I need a Solution for Slab Heating

Clickbait on 19/05/2026 - 17:26

I know I should do it myself, but it would be great to get some educated input.

We have about 60sq mts of heated slab, and it now costs a kings ransom to run, so last year we turned it off and got half the heat at half the cost.

Roof is about 40qs mts facing West at 45 degrees. Would solar generate enough heat to work, and can it be connected directly to the slab heating.

I don't want to talk to the Dealers because other than this, our electricity bill is SFA
It used to heat 11:00PM to 7:00AM plus topup 2:00PM to 4:00PM, but would 3-4 hours in th eafternoon contribute anything, making A/C athe topup?

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  • MS Paint on 19/05/2026 - 18:03

    As you're in Victoria just get it decommissioned. It's worth a heap of VEU credits. Put that credit towards split systems or ducted reverse unit.

    Would solar generate enough heat

    Solar doesn't generate heat.

    Also, how are the Bluetooth earbuds connected to your Google box working out for you?

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    • JIMB0 on 19/05/2026 - 21:53

      Solar doesn't generate heat

      Never heard of solar thermal? It's 5 times the energy of solar PV. Lower exergy, sure, but perfectly fine for low grade heating such as a slab.

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      • MS Paint on 19/05/2026 - 21:59

        Not in the context that the op is asking.

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        • JIMB0 on 19/05/2026 - 22:04

          Yes, I too am confused.

          so last year we turned it off and got half the heat at half the cost

          I can't work out what's going here with this cryptic wording. I also don't know if it's a hydronic setup or electric resistance cabling.

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          • Clickbait on 20/05/2026 - 18:38

            @JIMB0: Apologies. my electric Slab Heating radiates from the floor and warms you whole body.
            A/C does a great job of warming the ceiling. I have 16ft Cathedral and wait patiently to get a hot head, and residual to the rest

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            • JIMB0 on 21/05/2026 - 09:36

              @Clickbait: Sounds like there’s a lot of hot air collecting up there. Are you sure the AC is the only source?

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              • Clickbait on 21/05/2026 - 10:51

                @JIMB0: Done all that .
                Overstatement but 16 ft ceiling having to fill 13ft before it gets to me
                Slab heat was an inch away

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    • Clickbait on 20/05/2026 - 22:10

      revisit the thread. Bugger!

      • 0
  • yellowfever on 19/05/2026 - 19:35

    Why not live without underfloor heating like the rest of civilisation and be done with worrying about it

    • 3
    • Clickbait on 20/05/2026 - 18:42

      It's like driving a convertible, If you have never done it you are missing nothing

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      • yellowfever on 21/05/2026 - 12:55

        I've done it and I would happily bin that idea with the under floor heating

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        • Clickbait on 21/05/2026 - 14:13

          Yeah but…8KW mitsubishi at 10+ yo, and it looks like I have to get into heat pumps, replace my GAS hws with individual instantaneous units, chuck out the Gas heater in the lounge room, which really needs to be chucked out anyway, and the costs keep growing and growing, SO I CAN SAVE MONEY??
          WTF???

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          • yellowfever on 23/05/2026 - 10:26

            @Clickbait: Back to the my original suggestion. You could easily forget about UFH and be done with it. you'll be right. but you do you.

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  • jv on 19/05/2026 - 18:11

    It used to heat 11:00PM to 7:00AM

    Not the best time for solar…

    • 2
    • Clickbait on 20/05/2026 - 18:40

      That was for when Power stations ran 24*7, and their only problem was surplus power

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  • Aureus on 19/05/2026 - 20:00

    Just use normal AC and forget about the underfloor heating. Without proper hydronic it is too expensive to bother with.

    If you already have solar you could put your excess in to the floor, or if you are on a plan with free heating hours you might as well turn it on. I wouldn't get solar just to waste it on underfloor heating.

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  • Wiadro on 19/05/2026 - 19:35

    im rich but im not heated flooring rich

    • 1
    • Clickbait on 20/05/2026 - 18:41

      its 30 years old

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  • tephra on 20/05/2026 - 00:19

    What is your current heat source for the slab?

    Or is it resistive element embedded into the slab (like what they do in bathrooms)

    • 1
    • JimB on 20/05/2026 - 10:36

      OP has left out important information.

      I'd also want to know if it's hydronic or resistive element slab heating.

      • 1
    • Clickbait on 20/05/2026 - 18:46

      It's electric. Slab was poured over it in 1990's.
      It's on Offpeak which is m\now near premium rates
      If I turn off and disconnect Offpeak, and assuming it's legal would it be worthpushing solar into offpeak meter

      • 0
      • tephra on 21/05/2026 - 02:44

        yeh ok, thats unfortunate - if it was in-slab hydronic you would have some better options…

        for resistive you could get a battery and try and min-max it…

        but i honestly think mini-splits would be a better option:
        a) heating AND cooling
        b) being a heat pump you will get 3-4kw of heat output for 1kw of electricity

        • 0
  • jv on 19/05/2026 - 18:09

    I need a Solution for Slab Heating

    Copper sulfate ?

    • 0
    • tenpercent on 20/05/2026 - 18:48

      Poor choice. The specific heat capacity and freezing point of copper sulphate solution is approximately the same as pure water. And it's acidic.

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  • BOGOF on 20/05/2026 - 08:30

    Not sure what OP's current setup is like, but in the UK Underfloor heating is becoming very popular in new builds & extensions. UFH connected to a heatpump powered by solar during the day.

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  • Euphemistic on 23/05/2026 - 21:48

    You need to work out how much power it uses both wattage, and watts/hr. It might have a peak current but will alos likely run on a thermostat. So it might pull 2400W (or more), but only for half the time.

    On s you know these details, then you xan look at if its possible to power with solar. It might be cheaper to whack on a solar system than to reconfigure your heating to reverse cycle AC. Even if you do go fof AC, a solar system will be a win win anyway.

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