It is important to understand the relationship of ground water temperature and the flow rates of tankless water heaters. In Southern US States a tankless can produce substantially more hot water as the incoming water can be as warm as 75 degrees. The tankless system doesn’t have to work very hard to get the water up to 120 degrees (45 degree rise). Here in Ontario it’s a different story, our winter water temperatures dip into the low 40 degree range, this puts additional pressure on the tankless and requires the system to produce more heat to achieve the large temperature increase (roughly a 78 degree increase).
Here in Toronto we recommend tankless systems that are on the larger end of the spectrum, these systems usually produce about 199,000 BTU. This much energy allows the production of an adequate amount of water for most residential home demands from Toronto’s low winter water temperatures.
The Picture below shows water temperatures for most of the USA and some of Ontario of which you can determine average winter water temperatures for many cities and locations.
Although most tankless systems utilize very similar systems to heat water efficiently each tankless manufacturer has their own proprietary systems for heating the water. The unique of each system has created minute differences in hot water production at certain temperature levels. Though a lot of digging we have created a chart containing the most popular tankless systems and their respective hot water output at certain intervals.
We chose a 77 degree rise as a baseline for winter water temperatures that a tankless owner in Toronto or surrounding area would experience. We also included the stats for a 35 degree rise which is more common for summer water temperatures in Ontario. These two levels also enable you to see the production difference incoming water makes on a tankless water heater.
|Tankless Brand & Model||77˚F Rise||35˚F Rise|
|Bosch Tankless Systems||(Gallons Per Minute)||(Gallons Per Minute)||Bosch GWH 715||4.2||9.2|
|Bosch GWh C 920 ES||5.4||11.8||Bosch GWH-800ES||4.6||10.1|
|Bosch Therm C-1210||5.4||12.1||Bosch Therm C-1050||4.7||10.5||Bosch Therm C-950||4.2||9.3||Bosch Therm 940||4.2||9.3|
|Navien Tankless Systems||(Gallons Per Minute)||(Gallons Per Minute)||Navien 180||3.8||8.3||Navien 210||4.6||10||Navien 240||5.1||11||Navien 180A||3.8||8.3||Navien 210A||4.6||10||Navien 240A||5.1||11|
|Rinnai Tankless Systems||(Gallons Per Minute)||(Gallons Per Minute)||Rinnai RL94i||4.1||9.1||Rinnai RL75i||3.9||7.5||Rinnai RC98i||4.9||9.8||Rinnai RC80i||3.9||8|