Retrofit Underfloor Heating

Chickereeeee

I will be having an extension built to my 1920's detached house, and am uncertain about what heating to use.

Specifically, there are a number of retrofit wet UFH systems available, that are laid in insulating boards over suspended wooden floors. Has anybody any experience with these, and whether they work efficiently? I could live with it being 25mm thick or so. I imagine the extension could have  a 'normal' wet UFH installation, but could I combine this with the retrofit system? 

The rest of the house has traditional radiators, and I am thinking I could leave them in place in case the retrofit system is not up to the job, and they would be the only source of heating upstairs in the bedrooms. I am a bit concerned that the existing piping under the floorboards would become inaccessible, but otherwise would this set-up work, and has anybody any experience?

(Currentl gas boiler, but I guess ASHP at some stage in the future,..).

macman

Why not just extend the rads into the extension, if the boiler has capacity?
Not clear if this is a single or double floor extension?

Rosa_Damascena

I've had my wUFH system for a year and it's works fine. 

I switched it off entirely in January mind, because my energy bills were going crazy. It was literally like burning money.

ComicGeek

1920s detached house - so unlikely to be very well insulated or reasonably air tight.

So you would be very unlikely to get enough heat from UFH to heat the existing house, regardless of the system used. 

Rosa_Damascena

ComicGeek said:

1920s detached house - so unlikely to be very well insulated or reasonably air tight.

So you would be very unlikely to get enough heat from UFH to heat the existing house, regardless of the system used. 

Maybe I should have added that I'd had insulation added to my external walls (1920s built with no cavity) before having them rendered.

Doozergirl

ComicGeek said:

1920s detached house - so unlikely to be very well insulated or reasonably air tight.

So you would be very unlikely to get enough heat from UFH to heat the existing house, regardless of the system used. 

Agreed. 

You can't run low temperature heating without your house being capable
of holding onto that heat. 

 

Fabric first.  

Chickereeeee

macman said:

Why not just extend the rads into the extension, if the boiler has capacity?
Not clear if this is a single or double floor extension?

Double. And I am thinking about future ashp

Chickereeeee

Doozergirl said:

ComicGeek said:

1920s detached house - so unlikely to be very well insulated or reasonably air tight.

So you would be very unlikely to get enough heat from UFH to heat the existing house, regardless of the system used. 

Agreed. 

You can't run low temperature heating without your house being capable
of holding onto that heat. 

 

Fabric first.  

Actually the house is pretty good wrt draughts. Double glazed, good loft insulation. The extension would be built to modern standards, of  course, which would mean a couple of outside walls would be 'upgraded'. With a bit of internal insulation, half the house would be to modern insulation standards.The remainder  could have additional insulation added later.

But a large proportion of UK housing stock is of a similar build (or worse), and if ASHP are the only option in the near future, what's going to happen? Knock them all down and rebuild?

Also, the common idea with ASHP, As I understand it, is that you could use an existing system, but with larger radiators. Surely existing radiators + wUFH would have a similar output?

FreeBear

Rosa_Damascena said:

ComicGeek said:

1920s detached house - so unlikely to be very well insulated or reasonably air tight.

So you would be very unlikely to get enough heat from UFH to heat the existing house, regardless of the system used. 

Maybe I should have added that I'd had insulation added to my external walls (1920s built with no cavity) before having them rendered.

If done recently, and you rendered more than 25% of the envelope, building regs would have required you to add insulation. But there are cop outs if it is not technically possible or the simple pay back is greater than 15 years. In which case, Building Control will often accept other energy saving measures.

https://www.planningportal.co.uk/permission/common-projects/external-walls/building-regulations

https://www.planningportal.co.uk/permission/common-projects/insulation/building-regulations-solid-wall

Rosa_Damascena

FreeBear said:

Rosa_Damascena said:

ComicGeek said:

1920s detached house - so unlikely to be very well insulated or reasonably air tight.

So you would be very unlikely to get enough heat from UFH to heat the existing house, regardless of the system used. 

Maybe I should have added that I'd had insulation added to my external walls (1920s built with no cavity) before having them rendered.

If done recently, and you rendered more than 25% of the envelope, building regs would have required you to add insulation. But there are cop outs if it is not technically possible or the simple pay back is greater than 15 years. In which case, Building Control will often accept other energy saving measures.

https://www.planningportal.co.uk/permission/common-projects/external-walls/building-regulations

https://www.planningportal.co.uk/permission/common-projects/insulation/building-regulations-solid-wall

The rendering was done 3 years ago, wUFH last year at the same time as the new build (cavity insulation). It's insulated up to the eyeballs yet it's still freezing in the winter.

Current temperature -  going by my newly revitalised barometer - is 26°C. 

Gavin83

Rosa_Damascena said:

I've had my wUFH system for a year and it's works fine. 

I switched it off entirely in January mind, because my energy bills were going crazy. It was literally like burning money.

I always thought one of the benefits of wUFH was it's cost compared to traditional gas central heating.