Condensing tankless technology uses the normally wasted exhaust gases to preheat incoming water.
This has been on every one of Navien’s tankless water heaters since the beginning. The addition of the secondary heat exchanger adds about a 12-15 percent efficiency increase making a tankless water heater around 97-98 percent efficient.
With one of these systems for every dollar you send on natural gas or propane 97-98 cents are actually used to heat your water. A conventional type water heater is somewhere around 50 percent efficient so literally half of every dollar you spend on fuel is thrown away.
The Navien NPE series systems have an innovative twist to their condensing tankless. The burner and heat exchanger are flipped upside down and thus, when the burner kicks on flames shoot downward. This is completely opposite to most other condensing tankless manufacture designs who have designed their systems with flames that shoot upwards. Yes, it is actually counter intuitive as heat rises upwards so you would think naturally the burner should be at the bottom.
I spent some time with a Navien representative and he thoroughly explained this (brilliant) engineering difference which I’ll try to explain it to you (hopefully as elegant as he was able to do).
A condensing tankless has a substantial amount of water form on the outside of secondary heat exchanger where the exhaust gases are flowing past, this of course is what makes it a condensing tankless. With the presence of the exhaust the water is naturally acidic and will eat away at the heat exchanger over time. Navien having put the burner at the top with the secondary heat exchanger at the bottom prevents the condensate from dripping over the primary heat exchanger enhancing its lifespan.
This design has been tested thoroughly by Navien and they offer the industries best heat exchanger warranty at 15 years. The best warranty you will find on a heat exchanger with other tankless systems is 12 years.
We sell and service all makes and models of Navien condensing tankless water heaters. This is a brand we trust and a system that is personally owned by several of our staff. If you think a Navien might be right for your home give us a call to discuss.
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.
If you have any further question don’t hesitate to ask us