Heat Exchangers (Radiators) This is the other common way of dealing with excess heat. Heat exchangers are very effective: a small heat exchanger will dissipate as much heat as a large reservoir, but they are expensive and require a fan, usually electric. It’s important to size the heat exchanger properly – we can help with that. Some industrial systems use oil-to-water heat exchangers, which are very effective and also compact. And they don’t produce hot air which may be a problem indoors. Of course, they require a source of cool running water, and a place to return it to.