This feature, high water temperatures, is not required for condensing boiler installations. In fact, an installation using the lowest possible water temperatures will help a condensing boiler achieve the highest possible efficiencies. By cooling and condensing these super-heated flue gases, boiler efficiency can be increased by the recovery of both sensible and latent heat. Condensing boilers condense the water vapor produced in the combustion process and captures the latent heat released from this condensation via a secondary heat exchanger. A system that recovers additional heat from condensing moisture in the flue gas stream can achieve reductions in fuel consumption, operating costs and NOx and CO emissions.
Models are available in gas-fired or propane versions.
Boiler installation for recuperative systems is easier and cheaper, however, than the installation of conventional boilers due to the smaller footprint and direct side-wall venting. The exhaust gases from these types of boilers have lower temperatures and can be vented horizontally, eliminating the need for a chimney. Plastic vent pipe can also be used because flue gases are cooler, which can further simplify installation. An installation using the lowest possible water temperature will help a condensing boiler achieve the highest possible efficiency. If a condensing boiler is fitted to an installation with no control over the return water temperatures, then efficiencies will be sacrificed.