Tankless water heaters (also called on-demand water heaters) provide hot water only when you need it. They save money because you aren’t paying for energy to keep 40 to 80 gallons of water standing by 24/7. An on-demand system uses electricity only when the hot tap is turned on. (Gas-fired demand heaters have a pilot light, but that heat is captured and used to preheat the incoming water). The hot water flows directly from the heater to the tap without a side trip through a holding tank.
For homes that use around 40 gallons or less of hot water per day, tankless water heaters can be 24-34% more energy efficient than conventional storage tank water heaters. They can be 8-14% more energy efficient for homes that use a lot of hot water—more than 80 gallons per day. You can achieve greater energy savings (27-50%) and eliminate supply concerns by installing a small tankless water heater at each hot water outlet, but of course, that increases your capital outlay.
When a hot water tap is turned on, cold water is drawn through a pipe into the heating unit. Either a gas burner or a high-power electric element heats the water as it moves through copper tubes. The hot water then flows directly to the tap. Demand water heaters deliver a constant and unending supply of hot water.
If that sounds too good to be true, here is the catch: The supply is unending but not unlimited. Demand water heaters can only raise the temperature of a given volume of water by a certain amount as the water flows through them. Thus the amount of hot water produced is limited by the volume of water that can physically pass through the heater and by the water’s starting temperature.
Typically, demand water heaters provide 120 degree water at a rate of 2–5 gallons (7.6–15.2 liters) per minute (gpm). Most showers heads have flow restrictors that limit the shower to 2.5 gallons per minute. (Unrestricted showers use 5-10 gpm.) Gas-fired demand water heaters can produce higher flow rates than electric ones. Sometimes, however, even the largest models cannot provide enough hot water for simultaneous uses. For example, taking a shower and running the dishwasher at the same time can demand more hot water than a single unit can deliver.
Contact us today to let the experts at EDGE Energy guide you through the process of evaluating your hot water needs to determine if an on-demand system will be both effective and cost efficient for your home.
EDGE Energy is a highly-regarded Residential, Commercial, and Government renewable energy systems installer and “green” building contractor which is licensed, insured, and bonded in all counties of VA, DC, and MD. We design and install custom solutions for energy efficiency and renewable energy systems with pride and with proven track records. Our special focus is completing projects which decrease utility bills and energy consumption by 25% to well over 100% – even creating homes that are “net-positive.” An Energy Audit is the first step to your energy efficient home!
Visit our project maps page to learn about homeowners in your neighborhood that have worked with EDGE in the past. Remember, EDGE Energy works with HOA’s, civic groups, trade organizations, office pools, or just simply any GROUP of organized homeowners interested in completing blocks of energy audits AND retrofit services like weatherization, duct-sealing, or air-sealing, and attic insulation. Many special pricing offers have been extended in the past due to the hard work of various “Neighborhood Champions” – those who have dedicated extra time to organizing group meetings, gathering email distribution lists, and assisting with scheduling.
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To achieve Passivhaus certification, the homes have to achieve a minimum air tightness level of 0.60 ACH 50, which is five times “tighter” than the 3.0 ACH 50 required of new Maryland code-built houses. In this image, Robert Champ of...
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