Solar Thermal Systems FAQs

Solar Thermal Systems FAQs

Keeping propylene glycol from freezing in my solar thermal system.

A: How do I prevent my glycol from freezing during those rare deep freeze nights? Q: Your glycol, although rated for very low temperatures may be un-pumpable at a temperature higher than you expect. This can cause you system to overheat when the sun comes out in the morning. To prevent this you can activate the antifreeze function in your SmartMaxx controller. This function will turn the pump on as soon as your sensor 1 reaches a pre determined temperature, say -5 degrees. This will run only for a few minutes and then turn off, thus keeping your glycol above the un-pumpable temperature.

How do I remove air from my system?

Question: How do I remove air from my system? Answer: Take a deep breath and let all your air out… of your Solar thermal system One of the biggest issues with a successful commissioning is air removal. Any time you spend with this detail will be time well spent. Air pockets become entrained within your HTF and like to find places to hide. Air pockets can form between your HTF and the inner wall of piping (especially with flexible piping) and can only be removed through persistence and time. Here are a few things you can do to help this process. First, be sure that your air purger is located on the high and hot side of your collector series. The hotter the fluid the less the ability for dissolved gasses to stay in solution and the higher the air vent, the more likely you will effectively remove trapped air that, due to its buoyancy, will rise to the top. Once you feel most of the air has been removed this way, you can shut that air eliminator off or remove it all together. If you install a Titan Power Plus collector, you will have a manual air bleeder permanently installed in your line set connections. If you install a ThermoPower collector, you will include an air vent that should be isolated and de-commissioned at this point. Now, down to the pump station. The UniMaxx pump stations have an integral air eliminator with a scoop that will allow entrained air to collect and be bled off manually by opening the valve up to a full turn until HTF comes out. This can be done each day for the first few days or periodically checked. Smaller systems will take much less time removing the air. Another way of enabling the removal of air is to run the pump at maximum speed during commissioning, this will help to break the friction that holds the bubbles to the inner wall thus forcing the bubble through and out. After words, you should adjust your pump speed accordingly. If air persists in your system, it will inevitably find its way to the suction side of your pump and cause cavitation and eventual pump failure. If your pump appears to be not pumping, it is likely that although it is receiving 115v, it cannot pump because of air pockets. Simply unplug your pump and manual override and give it a few minutes. Air will work its way out, pump can run and then you need to go back to the air purging steps. Please view our SunMaxx technical manual (linked) for further instruction in effective system commissioning.

Do I need to use glycol if I live in an area where I only have a few days of freezing per year?

Question:
Do I need to use glycol if I live in an area where I only have a few days of freezing per year?
Answer: If you live in an area that doesn't get below freezing often (less than 5 days per year) it is possible to get away with using water instead of glycol. In order to make sure that the water doesn't freeze you need to have your controller (ie. SmartMaxx DHW-Plus) run with freeze protection. The freeze protection setting monitors the collector temp and when it goes below a specified temp (40 F) the pump will kick on the circulate the fluid which will prevent the water from freezing.