As a homeowner, there are a few important considerations which can help you choose the right sized and temperature system to meet your needs.
Sizing of system : 50; 65; 80 gallon
System sizing is based on your lifestyle and the facilities for hot water. An average traditional home may have showers only, and can consist of 4 persons in the family, each person requiring about 15 gallons. So a 65 gallon system @135 degrees F would be recommended.
The 3 bedroom home with a shower, tub and 4 persons would need an 80 gallon system.
An up-market modern home with a Jacuzzi would need 130 gallons to 160 gallons.
If the kitchen and laundry are far from the bedrooms, a separate system is recommended so as to minimize the wait for hot water.
A villa may house more persons and should be sized on the premise that it will be full at peak season.
A site inspection is necessary to determine the following:
- Size of family
- Type of facilities
- Type of roof
- Best location to fit system facing south or west (never east or north)
Hot Water Usage
Hot water usage may fall into three categories:
Conservative user: 15 gallons per person in the household
Average user: 20 gallons per person in the household
Generous user: 25 gallons per person in the household
Spa use: A volume of 50% of the capacity of a spa pool needs to be added where a spa is installed, to ensure an exhilarating experience.
Why does the capacity need to be larger than an electric storage heater?
Unlike a gas or an electrical water heater, the cumulative volume of hot water required for use in the evening and the morning following, needs to be generated and be in storage by 5.00 p.m. The typical electric water heater is capable of reheating its rated storage capacity every hour. Therefore a 30 gallon electric water heater can deliver 30 gals x 24 times in a day/night cycle.
Stop Valve Location
The homeowner should be aware of the location of the stop valve to the water heater. A stop cock or gate valve is required on the cold line to, as well as the hot line from, the solar hot water system. These valves should be located inside the home and be accessible.
The back- up electrical booster
An electrical immersion element is fitted to each solar hot water storage tank, together with a temperature control thermostat, to provide hot water when the stored solar heated water is depleted. This could happen when there is prolonged inclement weather. When the booster switch is activated, the system will function as an electric water heater. This is intended for use only in prolonged inclement weather conditions, and as an emergency measure only.
The use of the booster should be limited to 4 to 5 times a year only. If you are finding it necessary to use the booster frequently, or to leave it in the “on” position in order to get hot water, then the solar hot water system is not functioning as it is meant to.
Electrical cost of using the booster too often
The Barbados Light and Power Company in its 2010 Calendar advises that it costs 77 cents for the electricity it takes to run a 1500 Watt element for one hour. This totals $23.10 per month or $277.20 per year. It is better to increase the collector size to avoid using the electrical booster often.
The Solar Dynamics Guaranteed temperature provides the consumer protection against low performance.
When one considers the cumulative cost of using the electrical element in this way, it would be in one’s best interest to install the right sized system, with the right temperature to meet their needs.