Grundfos CU301 Constant Pressure Installation — Prince Frederick, MD
A Prince Frederick family was frustrated by pressure drops every time two showers ran simultaneously. We installed a Grundfos CU301 constant pressure controller — steady 55 PSI regardless of how many fixtures are running.
The Problem
A family of five in Prince Frederick called us about water pressure problems. Every morning, when multiple family members were showering simultaneously, the pressure would drop significantly — sometimes to a trickle. The well pump and pressure tank were only 4 years old and in good condition. The problem was the traditional on/off pump control system, which could not modulate output to match demand.
Our Diagnosis
We assessed the well system. The pump was a 1 HP Franklin submersible in good condition. The pressure tank was properly sized and charged. The issue was fundamental to traditional pump control: the pump runs at full speed until the pressure tank is charged to cut-out pressure (60 PSI), then shuts off. When multiple fixtures draw water simultaneously, the tank depletes quickly and pressure drops until the pump cycles back on. A constant pressure controller would solve this by running the pump at variable speed to maintain steady pressure.
The Repair Process
- 1Assessed existing pump motor compatibility with CU301 (confirmed compatible)
- 2Installed Grundfos CU301 constant pressure controller at pressure tank
- 3Wired CU301 to existing pump circuit
- 4Set target pressure to 55 PSI
- 5Configured dry-run protection settings
- 6Tested with multiple fixtures running simultaneously
- 7Verified steady pressure throughout demand range
The Outcome
Pressure is now steady at 53–57 PSI regardless of how many fixtures are running. The family reported that morning showers are no longer a pressure battle. The pump now runs at variable speed rather than cycling on and off — significantly extending its expected lifespan.
Key Takeaway
A constant pressure controller is the most cost-effective upgrade for homes with pressure fluctuation problems. At the cost of the repair installed, it is far less expensive than a new pump or pressure tank — and it solves the problem that those components cannot.
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