Underfloor heating dilemma

[SW3103]

Hi,

We’re currently in the middle of extending our house, and will be knocking through our existing kitchen wall into the dining room to make one big kitchen. We want this entire area to have underfloor heating, but after consulting with some electricians and plumbers, we don’t know which route to take.

The area is about 17m2, with about 70% of it being traditional floorboards, and the rest concrete. We will be tiling the entire floor, and will be installing a new Vaillant combi-boiler (having a water tank is not an option).

We initially wanted to go with a wet system, believing them to be more effective and cheaper to run. But from what I have read, this could work out quite costly and complicated to install with floorboards. This then led us to an idea of knocking down the walls into the floor, and building up with concrete to match the new extension. We were then told that even if we did that, a combi-boiler wouldn’t be good enough to run a wet system.

So that leaves us with electric. I have been told by a sparky friend that he installed a mat system in a bigger house than ours which worked really well. But my biggest concern is that even though the installation costs would be cheaper, wouldn’t it cost a lot to run? Even with the price of gas climbing as it is today, I would still imagine that it is the cheaper option. I’ve also read that you need at least 50mm of insulation, which either means dropping or building up the floor an extra 50mm.

Opinions please.

Thanks

 

[Agile]

You do seem to be embarking on a lot of work without proper prior planning or even professional advice.

I cannot write a text book for you but I can make some bullet points.

All UFH needs a MINIMUM of 50mm of insulation underneath!

A combi boiler can run a proper UFH system ( What idiot said otherwise? )

Gas heating is about 25% of the cost of electric heating.

The electrician is biased because he can only install electric systems.

Tony

 

[SW3103]

Thanks for your points.

It was actually the plumber who first suggested I go for electric (and suggested the boiler wouldn’t be suitable). But I suspect he was biased because he said that programming the boiler for UFH would be very complicated.

Even though the outlay and disruption for concreting the floors and installing a wet system will be greater, I still think this may be the way to go in the log term.

 

[picasso]

might be an idea to get yourself another plumber

 

[BarryCambs]

We are running an underfloor 30m zone quite happily from a vaillant ectoec combi boiler, so not sure why that would be a problem.

Most of the floor is screed and works very well. there is an old section of suspended floor, but this takes longer to warm up. 100mm of insulation under it all.

 

[SW3103]

Can I ask what model Vaillant you have? We are looking at the 837.

Was there anything special or tricky that needed to be done to the boiler for it to run your UFH?

 

[simond]

Seriously, if you have been told that there is anything dodgy about connecting UFH to an ecoTEC by a heating installer, you need to look elsewhere.

Condensing boilers work best with UFH. OK, its more expensive than rads to put in but it delivers a good performance from an aesthetic, comfort and running cost perpective.

 

[BarryCambs]

It's an ecotec 831 about 3 years old. Radiator circuit is controled by one 2 port valve and underfloor by a second. The underfloor mixer is john guest and works really well. eventually, it will be controlled by vaillant controls (vrc430, vr61 and vr81) but at the moment, its on 2 room thermostats while the wiring is finished. any simple 2 zone controller would do the job.