward height as most people are used to standard construction.  Also you will not be able to move and free standing white goods such as fridge, washing machine, dishwasher.  You really do need to rethink this.

Rosa_Damascena

This sounds like there might be unintended consequences that will return when it comes to selling. Why not get kick heaters / a few strategically placed Handy Heaters as an alternative?

If you're determined to do this then re-do the whole floor to match your plans (no point heating under units), lay flooring across the whole and then fit the units on top. It will mean no kitchen for a few weeks and a fair bit of hassle.