Description: This expanded product line includes Evergreen®, Ultra™ Series 4, and GV90+ ® cast-iron boilers. All operate with natural or propane gas and feature the latest hydronic heating technology.

Ray™ is a high-efficiency, low-mass fully condensing cast iron boiler. The residential unit can run on either natural gas or propane; no conversion kit is required. It delivers 40,000-199,000 Btuh at ...

Viessman says that, besides its eco-friendly credentials, propane also makes it easier to produce heat pumps that can supply water at 70°C—the sorts of temperatures that gas boilers produce.

The Germany manufacturer said its new heat pump systems use propane (R290) as the refrigerant and are able to provide a maximum flow temperature of 70 C. Their coefficient of performance ranges ...