Underfloor heating or not? Cost?

psychhead

Hi all!
So.. Finally bought a house, a lot of renovation needed and budget is tight to put it mildly. My query is around the heating, we are thinkin of pulling up the floors to lay insulation as its an old house (1960s/70s) and so there are vents in the underlay. So consequently we are debating whether or not to put down underfloor heating as opposed to rads, but cost is the issue. Any idea of a price for a 1200 sq foot bungalow? Or if it is worth the extra?
Also, as the price of oil/gas are going up, which should we be going for? And besides solar panels is there a relatively cheap option for something energy efficient that would help keep bills down?

Thanks in advance!! All advice welcomed as we are completely new to this renovation game!

BryanF

Concrete floor 10g - with below .1 u-value
External wall insulation to foundation and raised roof/ eaves insulation overlap 20g - with .15 u-value or better
New windows 10 to 20g below 1wm2k

If your not doing the above forget it

psychhead

There are double glazed windows already in the house, I think they were put in circa 1995. Would they be adequate? We are also planning on pumping insulation into the external walls and a lot of insulation into the attic. Afraid I'm a bit lost as to u values, but would that be decent enough? Thanks!

Outkast_IRE

As an plumber who installs such systems BryanF has hit the nail on the head.

Underfloor is a totally different way to heat your home, the idea is not to blast some heat when you need it (as you do with rads)

The idea is to create and maintain a comfortable ambiant room temperature pretty much all the time. The only way to do this cost effectively is excellent insulation, good airtightness as draughts wreck this ambiant temperature.

And lastly design considerations are much more important with underfloor, things like draught lobby at the front door become important.

Also many users of underfloor dont understand the system so they open windows to dump heat after setting the stats too high etc.


Also underfloor to work its best needs to have a lot of zones with good accurate thermostats in each zone.

Unless you like the sound of all the above in a retrofit home , then opt for rads.

Underfloor in a good spec newbuild is much easier to get right.

Outkast_IRE

psychhead wrote: »

There are double glazed windows already in the house, I think they were put in circa 1995. Would they be adequate? We are also planning on pumping insulation into the external walls and a lot of insulation into the attic. Afraid I'm a bit lost as to u values, but would that be decent enough? Thanks!

Double glazing around 1995 , im not the uvalue expert but i dont think they would hold up well against modern windows specifically designed for low u values.

Also pumping the cavity is fine, but unless theres a very wide cavity i dont think it will be enough .

If you really want underfloor to work well time to open the purse strings and pay someone to create a plan for you to achieve what we have said .

Do a quick search around these forums about underfloor , i post quite alot on the topic as im an advocate of it when used in the right situation and installed correctly. But there are loads of people on here posting about how many thousands of euros of oil they spend each year heating their poorly insulated homes with underfloor.

BryanF

psychhead wrote: »

There are double glazed windows already in the house, I think they were put in circa 1995. Would they be adequate? We are also planning on pumping insulation into the external walls and a lot of insulation into the attic. Afraid I'm a bit lost as to u values, but would that be decent enough? Thanks!

windows: not really up to modern standards, wall: not really up to modern standards, but ok apart from the likely-hood of thermal bridges and your new floor insulation would need to be circa 200mm with as much as possible at the perimeter edges maybe upwards of 50mm. I should have added that an UFH heating needs to be discussed in the context of ventilation strategy and air-tightness.

in the last few months I've been asked to survey several homes where UFH (often run of gas!) was installed, these homes were no more than 15 years old and had mental heating bills. imho put in rads or at least spend substantial money doing up the building fabric first

psychhead

Cheers for all the input guys! Have decided to stick with rads following yer advice and some other research I did. We are gona just insulate the hell outa the place and save the underfloor heating for when we eventually build down the line. Thanks again!