As tankless water heaters become more and more popular the number of manufactures and models are increasing. A tankless is also referred to as an on demand water heater and as you would expect there is no storage tank on these systems. Using a more powerful burner a tankless can heat water instantly removing the need for the storage tank. Although it uses more fuel while heating water it uses absolutely zero any other time, this results in an average of 40% fuel savings over a conventional tank that always keeps your water hot.
On the newer side of things are the condensing tankless water heaters available to home owners now. These units use two heat exchangers. The first is primarily used to heat water to your desired temperature. The second is smaller and located near the top of the unit where the exhaust gases are used to preheat the incoming water. Using this normally wasted heat in the exhaust bumps up the efficiency of a condensing tankless to 95% or better.
A conventional tankless doesn’t take advantage a second heat exchanger and thus the exhaust gases are much hotter and actually require special venting materials. This can sometimes add to the cost of installing a tankless. Whereas your condensing tankless utilizing that second heat exchanger significantly reduces exhaust temperatures, this allows contractors to use less expensive venting materials.
In general for Canadians a condensing tankless works a little better. Preheating the incoming water (which is cold during our winters) allows the tankless to throttle down its gas usage when only a little hot water is needed. Yet, when a high demand appliance requests a lot of hot water the tankless has more than enough power to supply the request. See the recommended Canadian tankless installers and tankless systems.
A condensing tankless cools the normally hot exhaust so much that moisture actually builds up inside the heat exchanger. Moisture and steam are by-products of combustion and this is a very normal result. As water clings to the side of the heat exchanger it builds up until it starts to drip down, this water is acidic due to combustion; the water has a pH between 3 and 5. Rheem has a buffer tank built into its tankless systems to neutralize the condensate. Rinnai has an external system that buffers this excess water. Other manufactures have different systems, if you’re interested in any particular one give us a call.
To Conclude condensing tankless water heaters are incredibly efficient (up to 98%), and use inexpensive venting material saving on installation costs. A condensing unit is more expensive to purchase but prices start to even out when purchasing exhaust materials for a regular tankless. The choice is yours with regards to which system you feel best fits the needs of your home.
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