Blog by Betsy Carstairs

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Hot Water Heaters

I have recently noticed that there are a variety of different domestic water heating systems available on the market as alternatives to conventional water heaters. What are the available types of water heaters, how do they work, and what are the advantages/disadvantages of the different systems?

Other than the conventional tank style water heaters that are found in most homes, there are tankless (or instantaneous) water heaters and solar water heaters. Most Canadians have a conventional tank style water heater that is in the form of a tall cylinder with several water pipes attached to it. Both tank-style and tankless water heaters can be electric or fuelled by oil, natural gas, propane and even wood. Solar water heaters are fuelled by the sun’s energy, but are typically used to supplement standard fuel-fired or electric water heaters since it is difficult to obtain sufficient energy from the sun to heat water to necessary temperatures on an ongoing basis. Water heaters fuelled by wood are very inefficient and very rare.

Tank style water heaters not only heat the water, they also store the water once it has been heated, which is why they are so large. The capacity of a tank usually ranges from 150 Litres to 230 Litres, depending on the hot water requirements of a household. Non – electric fuel-fired water heaters are equipped with a burner situated at the bottom of the tank to allow the exhaust gases to travel through either the middle of the tank or around the outside of the tank to the exterior of the home. The exhaust gases may be vented through a chimney out the roof or through a plastic or metal pipe out the side of the home. This style of water heater is not very efficient when both operating and off-cycle losses (heat loss that occurs through the walls of the tank) are taken into consideration.

Most oil and gas or propane fired units are only 50-60% efficient! Many people think that a typical side wall vented water heater is “high efficient” given that the side venting characteristics are similar to those of a high efficiency furnace (90% plus efficient); however this is not the case. Although some side vented water heaters are high efficient, the majority have similar efficiencies as conventional chimney vented water heaters. The advantage of a side vented water heater is that a chimney is not required to vent the exhaust gases generated from the water heater and therefore initial installation costs are reduced. 
This article was provided compliments of the Amerispec News letter. As I am researching a new hot water tank in my home I thought this would be useful information for others