Retrofitting/Installing Underfloor heating

Using AHT modules to retrofit underfloor heating.

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Welcome to the forum. Could you add the purpose of joining, apparently to post about your installation?

Are you affiliated with AHT? Are you looking for others who have done the same? Are you looking for advice or others’ experiences?

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Not related to AHT. Considering retrofitting my rural home and seeking comment/experience/advice.

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Hope you have either a good solar power system or deep pockets.

Our daughter and her family’s previous home in Mudgee, NSW, had in-slab heating, and our son-in-law said that the electricity costs for using it were unbelievable.

He would not turn all sectors on, and only leave it on for long enough to increase the inside temperature to a reasonable level in winter, and the power bills would jump from around $1,200 running their 3-phase heat-pump aircon system to $2,000 a quarter with running the in-slab heating.

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Hi Zara2,

Are there any reasons why you are thinking underfloor heating suits your home, and also why AHT might be a suitable solution?

Are there any other options you might be considering?

The AHT web site says AHT install a metalic underfloor ribbon to heat the underfloor layer (eg under a carpet). Assume this is electrically powered resistance heating of the floor area by the ribbon matting.

The web site for AHT was not very helpful for me unless I chose to engage with the pop up sales assistant or ask online for a quote?

When we considered heating our rural home in 2015 (cool winters only) we looked at numerous options, however underfloor electric radiant heating did not pop up as an obvious option. Some recommend it only for small areas such as bathrooms or bedrooms where you go barefoot often, but not larger living areas. It looks like a convenient solution, although perhaps not that energy efficient compared to some other options.

We settled on a mixed solution with reverse cycle air conditioners as they both heat and cool. We also insulated the ceilings in our old timber cottage. The energy efficiency (you can look at Choice reviews for air conditioners) is very good with 1kWh of electrical energy purchased giving up to 5kWh or more of cooling or heat output - depending on the model. We obviously also benefit from the cooling in summer.

For peak winter heating we had some help from Hunt Heating in Melbourne Vic, to upgrade our wood stove hot water circuit by adding two radiators to our living area (3.5kW peak each). I gather they also do underfloor heating and design if you need to look at other suppliers?

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Broadly heat-pump and aircon solutions give an increase in available energy transfer over direct conversion of electricity to heat of a factor of about 2 to 3. In other words for every dollar you spend on power you get 2-3 times the amount of heat inside the house. Aircon has the advantage that it can cool as well. I may be missing something but I can’t see why you would choose underfloor resistive heating.

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They person who had the house constructed had the aircon and the in-slab heating installed when it was built.

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Drum roll :rofl:

Although not up there in energy efficiency underslab and hydronic (and their simulated electric counterparts) heating systems have a comfort level inverter reverse cycle A/C units do not deliver.

The radiant heat (in operational theory) cycles within a small number of degrees (user settable on the thermostat control) so keeps a relatively constant temperature. In theory walls, ceilings, flooring, furniture, and occupants are warm and cozy at a set temperature +/-, without drafts.

A/C and hot air heating blow air. Even when they don’t cycle per the newer inverter systems there is a constant air circulation. Some may like it, but it is a different experience. Both underslab and hydronic are slow to heat a cold area compared to an inverter reverse cycle A/C.

Why do that in lieu of a wood stove (or fireplace)? The wood stove is radiant heat from a single area and is not nearly as convenient to fuel and keep at temperature as compared to an on/off switch with a thermostat.

In the end, underslab and hydronic prioritise absolute comfort over cost/efficiency, with other tradeoffs as compared to inverter reverse cycle A/C.

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For underfloor hydronic heating there are a number of energy efficient options.

These might include mass storage and roof top HW solar collectors, pellet heaters that can use waste materials or an electric powered refrigerant heat pump that will deliver 3-5 times more heat than the energy used, and can run off roof top PV or batteries as needed.

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True if your panel capable area is large enough. I’ll admit my thoughts focused on the traditional high efficiency gas fired boiler hydronic systems. Thanks for the gentle wake up :wink:

If one has enough suitable roof (or land) area, batteries, and a backup supply of some sort, electric everything make sense.

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