replace storage heater with underfloor heating

This all makes a very interesting read! I might have to install new heating very soon, if the purchase of the house comes through. It's an old house and doesn't have any heating at the moment. It also needs to be rewired, etc. From reading this and other posts, is there such a thing as a condensing modulating combi boiler? I thought that would be the best thing to go with if the water pressure is sufficient. But reading about this UFH heating, would this be a good idea? I just want to run the heating as cost efficiently as possible, so any advice would be greatly appreciated. It's a small house, with two bedrooms and bathroom upstairs and an open-plan living/kitchen area downstairs. Will hopefully extend at some stage, but that's a while off.

Hi extopia,

the rads are never on the UFH room - there is no need, so the UFH is the main and only source of heat in the room. The rads are on in the adjoining rooms but we have them turned down compared to the rads in the front hall and the upstairs landing. The oil urner is timed to come on at 7am (after the UFH recharge). My guess is that heat goes from the UFH room into the others rather than the other way around. We experimented with the doors on the adjoining rooms opened and closed and with the UFH at lower settings when the doors were closed. The optium for our situation is with the doors open and the children walking on the tiles without us chasing them to have their slippers etc on.

To be honest we are totally surprised at how good the underfloor heating is but we were lucky (I wish I could claim it was due to our research) that the room is suited for it.

forgot to say that it is devi mats that i am going to install, not the cable type. Will these mats be sufficient as the only heat source in the kitchen.(17sm) Anyone have experience of these?

Re: electric UVH versus water UFH

Before deciding for the one or the other heating system ALL relevant numbers should be included in the calculation.
UpTheBanner’s calculation gives us the number of €25 per bill and the heated surface of 44m2. These numbers on their own are not enough to be decisive.
The most important question is: How high is the heating energy DEMAND for the rooms that are to be heated?
With most existing buildings this number simply does not exist, neither in the form of a comprehensive calculation sheet based on assumptions nor in the form of a (measured) protocol.
So in this case all we only can rely on are the energy bills that we pay for, assuming that these are correct and taking for granted that there are no other influences in the energy consumption like for example passive solar gain, gain from neighbouring rooms and buildings, the building structure, insulation standards and personal preferences of the inhabitants.
And to compare such an energy demand assumption based on many unknown factors with that of another building can only be vague.
To show what I mean we can use UpTheBanner’s data, generously provided to us, thanks again for the points made.
The COSTS to heat a home are one major point but the demand of energy can be a different one.
Taking the numbers of €25.- per bill and the rooms surface of 44 m2
is leaving us with the pure consumer’s wallet question: ”Is it worth it?”
A fair question. So let’s have a look into the actual total bill:
There is the €25.- per bill for night safer electricity supply.
Questions: Are these two-monthly bills paid over the entire year? Are these bills paid according to a budget plan provided by the electricity supplier?
Do the €25.- include the charges for the night-safer meter? And what is about taxes-the VAT?
Here the alternative calculation, please correct me if anything is missing or added twice:
€ 25.- per bill , 6 bills per year = 150.-
Standing charges for the night safer meter € 10.48-, 6 times a year = 62.88
Resulting in a sum of 212.88
Plus VAT at 13.5% = 28.74
Total = 241.62
(This number does not include the government levy to support peat power plants)
So € 241.62 divided by 44 m2 gives us a cost sheet of € 5.49 / m2.
These € 5.49 per m2 is all we can rely on to compare one heating system with another i.e. is it worth it in terms of money.
An alternative to UF electric heating would be UF central heating fuelled with a condensing boiler running on LPG, since I use it myself let me compare the two in terms of money for last year’s/this heating season’s demand:
I buy around 1.000 l of LPG per year at a cost of € 400.- incl. VAT and government levy to subsidise environment destruction/ peat power plants.
My heated area is 96 m2, some of the LPG is used for cooking and domestic hot water, assuming 20 % of it.
1000 l LPG minus 20% = 800 l LPG
€ 400.- minus 20% = € 320.-
One boiler inspection per year = € 70.-
Electricity for the circulation pump for 240 days per year at 2.16 kWh/day
at general domestic rate of € 0.146 / kWh (240days x 2.16 kWh x 0.146 €/kWh) = € 75.67
Total €465.67

This results in a sum of € 465.67 / 96 m2,
or annual costs of € 4.85/ m2

So if our buildings and demands where the same then the savings for an LPG UFH compared with an electric storage UFH would be € 5.49/m2
- € 4.85/m2
= € 0.64/m2

So the UFH on LPG versus the UFH on electricity is 11.66 % cheaper to run.
Or the UFH on electricity versus the UFH on LPG is 13.2 % more expensive to run.

Of course these numbers can’t be compared with each other in this particular case due to the lack of data about the actual demand, see above.

FUTURE impacts like price increases are not considered as well. One should keep in mind that most of our electricity is made from fossil fuels, and the ratio of converting a fossil fuel into electricity is worse than one to two. So if for example LPG doubles in price then the electricity prices would threefold.
Another future impact to be considered would be the technical developments concerning efficiency: A boiler like mine is oversized, therefore not the most efficient solution. At the time of purchase it was the most efficient, but technical developments never stop.
As well I could supply the heating energy with a solar panel/storage tank. Theoretical a warm water UFH system with a low output demand (kW/m2) could be running independently on solar panels/storage tank. Much easier and more economical to install then an electric heating UFH system that would have to be fed for example by photovoltaic cells or a small (maybe combined heat and-) power plant running on renewable energy like geothermal energy or bio fuel. This advantage is caused by the low energy demand for transmission of energy, bringing solar energy from the roof into the floor. The electric pump in a warm water solar system is the major consumer of electricity.
But “savings on the pump” could be made also in the existing UFH system. There are already high efficient pumps available for around € 200.- (for example the Wilo Stratos Eco 30/1-5) which use only a third of electric energy to produce the same amount of pressure (“head”) compared to the old ones.
So an UFH heating system running on warm water is easily converted to a different source of energy – if necessary it could be switched to electricity as well.
But an UFH system based on electric cables will always depend on the more expensive electric energy with no choice left.

P.s. Sorry for the formating.