Solar domestic hot water (DHW) systems use sunshine to heat the water for your home or office. There are different kinds of solar domestic hot water systems. NW Mechanical solar hot water systems are designed to maximize the solar potential in the area where you live, offering our customers an efficient and effective way to cut their payments to the utility company. Our licensed plumbers install your system. Additionally, you receive the high quality customer service of NW Mechanical. You can see below the last 24 hours of production from the Apricus 22 evacuated tube system we have installed on our front entry roof. This system is matched with a 60 gallon TriangleTube storage tank. You won't see a lot of action from our system because the water is generally only used on thursdays when our field technicians wash their trucks. There's a weird reason for that and it has to do with the building have been an oil change shop prior to us being here.
The Last 24 hours of production for Northwest Mechanical
WHY USE SOLAR?
There are many reasons to use a solar in the Pacific Northwest. Solar domestic hot water systems pay dividends through a Federal energy tax credit and offset energy usage. Solar domestic hot water systems installed by Northwest Mechanical are reliable, quiet, sharp looking, and designed to last. Solar also improves the quality of the air we breathe by reducing greenhouse gas emissions while generating energy without pollution. In addition, having a solar domestic hot water system on your house can increase the value of your home and even increase resale value.
SOLAR ON CLOUDY DAYS, IN RAINY SEATTLE?
Solar domestic hot water (DHW) systems can produce hot water on cloudy days, but just not as much as on a sunny day. The type of solar DHW system that NW Mechanical uses – evacuated tubes – is very efficient in soaking up the sun’s rays to heat the water and is particularly effective in cloudy areas compared to other types of DHW systems. Although it might be surprising, Seattle receives about 70% of the annual solar potential that the Los Angeles area receives; so our solar potential is far higher than most believe.
BASICS OF SOLAR DOMESTIC HOT WATER SYSTEMS
Solar domestic hot water systems use the sun’s rays to heat water reliably and pollution-free. The solar domestic hot water systems designed, installed and serviced by NW Mechanical use Apricus evacuated tubes to harness the sun to heat water.
In a nutshell, the Apricus DHW system includes a collector where the heat from the sun is collected inside glass tubes. These tubes then are attached to a header where the heat from the tubes is transferred to a liquid that flows to the solar hot water tank. At the solar hot water tank the heat is transferred to the water in the tank. This water typically is a pre-heater to your regular house hot water tank, but you can use the solar hot water tank as your sole source of hot water if you wish. The sections below outline these different parts in more detail.
THE COLLECTOR
The collector is the core of the Apricus DHW system. It is made up of glass tubes that collect the heat from the sun. The collector typically is placed on your roof since it often is the easiest access to sun and space to mount.
Glass tubes
The Apricus tubes are long, round and narrow. The tubes are sealed and have two layers of glass. The space between the two layers of glass has been evacuated (that is, the air has been drawn out). Because of this evacuated space, the tubes are very effective in holding heat – similar to how a thermos keeps liquid hot because of the outer shell of evacuated air. The glass tubes are specially designed to capture and utilize sunrays from many angles (absorbing 92-93% of the sunlight striking the tubes).
Rod
A small copper rod is inside the tube. This tube also has been evacuated, which forms a vacuum, and has a small amount of water inside. Under these conditions, the water vaporizes at a low temperature, rapidly transports the heat to the top of the pipe, off-loads (or transfers) its heat to the fluid in the system (see “heat transfer fluid” section), condenses, and flows back to the bottom to repeat the cycle.
Header
The header is the top of the collector. The glass tubes connect in to the header. The header is where the heat from the copper rod is transferred to the fluid that flows to your solar hot water tank.
With this system, it takes only a small amount of sun to quickly and effectively heat your water.
A collector can contain various numbers of glass tubes, and a system can contain more than one collector to increase the amount of heat you collect. Apricus systems from NW Mechanical are sized to meet your needs.
HEAT TRANSFER FLUID
In NW Mechanical’s systems, the fluid used to transfer the heat from the collector to the solar hot water tanks is a non-toxic antifreeze liquid.
SOLAR HOT WATER TANK
A solar hot water tank is used in our Apricus systems, separate from your regular hot water tank. NW Mechanical tanks are high quality, stainless steel tanks that are very durable and long-lasting. The solar tank has a very efficient system to move the heat from the fluid that has come from the collector to the water that is in the tank through the natural process of heat transfer.
PUMP
A pump is used to move the heat transfer fluid through the system from rooftop to the solar hot water tank and back to the roof. The pump runs only when the controller allows it to (see “controller” section).
CONTROLLER
The controller monitors the temperature of the heat transfer fluid and the water in the solar hot water tank. Only if specific conditions are met will the pump run – e.g. the collector fluid is hotter than the tank fluid, the hot water tank is below its desired temperature. This way the water in the tank is not overheated and the pump runs only when heat is needed and available.
RESOURCES FOR MORE INFORMATION
If you would like to learn more details about solar domestic hot water systems, including other types of panels and configurations of systems and educational opportunities, there are many resources. We have listed a few here.
Home Power Magazine, homepower.com
Department of Energy, www.energy.gov/energysources/solar.htm
Solar Energy International, www.solarenergy.org
American Solar Energy Society, ases.org/index.htm
Solar Washington, www.solarwashington.org
Shoreline Solar Project, www.shorelinesolar.org
