SYSTEM PRESSURE:

All “closed” Radiant Direct system pressure should be maintained between 12 and 20 psi. Without the proper pressure, the pumps on a hydronic system can stop circulating water. No circulation means no heat and likely a burnt out pump. Keeping an eye on the pressure, throughout the heating season can save costly down time and repairs. 

It is not uncommon to loose a small amount of pressure over the seasons, however, if your system is loosing pressure regularly, and or, you are continuously adding water to bring up the pressure, you should do a thorough inspection for leaks. 

 

To check for possible leaks in a system, do a visual inspection of all the system components. Hard water deposits or streaks are an indication of a leak. Don’t, however, rely on a visually inspection for the PEX locations. The lack of physical damage to the house does not mean the system is leak free. There have been instances where a circuit has a small leak, but because of the warm environment, and insulation, any water coming from the circuits dries up and prevents damage. 

The only sure way to rule out a leak, in a PEX line, is to shut the system down, drain it, and pressure test each individual circuit to 100 psi for 30 minutes. If no pressure is lost it’s safe to assume the circuit is sound. Once you are confident that the system is leak free you should continue to check the system pressure monthly, during the heating season. 

Some Radiant Direct systems were sold with pre-plumbed, auto fill valves and duel check valves. In these systems, domestic cold water is attached to the inlet side of the dual check valve; the auto fill valve then “monitors” the system pressure and adds water to the system, if the system pressure drops below 12psi. If you would like to take advantage of this “auto fill” feature, you can install an auto fill valve on a closed system. 

Pictured are some examples of good auto fill valve locations. Many local codes indicate that a dual check valve be used along with an auto fill valve. All local codes must be followed when adding any new component to your Radiant Direct system. Adding an auto fill valve does not mean you won’t need to inspect the system regularly during the heating season.