In the United States alone, there are over 400,000 commercial swimming pools. Over two-thirds of those pools are heated to a comfortable swimming temperature through the burning of fossil-fuels. In a world where fossil-fuel pool heating is a luxury we can no longer afford, Dave Sizelove, President &CEO of solar panel manufacturer Aquatherm Industries provides a comparative cost and payback analysis of two of the most popular types of systems designed to harness the sun for free heat.

1. Distributed Solar Thermal:
Rebirthing a Mature Technology
Pool Heating - “Open Loop” vs “Closed Loop”
Dave Sizelove, President & CEO
Aquatherm Industries, Inc.

2. The Market
In the United States alone there are...
• 5,000,000 In-Ground Residential Pools
• 400,000 Commercial Pools
Heated vs Unheated Indoor vs Outdoor
Heated Unheated Outdoor Indoor
67% 33% 60% 40%
Heated with natural gas...
CO2 emissions = 6.6 MILLION cars
(driven 12,500 miles annually)

3. The Solution
A hybrid solar pool heater consists of...
✓The most cost-effective primary heater Goal:
(Solar is free heat from the sun)
To engineer a
“reasonable balance”
✓The existing natural gas, propane or between cost and
electric pool heater for anytime heat BTU heat collection
(for times when solar will not be enough) from solar.
Projected Energy Savings w/ Hybrid Solar Pool Heater:
Year-round Pool: 40-60% Seasonal Pool: Up to 100%

4. System Types
Open Loop: Closed Loop:
Direct heating with Low-Temperature Indirect heating with a heat exchanger using
Unglazed Polymer Collectors Medium-Temperature or Evacuated-Tube Collectors
Collectors
Controller
Existing Pump & Filter Existing
Heater

5. Open Loop
Open Loop: Benefits
Direct heating with Low-Temperature
Unglazed Polymer Collectors ✓ Designed to economically raise temperatureabove
large volumes of water (like a pool)10-15 F
of
o
ambient air temperature.
Collectors
✓ Specifically designed for low-temp feed/return lines.
pool heating; inexpensive PVC for
applications like
✓ Approx. Cost - $15-20 per sq. ft. (commercial).
Considerations
‣
Controller
Little or no performance when ambient is more
than 25o F cooler than pool water temperature.
‣
Existing Pump & Filter Existing
Heater Sensitive to areas with a cool prevailing breeze.
‣ Life expectancy of 15-20 years

6. Closed Loop
Closed Loop: Benefits
Indirect heating with a heat exchanger using
Medium-Temperature or Evacuated-Tube Collectors ✓ Good year-roundclimates. especially in
cooler, northern
performance,
✓ Less sensitive to cool prevailing breezes.
✓ Life expectancy of 20-25 years.
Considerations
‣ Performance losses of 17-25% due to glazing
and use of a heat exchanger.
‣ Feed and return lines must be insulated copper
to prevent heat loss from higher temps generated.
‣ Approx. Cost - $80-100 per sq. ft. (commercial).

7. Case Studies
Annual Savings Comparison Based on D.O.E. RSPEC Program Simulations
$6,725 Based on:
Portland, OR
$9,290
‣ 4,000 sq. ft. indoor pool
$13,360
Dallas, TX ‣ 80o F pool temperature
$14,375
‣ 82o F room temperature
$9,969
Washington, DC ‣ 50% room humidity
$11,953
‣ $1.00 per therm
$8,516
Chicago, IL ‣ 75% efficient heater
$11,421
‣ 3,000 sq. ft solar area
$11,445
Atlanta, GA
$12,620 ‣ $15 / sq. ft. open loop
‣ $80 / sq. ft. closed loop
Annual Average Savings Open Loop Closed Loop

8. Case Studies
Comparative Payback Analysis Based on D.O.E. RSPEC Program Simulations
32.5000 Based on:
26 Open Loop Closed Loop
‣ 4,000 sq. ft. indoor pool
Payback Period (in years)
27.0833
21 ‣ 80o F pool temperature
20
21.6667 19 ‣ 82o F room temperature
17 ‣ 50% room humidity
16.2500
‣ $1.00 per therm
10.8333 ‣ 75% efficient heater
‣ 3,000 sq. ft solar area
5.4167 7
5 5 ‣ $15 / sq. ft. open loop
3 4
0 ‣ $80 / sq. ft. closed loop
Portland, OR Dallas, TX Washington, DC Chicago, IL Atlanta, GA