What is a Hydronic System?

A hydronic system uses water to move heat between a heat source (e.g. a boiler, heat pump) and a heat emitter. Hydronic systems are often associated with radiant heating, but isn’t always the case.

A hydronic distribution system doesn’t have to terminate at a radiant emitter (e.g. radiator panels, in-floor tubing). It can also deliver that heated (or chilled, if the source is a heat pump) water to an air handler and then blow it through a duct system into your conditioned spaces.

A Real Life Heating/Cooling Design Challenge

In fact, that’s exactly what we did for a new house construction on the western shore of Cayuga Lake recently. Working with the homeowner’s rough prints, we initially planned a water-to-air or forced-air geothermal (aka ground sourced heat pump) system to provide heating and cooling, but when we did the room-by-room heat load analysis (Manual J), we discovered that there were three distinct areas in the house in terms of heat gain/loss – the open-concept lake room containing the kitchen, dining, and living spaces which would have a lot of window glass facing the lake (and the morning sun), the master bedroom suite tucked in the back of the first floor and heavily shaded by trees (and a steep and gorgeous waterfall and cliff), and the second floor with a vaulted ceiling to a cupola surrounded by bedrooms, bathrooms, and a laundry room.

Glass Walls can be the root of radiant heating challenges
Glass wall in lake home

Attempting to control the thermal conditioning of this house with one thermostat was most certainly going to compromise comfort in one or both of the areas that did not contain the thermostat. For example, if the thermostat were located in the lake room as per usual, imagine:

  • A sunny but crisp autumn morning with plenty of passive solar heating through the heavily windowed east-facing exterior wall, so much so that the thermostat rarely (if at all) calls for heat; meanwhile, the west-facing master suite feels the “crisp” but not the “sunny” aspect of the morning and, without it’s own thermostatic control, remains chilly throughout the morning.
  • After a warm spring (or fall) day, the outdoor temperature drops into the 50s (and maybe even the 40s) by evening. The lake room loses heat much more rapidly than the rest of the house as windows are relatively poor thermal insulators – the best are R-4 – as compared to exterior walls (minimum R-19), causing room temperature to drop faster. The thermostat calls for heat… to the entire house, and soon the second floor and master suite which contain all the sleeping areas quickly become uncomfortably warm. What was going to be a good night for sleeping is no longer.

Relocating the thermostat would only move the conditioning problem to different areas of the house, so the obvious solution was to create separate zones, each independently thermostatically controlled.

In theory, we could design and install a “zoned” air duct system using thermostatically controlled dampers and a variable speed ECM blower fan in the air handler, but the challenge was how to get two 8- to 12-inch diameter ducts – one each for supply and return air – from the basement (where the ground-sourced heat pump would be) to the second floor zone through an open-concept first floor layout where there were few internal walls and no room for a dedicated chase. Near to impossible!

Hydronic System is the Solution

To achieve comfort cost effectively, a hydronic system was the best solution. Each zone would have a dedicated hydronic air handler which would be supplied hot or chilled water by ¾-inch PEX tubing connected to manifolds coming off a buffer tank and a Geostar water-to-water geothermal heat pump. Now we only needed to find enough space to snake two insulated tubing lines – approximately 2 inches in diameter – from the basement to the second-floor air handler positioned in the attic through one of the few interior walls. With the two first-floor air handlers positioned in the basement, the duct runs only need to run horizontally before penetrating the floor or, for the second floor zone, the ceiling.

We added an ECM circulator, which can automatically adjust to the constantly varying total heat load demand as each zone opens and closes independently, and we had a complete solution: independently heating and cooling three thermally-distinct spaces… cost-effectively, unobtrusively, and (most importantly) comfortably.

If you’re building new or have an existing space heating or cooling challenge, contact us to discuss if geothermal and/or hydronics might be the perfect solution for you.

Lake Country Geothermal, Inc. services the Finger Lakes and Greater Rochester NY areas, including Albion, Auburn, Avon, Batavia, Bloomfield, Branchport, Brighton, Bristol, Brockport, Caledonia, Canandaigua, Clifton Springs, Clyde, Cohocton, Conesus, Churchville, Dansville, Fairport, Farmington, Gates, Geneseo, Greece, Groveland, Hamlin, Hemlock, Henrietta, Hilton, Honeoye, Honeoye Falls, Ionia, Interlaken, Irondequiot, Kendall, Keuka Park, Leroy, Lima, Livonia, Lodi, Lyons, Macedon, Marion, Macedon, Mendon, Mount Morris, Mumford, Newark, North Rose, Ontario, Ovid, Palmyra, Pavilion, Penfield, Penn Yan, Pittsford, Port Byron, Prattsbugh, Pultneyville, Red Creek, Riga, Rush, Savannah, Scottsville, Seneca Falls, Sodus, Shortsville, Spencerport, Springwater, Victor, Walworth, Wayland, Webster, Weedsport, Williamson, Wolcott, Wyoming.

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