Available Sizes | FAQ | Pool Heating Glossary

specs & sizes

FAQ's

Sometimes we all need a little help with pool product decisions and processes. Here we present some Frequently Asked Questions regarding pool heating systems and energy-related issues.

1) Should a solar blanket be taken off an unheated pool during the day?
During the day, solar energy from the sun heats the pool. While there are plenty of manufacturer claims saying their blankets "heats" the pool, this is false. All blankets block some of the solar energy coming from the sun. Industry data indicates that clear covers block 5% to 15% of the sun, while colored blankets block 20% to 40%. So, should a pool owner uncover the pool during the day when it is not in use? It depends. On calm, humid days, take it off because the extra heat outweighs evaporation. On dry, windy days, the evaporation loss outweighs the cover loss, so it's advisable to leave it on. The darker the cover, the more beneficial it is to take it off. Always leave a cover for cloudy days and at night.

Quick tip: Check out the dew point from your local weather service. If it's below your pool's current temperature, keep the cover on. If it's above your pool's temperature, take it off. This isn't a perfect method, but it will always come close. On a very sunny day, it might be better to keep the solar cover off even if the dew point is a couple degrees below your pool's temperature.

2) What types of pool heaters are available today, and how does each work to heat the water of a pool or spa?

• Direct Heater: Heats the tubes through which water circulates.

• Electric Heaters: Elements submerged in water use electrical energy to extract heat from the air, upgrade it with a compressor, and then transfer it into the water.

• Fossil-Fueled Heaters: Natural or Propane gas is burned in a combustion chamber whereby the heat is then transferred into the pool water.

• Indirect Heaters: Circulate steam or hot water inside an exchanger through which water flows.

• Solar Pool Heaters: Transfer energy derived from the sun's rays to heat the water as it passes through the solar panels. Solar Pool heaters are available for both in-ground and above-ground pools.

3) How does someone determine what size and type of pool heater is best them?
While each situation is different, this list of factors should always be considered when sizing and selecting a pool heater:

• Desired swim season length;

• Preferred water temperature;

• Type of pool use (exercise, kids playing, casual dips, etc.);

• Therapeutic requirement;

• Screen enclosures and other direct shading of pool surface;

• Open space and windbreaks, especially along northwest to northeast exposures;

• Waterfront location;

• Distance between pool equipment pad and pool heater;

• Availability of sufficient unshaded roof or other installation location, if considering solar heaters;

• Direction best available roof area faces, if considering solar heaters;

• Willingness to use a pool blanket; and

• Ability and willingness to pay increasing energy costs.

4) What will solar energy cost me if I want to use solar energy to heat my swimming pool or hot tub?
A pre-fab system can be purchased for several hundred dollars. Heating an average pool for the swimming season uses about the same amount of energy as most homes require per year. The costs go beyond monthly heating bills when considering greenhouse gas emissions involved. A solar pool heater pays for itself quickly. Solar pool blankets are the cheapest way to reduce heat loss and save energy. A pool owner also can make their own solar pool heater using a simple pump and some black PVC piping.

A solar pool heating system will cost between $2,000 and $4,000, depending on size, model specifications and options—e.g., automatic controls. Since energy is being saved, the pool owner may qualify for government financing incentives. As with most solar power, the closer you are to the equator, the more energy you will get out of your system.
Almost anywhere in the world, a solar pool heater is a good investment.

Typically, a solar collector should be at least half the square footage of the pool surface area. Collectors should be facing the sun. In more northern areas, there will be just one setting for summer swimming fun. Those who live in warmer climes will need to adjust their solar panels with the seasonally moving sunlight.

A solar pool heater simply plugs into the existing filtration unit. The option exists for an automatic system, which will have a controller and sensors to open and close a valve, deciding whether to send water back into the pool or through the collectors.

5) What should the temperature of a swimming pool be?
The answer resides with the individual pool owner. However, the pool temperature recommended by the American Red Cross for competitive swimming is 78° F. This may be too cool for young children and the elderly, who may desire 80° F or higher. The typical range is 78°- 82° F.
Keep in mind that the energy consumption for each degree rise in warmth will cost from 10% to 30% more in energy costs, depending on location. In warmer climates the percentage is higher due to the relatively low cost of heating to 78° F.

6) What are some ways to reduce pool heating costs?
Regardless of the type of pool heater purchased, there are a number of ways to reduce heating costs. Browse this tip list for help:

• Keep a thermometer in the water. It will determine the temperature that is perfect for you.

• Keep the thermostat at the lowest setting that still maintains a comfortable swimming environment.

• Mark the "comfort setting" on the thermostat dial to avoid accidental or careless overheating.

• Lower the thermostat setting to 70 degrees when the pool will go unused for three or four days. For longer periods, shut the pool heater off.

• Protect the pool from wind using a fence or hedge. A 7-mph wind at the water surface can triple a pool's heat loss.

• Use a pool cover when the pool is not in use. This will reduce energy consumption by 50% to 75%.

• A pool heater should be tuned up annually to operate at peak efficiency.

Editor's note: References excerpted from
http://www.thesolarguide.com/solar-thermal/pool-heaters.aspx
http://www.swimmingpool.info/
http://www.americansolarenergy.com/

Pool Heating Glossary

Browse our complete library of commonly used terminology relevant to swimming pool heating, power terms, and energy forms.

Acid rain: Rain with a harmful level of sulfuric, nitric, and other acids. Proven deadly to some ecosystems, it arises from emissions released in burning of fossil fuels.

Alternating current (AC): An electric current that alternates direction between positive and negative cycles, usually 50 or 60 times per second. Alternating current is the current typically available from power outlets in a household.

Ampere: A measure of electrical current. It is the number of electrons flowing past a given point in an electrical conductor in a given amount of time.

Base load: The minimum energy level a company provides its customers on a constant basis.

Biomass: Any organic material—especially trees and other vegetation—grown or produced for use as a renewable energy resource. Also called stored solar energy, wood burning, agricultural wastes, or methane gases spin turbines that then generate electricity.

BTU: Stands for British Thermal Unit—the amount of heat energy needed to raise the temperature of one pound of water by one degree Fahrenheit.

Calorie: Metric thermal unit: the amount of heat energy needed to raise the temperature of one kilogram of water by one degree Centigrade. The word is used in two contexts: large calories and small calorie. The "small calorie" used in fuel research, is the amount of energy needed to raise the temperature of one gram of water one degree Celsius.

Carbon Dioxide (CO2): The colorless, odorless gas that is formed during normal human breathing. It is also emitted by combustion activities used to produce electricity. CO2 is a major cause of the greenhouse effect that traps radiant energy near the earth's surface.

Clean energy: See Renewable energy.

Concentrator: Usually a reflective mirror that focuses and enhances the sun's rays onto a photovoltaic surface. This may sometimes refer to a lens with the same purpose.

Competitive Power Supply: Any company that usually generates and then sells power.

Conservation: Achieving the reduction of energy usage through increased efficiency or reduced waste.

Deep cycle battery: A battery designed to tolerate up to 80% discharge of its capacity.

Depth of discharge (DOD): The amount of energy (expressed in percentage of its rated capacity) withdrawn from a battery, a battery bank, or a cell.

Deregulation: Governmental relaxation of controls. In terms of the electricity market, deregulation refers to ending monopolies by local utilities and allowing privatization.

Direct Current (DC): Electric current flowing in one direction in invariable amperage. This is most often associated with battery power.

Distributed Generation (Distributed Energy Resources): Electricity that is provided by small power generators located at or near end users.

Electric utility: Any agency or authority aligned with distribution facilities for delivery of electrical energy to the public. The notion of utility varies widely from state to state and from time to time, depending on fickle laws concerning regulation and deregulation.

Electric Utility Restructuring: Also called deregulation, this is the introduction of competition into various phases of electricity production.

Emissions: In the context of global warming, this is the release of radiatively relevant greenhouse gases. One example is the release of carbon dioxide during fuel combustion in an automobile engine.

Energy-efficient: A qualification of electrical products, in which they achieve an appropriate ratio of energy usage to work-type output. For example, an energy-efficient light bulb will use most of the input electrical energy to produce light, not heat.

Energy: The capacity to do work.

Energy sources: Three primary categories are fossil fuels (coal, oil, gas); nuclear (fission and fusion); and renewable (solar, wind, geothermal, biomass, hydro).

Evacuated tube: Used in solar thermal collectors, these are glass absorber tubes with the air evacuated and through which collector fluids (water or perhaps glycol) flows.

FERC: In the USA, The Federal Energy Regulatory Commission is an independent government agency that regulates rates charged by public utilities. Its jurisdiction is somewhat disputed but it includes the sale of electric power for resale.

Flat Plate Pumped: Most widely used among solar thermal collectors, this typically consists of a metal frame, glazing, absorbers (usually metal), and insulation with a pump liquid (typically glycol) as the heat-transfer medium: used in water heating applications.

Fluorescent light: A lighting device that uses an electrified gas rather than filament.

Fossil fuels: Fuels (oil, coal, and gas) formed eons ago from decayed plants and animals.

Fuel Cell: A device producing electricity at high efficiency using a fuel and a chemical (usually an oxidizer) that reacts with it at two separate terminals, producing electricity.

Geothermal: Heat from the earth, customarily applied to energy from geysers and hot springs—which is now better characterized as hydro-geothermal. In recent years, this term is applied to any heat stored in earth and available as a renewable energy resource.

Global warming: The earth's gradual warming due to the "greenhouse effect."

Greenhouse effect: The effect achieved by the buildup of gases—e.g., CFCs and carbon dioxide—in the earth's atmosphere causing the earth to become hot (as a greenhouse).

Grid: The electrical distribution system, as laid out by wires, conductors, stations, etc.

Heater: A device used to heat the water of a pool or spa.

• Direct Heater: Heats the tubes through which water circulates.

• Electric Heaters: Elements submerged in water use electrical energy to extract heat from the air, upgrade it with a compressor, and then transfer it into the water.

• Fossil-Fueled Heaters: Natural or Propane gas is burned in a combustion chamber whereby the heat is then transferred into the pool water.

• Indirect Heaters: Circulate steam or hot water inside an exchanger through which water flows.

• Solar Pool Heaters: Transfer energy derived from the sun's rays to heat the water as it passes through the solar panels. Solar Pool heaters are available for both in-ground and above-ground pools.

Heat exchanger: An indirect pool heater that transfers heat (through a solid) from one fluid to another without mixing the two fluids which is the main heating feature of a pool heater.

Heat Pump: A direct pool heater in which a fan pulls warm outside air past Freon gas, transferring the latent heat in the outside air to the Freon gas that is being pumped through a condenser coil. The heat is then released to the water in the pool as it passes by the Freon gas in the evaporator coil. This process's efficiency depends upon the amount of latent heat in the outside air and the relative humidity. The cooler the outside air and the lower the humidity, the less effective the unit is in heating the swimming pool.

Hydropower: Power obtained from the (typically gravitational) movement of water.

Incandescent light: A bulb using resistance to produce light when an electrical current passes through it. The conductor is usually a wire or filament.

Incentives Subsidies: Government actions in which indirect money is given to consumers under certain conditions.

Insolation (Solar): Radiant energy impinging on the earth in any given region or area.

Inverter: A device that changes direct current (DC) into alternating current (AC).

Joules: A measure of work or energy used in the Imperial System. A measure of work or energy. A simple definition is that a joule is the work required to lift a mass of about 100 g for one meter under the earth's gravity.

Kilowatt (kW): One thousand watts of electricity (see Watt).


Kilowatthour (kWh): One thousand watthours.
Load: The electricity required and used by any single or collection of electrical item(s).

Load profile: Collected information on a customer's usage over a set period of time. It is sometimes shown as a graph on the customer's bill.

Maximum power point (MPP): The voltage at which a PV array is producing maximum power.

Maximum power point tracker (MPPT): A power conditioning unit that increases the power of a PV system by ensuring operation of the PV generator at its Maximum Power Point (MPP). The ability to do so can depend on climate and the battery's state of charge.

Megawatt (MW): One million watts of electricity (see Watt).

Net Metering: An arrangement permitting a household or business (using a utility meter that spins forward and backward, reading both inflows and outflows of electricity) to sell excesses of power generated over its load back to the utility supplier to offset costs.

Nuclear fusion: A potentially limitless source of energy in which nuclei are fused, with an accompanying release of energy.

Off Peak/ On Peak: Times when energy demand and price is low (off-peak) or high (on-peak).

Ozone: A major agent in the formation of air pollution, this is actually a form of oxygen. Ozone is a result of photochemical reactions involving emissions from automobile and industrial processes. Ozone does occur naturally in earth's upper atmosphere (the ozone layer) where it protects the earth's surface against harmful effects of the sun's radiation. Ozone accumulation close to the earth's surface is harmful. Ozone depletion in the upper atmosphere is also harmful, as the ozone layer is essential to the preservation of the earth.

Passive Solar: A system in which solar energy alone is used for the transfer of thermal energy. Pumps, blowers, or other heat transfer devices that use energy other than solar are not used.

Peak load: The maximum demand for energy on a utility system that has to be met by the utility's power generating capacity.

Peak Watt: A manufacturer's unit indicating the amount of power a photovoltaic cell or module will produce at standard test conditions (normally 1,000 watts per square meter and 25 degrees Celsius).

Renewable energy: Energy from sources that cannot be used up or that are naturally replenishing: sunshine, water flow, wind and vegetation. Some add the qualification "Cannot be used up in one lifetime." Still other note that these are "flow-limited," in that there is a limited amount of energy per unit of time.

Renewable energy device: Any device that harvests a renewable energy resource. Solar panels, solar collectors, wind machines, hydroelectric turbines are a few examples.

The Renewable Portfolio Standard (RPS): In the U.S., this is a mandate requiring that renewable energy provide a certain percentage of total energy generation or consumption.

Solar cell: A device made of silicon and semiconductor materials, producing electricity when exposed to sunlight. Movement of electrons is produced by fabrication of adjacent layers of materials with different characteristics.

Solar cooling: The use of devices that absorb sunlight to facilitate convection, similar to processes used in gas-fired refrigerators.

Solar electricity: Electricity produced in photovoltaic processes, by action of sunlight.

Solar energy: The radiant energy of the sun. This can be converted into usable forms of energy, such as heat or electricity.

Solar modules: Also called solar panels, these are the large collections of solar cells that can produce electricity at a worthwhile rate. These are packaged for end use and suited to be incorporated into solar energy or solar electricity) systems.

Solar Thermal collector: A device designed to collect solar radiation and convert it into thermal energy (usually to heat water).

Solar Thermal energy systems: Systems that collect the sun's energy to produce heat—usually to heat water.

Thermal: Pertaining to heat gain and heat retention.

Uninterruptible power supply: A device (likely containing batteries) that stores power for use when conventional power is unavailable—e.g., during a blackout.

Utility-Interactive System: Any solar PV installation that is connected to and interacting with a utility power line.

Volt: The unit of electric potential (intensity) and potential difference. It is also a relation of current to resistance—i.e., 1 volt is the potential difference across a resistance of 1 Ohm when a current of 1 Amp is flowing.

Watt (Electric): The basic unit of electrical power. It is only ever defined in reference to current and intensity—as in 1 watt equals 1 ampere of current under pressure of 1 volt.

Watt (Thermal): A unit of power in the metric system, expressed as energy per second.

Watt hour (Wh): A measure of energy, equal to 1 watt of power used or received by an electric circuit steadily for the duration of one hour.

Editor's note: Taken from sources found at
http://www.thesolarguide.com/glossary.aspx
http://www.pcpools.com/poolq4.aspx

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