Entry # 146
Designer: Stuart Conway
Customer: Residential Home
Installation Location: Balmoral St. (Halifax, Nova Scotia)
Brief overview of the project
Five types of hydronic heat emitters and domestic hot water that are fired by either propane or electric at the flick of a low voltage switch. Utilized Caleffi 548 Series hydraulic separator, Z-one Series zone valves and ZVR Series relay controls, 519 Series differential pressure bypass valve as well as a 573 Series AutoFill combo and a 521 Series mixing valve by Caleffi.
The design goal was to provide outdoor reset controlled heating to in-concrete, staple-up, radiant panels, fan convector and baseboard convector. The customer requested system be able to switch from propane to electric. Also, as always, to make it simple for the end user.
Both boilers have onboard outdoor reset, which covered nine of the ten zones. The in concrete was a single zone only 350 sq. ft., so I used a Grundfos Mixmizer circulator with an outdoor reset control built in. It parallel-pipes the injection circuit from the hydronic separator, requiring only two pumps for the low temperature system.
The other four types of heat delivery all had to be designed to deliver the calculated load at the same temperature. The emitters being Stelrad panel radiators, staple-up in half of the first floor, a recessed fan coil in the garage and a baseboard convector in the basement storage. The zoning system includes a pressure bypass valve, to limit velocities under partial load. Grundfos didn't have a pressure differential operated circulator in the size required at the time.
A special challenge was the glass-fronted twenty foot tall main entry without being able to utilize any floor space or wall space. The staple-up is packed as tight as possible underneath, enough to cover the heat loss of the first ten feet of height. The rest is being handled by a panel rad on the second floor catwalk.
Changing between boilers requires only one switch, which switches the heat and DHW demands to the respective boiler and some circulators, which also supplies power to the gas boiler, providing a simple visual reference.
Also, the 80 gallons of domestic hot water is anti-Legionella stored at 145 degrees Fahrenheit, tempered to 125 degrees, with a Caleffi 1" mixing valve.
This is a new installation on an existing foundation and floor, 4000+ sq. ft. System provides heat and enough domestic hot water to support four baths and a 200 gallon Jacuzzi.
I went to visit my customer, one year later, to ask him how the system peforms. Works seamlesly, alwaws comfortable, without being noticeable or intrusive. And the DHW is unstoppable.