Browse Forums General Discussion Re: Underfloor heating. Advice, comments, experience etc 2Jun 17, 2018 8:24 am Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Underfloor heating. Advice, comments, experience etc 13Jun 18, 2018 10:36 pm stubot So alexp79, can I ask. Did you end up getting hydronic heating in slab or other. Whats your opinion of how it operates. Any negativity in the decision. What sort of air temps would one expect etc and any other useful points. If you did go that way that is Also I asked an above a question on timing to ask builder. Whats your thought on that one. Thanks again Nope, I have decided to fully insulate my slab instead (under slab, edges, thermal breaks where needed), put "warm" timber to the ground floor throughout, apply some insulated thermal mass here and there and just use normal reverse cycle or gas fireplace to heat up the house (which, to my understanding, may be only needed for a few days in a year), considering calculated 12 hours temperature lag (due to presence of insulated thermal mass) coupled with 21-26 temperature range throughout annual temperature fluctuations. Still deciding if I would need some underfloor electrical heating in my bathrooms though. With regard to the timing - better sooner than later. Definitely BEFORE they quote you. Re: Underfloor heating. Advice, comments, experience etc 14Jun 18, 2018 11:11 pm ok thanks again alexp79. Re: With regard to the timing - better sooner than later. Definitely BEFORE they quote you. One last question.So I paid 2k to submit to tender and get that process inlvolved then I guess i get final quote once architectural draftsmen and such have finalised everything is ok and they give me a contract. So you think i should speak to someone now about hydronics and if the sales lady didnt seem handy. She was advising not to ask officially, yet talk to site manager when building but this is too late and am already stuck in contract. So how might one get around sales and venture onto someone a bit more knowledgeable as to achieve my outcomes. Also, do you think if i had to because builder said no way to hydronic in slab that a smaller custom builder could offer similar price to what my estimate has been. Like within 5k max Thanks heaps for your time, it's appreciated. Re: Underfloor heating. Advice, comments, experience etc 15Jun 19, 2018 12:51 am As I said, it will most likely require different slab design, so makes sense to discuss at least before they start structural engineering and provide you with the final quotation. You would not need this details for your council approval though, but would definitely require them on your drawings for the construction certification. If you are in NSW, very helpful for the BASIX too. Otherwise, your construction certifier might not be very agreeable to such variation on the way. May be you would need to speak to someone who is doing your building design and managing DA/construction certificate paper work. Custom is generally more expensive to build than project, but a lot depends on a builder and what he is agreeable to. I have seen few exсeptions. Re: Underfloor heating. Advice, comments, experience etc 16Jun 19, 2018 3:03 am Hi OP, I was curious what sort of underfloor heating you'd be quoted for, as you have an interesting mix of requests, with radiators, & underfloor in the bathrooms & downstairs. I certainly wouldn't be going electric underfloor for a large area downstairs, as it can be frightfully expensive to operate. It should be reserved for small floor areas, if used at all. I'd forgo it completely, unless the wife insists. In which case I'd just install it in her bathroom. FYI, ignoring heat losses, electric underfloor heating, like most electric heat sources, is 100% efficient. Which, due to the price of electricity, makes it very expensive to operate. The only electric heat sources which are cheap to operate are heat pumps (of which reverse cycle air conditioners are a type), which are between 300-500% efficient (referred to as COP). So for every 1kW of electricity used, electric underfloor will produce 1kW of heat. While for the same 1kW of electricity a reverse cycle air conditioner will produce between 3 & 5 kW of heat, making it the cheapest of any heat source. Also note that hydronic panels (unless super-sized) operate at a much higher temperature than hydronic underfloor. This would complicate any hydronic system that includes both panels & underfloor hydronics, increasing installation costs. After reflecting about all this, I'd be installing split systems air conditioners upstairs. They are the cheapest to run, & will also cool bedrooms if required (though fans are much cheaper to run). As for downstairs, if you do go underfloor heating, I wouldn't recommend installing the hydronics in the slab. You will lose some heat to the ground, particularly if the slab isn't very well insulated. But even more importantly your hydronic system would be coupled with the very high thermal mass of the slab. This results in extremely slow reaction times to changes of temperature, measured over many, many hours. This is really only recommended overseas in cold climates which require constant heating over many months. Not for 99% of Aussie climates, that have variable winter weather conditions. So if you do go for underfloor hydronics, I'd recommend using special XPS boards above the slab. The hydronic PEX tubing is inserted into these, & then a topping screed is used. This system will not suffer heat losses to the ground, decoupling the thermal mass of the slab from the hydronics, significantly lowering the thermal mass of the overall system. As mentioned, electric underfloor heating downstairs would be frightfully expensive to operate. Leaving either gas or a heat pump as your choice for your hydronic heat source. Gas will be cheaper to install, while a heat pump (using the same technology as AC's) will be the cheapest to operate, though expensive to install. Yes, underfloor heating would be a very pleasant heat source (particularly for allergy sufferers). But due to the added cost, & the fact that it is far from a mature market in Australia (meaning that the quality of installers vary greatly, with some horror stories), I'd forgo the underfloor heating all together. Unless you want the best, & have the funds to throw money at what will be an expensive installation. Personally, I'd stick to reverse cycle air conditioners in most cases, which are now the cheapest heat source. Add a nice big 6.6kW solar PV system in the roof, & you can heat the house for free while the sun is up. Re: Underfloor heating. Advice, comments, experience etc 17Jun 19, 2018 2:02 pm I am second to ddaroch here. Consider in screen instead of in slab, insulate your slab properly (under the slab + edges). Consider heat pump vs gas. You don't need radiators in 2 story house - they take space, cost money, require different (more expensive) boiler and usually you do not require so much of a heat in your bedrooms - heat from the ground floor will be lifting up, anyway. Alternatively, check out Discreet Heat - they have very elegant hydronic skirting board heat solution which you might like more - it will be significantly more efficient than raditors and in slab/in screed heating. Re: Underfloor heating. Advice, comments, experience etc 19Jun 19, 2018 10:14 pm alexp79 stubot So alexp79, can I ask. Did you end up getting hydronic heating in slab or other. Whats your opinion of how it operates. Any negativity in the decision. What sort of air temps would one expect etc and any other useful points. If you did go that way that is Also I asked an above a question on timing to ask builder. Whats your thought on that one. Thanks again Nope, I have decided to fully insulate my slab instead (under slab, edges, thermal breaks where needed), put "warm" timber to the ground floor throughout, apply some insulated thermal mass here and there and just use normal reverse cycle or gas fireplace to heat up the house (which, to my understanding, may be only needed for a few days in a year), considering calculated 12 hours temperature lag (due to presence of insulated thermal mass) coupled with 21-26 temperature range throughout annual temperature fluctuations. Still deciding if I would need some underfloor electrical heating in my bathrooms though. With regard to the timing - better sooner than later. Definitely BEFORE they quote you. Hi Alex, how are you insulating the edge of the slab? Re: Underfloor heating. Advice, comments, experience etc 20Jun 19, 2018 10:35 pm Brilliant info Ddaroch I have electric under tile heating in bathroom Wouldn’t install it again. It’s cheap to run as it’s a small area and you’d only have it in short periods. But I also have central heating ceiling vents in the bathrooms so rarely bother with it. Reverse cycle heating / air con for upstairs is great idea......in summer upstairs is warm. Much cheaper to run than cooling all rooms upstairs. I’d do that next time 1 10136 I am building Enfield 201 by Mimosa Homes - York Facade Link: https://www.mimosahomes.com.au/new-homes/enfield-201/ I did my colour appointment last week. I am looking… 0 587 I apologise for any confusion, but your understanding is correct. We approached our situation differently based on advice from… 11 53225 |