Underfloor heating

[Nikki]

Sorry if this has been discussed before, but I searched and came up with nothing.

Anyway, we'll be building our house and we were considering underfloor heating. I thought I had read that it was a very energy efficient way to heat a home. Obviously, if you could use a renewable source of energy to power it so much the better. But basically, it's supposed to be efficient because it heats from the ground up and can be used effectively on low settings.

However, I've been told by a couple of people that it uses a lot of energy to run, so that (if you're on grid) it's very expensive.

Could somebody clear this up for me?

[Martin]

the only time underfloor heating usually makes sense is on a new build - it can use the "low grade" heat supplied by a ground or air source heat pump very effectively - BUT there is then the big stumbling block of the heat pumps - ok you may get 3 free units of energy for 1 unit that you put in, but that unit is electricity (at 10p unit, and rising fast!) as opposed to mains gas at 2p...........
IF you're generating your own power, gshp is great, otherwise..........
By all means use something like a woodburner with back boiler to do underfloor heating, but do your sums VERY carefully if thinking of heat pumps!

[Nikki]

Hey Martin.

We'll be on mains electric. Thinking of those solar water heating panels and solar cooker, and other bits and bobs that we can afford. Might do a wood burner, just not sure about chopping down trees. No pumps.

Anyway, the underfloor heating would be mains electric, so sounds like it isn't energy efficient at all really.

[Martin]

you'll be pleasantly surprised to find that most logs available locally are from sustainable sources - if you have the acreage, coppiced trees will give you all you need!
Heat pumps cost the proverbial arm and leg to install - to do it properly you've got to tear up a lot of ground, and relay it with the pipework buried - it's a lot of hassle , and as you've found, just not economic! (unless you generate the power)
For an "alternative" suggestion, go for a Listeroid vegetable-oil fuelled genset, giving all your electricity and a great deal of your heating (from the cooling jacket)......you could even run a heat pump.....
To b e self sufficient you'd need something like 5 acres of oilseed rape, or 8 of sunflowers, and a manual press and filter.............
Like my friend Ken's setup - http://www.powercubes.com/listers.html
(possibly the best big boy's toy ever invented!)

[Annpan]

Are you talking about electric under-floor heating? rather than hot water you have a wire running under your floor which low voltage electricity is passed through.

We have been looking at that and we have also been told that if you have to heat your house with electricity then it is the most efficient.

It heats differently though, by conduction (rather than radiation or convection) I have heard that it takes some getting used too.

I'd imagine if you were running it off of PVs it might not be so good, as you'd have your electricity in the summer - not when you need it in the winter. If you look at wind turbine or water if you had the option, that might make more sense.

Seriously consider a wood burner... they are great, especially if you have loads of insulation. You will come to love chopping wood.

Since you are building your house, if I were you I'd think ahead as much as possible. Insulate, build in a chimney, put in the cableing for underfloor heating. That means that if you decide to go ahead with the woodburner or underfloor heating, the difficult bits are already done. It is a nightmare to retro fit these things.



I speak as someone who is currently trying to renovate an old house with no heating. We have put in a woodburner and we are trying to fit as much insulation as is possible. It is cold and uncomfortable at the moment. We also have a baby (15 months) You do not want to be thinking about this in a cold winter when you have a baby.

Good luck.

[Martin]

it may be a more efficient use of electricity, but it is still the very last choice in cost! (and it'll get worse!)

[Nikki]

I'm trying to get my head around the differences and pay-offs between efficient use of resource vs running cost vs set up costs vs eco-friendliness! lol

Ok, if I have this straight, if you must use electricity to heat the home, then underfloor heating is an efficient option.
However, if you have another resource as a heating option, then underfloor heating is not the most economical overall. Right?

I'm unsure about where the wood around here comes from (Montenegro coast). Almost all the locals use woodburners for the winter, so I know that it is economical (about 250 euros for the winter). However, I need to be sure of where this wood is coming from.
We would be able to get some deadwood, but I think you need larger logs, otherwise you'll be adding twigs every few minutes I'm imagining.

We just had a discussion tonight with a local and friend (also our builder), who explained that our wood burning system would run as a cooker with a boiler. So hot water and central heating and cooking over the winter. Sounds good. If the wood is from ethical sources, then I'd be very happy with that.

8 acres of sunflowers???!!!

[Martin]

I always say "what would I do?" - wood burning range with back boiler (possibly second woodburner in main living room with another back boiler) for winter, and solar hot water for spring/summer/autumn -THEN all you need is a relatively small amount of electricity for those things which you can't power any other way
(only use "high grade" energy where you must!).
All of the technologies mentioned are relatively simple and inexpensive (especially compared to heat pumps and the like)
About the only downside of wood is that you have to obtain it, store it in the dry, and feed your appliances (but good exercise!)

[Annpan]

Ok, if I have this straight, if you must use electricity to heat the home, then underfloor heating is an efficient option.
However, if you have another resource as a heating option, then underfloor heating is not the most economical overall. Right?

From what I have read, yes... only if you must use electricity.


You can get ranges (rayburn is the brand name to google) that will do hot water, central heating, and cooking (plus drying and ironing clothes too) - this is by far the best method if you can get a reasonable cheap/free supply of wood. I'd guess the logs are fairly local as it can cost a lot to transport them (and that would increase the price subsantially)

Depending on the size/ layout of your house, you can have a rayburn in the kitchen and a smaller stove in the livingroom, both of them can go to your hotwater tank along with your solar hot water. That in turn would give you hot water and run radiators.

You might want to find out how much wood you get for your €250. we are going through about 1 ton every 6 weeks at the moment - that is running on full, all day, it's about 3 - 6oC outside (I hope that helps with a ball park figure of how much you can expect to use) You can also use building off-cuts, pallets, fallen wood, etc to burn.



Clear as mud, right [/quote]

*edit - I don't mean to repeat anything Martin says, or contradict it ... we keep posting at the same time *

[Martin]

no probs!
both posts nearly said the same, so great minds and all that!

[Nikki]

Thanks guys! That really helps a lot.

As for great minds, we were discussing last night about having a little stove in the living room just as an extra.
Looks like this is going to be the way to go for us.

Love this forum!

[mybarnconversion]

Mains electricity driven underfloor heating is far from a green or sustainable heating method if that's one of your aims.

Heat pumps are expensive but only in comparison with mains electricity if you take a short term view, in the medium to long term view there should be a pay-off so long as the system is sized and designed properly.

There are other type of heat pumps than Ground Source - such as Air or Water source that do not require extensive land for installing pipe work. Ground Source can also be installed into boreholes than are deep rather than wide and don't need much space at all.

Although I appreciate your worrying over the sourcing of wood, to me such concerns can't turn the argument from the use of a wood burner to electricity for heating. Electric (carbon fuel) powered heating just has no green credentials at all...

If you can handle the wood collection and storage demands (which shouldn't be under-estimated) then martins wood-burner / back boiler with secondary wood-burners seems a good non-heat pump solution.

Don't forget to think about insulation as well ... no point pumping out all that heat for it just to warm the outside air...

Sorry to add to the confusion...

[Nikki]

Thanks. No, it adds to our decision to go for the wood burner. Have been looking into it some more and we think the wood collection should be quite do-able. I do love the idea of a wood burner, just was suspect of the tree issue. But we have a TON of deadwood avaialble, and we should also be able to plant trees too.

thanks again

[thermodix]

the only time underfloor heating usually makes sense is on a new build - it can use the "low grade" heat supplied by a ground or air source heat pump very effectively - BUT there is then the big stumbling block of the heat pumps - ok you may get 3 free units of energy for 1 unit that you put in, but that unit is electricity (at 10p unit, and rising fast!) as opposed to mains gas at 2p...........
IF you're generating your own power, gshp is great, otherwise..........
By all means use something like a woodburner with back boiler to do underfloor heating, but do your sums VERY carefully if thinking of heat pumps!

I think better for a geothermal heat pumps right... renewable energy for it...



_________________
Programmable Thermostats

[Elizabeth]

We have underfloor electric heating in our kitchen! It is excellent and very ecconomical.

We currently only have electric to heat the house and our electricity consumption is really quite low. We can set the temperature and it warms the slate it is under and is very efficient (it also heats the loung and dining room!). It is only a small room. I think the material you use over the top will effect the efficiency, so look into that. It was easy to lay too! No expensive builders required!

You need to take into account where you are going to store your food, put bowls down for animals and more importantly where you want it warm for doing the washing up and preparing the breakfast!

Sadly not all of us live in houses or have a life style where you can have woodburners etc so we looked at the best thing for use with electricity (we are not on the gas mains).