ThermaSkirt vs radiators vs underfloor heating: choosing a hydronic emitter (2026)

ThermaSkirt replaces an ordinary skirting board with a hollow aluminium profile, 22 mm deep and about 150 mm tall, carrying integrated 12 mm hydronic pipework. Warm water at 45–55 °C runs right around the room, so heat is released low down along the external walls and under the windows, which is exactly where a room loses it. Each room still gets its own thermostat through a manifold. As an authorised installer of ThermaSkirt in Australia, we reach for it when an owner wants whole-home hydronic warmth and doesn’t want to see any of it.

When a room falls short, we don’t compromise the whole house. We seal draughts and insulate first, because cutting heat loss is cheaper than adding emitters, then top up with a kick-space plinth heater in the kitchen or one slim radiator in the room that needs it. Our heritage Sydney ThermaSkirt renovation, a heritage-listed Federation terrace in Paddington, shows the approach end to end: no visible plant, and not one original feature disturbed.

Radiators are the most flexible emitter of the three. From the IMAS radiator range, held in Australian stock, we fit European steel panels from K11 to K33, flat-fronted panels, Klassic column radiators for period rooms and Alubain towel warmers for bathrooms, alongside the wider range of hydronic radiators we supply. Every radiator has its own thermostatic valve (TRV), so each room runs at its own temperature.

The most expensive radiator mistake we see is copying the old panel sizes when a gas system is converted to a heat pump. Our hydronic radiator sizing guide walks through the correction with worked examples, and our hydronic radiators Melbourne page covers sizing for long, cold Victorian winters.

Underfloor heating lays PEX-A pipe in the slab on a new build, in a 30–35 mm self-levelling screed over an existing subfloor, or directly under timber, tile or stone. The whole floor becomes one large, low-temperature emitter. Add a reversible heat pump and a dew-point sensor, and the same loops carry chilled water in summer.

If you’re only weighing up two of the three, our earlier comparison of underfloor heating vs radiators goes deeper on that pair. For local slab and screed detail, see hydronic underfloor heating Sydney.

Skirting board heating vs radiators

These two are the retrofit pair. Both go in without lifting floors, both connect to a manifold with a thermostat per room, and both run happily from a heat pump at 45–55 °C. The difference is how the heat is packaged. A radiator concentrates a lot of output into one panel, so it can heat a cold room quickly from a small piece of wall. ThermaSkirt spreads a smaller output thinly around the whole perimeter, so it disappears visually but is capped by how many metres of clear skirting a room has. Our rule of thumb: ThermaSkirt where the look matters and the runs are long; radiators where a room’s heat loss outstrips its walls, or where you want heat in 15–25 minutes.

Skirting board heating vs underfloor

These two are the invisible pair. Both are low-temperature, low-profile and kind to a heat pump, but underfloor runs cooler still, feels more even and can cool in summer. What it asks in return is a floor you’re prepared to replace. ThermaSkirt wins whenever the floor stays: original boards, a stone floor you laid two years ago, or an apartment where changing the floor build-up means a conversation with strata. Underfloor wins in new slabs, full strip-outs and new extensions, which is why a period home with a new extension often ends up with both.

There’s no single best hydronic emitter, but there is a usual best for each kind of home. This is where we typically land after the site visit and heat-loss calculation.

Most whole-home systems we design use more than one emitter, because rooms are used differently. A typical layout for a period home with a new rear extension looks like this:

• Extension and open-plan living: in-slab underfloor, which also cools in summer on a reversible heat pump.
• Original front rooms and hallway: ThermaSkirt, so the heritage rooms look untouched.
• Bathrooms and ensuites: hydronic towel rails, with an optional electric element for summer towel drying, plus a panel radiator where a room needs more heat than a rail gives.
• Kitchen: a plinth heater in the kick-space, where joinery leaves no skirting and no wall.

It all runs from one heat pump through one or more manifolds, with every room on its own thermostat. The design rule that matters is simple: the heat pump makes water at the temperature the most demanding circuit needs, and cooler circuits are blended down from there. If the radiators need 50 °C and the underfloor 40 °C, the heat pump works at 50 °C whenever the radiators call for heat. The more of the house you design for low-temperature water, the cheaper the whole system runs, so on mixed systems we often upsize radiators to let them run nearer the underfloor’s temperature. Our heritage home extension case study with Maxa, Viessmann and ThermaSkirt works through a mixed system of exactly this kind, from heat-loss figures to circuit temperatures.

These are installed ranges for typical homes. Your quote depends on floor area, heat loss, heat source and the emitter mix.

Across all emitters, whole-home hydronic systems typically land between $20,000 and $60,000+ installed. ThermaSkirt is priced per lineal metre, so its cost tracks the length of wall being heated, and we don’t publish a per-metre figure for the same reason we don’t quote radiators off a floor plan: the number only means something once the room-by-room heat loss tells us how many metres each room needs and whether any room needs a top-up emitter. Our design and quote is fixed-fee and back within 24 hours of the site visit.

On running costs, the heat source matters far more than the emitter. A heat pump typically costs 60–75% less to run than gas, and the cooler the water it makes, the better it does, which slightly favours underfloor, with ThermaSkirt and properly sized radiators close behind. Our hydronic heating running costs guide has the full comparison. One rebate note: air-to-water heat pumps used for hydronic space heating aren’t eligible for STCs, as our heat pump rebates guide explains.

A heat pump is sized to the whole home’s heat loss on the design day, not to the emitter. A Melbourne home designed to −1 °C, with around 1,500 heating degree-days a year, needs more capacity than the same house in Sydney at roughly 700–900. What the emitters change is the water temperature the heat pump has to produce, and that decides how efficiently it works. Our heat pump systems run at a COP of roughly 3.5–5.5, and the cooler the water, the nearer the top of that range they sit.

• Underfloor (35–45 °C): the easiest load for a heat pump. Output is limited by floor surface temperature and the floor finish, which the design allows for.
• ThermaSkirt (45–55 °C): output is set by metres of skirting, so a room that falls short is better topped up, or insulated, than solved by running the whole house hotter.
• Radiators (45–55 °C when sized for a heat pump): panels rated at ΔT50 deliver roughly a third to a half of that figure at these temperatures, so they’re sized up. Our radiator sizing guide for heat pumps shows the maths.
• Mixed systems: the warmest circuit sets the flow temperature, so we size the warm-water emitters generously to keep it down.

Because a heat pump’s output and efficiency both rise as water temperature falls, a house designed around low-temperature emitters can sometimes use a smaller unit. Our hydronic heat pump range includes the Maxa i-290 R290 monoblock from 6 to 27 kW, which lets us match capacity closely to the calculated load rather than rounding up to the nearest big box.