How do Hydronic Solar Water Heating Works?

Canada Solar Radiation Map:

How Do Hydronic Solar Water Heating Works

Most major Canadian Cities, such as Toronto, Montreal, Winipeg, Ottawa, Regina etc..., are spread along the Canada - US borders where solar insolation is at its peaks. With almost eight months a year of  buildings external envelope heating demand and a full year domestic hot water heating demand as well as other processes water heating (such as pools heating in the summer, industrial processes, etc...), solar energy is one of the most promising renewable energy for Canada.

How do Solar Thermal Water Heating Works?

How Do Hydronic Solar Water Heating Works

Our Vacuum Tubes Solar Collectors (Available is 15, 20, 25 and 30 tubes) absorb solar radiated energy and transfer the harvested solar energy into a closed loop Polypropylene Glycol with a heat exchange Coil immersed into a pressurized hot water tank.

In a typical Pressurized Polypropylene Glycol Solar Line configuration (Fig.1) the immersed Coil  will transfer the harvested solar heat into the Hot Water Storage Tank. in That Case the storage tank will be filled with water. This configuration is mostly used in cold climates with Vacuum Tubes type solar collectors. Also this configuration works well in retrofit context where an electric or natural gas domestic hot water heater is already installed. In That case the Solar Hot Water Storage Tank will preheat domestic cold water before entering into the existing hot water heater.

In places heated with hydronic radiant floor heating (Fig.2), Solar Heat could be transferred to hydronic floor heating loops. To do that solar water storage tank should be ordered with double immersed coils: the lower coil will be used to harvest solar energy collected by solar collectors and the upper coil will be used to transfer solar energy to hydronic heating loops.

How Do Hydronic Solar Water Heating Works

Fig.1 (TypicalPressurised Polypropylene Glycol Solar Line) 

How Do Hydronic Solar Water Heating Works

Fig.2 (Typical Combination of Solar Water Heater (Fig.1) and Space Heating with a boiler makeup heat) 

In a typical Non Pressurised Polypropylene Glycol (PG) Solar Line configuration (Fig.3) hot PG is returned into the storage tank the immersed Coils (whether one or two coils) will be used to preheat Domestic Hot water (DHW) in an open loop configuration and / or heat hydronic heating loop return in a closed configuration.

This type of installation is more common in hot to mild climates. When the solar system is not being used, owner don't need to worry about rising storage tank temperature above safe limits. Once the pump is manually turned off (long time away from home), solar collectors will drain to the ''Air Pressure'' zone and collectors will be filled with air. Also this type of installation is more common with Flat Plate type solar collectors used in places like Colorado, California, Florida, etc...

 How Do Hydronic Solar Water Heating Works 

Fig.3 (Typical Non Pressurised Polypropylene Glycol Solar Line) 

What do Hydro Solar Recommend?

For our Canadian and northern US customers, we recommend installations similar to what's shown in Fig.1. This configuration works well when storage is properly sized and safety valves at the PG line and the top of the tank are properly selected for the operating conditions of the solar system.