Incoming Water – Solar Thermal
Incoming Water Temperatures
Water is very dense and difficult to heat up. It takes a lot of energy to raise the temperature of 1 cubic centimetre of water 1 degree Celsius; actually it takes about 4 Joules. Now when you start thinking about a tankless water heater and how quickly it needs to heat up water it is actually quite fascinating.
Let’s break it down a bit.
Incoming water temperatures in the winter of an average home in Toronto and surrounding areas is about 5 degrees Celsius. Your homes hot water needs are usually set at between 49°C and 60°C (for storage water tanks 60°C is highly recommended to avoid the potential growth of Legionella bacteria). Let’s assume that you have a tankless and since there is no standing water and no risk for Legionnaires’ disease you have the ability to set the temperature a bit lower than a home with a conventional tank.
- At 60°C it takes 6 seconds to receive a bad enough burn that medical treatment will be required.
- At 52°C it takes 2 minutes to receive a bad enough burn that medical treatment will be required.
- At 49°C it takes 10 minutes to receive a bad enough burn that medical treatment will be required.
Hot Water Safety
Out of safety for you and your family a tankless is usually set to 49°C. So here in Ontario in the winter months the tankless will be tasked with bringing incoming water up from 5°C to 49°C almost instantly. This is no light task and takes a significant amount of energy. The tankless systems we recommend be installed usually have no less than 170,000 BTU heating capacity. This, in our Canadian climate is sufficient to meet the needs of a regular home.
Solar Thermal Water Heating
As tankless systems evolve they have gained the ability to adapt to certain increased circumstances. Today’s generation of tankless water heaters are capable of being integrated into solar thermal applications. These systems preheat water with solar collectors on roofs and in sun drenched locations to reduce the energy needed for domestic hot water needs.
Typically a solar thermal application within Toronto and the GTA can preheat water in the middle of winter to over 25°C. The smart generation of tankless systems now measure incoming water temperatures and adapt their burners to fire at a reduced rate to compensate for the much warmer incoming water temperatures.
There are always additional costs with these more advanced systems but they are always upgradeable. So if you can’t afford the solar collector side of the system immediately know that your tankless has all the parts installed ready for when you decide to make the upgrade.