Replacing the beast By Don Peladeau, Hydronics Consultant, Millennium Mechanical Ltd.
Fully assembled multiple modulating condensing boiler system.
Multiple modulating condensing boilers are replacing the boilers of yesterday with great success. When it’s time to consider replacing the heating plant, there is a lot to think about; the obvious ones are the heatloss of the structure, and the designed maximum water temperature required for the heat-emitters, for starters. But there is a lot more to consider these days. In the past, generally the old equipment was installed with redundancy in mind, so two boilers were installed, each capable of 80 to 100 per cent of the total heating load just in case (this gets very expensive when you consider the upfront costs of installation and then the ongoing maintenance costs). The boilers had a minimum operating temperature at or near the maximum operating temperature to prevent flue gas condensation in the boiler and venting system. 24
Ops Talk • Fall 2013
Sometimes the building supply water would be mixed down with the return
water to reduce the heat losses associated with pumping high-temperature water around the whole building when not needed. Today, the main advantage with multiple modulating condensing boilers is that we can size the heating plant right in order to match the heat loss of the structure and not worry about having to double the heating plant for redundancy. Each boiler in a modulating condensing boiler system is just one small part of the bigger system. For example, a system might consist of six modulating condensing boilers all working together to heat the building. In mild weather, the boilers will automatically modulate, stage, rotate and adjust the building supply water temperature so that the heat loss of the system is matched exact-
Assembly of a modern racking system, complete with plumbing, pumps, headers, valves, etc. – easy to assemble in a day.
