Underfloor heating ! Dont install it !!!

[mattysupra]

Im going to ask you all to think twice before going ahead and installing under floor heating. I have come across a big problem today which looks like it will leave me £8000 out of pocket! And i haven't even attempted to fit any flooring yet!

So my reasons for not having underfloor heating-
Electric type-

Can be dangerous as most are 240v, if any mistakes or damage happen with fitting. (Nothing like getting out of a bath and treading onto a wet floor that has mains voltage 3mm under your feet or maybe your young child that sticks a drawing pin or some thing similar through your lounge carpet into the 240v wires below)

It is also a health risk. Your kitchen floor sits there growing bacteria at a massive rate compared to normal situation.

Another health problem is that it can dry your skin and dust mites will love your warm carpet.

It can also cause structural problems. Over drying concrete and screed bases which makes them weak. Also cause levelling compounds to shear from the surface.

Your carpets will also dry out much faster causing delamination of the backing of the carpet. Can also cause your carpets to ruck after new install. Not a fitting error but the heat making the carpet grow.

Also can cause carpets to wear much faster.

Dont get thinking you can have that lovely wooden floor fitted you always wanted! Can destroy these to. I will leave this bit to some one else on the forum to make there own comments ( you know , just show its not me being the only person in the trade moaning here! ) woody help

You also cant just turn the heating off. You have to lower the temperature slowly other wise damage can been caused. Same for heating it back up to! Just what you want on a red hot day and your heating is stuck on. Or maybe your cold when you get home and turn the heat on Guess what, You going to be sat there a few hours before you will feel the heat!



If there is any one else there out there in the trade that has more comments could you please post to help inform the public how rubbish and how much trouble under floor heating is. Thanks matt.

 

[DenzB]

Some points to note:
1. Electric systems are perfectly safe if installed properly.
2. A wet system is more efficient/cheaper to run than electric.
3. Underfloor heating is the most effective method of space heating.
4. You would have to be particularly dumb to put carpet over a heated floor, it's the equivalent of covering radiators with duvets.

 

[freddiemercurystwin]

I know of several projects both domestic and commercial where its been very successful, installations in insulation and within screeds, under carpet, tiling and wood. Failing to plan is planning to fail!

 

[Softus]

Im going to ask you all to think twice before going ahead and installing under floor heating.

I've thought twice, and each time it seemed like an overall good idea.

 

[Deluks]

I have come across a big problem today which looks like it will leave me £8000 out of pocket!

Come on then, fill us in. A problem shared is an idiot mocked, erm er, I mean problem halved

 

[big-all]

Some points to note:
1. Electric systems are perfectly safe if installed properly.
2. A wet system is more efficient/cheaper to run than electric.
3. Underfloor heating is the most effective method of space heating.
4. You would have to be particularly dumb to put carpet over a heated floor, it's the equivalent of covering radiators with duvets.

heeellloo DenzB hows it going

point 3
could you please clarify how an underfloor system can be the most efficient !!!

you have burried elements with insulation above causing a time lag in heating and reduce efficiency
with a 1hr cycle for normal central heating to warm the room your underfloor must lag a good 30 mins behind so wasting energy

i would have though underfloor was only 50% as efficiant as the same heat source directly feeding into a room as theres no time lag or extra thermal losses where as the underfloor has extra heat loss into the floor underneath!!!

 

[Softus]

could you please clarify how an underfloor system can be the most efficient

He said more effective, not more efficient.

you have burried elements with insulation above causing a time lag in heating and reduce efficiency

A lag does not mean that it's less efficient. It means there's a lag.

with a 1hr cycle for normal central heating to warm the room your underfloor must lag a good 30 mins behind so wasting energy

A lag does not mean that it wastes energy. It means there's a lag.

i would have though underfloor was only 50% as efficiant as the same heat source directly feeding into a room as theres no time lag or extra thermal losses where as the underfloor has extra heat loss into the floor underneath!!!

Why? With underfloor heating the floor is insulated more effectively than otherwise.

 

[mattysupra]

Some points to note:
1. Electric systems are perfectly safe if installed properly.
2. A wet system is more efficient/cheaper to run than electric.
3. Underfloor heating is the most effective method of space heating.
4. You would have to be particularly dumb to put carpet over a heated floor, it's the equivalent of covering radiators with duvets.

1 Yes thats correct if installed correct. As i said.
2 Yes thats correct but im not talking about which system is cheaper to run! In fact the job i have been on had a problem that when all the rooms where turned it wanted to pull 120amps. The house only has 100amp supply. (bet thats cheap to run )
3 yes thats correct after the system has Heated up and the whole entire floor has heating cells installed. If only half or 3/4 of the room has it installed then no it isn't the most effective method.
4 Im seeing one or two underfloor heating jobs a week at the moment and i would say 90% of them have carpet installed over them. But most of these are the water system. The electric systems have gone mad in the last year and are the ones causing the most problems.

 

[mattysupra]

I have come across a big problem today which looks like it will leave me £8000 out of pocket!

Come on then, fill us in. A problem shared is an idiot mocked, erm er, I mean problem halved

Basically i have brought in stock which has been special order for a job having underfloor heating installed. These include special underlay and carpet with a specific tog rating as needed to get the new efficiency certificate. The site foreman has gone a head and installed this new mat system (electric) as instructed by the manufacturer. I have turned up to install flooring and there is un earthed 240v cables running to each heating mat. The mats are also 240v and are earthed but have to protection ( sunk in screed/what ever) to protect them from foot traffic, furniture etc. The problem is to the flooring trade is that you are not allowed to install over 240v cables unless correctly protected (under the floor etc) So what do i do ?? They cant be sunk into the floor in any way or sreeded over as they big sections of tin foil basically and not the normall mesh. The manufacturer says they have been installed correctly but the 'national institute of carpet and floor layers' and the FITA training college who do all teaching nvq, masters degrees etc say you cant install on it. Im stuck with 8 grand of stock that nobody wants any more!!!

 

[WoodYouLike]

Our thoughts on Underfloor Heating in general and in regards of wooden flooring.

General: against it for various reasons. UK is not really a country for efficient UFH use, basically for the main reason we are against it: customers miss-using the system i.e. treating it like it still is a conventional central heating with radiators (on-off-on-off). Remember the first week of August? (Or first weeks of April, when we did have Summer!) Hot weather followed by a steep drop in temperature - before your UFH is really heating your chilled house, weather has changed again.

Again, our main reason against it is not knowing (or not properly 'educated' by the companies that supply these systems - electric or wet) how to use an UFH correctly.

When installed and used correctly UFH can be a good heating system - efficient too, but also tends to dry out your house and skin rapidly - and various types of wooden flooring can be installed on it AS LONG AS YOU FOLLOW THE CORRECT PROCEDURES before, during and after installation.

But, we're not in favour of it, even if we carry a product that is guaranteed on UFH.

 

[WoodYouLike]

Besides this wonderful DIY-not forum we also follow the E-build forum.

On there is a category dedicated to UnderFloor Heating, problems, experiences, problem solving and other ideas.

Have a look there, various good and bad experiences from a lot of self-builders.

 

[mattysupra]

Thanks woody.
Anyway, after long talks with manufacturer today they have talked me through there fitting instructions that state i can fit carpet over the top of there heating system. !
Any carpet fitters out there?

The fitting instructions i have been given today are to use no underlay over the heating matting and to fit over the the un-earthed 240v cables ( Nice ). To fix the secondary backed carpet around the edges, use normal gripper and stretch fit without the underlay

So who thinks they have actually tested this system and have any idea of how to install a carpet! Your comments please

 

[mac391]

I like it!!

 

[mointainwalker]

@mattysupra

I'm not sure whether I should be saying that you are unwise for buying something you didn't understand or whether you are unwise for buying something without a firm order.

I'm also unsure how far your involvement in the whole business goes, but underlay on top of UFH is not very clever.

 

[lymmranger]

The problem Matty has is typical of the "poo" the flooring trade has to endure.
He will have had little input in his choice of materials - the contract will have specified them (probably right down to the colour)
Also a secondry backed carpet (specified not chosen remember) is designed to be fitted on underlay - fitting it without will result in rapid wear, heat will also effect it adversly - likely outcome Matty WILL get a complaint from the customer
Matty did the right thing. He did his research and realised that underfloor heating systems require a special low tog underlay. He then bought in this special underlay, costing a great deal more than standard underlay (and therefore unsaleable to anyone else - we have used it once in over 10,000 jobs)

....this is typical of Architects specifying "systems" they dont understand and cant be bothered to research properly and as always the last person on site carries the can

Hope you sort it (and get paid)