The ESP Ecocent Air MVHR L500orks completely independently. The unit has a fan motor, air filter, heat recovery heat exchanger and a heat pump built-in. It can provide heating combined with the ventilation system in a house. Frsh air coming in from outside can be driectly treated by the unit and polluted indoor air can be exhuasted. The heated polluted indoor air is recovered and recirculated throughoutb the building.