Tips & Troubleshooting
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Last winter I used a direct mount model thermostat with an angle model valve. I got several call backs from customers complaining that the room was too cold. It should have been fine. What was the problem?

Many people try to use a direct mount model thermostat with a vertical angle, "E" model valve. We do not recommend this application. If a direct mount thermostat/actuator is mounted over the valve, hot rising air would affect the sensor in the thermostat, even when the valve is closed, and would result in under heating the room. A better solution would be to use the "D" model valve, or the horizontal "F" model valve.

Differential Pressure Regulating Valve:

What is it?

The differential pressure regulating valve is a control valve that opens and closes automatically to maintain a near constant differential pressure across the inlet and outlet ports.

Why use it?

Hydronic systems are typically designed to operate at a certain differential pressure across the components. The differential pressure can increase or decrease as pump flow does down or up respectively. As the differential pressure rises there can be noise, premature valve wear, damage due to hammering, and valve malfunction (exceeds close off pressure).

A common reason for the pressure variation is due to the characteristics of the pump. Zone valves begin to close and the total flow through circulating pump decreases. With a typical pump, the head pressure drops with flow. So typical pump sizing looks at the total sysstem demand at a given differential pressure and that sets the pump size at the "design condition". Off design condition, which is most of the time, the pump will be delivering more pressure than required.

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