Replacing the beast

By Don Peladeau, Hydronics Consultant, Millennium Mechanical Ltd.

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 tem-

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, Fully assembled multiple modulating condensing boiler system. the boilers will automatically modulate, Multiple modulating condensing boil- Sometimes the building supply water supply water temperature so that the ers are replacing the boilers of yesterday would be mixed down with the return heat loss of the system is matched exact-

stage, rotate and adjust the building perature to prevent flue gas condensaAssembly of a modern racking system, complete with plumbing, pumps, headers, valves, tion in the boiler and venting system. etc. – easy to assemble in a day.

“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.”

The “old beasts” – the boilers of yesteryear.

ly down to as low as 80,000BTU/h and up to 2,400,000BTU/h. This is a turn-down ratio of 30:1, unmatched any other way. With a modern building automation system, the master boiler can be given a target water temperature based on the heating requirements of the building and outdoor temperature. The boilers will work together to meet the demands of the building.

The second advantage with multiple modulating condensing boilers is that when maintenance is required, it can be performed at any time of the year – including the middle of the heating season – as you are only working on one of six units at a time. The other five units are still humming away, meeting the demands of the building.

Another advantage to this type of system is that the boiler pumps can be the small water-lubricated ones that require no maintenance; plus, the cost to replace these pumps down the road is quite reasonable. In addition, these pumps are very electrically efficient and only run when a boiler is calling for heat.

Multiple modulating condensing boilers just make sense!

About the Author: Don Peladeau is a qualified hydronics consultant with over 30 years of experience in the institutional, commercial and residential sectors. Throughout his career he has worked in the field as a qualified gas-fitter and as a design consultant throughout B.C. b