underfloor heating

Hi all,

we are having house built in the next few months on a section here in Tauranga. We have looked into various heating/cooling systems, and are considering underfloor heating - does anyone here have any experience of such systems and whether they are any good or not. The quote we have had is for around $8000 (plus GST) for a 230m2 bungalow which seemed very reasonable as we were advised that for heat pumps or a ducted system for that area we would be looking at $15-25k which would blow the budget!!

Any advice or comments gratefully received! :icon_biggrin:

Maggie x

Only in the UK. But can't be that different. You can have 3 different types of UF heating.
Pipes thorugh concrete/screed - hot wated pumped through pipes in the concrete floor. Concrete provides a fair storage slab for heat savings in the long term but can take a while for the heat to come through.

Pipes through joists - As above but in the cavity created by floor joists, Not so popular as there are a number of issues with temperture control but can be done and heat is pretty instant as you can imagine. Obviously nothing to store the heat in tho so when it's off the floors cold and when it's on you'll need more energy but instant heat is a bonus ay. Also make sure there is a reflective surface below the pipes to bounce the heat in the right direction. Otherwise you'll lost up to 20% through the foundations and building permieter.

Electric mat, similar to above, basically the same as an electric blanket but underneath your timber floor. A flat mat with heated wire going through it offering instant heat and greater control over temperature with thermostatfeatres etc. etc.

Price sounds good for a building that size. Good on yer.

Hi

My friend has just been quoted $450 for her bathroom which is 2m x 2m roughly and was told if she used it in the morning and evening it would add an extra $10 per month onto her bills. This also includes installing the thermostats etc.

She's still not sure if she'll get it as they are quite happy with the way things are just now. They have every room carpeted apart from the bathroom and kitchen and the heat seems to hold in quite nicely without underfloor heating.

Our house in NZ has underfloor heating, but it?s been disconnected by the previous owner as being too costly and ineffective. Of course, with the house being 40 years old, maybe the system was a bit out of date although I?ve heard from others that underfloor heating isn?t often very effective. Must admit I always wonder how a room can be effectively heated when the heat source has to force its way up through various types of flooring, but that?s just me. Surely some of that valuable heat must get lost on the way up?

The house has a good woodburner in the lounge, but nothing to heat the remainder of the rooms. We are seriously considering having heat pumps installed at some point in the most frequently used rooms to see how we get on with it cost-wise and performance-wise. As well as providing heat there is also the option of cooling in the summer time and it acts as a dehumidifier too. You can have one single unit installed or several and can use each unit individually rather than having to have the whole system running when you?re not using some of the rooms. What more can you want? From the installer?s blurb, it looks like you can add on extra heat pumps as and when you need them so we?ll see how it goes. Some makes like Daikin and Mitsubishi perform better than others and there are different systems to suit each type of usage, so it?s good to do some research beforehand.

Our friends have just had a heat pump installed, and just one unit heats their whole house, which is around 200m2. The manufacturers blurb says it costs around 20c per day to have the unit on constantly. That unit, including fitting, was $4500.

Some other friends also have a heat pump, but that doesnt quite do the whole house, more so due to the layout of the house than efficiency of the unit.

If you've been quoted $15-20k for a heat pump system, then you really need to get a quote from somewhere else! You shouldnt need more than 2 units on a split system to heat a house that size.

Hi Maggie,

I'm looking at heating options at the moment and, like Taffy says, $15-20K is way too much for a heat pumps system. Of course, it can depend on what units you are thinking of inside - the ceiling ones are quite expensive. I think we will go for an outside unit able to supply two inside wall units which should cost around $5k before fitting. On top of that we will have a free-standing woodburner in the living area (around $1,750 before fitting) and, maybe a duct in the ceiling to take hot air from the warmer part of the house to the cooler (am still thinking about this).

Our UK house had underfloor heating in the downstairs bathroom and, yes it was nice because we were often in the bathroom with bare feet, but it did not impact much on the room temperature. It can also be costly to repair if there are any problems due to it being set in concrete or under floor tiles - something to think about in earthquake-prone areas.

Good luck with your choices!

:icon_biggrin:

In talking to 2 seperate people that have done central heating (which is a much quicker acting heat than underfloor heating) it cost them around $10K to 12K (one in Welly, one in Chch).

When I get a house I'll seriously consider both central heating and a heat pump. To me it seems that the prices will be around the same price (depending on the size of the house.....central heating probably being the better option the more rooms in the home). The only thing I'll look at as far as the floor goes is insulation.


As long as the home is properly insulated (double glazed windows/insulated walls and attic/underfloor insulation) it shouldn't take long to heat up the house, and shouldn't be too hard to keep it warm.

Hi All,

I would have posted this sooner, but we?re packing to leave for NZ on Oct 10th ? ;D so time has been at a premium! ?Anyway, hope it?s not too late to add to the debate!

Our current house has got a mixed heating system with part radiators and part underfloor heating. ?The radiators were here when we bought the place, but I installed the underfloor circuit when I built a conservatory about two years ago. ?I bought all the bits (underfloor pipe, manifold, pump and regulators) and fitted it myself for under ?350. ?(I think this is where I need to say that you should only work on a central heating system if you?re a competent person and never on gas-fired systems unless you?re a registered fitter!) ?

I decided on an underfloor system because the conservatory walls weren?t high enough to hang standard radiators. ?Underfloor is non-intrusive so you can put furniture where you want it. ?The heat distribution is much more even that with woodburners or radiators. ?And (this is a biggy) you don?t have to mess about taking radiators off when you want to decorate.

Here?s a summary of the technical bits?.

Construction is fairly straight forward, even more so if you?re building from new. ?Put 100mm polystyrene foam sheets on top of the concrete sub-floor and cover it with loops of triple-ply 15mm plastic tubing, spaced at 200mm centres. ?(I wish someone had told me that 200 metre rolls of plastic pipe put up quite a fight, especially when you?re working in a greenhouse on a sunny day. ?I reckon I lost 10kgs by the time I'd finished!) ?Pressure test for leaks, then cover the whole floor with 70mm of sand and cement screed.

In our case, we had two loops of pipe, which went back to a two port manifold ? the set of valves and pump which control the rate of flow and the temperature of the water going through the loops. ?It sounds complicated, but it was put together by the supplier who sent an installation manual with lots of big colour photos. ?One pipe went from the indirect hot water flow on the boiler to the inlet port, another from the outlet back to the boiler return. ?The four ends of the underfloor pipes (two out, two back) attached to the manifold and hey presto. ?The only extra bit I had to add was a second pump and a non-return valve to push the water to and from the boiler.

Because I piped into the indirect hot water feed on the boiler, the underfloor circuit worked from the hot water system and could be heated without having to heat the rest of the house. ?We burnt a bit more oil, but not loads and will definitely go with underfloor again if I get the chance. ?Feel free to PM if you want a more detailed guide - I kept all the spec from the supplier!

Very helpful post Kokopeli.

Just a little update - we decided not to go for the underfloor heating in the end as we were pushed for the time in getting all the variations in on time so that we could be in for Christmas. We have instead gone for a mixture of 2 heat pumps in the family room and the formal lounge, and panel heaters in the bedrooms (the kids rooms are south facing so they will be chilly in the winter but - hopefully - cool in the Summer) -and the quote was well under what we were expecting.

Maggie x