This week the ‘middle of Lidl’ aisle has included a double woodstove fan among its wares. I’ve been interested in one of these devices for a while and picked one up earlier today.

This type of fan uses a Peltier cell and relies on the Seebeck Effect, which are explained in the video below. The short version is that, if there is a heat difference between the two sides of the cell, a small electrical current is generated. One way of creating that difference is to attach the lower side to a metal structure that sits on top of a woodstove and conducts heat. The topside is designed as a large, passive heatsink, which dissipates heat and that generates the required differential to drive a small electric motor.

In the case of the Vonhaus unit I bought, it has two fans. So far, it seems to work well. You can feel a gentle breeze when it gets going but it runs silently. I need to have a think about how to measure the temperature at different spots and whether I can demonstrate that the room heats up more quickly and evenly but it at least creates a convincing effect so I won’t be popping back tomorrow for a refund.