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Author Topic: Electric UFH anyone?  (Read 10869 times)
camillitech
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« on: March 17, 2014, 07:55:49 PM »

Now bear with me on this peeps,

I know it's frowned upon by most people with green leanings, who, on the whole rely on grid supplied power and I know Clockman is a great fan. However I generate my own, can't export it and have had lots to spare this winter. The house I live in at the moment is poorly insulated but has been kept pretty warm by excess power dumped to AC oil filled radiators and one 750w convector that has been left on since November.

We're building a new house to well beyond current regs and had planned wet UFH via a TS but I've been so impressed with our AC dumps this winter that I'm thinking electric UFH would be a far cheaper and simpler solution. Trouble is I can't really find a good word said about it on the net and quite a few "I installed EUFH 6,12,18 months ago, now it's failed how do I dig my floor up" Are there any good systems out there? what sort of cost per square meter for a 120m square bungalow?

Any thoughts chaps, bearing in mind that we're 'off grid' and the supply will be 100% renewable, it's reliability, durability and simplicity I'm after. On the face of it EUFH does seem a whole lot simpler and have less to wrong with it than a wet system.

Cheers, Paul
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clockmanFR
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« Reply #1 on: March 17, 2014, 08:22:21 PM »

Yes, I am a fan of electric underfloor heating, but remembr it will take up to 24 hours to get the room/floor up to temp.

Over the past 10 years or so I have been using Kilma matts and I always put them under tiles, but you will need flexable tile adhesive and 4 times the normal amount. For a 1.2kw matt I use about 5off 25 kg sacks of ahdesive.

http://www.screwfix.com/p/klima-underfloor-heating-mat-10-sq-m/45465

At first I bought the 1.5kw  big matts from Screwfix, now I just keep an eye on Kilma matts on fleebay.

Wickes matts are okay as well. But watch the wattage per sqm nothing under 150w.

Paul, I tend to do one matt per room, and I have master switches that I can switchover to different sizes of matt/room depending on how much the turbines and PV are dumping on my AC side. With each matt I fit a heat sensor and thermostat nothing complicated, just a manual type with relay inside.

Yes they are under tiles, and no, in ten years I have not had a failure, but even so I could just lift the tiles.

Trust this helps.

Pic shows the Library floor getting a matt, these tiles are 500mm by 500mm and the matt is 500mm wide so I just put the matt down and another row of tiles, but do work it out first so the in out cables come where you want them.




* PA080282aa.jpg (109.85 KB, 599x799 - viewed 1666 times.)
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camillitech
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« Reply #2 on: March 17, 2014, 08:45:04 PM »

Cheers CM,

I was looking at the Kilma system right enough, but thought that an 'in screed' system like this http://www.ambient-elec.co.uk/shop/floor-heating-inscreed-kits/23/?r=3; would be more durable and suited to our new build. Your idea of tiles and adhesive seems easier to repair though. I'm not so worried about the time to heat up the room, as hopefully or supply will be quite constant so we can open windows to cool down rather than turn on heating to warm up  fingers crossed!

Thanks, Paul
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'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 9kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
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« Reply #3 on: March 17, 2014, 08:58:07 PM »

I did try the loose cable system but gave up as the wire would not stay still where I put it, and the holding tape and glue supplied was a joke.

But, then my floor screeds are a bit rough and dusty.  faint
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camillitech
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« Reply #4 on: March 17, 2014, 09:03:10 PM »

I did try the loose cable system but gave up as the wire would not stay still where I put it, and the holding tape and glue supplied was a joke.

But, then my floor screeds are a bit rough and dusty.  faint

If your floor screeds are a bit rough and dusty I dread to think what mine would be like  Grin
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 9kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
ianh64
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« Reply #5 on: March 17, 2014, 09:17:51 PM »

Is UFH compatible with Optimmersion proportional power type devices? I can see that the element would work ok, but what about the thermostat/controller?

Another option with Optimmersion is to run it of an Optismart Switch ie on/off. I assume that 2-300W through one of those switches would be ok, but again, how do the controllers cope with being powered on/off. I briefly looked at the Wickes products that say they must be used in conjunction with thermostat/controller.

Ive got a small utility room that I'm about to improve and upgrade insulation and would probably take 1-2m2 of UF heating. Its adjacent to our unheated kitchen an thinking that if i could put a bit of heat into that room, it may prevent kitchen getting less cold.
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biff
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« Reply #6 on: March 17, 2014, 09:24:33 PM »

Paul,
      The expensive part of the UFCH is the controls,tanks and copper.You can buy a lot of heating pipe for 450.00.Staple it to the insulation and bring the tails into a little small room and clip the flow and return of each room to a piece of 4 x 1" timber about 4ft long. This means that you can go ahead and pour your screeds after you have charged the pipes(filled them with water) You do every room independant and take the tails back to this board which is screwed to a wall about 18" up off the floor.Label every pipe in pairs so no matter how long you have to wait to get the full kit to complete it it will be just a straightforward job.
                Now you can lay your floor and put Clockman type lecky heated floor under the tiles. Underfloor heating operates at a much lower temperature than a rad system,So if you have a 2kw 48volt dc immersion dump load,the heat will go right to where you need it. extrahappy
                                                                      Biff
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clockmanFR
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« Reply #7 on: March 17, 2014, 09:30:33 PM »

There are a lot of different controllers, but I stick to the simple manual type without the need for LCD turbo nutter b.astard display. As I found out, they fail, or I forget how to reset them.  Roll Eyes

In the winter I turn each thermostat right up and stop the cycling, in the summer I just do not turn the heating matts on or just select what i want.

Ian, get as much matt as you can in that small area, it does work okay but somehow never as well as in a bigger room.

Just remember to plan the room and keep stuff away from the tiles with a surface area of more than 40mm by 30mm, do not put carpets down, the floor gets mighty hot, and would probably burn the element wire out.  
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titan
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« Reply #8 on: March 18, 2014, 08:39:54 AM »

If you are putting in new floors I think a wet ufh system gives more flexibility and the ability  to use an alternative heat source sometime in the future. I good tiler I know will no longer install electric mats direct into the adhesive because when the mats fail the supply companies say the mats were badly installed and it is just hassle he can do without. He will install mats but only if he embeds the mat in self levelling compound first, he has tried just using a thicker adhesive bed but he thinks this is a better method. His clients can see the mat is covered and electrically tested before he starts tiling.
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camillitech
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« Reply #9 on: March 18, 2014, 09:00:15 AM »

If you are putting in new floors I think a wet ufh system gives more flexibility and the ability  to use an alternative heat source sometime in the future.

That was our original plan Titan but as we'll be totally electric anyway it seemed like a much cheaper option than the TS and wet UFH. I'm just concerned about the reliability really, I know pumps can fail on wet systems but I've never actually heard of pipes failing under a screed. On the other hand I've read of plenty of mat failures. However CM seems quite chuffed with his setup, decisions, decisions  facepalm
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 9kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
biff
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« Reply #10 on: March 18, 2014, 09:05:49 AM »

It would be kind of daft not to install the UFCH pipes Paul,
                                               Sometime in the future you might have a glut of electricity like you do now,sure you can use the mats but the UFCH gets the place toasty but still only using low temperature water.It could be possible to install a large waterheater store like we have in the hall downstairs which provided good background heat but also can dump the excess into the rads indirectly. The advantage of the wet system is that it can move a lot of heat quickly to where you want it and adjust to temperature settings quicker even though the floor remains cool.
          The mats are a brilliant idea but the water heater storage tank can actually act like a battery
                                                                              Biff
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Countrypaul
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« Reply #11 on: March 18, 2014, 09:13:08 AM »

I don't have EUFH and don't currently plan to, but have read this thread with interest.

I assume the mats are designed for 230/240v operation and that most people use them on mains electricity where the voltage is about 230/240. If they behave like light bulbs then the higher the voltage the more likely premature failure is, if the voltage is over 250 then bulbs (oven elements etc) tend to last alot shorter than expected (don't ask me how I know...). Conversely if the voltage is lower, then presumably the mats would last much longer and be altogether less likely to fail. If running off grid and having control over the voltage supplied would running them at say 200v give an advantage in lifetime and reduced likelyhood of failure? Obviously the power will be well down compared to 240V, but again that could easily be mitigated by using a larger mat or longer run time which doesn't sound like a problem for Paul.  I have no idea how the controls would cope with the lower voltage, but simple thermostats shouldn't have any problem.

Paul
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clockmanFR
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« Reply #12 on: March 18, 2014, 09:56:14 AM »

Yes my first matts were installed into a self levelling compound, but this method was soon discarded as it just created excess work and levelling problems.  fingers crossed!

As I say, the last 6 matts have been installed directly on to the concrete level floor screed that's on the insulation. At first I was weary of the element failing so developed my method for simplicity.
I stuck to good quality brands like Wickes and Kilma, and used plenty of flexible/heatable tile adhesive, put some on the concrete then bed the matt in,then more adhesive on top for the tile, but great care should be taken not to damage the heating element wire with your tile float.

At 45euros a 25kg sack for the special flexible tile adhesive just ensure you have enough.

Me thinks Titan, that the extra work and extra care is just to much for the average Tile installer, As they have to be a heating engineer and electrician all at the same time.

I think the heating element wire will fail if it is not allowed to dissipate its heat, as I said do not cover the tile.

" have no idea how the controls would cope with the lower voltage, but simple thermostats shouldn't have any problem"
As I said the simpler the better, mine are just that, and had no problems with my 200vac-220vc Eco,for the past 4 years.

My Philosophy keep it simple and robust and don't spend a fortune, if it doesn't work or fill you expectations, then you haven't lost a lot.



« Last Edit: March 18, 2014, 09:59:04 AM by clockmanFR » Logged

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chasfromnorfolk
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« Reply #13 on: March 18, 2014, 10:07:14 AM »

... had planned wet UFH via a TS but I've been so impressed with our AC dumps this winter that I'm thinking electric UFH would be a far cheaper and simpler solution... a 120m square bungalow

Any thoughts chaps, bearing in mind that we're 'off grid' and the supply will be 100% renewable, it's reliability, durability and simplicity I'm after. On the face of it EUFH does seem a whole lot simpler and have less to wrong with it than a wet system.

Cheers, Paul

Hi Paul, random thoughts, having some experience of both wet and dry:
I'd say they both have their merits... the cables we installed under the holiday cottage bathroom tiles don't have to heat the room - they get switched on a couple of hours ahead of use and I love the underfoot warmth. Mrs Chas, against prediction, doesn't bother. If I had my time again, I'd have put them under the wetroom tiles at home - there wasn't the depth to add pipes and screed and at that time I didn't 'trust' mats/cables.

In about 60m2 of newbuild at home I put 2 x 30m Speedfit 'wet kits' through one manifold linked to an Aztec 6kw boiler. It coped perfectly (so I'm guessing you need 12kw ish, for your 120m2, less if insulated really well?) but was dearer to run off the mains than a wood pellet boiler, so we switched to that after a couple of years when we got the choice. If I had plenty of off-grid power to burn, particularly in winter, then I'd go back to the Aztec.

I'm planning a dotage-house and have a couple of spare Aztecs that may yet see use...

Chas
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A.L.
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« Reply #14 on: March 18, 2014, 10:51:17 AM »

We're building a new house to well beyond current regs and had planned wet UFH via a TS but I've been so impressed with our AC dumps this winter that I'm thinking electric UFH would be a far cheaper and simpler solution.

You will still need a DHW cylinder, will it be sufficently cheaper to forego the flexibility wet UFH has in terms of heating source?

I think you need in-screed cable rather than mats

http://www.warmup.co.uk/uk/inscreed-underfloor-heating-prices.phtml

- if yes then I think circuit(s) totalling 3kw will be plenty and suitable for the various diversion controllers
« Last Edit: March 18, 2014, 10:55:25 AM by A.L. » Logged
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