Gas underfloor heating cost

[nomoneytreehere]

We are just coming to the end of a big build.

We have had wet underfloor heating put in downstairs and the builders have just started running it on low. We sre still not in the house and its not on all the time. We have a boiler and a big megaflo tank system.

According to my smart meter on one day last week i spent £22 on gas. Standing charge about 50p. Please god tell me this isn't right. Its not even on full and we haven't switched the hot water on yet. I know the price of energy has gone up but this is ridiculous.

That sounds really high. Is your house very large or poorly insulated? Our underfloor heating cost the same or less to run as the radiators it replaced. What was your heating bill before?

Its hard to know as energy prices have gone up so much but previously we were paying £150pm for both gas and electricity.

The underfloor is over a large area (100sqm) but only 60sqm is turned on so far.

I need to speak to the plumbers i think.

The area with the ufh is really well insulated.

It is most likely as heating from very cold and build drying out. We have UFH of about 60m2...is definitely very efficient with traditional in rest of the house. Last week has in a day was £22 on a sat with the main house being off between 9 and 3 but UFH in all day.

Once it has been used for a month regularly, you will find periods it doesn't come on as it will retain heat if well insulated. Be aware thought it takes time to heat up but once hot retains. Ie ours switches off at 6pm and is warm all night, but takes hours to get to temp in a morning

perhaps they’ve put it on at a very high temperature? Or it’s very cold where you are? With current gas prices it’s costing me about £7 a day to heat the house but that’s only to average 18/19c and it’s currently 8c
outside.

I think probably due to heating from cold. If they have ripped up the entire floor and have been moving materials in from outside they may have let the house get down to near outside temperatures.

If I let my house get down to 5 degrees C I reckon it would take 10-15 quids worth of gas to get it back to temperature, and its not even a big house.

Hi OP - have you moved in yet and has the running cost dropped?
We are at the point of needing to decide whether to allow for underfloor heating on our foundations and I am in two minds - more so after seeing this thread.

If the system is well specced for the building it should be as efficient (or more) to run as any other system which heats your space.
Things that can make an ufh system less efficient are

• Badly positioned thermostat making the heating demanded greater than it needs to be
• Badly specced pipework, so pipe capacity (spacing and lay out) under specced for the heat requirements making the boiler have to work harder
• Unsuitable floor covering not allowing the heat generated to transmit to the space you want to be warm
• badly insulated floor slab meaning heat is lost downwards to the ground.
• Floor structure losing heat to the outside too easily (floor slab conducting heat to the outside easily thus losing that heat which should go to the inside). Though your building envelope might be well insulated you might have cold bridging round the floor slab.
• if these aren't true, then it's probably just the excess demand from the standing start from cold.

We have wet underfloor heating and a scuba tank. The heating works so well it keeps the house warm but isn’t actually on for most of the day. We have hard floors which I think helps. Ours is very reasonable to run.

It will be starting from a very low temperature, the house will be drying out from building works.
Once temperature is settled costs will reduce.

So, its not as bad as it was but we are running at around £15-20 a day on gas. Its warm but i wouldn't say hot - we are all wearing jumpers.

The problem, i think, is that as it is a large house, we have a big boiler.

We only had the heating on for 2hr 50 minutes altogether yesterday and we appear to have used 133kwh of energy in just that time. Radiators are turned off alltogeher in a number of rooms as we are still mid renovation. The hot water was on for under an hour.

I suspect for smaller well insulated houses with appropriately sized boilers its great.

It will be expensive until the slab and everything around it as dried out and warmed up. Our underfloor heating is actually really cheap (I checked last week) compared to the radiators in the rest of the house, and such a nice heat too.

We should be well past that. We have been living in the house since mid december. Roll on spring (if i'm not bankrupt by then)!

@CleopatrasBeautifulNose i'm really interested about what you say about the cold bridging. It is cold around our bifolds. Is there anythjng that can be done?

When you say 133 kWh do you mean gas and electric or just gas ?

Is this underfloor heating alone or with radiators as well ?

What is the kW rating of your boiler and is it compatible with your gas usage ?

For example a 24 kW boiler can use 24 kW of gas per hour max - usually its a lot less.

There is a fairly common fault where they mix the gas units up on the meter. This increases your gas bill by x2.8. So although I think £7 a day sounds a bit cheap, its probably a lot more compatible with 3 hours worth of heating.

I’d say your prices are about right, sounds like you have a big house, my brother has a large house and says he can easily spend £25 a day on heating.

I read on one forum that a guy with a old listed ( large ) house spent £1500 on heating in November alone , that’s 50 a day !!!!!!

We seems to have a very similar house and extension (large) with UFH. During Dec and jan, the UFH was pumping constantly to keep warm. Costing roughly £1 an hour when on. It goes off at 6pm at night as the heat retains.