condensing gas water heaters

A condensing water heater (or a condensing boiler) is a particularly efficient water heater (boiler) using a technology that forces the combustion gases to travel a long way before they exit the appliance, generating more heat and heating more water with the same fuel.

Two types of gas condensing water heaters

Condensing vs. Standard Water Heaters Condensing water heater can be...

- tank-style: A. O Smith (Vertix series), Heat Transfer (Phonex Series) and the American Water Heaters (Gas Efficient series)… or
- tankless: Navien, Rinnai, Noritz (N-0842MC) Bosch (GWHC 920ES/ESC), Takagi (Flash T-Hi)...

Image (from Energy Star): Condensing and standard gas tank-style water heaters

Which model to choose?

The possible advantage of buying a tank-style condensing water heater is that it can replace your old tank model without upgrades to gas lines or to the venting system, saving a lot of money in installation costs.

Otherwise, tankless condensing water heaters can be a better option, slightly less expensive.

Condensing Water Heater: the inside Left: Energy star image with diagram of tank-style condensing water heaters. These units convert over 90% of the fuel in use (gas, oil…), which is far more than that of other water heaters (50% in the case of many older water heaters), helping to reduce our carbon footprint.In Europe the condensing technology is largely used for both air-space heating and standard hot water uses in bathrooms and kitchens (the term boiler in the UK is basically equivalent to water heater in USA).

Pros

Qualified gas condensing water heaters may cut water heating expenses by 30% or more, with smaller greenhouse emissions.

Tank-style models provide an easy installation when replacing old tank-storage models, responding to the prevailing North-American home designs…

cons

Condensing water heaters are pricey: expect prices above $1.500 for qualified models (rebates and tax credits in USA up to 30% in 2010…).

The condensing technology makes more economical sense for larger uses (including space heating, as it is the case of their domestic applications in Europe).

See: Water heaters prices

Manufacturers

The list of manufacturers offering condensing water heaters in USA or Canada isn’t as large as in Europe. But it includes names like A.O. Smith, American, GE/Rheem, Heat Transfer, Navien, Noritz, Rinnai, Takagi...