eCoHeat Low Power Immersion Heaters

The eCoHeat range is Backer Heatrod’s low wattage immersion heater for systems that cannot supply, or do not need, a full 3kW load. Each eCoHeat heater draws 1kW, 1.5kW or 2kW, which matches the output profile of solar PV, ground and air source heat pumps, and marine supplies far more closely than a standard element.

That is what makes it a practical eco immersion heater rather than a marketing description. Surplus solar generation that would otherwise be exported can be diverted into the cylinder, and a heat pump system can hold cylinder temperature without a 3kW boost element cycling on and off against it.


All three low power immersion heaters are fitted with a dual function thermostat, giving water temperature control and over temperature protection in one unit, and are supplied in 11" (270mm), 14" (340mm) and 27" (670mm) immersed lengths. Head sizes are available built to order in 1¾", 2" and 2¼" BSP to match the boss on your cylinder, alongside bespoke lengths and loadings.


Every unit is built to BS EN 60335-2-73, which is what makes the range suitable for marine vessels as well as domestic and light commercial cylinders. Next day delivery is available on in-stock items.

Our Range of eCoHeat Immersion Heaters

Benefits of Low Wattage Immersion Heaters

A standard 3kW element is sized for a mains supply that can deliver 3kW on demand. A renewable system usually cannot, or can only do so intermittently. Running a low wattage immersion heater at 1kW to 2kW means the element can absorb what the system is actually producing, for longer periods, instead of switching on and off as generation fluctuates. In a solar PV installation that turns exported surplus into stored hot water. On a heat pump system it lets the cylinder hold temperature without the boost element fighting the heat pump. On a boat or in an off-grid property, it keeps the draw within what the supply can carry.

Which eCoHeat Immersion Heater Do I Need?

Match three things to your cylinder: the output, the immersed length and the head size. The HE1 at 1kW suits smaller cylinders and systems with modest surplus. The HE1.5 sits between the two. The HE2 at 2kW is the choice where there is more generation available or the cylinder is larger. Immersed lengths of 11" (270mm), 14" (340mm) and 27" (670mm) cover most UK cylinders, and heads are available in 1¾", 2" and 2¼" BSP. If you are replacing an existing element, match the head size to the boss you are unscrewing from.

Key features

  • eCOHeat is available in 1kW, 1.5kW & 2kW loadings and immersed lengths of 11" (270mm), 14" (340mm), 27" (670mm)
  • All of the heaters are fitted with a dual function thermostat providing control of the water temperature and over temperature protection of the water cylinder
  • Compliant with BS EN 60335-2-73 these heaters are also suitable for domestic water applications on marine vessels.
  • The range is complimented by the availability of built to order heaters available in a range of head sizes that include 1¾”, 2” & 2 ¼” BSP head sizes and a range of bespoke lengths and loadings to suit almost any application.
  • We believe this provides the most comprehensive range of renewable heaters available today.

eCoHeat and Solar PV

Diverting surplus solar generation into a hot water cylinder is one of the more reliable ways to use electricity that would otherwise be exported at a low rate. An eco immersion heater rated at 1kW or 1.5kW is generally a better match for a domestic array than a 3kW element, because it can run for longer on the power available rather than waiting for a threshold that a UK array only reaches for part of the day.