Radiant & Hydronics

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A recent design approach for air-to-water and water-to-water heat pumps is "direct-to-load" piping. This method utilizes an inverter-driven scroll compressor, which operates across a wide range of speeds and can handle on/off cycling without the high inrush current typically seen in fixed-speed compressors.

Most heat pumps in North America extract heat from outside air to warm interiors, which is why we call them "air-to-air" heat pumps. However, this term is incomplete, as heat pumps can also provide comfort without relying on forced air delivery.

Last month's column discussed piping for air-to-water heat pumps. A 2-pipe system allows staging but not simultaneous heating and cooling, while a 4-pipe system with motorized valves enables both modes of operation.

Last month, we started with an air-to-water heat pump for space heating and added an auxiliary heat source and chilled water cooling. This month, we’re adding domestic water heating, similar to last month’s setup.

An emergency call led a team to a school with a leaking boiler, which was shut down due to safety concerns. After clarifying the need for urgent repairs, the executive director approved the work. Complications arose from snow and transport challenges, but a friend connected them with a group of young workers willing to help, easing manpower concerns.

Occupants of a building using a hydro-split air-to-water heat pump are facing slow recovery after night setbacks and inadequate hot water during peak demand. The system, composed of an outdoor and indoor unit, struggles with heating efficiency. What improvements could enhance its performance?

We tackled issues at a 1953 apartment complex with a failing steam system, repairing pumps and leaks. This year, we discovered significant deterioration in the 6-inch steel steam main while preparing for its replacement, highlighting the poor condition of the aging infrastructure.

Standardized piping layouts for air-to-water heat pumps can improve acceptance by facilitating a basic heating system that uses a monobloc heat pump with a 30% propylene glycol solution for freeze protection.

Advancements in the plumbing industry are driven by U.S. Department of Energy regulations, with new efficiency standards for fractional horsepower pumps set for 2028. Plumbing & Mechanical's Nicole Krawcke discussed these changes and performance improvements with Becky Henderson from Grundfos Pumps.

Edward Little High School in Auburn, Maine, utilizes an efficient radiant floor heating system designed by Harriman Associates, using lower temperature water and primarily geothermal energy for a comfortable, sun-like warmth.