Retrofitting Underfloor Heating

CantThinkOfANam

Hi all,

We bought a new built house in 2019 which is fitted with a gas boiler, rads downstairs and upstairs. It has a BER of A3.

Herself wants to change the floorboards downstairs and this got me thinking about the possibility of fitting underfloor heating downstairs.

Is it possible/feasible to run underfloor heating with a gas boiler or should I be looking at getting a heat pump installed (possible grant?).

Would appreciate any help or guidance before I get a technical advisor.

Thanks very much.

wandererz

Have you considered electric underfloor heating?

Easy enough to install.

Citizen Six

I wouldn't be bothered with that hassle and expense on a five year old house.

CantThinkOfANam

No, I have heard of it but haven’t done any research.

CantThinkOfANam

Regardless of the age of the house it is a nice comfort to have.

Bungusbeefcake

I run UFH on an oil boiler, it runs fine. I expect it would be a significant remodel to install it, you would have to either remove the existing subfloor for all downstairs or raise all the floors by installing it on top of the current subfloor, and then plumb the UFH system, ensuring there's a significant space to install all the pumps, controllers, manifolds and keep it out of sight.

I like the UFH, feels great on the feet. How much are you thinking it'll cost you, that's the question and if it's worth the significant remodel and cost.

wandererz

Have a look at this.

I installed this several years ago when I installed wood flooring.

Installed it myself and then got an electrician to connect it and app controlled/alexa enabled thermostat.

https://youtu.be/lllHaV3CxnI?si=0D2NnggC_yQsuedf

Citizen Six

https://www.boards.ie/discussion/comment/121818944#Comment_121818944

Well if you have the money then go for it.

I’m just someone who wouldn’t like the stress of a retrofit like that. Grand if it was a renovation, but on a new house I personally wouldn't be into it.

wandererz

https://www.boards.ie/discussion/comment/121824884#Comment_121824884

To each, ones own.

My neighbours come over on movie nights and sit on the floor rather than the couches because of the warmth.

It may cost quite a bit for the old style underfloor heating but with the electric that I linked above it does not cost much when replacing flooring.

If everything is perfectly warm then simply just don't turn it on. If not, just ask Alexa or Google to set the lounge to 23 degrees celcius. (note, the temperature below is always higher than the temperature in the room).

Citizen Six

https://www.boards.ie/discussion/comment/121826522#Comment_121826522

System look interesting alright. Does it cost much more to run compared to gas heating? I would have wired similar systems back in the day, for bathrooms, for warm floors when people were barefoot.

Padre_Pio

https://www.boards.ie/discussion/comment/121828236#Comment_121828236

Cost of electricity vs cost of gas.

Citizen Six

https://www.boards.ie/discussion/comment/121828272#Comment_121828272

About 20% more expensive.

Water John

Problem is insulation. You're heating the concrete floor underneath. UFH with water has 150mm insulation with 25mm around the edge and no bridging.

wandererz

https://www.boards.ie/discussion/comment/121829345#Comment_121829345

Care to explain that to the layman?

Water John

The heating from the electrical strip goes two ways down and up. The concrete underneath has a higher conductivity than the timber or air about. The thin insulation layer is almost irrelevant. So the majority of the heat goes into a concrete floor which is also connected to the walls and sub floor, very inefficient.

That heating system would work on a first floor that's of timber construction.

wandererz

https://www.boards.ie/discussion/comment/121829474#Comment_121829474

And what about the other side of the explanation?

Citizen Six

https://www.boards.ie/discussion/comment/121829474#Comment_121829474

Well it would work on a ground floor concrete floor, but be expensive and inefficient.

Padre_Pio

https://www.boards.ie/discussion/comment/121828390#Comment_121828390

Really? I think electricity is far more expensive than gas heating.

Underfloor is generally run from gas boilers, or heat pumps in new homes. I would have though it was too expensive to run electric underfloor for an entire ground floor, unless you're getting fantastic night rates and you're using the concrete as a storage heater.

Citizen Six

https://www.boards.ie/discussion/comment/121829610#Comment_121829610

So you think it's far more than 20%?

Padre_Pio

I would have thought it was 50-100% more expensive, depending on the time of day the heating is on, and heating an entire downstairs it will be on for a good few hours each day.

DataDude

https://www.boards.ie/discussion/comment/121829691#Comment_121829691

Electricity is hovering around 3x gas prices on a typical 24 hour rate. A good night rate might be 1-1.5x more, but then the day rate will be more than 3x.

It would be ferociously expensive to heat most houses with electricity unless you have a heat pump.

Citizen Six

https://www.boards.ie/discussion/comment/121830049#Comment_121830049

I think we need @wandererz to give us some guidelines on his heating costs.

Pataman

I am currently retrofitting my sons house with these: https://www.amazon.de/-/en/Underfloor-Heating-Installation-Drywall-Transfer/dp/B095194DK7

I have only 1 room done so far, but it seems very effective. Very quick to react, quick to heat up. Its run off oil boiler

I have traditional underfloor heating in my house with 75mm wet screed.

My sons would be my preference.

DataDude

https://www.boards.ie/discussion/comment/121830340#Comment_121830340

The maths is pretty factual. A KWh of energy is a kWh of energy regardless of its means of production.

A KWh of gas these days is c 8-9cent

A KWh of electricity (on a non smart rate) is c 28-32cent

Electric underfloor will be c. 3x the cost to run vs gas without a heat pump or clever use of a smart meter.

Depending on size of house, the level of insulation and frequency of use, this might not matter. 3x a small number might still be a small number.

One persons experience won’t tell you much more than the above.

Kildare787

Well did you go for it in the end? Similar situation, A3 gas boiler, house 8 years old. Wouldn't go near electric one as too expensive to run. Looking at water UFH retrofit. Hard to get any information from anyone who has actually done it. We had air to water in our last home. The heated floors make the place so much cosier it's unbelievable. Would love it back.

CantThinkOfANam

No, I spoke to someone in the trade that done my Dad’s house and he said I would be mad to do. Too much work and expense.

Fully agree though, UFH is soo cosy.