The Calvary Lutheran Church in Alexandria, Minnesota was built in the 1950s using hot water wall convectors, baseboard and fan coils to heat the sanctuary, offices, classrooms and meeting areas. Over the years, multiple building additions were added as well as zones off the old boiler system. Uneven heating and constant air bound zones were common.
Many contractors tried their hand at solving the problems with various valves, bleeders, pumps, controls and piping strategies. About 10 years ago, the high-mass boilers were replaced with mod-con boilers, which added a new dimension to the system’s ills. Again more components were added to try to keep the congregation warm. Air was a constant issue especially in the expansive sanctuary of the church. Every day the heating system needed to be checked and often the sanctuary zone would be air bound. Air would need to be bled, water added to the boilers and all the wall radiators needed to be bled with a screwdriver.
After having the systems go down over a dozen times in the winter, the church elders decided to find a solution once and for all. A committee was formed to start a fact-finding process. This resulted with interviews, diagnosis and bids from over 15 contractors. Finally it was decided that Koegel Plumbing & Heating Solutions presented the best solution to cure the current problem, prevent future issues and cut energy cost.
To fix the heating system it would be necessary to strip out the many layers of pipe and multiple pumps. All of the boiler and most of the distribution piping was removed back to the walls of the boiler room along with the old compression tanks. With a clean slate, the system could be redesigned so the old distribution piping and new boilers could work in unison without air or flow issues. All of the work needed to be finished within a two week period without disrupting daily church functions.
In order to make the system function correctly, it was necessary to hydraulically separate the boilers from the 6 zones with the largest zone being 2 ½” and the smallest 1″. This is where the Caleffi 4″ HydroCal would shine. The zone piping was buried in plaster walls and ceilings so exact fitting take offs and pipe lengths could not be determined for pump sizing. Grundfos Magna3 pumps were chosen for their auto adapt feature along with Caleffi QuickSetter balancing valves on the multiple returns. 2 ½’’ copper was used to connect the two 399K Btu boilers to the 4″ HydroCal and 4″ copper was used for the supply and return headers to the six heating zones. A bladder type expansion tank was used along with a Caleffi ¾” AutoFill and backflow preventer for quick air purging.
Since startup the system has performed perfectly quiet, totally comfortable and super efficiently. The parishioners are warm, no one needs to babysit the system and the screwdriver has been retired. The boilers can now work to their full potential and be protected from dirt coming from the old pipes, thanks to the HydroCal unit. All the zones can be individually monitored and balanced by the QuickSetter balancing valves and steady pressure is assured by the Caleffi AutoFill unit. The boiler room has become a church tourist attraction of sorts and everyone involved couldn’t be more pleased with the results.