Backflow covers are used to protect backflow valves and help with freeze protection when the valves are left out in conditions where the temperature may dip below freezing. Many home owners find out the hard way, when a backflow prevention valve freezes, it doesn’t take long for it to break.
The delicate springs and rubber gaskets inside don’t hold up well to icy water. And replacing a valve can be quite expensive.
The type of backflow covers required depends greatly on the climate of the area you live in, and also the type of valve you have. Potable water valves tend to be more active all year long, with water flowing through them day and night. Moving water does not freeze as easily in these vs irrigation types which may sit dormant for weeks or months with stagnant water in them that is prime for freeze.
ASSE Class 1, 2, 3 Backflow Covers (American Society Of Safety Engineers)
Backflow enclosures are available in 3 different primary ASSE classes, each providing a different level of protection against freeze:
ASSE Class 3 – this level offers impact damage and wind protection. Some of these enclosures are also lockable to prevent theft and tampering. ASSE Classe 3 is not insulated or heated. These primarily consist of the hard fiberglass or plastic outer shell with vents for drainage near the bottom.
ASSE Class 2 – this class features an impact-resistant outer shell that is lockable, water drainage venting, plus added insulation for additional freeze protection. The Class 2 backflow covers are probably the most popular format in today’s irrigation market.
ASSE Class 1 – In addition to the hard shell, drainage venting and insulation, this class incorporates an electric heat system. In most cases the heat is provided via a heat tape which is wrapped around the piping and the valve body. The heat tape is plugged into an outlet and the generated heat is conducted through the metal pipes to prevent the water from becoming too cold and freezing.
In most cases, if you reside in an area where the temperature dips below freezing for a couple hours at night, then remains above freezing during the day an ASSE Class 2 option will suffice. Going with an ASSE Class 3 could be risky depending on how long the temps dip below the freezing mark and how windy it is. Remember, the wind robs heat very quickly. If you live in a windy area it’s best to error on the side of caution and go the insulated route vs just the Class 3 which does not provide any additional R-value or heat to help fight freezing pipes and valves.
Sizing is also important. Always carefully measure the height, length and width of the entire unit and compare those dimensions with the available interior space of the enclosure you are considering. Plumbers are often required to keep the valves up aways off the ground when the units are installed, so some of these can be quite high and awkwardly shaped depending on what the building codes are like in your municipality.