As a representative for Danfoss VLT variable frequency drives (VFD), we often are asked about the use of the VFD when single-phase power is the …
Pumping From an Atmospheric Tank: Pump and Tank Control (Part 3)
Let me start by wishing everyone a Happy and Prosperous New Year. This blog begins the 14th year of the R. L. Deppmann Monday Morning …
Minimum Flow in Variable Speed Pumps for Building Hydronic HVAC Systems (Part 2)
The HVAC engineer designing a hydronic system understands the need to protect the circulating pumps from a dead head or no flow condition. This week, …
Minimum Flow in Variable Speed Pumps for Building Hydronic HVAC Systems (Part 1)
Every week a question comes into R. L. Deppmann about the minimum flow rate through hydronic pumps and the best way to achieve it. Today, …
Variable Speed Hydronic Pump Selection – Should I Specify the Largest Impeller?
We recently received an inquiry from an engineering firm deciding whether to change their pump schedule. They currently select the pumps at design capacity and …
Variable Speed Chilled Water Systems: Demand Reset
There are multiple methods to vary pump speed in HVAC chilled water systems. A common method is the use of a differential pressure transmitter at …
How to Limit the Speed of the Pump using a Danfoss Variable Frequency Drive
In this Service Tip of the Month, we demonstrate how to limit the speed of the pump using the Danfoss Variable Frequency Drive (VFD).
Create a New Variable Speed Pump Control Curve after Hydronic Balancing
This week, the R. L. Deppmann Monday Morning Minutes will explain how to show multiple speeds on a pump curve and how to determine what …
Hydronic Pump Balance using the Variable Speed Drive (VFD) with No Balance Valve on Pump
When there is no hydronic pump discharge balance valve, the variable frequency drive (VFD) is an important part of the balance procedure. How does the …
Hydronic Pump Balance using the Variable Speed Drive (VFD) with Assistance from a Triple Duty Valve
Most centrifugal pumps in heating and cooling systems have some oversizing in the head calculation. Once the HVAC hydronic system is proportionally balanced per ASHRAE …