Old Versus New
Most homes here in New England use a pin style single pass boiler. The rising oil cost and harsh winters here have a lot of wondering how to save on those heating bills. This has brought on a surge of European boilers to the market that are much more efficient. These boilers are referred to as low mass triple pass boilers and in some cases can save you 40% or more on your heating bill.
Bigger isn’t always better: Large-Mass vs. Low-Mass
If you were heating water for a cup of tea, would you use a pasta pot or a teapot? Think of the typical, large-mass, single pass boiler as a pasta pot (boilers typically hold 15-17 gallons of water)and a low-mass, 3-pass boiler as a teapot. European systems in today’s houses only hold 5-8 gallons of water. Why burn all the fuel necessary to heat 17 gals. of boiler water in a 600lb., single pass boiler? A low-mass European boiler with it’s 3-pass design and 4 gals. of water content will satisfy the call for heat before the single pass boiler has even warmed up. The single pass boiler has heated twice the amount of iron and four times the amount of water. All that excess heat goes “up the chimney” with your fuel dollars.
Tankless coil and indirect water heaters use a home’s space heating system to heat water. They’re part of what’s called integrated or combination water and space heating systems.
How They Work
A tankless coil water heater uses a heating coil or heat exchanger installed in a main furnace or boiler. Whenever a hot water faucet is turned on, the water flows through the heat exchanger. These water heaters provide hot water on demand without a tank, like a demand water heater, but because they rely on the furnace or boiler to heat the water directly, tankless coil water heaters work most efficiently during cold months when the heating system is used regularly. That’s why they can be an inefficient choice for many homes, especially for those in warmer climates.
Indirect water heaters offer a more efficient choice for most homes, even though they require a storage tank. An indirect water heater uses the main furnace or boiler to heat a fluid that’s circulated through a heat exchanger in the storage tank. The energy stored by the water tank allows the furnace to turn off and on less often, which saves energy. Therefore, an indirect water heater is used with a high-efficiency boiler and well-insulated tank can be the least expensive means of providing hot water.
Indirect systems can be fired by gas, oil, propane, electric, solar energy, or a combination of any of these. Tankless systems are typically electric or gas-fired. Also, these integrated or combination water heating systems not only can work with forced air systems but also with hydronic or radiant floor heating systems.