A heat pump is a device that uses a small amount of energy to transfer heat and store it. This technology has become increasingly available in both water- and space-heating equipment. Heat pumps are typically selected based on which source of heat will be most efficient. Some household systems (such as the one shown) include both air- and water-source pumps that condition air, before distributing it through ducts to the home. The water-to-air unit, for example, might be better for heating in the winter months, while the water-to-water unit will efficiently provide cooling in the summer.
In large or multi-family homes, if the heating unit is far from the point of use, you can waste a lot of water waiting for the hot water to reach your faucet—as much as 40 gallons a day or 14,000 gallons a year for the average U.S. household. Recirculating pumps move hot water from the source and back again, creating a hot water “loop.” This allows you to have instant hot water access from any faucet. The pump can be activated by a motion sensor, then automatically shut off after a few minutes. No water is wasted, and the cost to run the pump is minimal. The Uponor D’Mand Hot Water Delivery System is shown here.
Insulated Water Tank
The best hot water storage tanks lose only about half a degree of water temperature every hour. That amounts to big savings, because water that’s not used immediately doesn’t have to reheated all day. Standard boilers used with insulated tanks are sometimes called “indirect” water heating systems--and are sometimes a good retrofit option or a more affordable choice than on-demand boilers.
An often overlooked factor in heating and cooling performance in homes with forced-air systems (vents and registers) is heat loss through ducts. By some estimates, duct leakage accounts for up to 70% of a home’s air leakage when the furnace blower is operating. To prevent this, all duct seams and joints should be carefully sealed. Ducts that pass through unconditioned or partially conditioned spaces such as attics and basements should be insulated.
The boiler shown above is for a very specific purpose—to keep two hot water tanks at the ready for a radiant floor heating system in the home. As such, the water produced is not intended for drinking. It’s part of the heating loop. This type of boiler has been around a long time, but the science of “modulation” keeps improving. Modern, high efficiency boilers have computerized controls that adjust performance based on demand—to produce the most hot water at the lowest energy cost.
Bosch “Instant” Hot Water
An alternative to storing hot water is an “instant” on-demand boiler. These units typically create only as much hot water as is needed, rather than storing it in tanks. Before you buy, however, check how much hot water the unit can produce. If you plan to run a shower and a dishwasher simultaneously, you’ll need the right fire power. The Bosch Greentherm Model C950 ES is shown. Bosch also offers a “Bosch ProSizing” app you can use on a smartphone, available on Google Play.