Placitas Solar Combisystem Retrofit

Overview

System type: Closed-loop antifreeze SHW with single heat exchanger feeding hot water flow center. Solar combisystem provides both space heating and domestic hot water

Location: Placitas, New Mexico

Solar resource: 6.7 average daily peak sun-hours

Production: 9,333 kBtu per month, average

Domestic hot water produced annually: 91%

Hot water (boiler fluid) produced annually: 60% fuel savings

Solar Equipment

Collectors: 12 Solar Skies SS-40 , 480 sq. ft. nominal area

Collector installation: Low-profile, roof-mounted at a 75° tilt

Heat-transfer fluid: 50/50 propylene glycol/water

Circulation pumps: 2 Laing D5

Pump power supply: 2 BP350J 50 W PV modules (one for each D5 pump)

Storage

Domestic hot water storage tanks: Oventrop 115-gal., dual-coil, in-tank heat exchangers

Heat exchanger: Triangle Tube TTP3-40 flat-plate

Backup DHW: No other tanks installed. Boiler backup for Oventrop tank

Performance Monitoring

Dial thermometer: 3 probe-type, in brass wells

Pressure & temperature dial gauge: 2 generic P&T gauges in brass wells

Data logging, diagnostic & control package: Solar Logic Integrated Control (SLIC) Gen1 (The SLIC controller monitors and operates all sensors, pumps, and valves)

Room sensors: 10 standard 10 kOhm thermistors in thermostats

System sensors: 6 standard 10 kOhm thermistors on heat system piping and tank

Radiant Floor System

Floor tubing: Wirsbo (Uponor) 1/2-inch HePEX

Boiler: Triangle Tube Prestige Solo (LP); 175 kBtu/hr.

Length of tubing: 5,000 ft.

Number of zones: 8

Circulation pump: 5 Grundfos UPS15-58 (three-speed)

Pump Controller: SLIC Gen1 operates all circulator pumps

Zone valves: 8 Belimo 3/4 in., latching valves, 24 VDC, LRB24-3-S

Tempering valve: Honeywell 1 in., AM102R-US-1; set to between 70°F and 180°F

Auxiliary Heat Source(s) to Solar Storage

Source: Same boiler used for zone heat (listed above) is used for DHW backup

Circulation pump: Listed previously; one of five circulators, all identical

Pump controller: SLIC Gen1 operates all pumps

Other Equipment

Overtemperature dump valve: All zone valves and all circulators listed previously can be used by the SLIC control system to dissipate extra heat into the concrete floors by day and through the solar collectors by night

Overtemperature dump-valve controller: Heat dissipation is controlled by the SLIC Gen1