Hydronic Controls On Gas Systems: Part 2

摘要

There are many differences between gas and oil hydronics. The obvious one is that the burners and fuels are different. The controls, however, are typically the same with some exceptions. In this series of articles, I am going to address some of the differences and how to work with them. Our emphasis will be on forced hot water systems used on both natural gas and propane systems. We will be emphasizing the older systems (not modulating/condensing equipment). I want to address controls that are unique to gas. For many years we had some basic rules that could be applied to the operation of both gas and oil systems. Oil systems typically had a tankless coil system and maintained hot water for domestic use. Most gas boilers were what we called ‘cold start’ in that they did not have a domestic hot water function. They usually had a separate storage gas water heater of 30, 40 or 50-gallon capacity. It was not unusual to see oil boilers that had been converted to gas by the use of a gas power conversion burner. These conversions were often carried out without replacing the existing boiler controls. The domestic hot water (tankless) system was also eliminated. The rules for both oil and gas systems were the same for many years.