UFH - Gas or Electric?

[Walshie]

HI - I'd appreciate some advice please.

A new rear extension - about 5.5m x 6.5m - which will have two walls predominantly glass and will be a kitchen dining / sitting area.

I want to keep the walls free and so UFH seems like a good option. 

Currently have an efficient gas boiler, new in last 12 months which has capacity. Rest of house is heated via radiators.

 

New extension will have a new slab and will be insulated etc. The build will include solar PV and a battery.

 

A two part question:

• Is it more effective to have a wet or dry UFH set-up.
• Is it more efficient to heat the UFH on gas or electricity?

 

I'm leaning towards dry / electric  - quicker to respond, advantage of solar / battery etc - but would appreciate any thoughts from you knowledgeable folks!

 

Thanks for your help,

W

 

 

[JohnMo]

  On 07/11/2024 at 12:09, Walshie said:

The build will include solar PV and a battery.

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When you need heat it unlikely the PV will produce much, especially in winter.

 

Gas will cost you 5p per kWh, electric 25p.  Even on the best tariff electric will still cost you more, it will also deplete a battery quickly.

 

  On 07/11/2024 at 12:09, Walshie said:

two part question:

• Is it more effective to have a wet or dry UFH set-up.
• Is it more efficient to heat the UFH on gas or electricity?

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Effective depends on what criteria you apply, if you just want warm feet quickly electric, if you need to heat the room either.

Efficient both the same really. Unless you consider cost to run - Cost gas about a 1/5th the price of standard rate electric.

[nod]

With electric nearly four times the price of gas It’s a no brainer 

[SteamyTea]

  On 07/11/2024 at 12:09, Walshie said:

which will have two walls predominantly glass

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Have you thought about cooling, A/C units (A2AHP) can heat as well, and are usually cheaper than gas to run.

Edited November 7, 2024 by SteamyTea

[Thorfun]

also, won't the gas boiler already be running to heat the rest of the house so adding a bit of wet ufh to the boiler won't make much of a difference, right? not sure why you're even considering electric tbh.

[Alan Ambrose]

For expense, probably gas unless you have lots of insulation underfloor. Some on here, add both, so that they can have pampered toes when it's a bit cool but not warm enough to have the boiler running.

[nod]

  On 07/11/2024 at 14:07, Thorfun said:

also, won't the gas boiler already be running to heat the rest of the house so adding a bit of wet ufh to the boiler won't make much of a difference, right? not sure why you're even considering electric tbh.

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Exactly It Will hardly be noticed on the monthly bill