Thermann installer, Melbourne’s south-east.

Tank and heat pump in one shell, with nothing going outside. The 200 L is the size for a couple or a small household, and the single-unit build is what makes it fit where a split system's outdoor unit has nowhere to sit.

285 L in a single shell, tank and heat pump together, nothing to place outside. Our default Thermann when there's no clean run to an outdoor position but there is room where the old tank was standing.

Thermann build their split in one tank finish, glass-lined with a sacrificial anode, and now across four sizes: 160, 250, 315 and 400 litres, so it covers a single unit through to a big household. The anode is a part we swap every five to seven years and the tank warranty depends on it being done, so it wants to be on the service list rather than forgotten. Pick it when the tank needs to live in one place and the heat pump in another, and let us size it off how many of you actually shower.

The 16 L/min G-series suits a couple or a single-bathroom household. Two showers that might run at once want the 20 L/min instead, which is a question of outlets rather than of spend.

The 20 L/min is our most-installed continuous flow. It carries two showers running at once without either of them going thin, which is the moment most households find out what they actually bought.

The 26 L/min G-series handles two bathrooms simultaneously plus a kitchen tap without pressure drop. Our default for family homes with more than one bathroom.

The biggest continuous flow we install. It's for three bathrooms and up, or any house where the taps genuinely run at the same time, and it's sized by outlets rather than by people.

The compact gas storage tank, natural gas or LPG, 4-star. It suits a unit or a small household where the daily draw really is low. Past two people it runs out mid-morning, and at that point the 170 L or a heat pump is the honest answer, so we'll price whichever fits the site.

170 L is the gas storage size for a three or four person household, where a smaller tank runs dry partway through the back-to-back showers. Same 4-star efficiency and the same warranty position as the 135, in a taller body, so the cupboard needs checking before we order it.

The compact size in the Smart Electric range, and it suits a studio or a granny flat where a heat pump has nowhere to sit. Worth knowing before you buy: electric storage doesn't attract the VEU rebate and it's the dearest fuel to run, so wherever a heat pump physically fits we'll price one next to it.

125 L suits a one or two person household. Electric storage doesn't attract the VEU rebate, so where a heat pump can physically go, we'll price one. Where it can't, a body corporate rule, a rental, no outdoor position at all, this is the size that fits.

160 L with the 2.4 kW element for a 2-person household. Element size steps up here so recovery time stays reasonable as draw increases.

250 L is the electric size for a three or four person household, with a twin-element option if recovery time matters. Where it earns its place is the day the old tank goes and hot water has to be back on before tonight. If the change is planned rather than forced, we'll put a heat pump price beside it, because it runs at roughly half the cost a year.

315 L for a four or five person household, twin element available. This is the one that goes in on a burst-tank Friday with five people in the house and hot water needed today. When there's time to plan instead, the heat pump equivalent takes the VEU rebate and runs at a fraction of the cost, so we'll show you both.

400 L is the biggest Smart Electric tank, for high-draw households and acreage where a 315 runs out before the day does. Same note as the rest of the electric range: on a planned changeover the Reclaim CO₂ 400 L or a Thermann heat pump takes the rebate and costs far less to run, and on an emergency this gets the water hot tonight.