A system designed by NRT and installed by Garret Plumbing and Heating for a complete renovation project, including active solar hot water collection.

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Download a 50% size copy of the Cyr design drawings here.

The Cyr project didn't consider radiant until the large scale renovation was already well underway. The building required a low profile, over the floor solution to avoid a hard-to-seal crawlspace, and also to maximize solar utilization and efficiency with lower water temperatures.

A thin pour of concrete would have been nice, but the higher profile required and the additional mass added ruled it out. Given the floor height limitations and additional factors, Wirsbo Quik Trak was chosen as the radiant distribution method on the first floor. This radiant floor heating application does lend itself to two important benefits. First, Quik-Trak is a low-mass product and the customer will experience faster response times to thermostat settings. And secondly, the building has a high southern glazing exposure and will experience rapid passive solar heating. The Quik-Trak does not store heat like a concrete slab and will not contribute to overheating of the spaces during sunny days.

Also, since the crawlspace was unusable, the mechanicals had to be located in a small closet in an office. This made the Baxi Luna a very attractive choice for primary heat, given its small space requirements as a wall hung boiler, quiet operation, direct vent capabilities, and because a sealed combustion unit was required given the proximity of the unit to primary well-sealed living space.

Solar market was called in for their expertise on solar hot water panel supply, installation and sizing. The Sunda panels were installed on the roof, and a closed piping arrangement was used so the system could be filled with glycol to prevent winter time freezing. Utilizing a small photo voltaic panel on the roof, a small DC pump circulates the system fluid when the sun is shining, preventing heat loss through the panels at night or on cloudy days. The collected energy is transfered to the storage tank where in the winter it is then available for primary radiant floor heating or domestic hot water preheating, or in the summer it can be utilized for domestic hot water. Note that in the summer months the domestic hot water will need to be tempered since the water temperature in the storage tank can be much higher than domestic hot water requirements. This is achieved with a regular tempering valve.

The radiant supply water temperature to the zones is determined by outdoor reset and indoor feedback by modulating the output of the variable speed injection using a Tekmar 363 Mixing Control and a Tekmar 369 zone control. Both outdoor reset and indoor feedback are used to dynamically minimize the radiant water temperatures and match the heat load of the space as closely as possible. The tekmar 363 has a storage tank input feature where the solar heated water is utilized first, to maximize the efficiency of the system before calling for the Baxi Luna back up. Finally, this minimal water temperature setup helps us protect the hardwood floors installed throughout the home. Additionally, a single zone of baseboard was installed on the 2nd floor. This zone requires supply water temperatures higher than the Quik-Trak and is not operating at radiant reset water temperatures. Instead, a 2nd floor heating demand will place a separate heat demand on the Baxi Luna since the water temperature requirements exceed anything we could get from the solar. Finally, to safeguard against a possible dangerous overheating of the system water in the solar piping, a crawlspace “dump zone” air handler was installed where the system water is diverted to the air handler to rid the system of excess heat. This will be required during the summer months.