Solar Water Heating Bob Ramlow Chapter 3: Types of Solar Water Heaters Bruce Hesher Engineering Technology Brevard Community College

Major Collector Types Standard Electric: Low equipment cost and simple system. High electric energy cost! ICS Integrated Collector System: Collector is storage tank. Flat Plate Collectors: Most common type. Used with a tank. Evacuated Tube Collectors: Used in commercial settings where high temperatures are needed. Concentrating Collectors: Used to make steam for electical generation. Pool Collectors: Black plastic tubing using high volumeof water flow. Air Collectors: Used to heat buildings.

Standard Electric System Commonly installed original equipment. Install a water heater blanket. Insulate the hot water lines throughout the building. Shortest life expectancy (6-10 years). Have 2 heater elements; one in top of tank and one at bottom of tank.

Lower Water Heating Temperature for Energy Savings The temperature is often set by turning a dial on the element itself. Set temperature to lowest acceptable setting and install a timer so the tank is not kept hot all night long. Higher temps accelerate mineral build-up. See: Mineral build-up on the elements reduce efficiency. The lower element is more susceptible to buildup. Shut off power to the tank, drain it, remove and clean the elements annually.

ICS Collectors Roof mounted and do not use a tank in the building. Heavy lbs when full. May require roof reinforcement. Used where freezing is not an issue. They are “Direct” systems. Good for areas with there are hard water problems due less small diameter piping. They are simple and inexpensive. Mount at an angle so that they will drain properly.

Flat Plate Collectors Most widely used type for domestic SWH. Durable effective. Mount tilted so it will drain. Used with a tank. See diagram page 24.

Evacuated Tube Collectors Used where high temperatures are needed. Restaurants, motels, hospitals, etc. Heat absorbing tube surrounded by a vacuum to limit convective losses. Often have a parabolic reflector to concentrate light on the absorbing tube.

Comparing Flat Plate and Evacuated Tube Collectors Flat plate are residential, evacuated tube are commercial. Evacuated tube are high temp. Efficiency is only one metric, also look at cost. Remember, unused hot water is no benefit. Flat plate collectors are not as sensitive to shading as Solar electric modules (panels) so, reserve best roof estate for PV! See

Concentrating Collectors (CSP) Used in commercial power stream generation. Mirrors reflect on a water tank to make steam. Or a mirrored parabolic dish is used to heat oil then run through a heat excahnger to make steam for a turbine. See

Pool Collectors Low pressure high volume. Goal is to keep the collectors cool by capturing heat energy in the pool! If collector gets warm it will re-radiate to surrounding air. Roof top collectors still require circulation but this can be on return line of pool pump so long as there is enough head to pump water to roof. Keep water flow volume high as possible. Pool blankets are passive and effective. Work by reducing the heat loss due to surface evaporation. 70% of heat loss is surface evaporation.

Air Collectors Used to heat air for building space heating. Not popular in Florida. Construction similar to flat plate collectors but no water or piping.