Solar Hot Water
Solar domestic hot water systems are highly effective at reducing fossil fuel costs and reducing CO2 emissions. A typical residential system can reduce carbon emissions by more than 5,000 pounds and can save more than 300 gallons of oil per year, depending on your current hot water heating system.
After 10 years installing and servicing Solar Hot Water systems in Maine’s harsh climate, we've distilled our knowledge into a design we believe to have the highest efficiency and longevity, with the lowest installation costs.
ReVision Energy’s solar hot water systems are compatible with any existing water heating system, whether it's electric, gas, or oil-fired. Would an investment in solar domestic hot water make sense for your home? Contact us for a solar site evaluation to help answer that question.
Oil Boiler Control Upgrades
Does your furnace kick on in the middle of a hot sunny summer day? This is a common problem in the northeast because most boilers are set up in a ‘hot start’ mode whereby the boiler maintains an internal temperature of 180 degrees 24/7, 365 days per year. This is terribly wasteful in the summer months and the shoulder seasons because roughly 85% of your heat energy is going up the chimney and warming your basement. We can help you solve these problems.
Cold Start Boiler Control Option
At ReVision Energy, we have found that modifying the controls on your boiler, in conjunction with a solar hot water installation, can save a bunch of oil and the associated CO2 emissions. By converting a boiler to a ‘cold start’ mode, we can effectively shut down the boiler for most of the time from May to October. In this mode, the boiler only fires when it is called by a thermostat to produce heat, or called by the solar storage tank to provide supplemental hot water. This control upgrade is possible for most boilers and is generally included in our system quote.
Intellicon Boiler Control Option
Another control upgrade that can result in a savings of fuel is the Intellicon smart burner control. IntelliCon®-HW+ is a microprocessor-controlled, fuel-saving device for hot water (hydronic) heating systems. IntelliCon-HW reduces fuel consumption, wear on parts, flue emissions and electrical usage, when installed on any new or existing gas or oil burner. IntelliCon-HW+ saves energy by adjusting the burner run pattern to match the system’s "heat load." Its action is similar to the industry-accepted method of "outdoor-air temperature reset control," but does not require an outdoor-air temperature sensor or the need to profile the building in order to adjust the "reset" controller properly. IntelliCon-HW+ determines the "heat load" by using an easily installed strap-on temperature sensor that monitors the boiler’s out-flow water temperature and the rate that this temperature is changing. The additional cost is assessed on a case-by-case basis.
Outdoor Reset Boiler Control Option
Outdoor reset controller modulates the boiler supply temperature based on outdoor air temperature. This enables the boiler to operate at an increased efficiency and reduce fuel consumption by roughly 10%. For addition information, log on to: 
www.taco-hvac.com/uploads/FileLibrary/OM01.pdf. The additional cost is assessed on a case-by-case basis.
Post Purge Upgrade Option
The solid-state Taco Post Purge Plug-In Card maintains power to the circulator once the priority zone is satisfied, but does not fire the boiler. The circulator purges excess heat into the priority zone, minimizing stand-by heat losses during warm weather months and optimizing boiler operation when used with a boiler reset control. Power can be maintained to the circulator from 20 seconds to 7 minutes using an adjustable potentiometer. The additional cost is assessed on a case-by-case basis.
Why Go Solar?
SAVE MONEY
Because domestic hot water is something we use year-round, its production is the number two energy hog in most households, behind only space heating. From the very first day a solar hot water system is installed, you will save money that was previously spent on fossil fuel energy.
SAVE THE ENVIRONMENT
Each 30 tube solar collector saves 1,770 lbs of CO2, 4 lbs of sulfur emissions, and 5.4 lbs of nitric emissions each year (compared to electricity).
SOLAR SHOWERS FEEL BETTER
You'll feel better knowing you are doing your part to preserve our planet and save our environment. We can't promise you'll be cleaner, but you might end up taking longer showers knowing the heat is from the sun.
How it Works
Whenever sunshine makes the solar hot water collectors hotter than the water in the bottom of the solar storage tank, a differential temperature sensor automatically activates the solar pump affixed to the tank. Sun-heated antifreeze is pumped from the collectors and circulated through a heat exchange coil located in the bottom of the storage tank, transferring the heat from the sun to your domestic hot water supply. ReVision Energy builds automatic backup into all solar domestic hot water systems so that when the sun can't get the job done, you don't have to worry about cold showers. The solar storage tank has a secondary heat exchange coil located in the top of the tank, which is plumbed to your existing heating system for backup. If this is not possible, alternative solutions include using a special tank with an electric element for backup, or installing an on-demand hot water heater.
The following major components make up the bulk of the system:
COLLECTORS: ReVision Energy recommends Apricus evacuated tube collectors www.apricus.com for most solar domestic hot water systems. After installing hundreds of Apricus collectors, we have found that in real-world applications the collectors meet, and often exceed, the performance specifications on the manufacturer’s website. In Maine’s relatively harsh climate, the superior insulation of the vacuum tube design prevents system heat losses during cold weather. Flat plate collectors offer slightly better summertime performance than evacuated tubes. In applications where high demand will come in the warmer months (seasonal homes, i.e.), or where cost is a primary concern, we offer the Stiebel Eltron Flat Plate collector www.stiebel-eltron-usa.com.
SOLAR STORAGE TANK: We believe Stiebel Eltron manufactures the best dual coil solar storage tank on the market www.stiebel-eltron-usa.com/ifwh.html. Stiebel's purpose-built tanks are super-insulated to store precious BTUs harvested from the sun and its two internal heat exchange coils allow for easy integration with almost any boiler-based heating system. This porcelain-lined steel tank comes with three inches of foam insulation and a sacrificial anode that is easy to view and replace if necessary. For applications where access is difficult, where backup hot water is provided with electricity, or where a two tank solution is preferable, we use Superstor or Marathon water heaters.
CLOSED CIRCULATING LOOP: Two ½-inch copper pipes form the closed solar circulating loop, which travels from the solar collectors down through the interior of the home (or exterior) to the solar storage tank. Non-toxic, breakdown-resistant propylene glycol antifreeze fluid www.dow.com/heattrans/family/dowfrhd carries the heat from the collectors to the heat exchange coil in the bottom of the storage tank.
STIEBEL ELTRON FLOWSTAR PUMP STATION
JOHNSON CONTROLS DIGITAL SETPOINT CONTROLLER
HONEYWELL AM-1 SOLAR QUALITY ANTI-SCALD MIXING VALVE
EXPANSION TANK
Commercial Projects
Businesses that have high hot water usage can dramatically reduce their fossil fuel costs and CO2 emissions by having Revision Energy install a solar hot water system.
Solar Space Heating
Solar space heating is a challenging application for solar hot water collectors, but it is viable under very specific conditions. If the building is super insulated, has a high efficiency boiler, and has low temperature radiant distribution, solar space heating may be viable.
Learn more about Solar Space Heating
Incentives
The federal government offers a 30% tax credit for solar hot water systems (uncapped for commercial projects, capped at $2,000 for residential projects). We recommend you contact your accountant or financial advisor to see if your project qualifies for the federal tax credit.
Estimated Costs
Estimated costs are based on average conditions of roof height, roofing materials, distance from tank to collectors and other factors. Before any installation, we will visit your home or business to determine how to best meet your needs, and we will prepare a detailed quote.
40-tube system with an 85 gallon tank (good for a family of 2-3):
- Roughly $10,000 before the federal tax credit
60-tube system with a 105 gallon tank (good for a family of 4-6)
- Roughly $11,000 before the federal tax credit