Accumulator tank

What it does

An accumulator stores a small cushion of pressurized water. It smooths pulses, reduces rapid pump starts and can deliver tiny flows without immediately running the pump.

Need or not

Fixed-speed bypass pumps may work acceptably without one; variable-speed pumps often do not need one. Add it for objectionable cycling/noise or low-flow stability, not because every diagram shows it.

Pre-charge

Set air pre-charge with the water side depressurized, using the accumulator and pump instructions. Too high or too low reduces useful drawdown and can worsen cycling.

Placement

Put it near the pump outlet or distribution where accessible, support its wet weight and allow access to the air valve. Do not hide a threaded connection behind finished walls.

Build rule

If you cannot reach it, isolate it, drain it and explain its pressure/temperature or water-quality job, it is not ready to hide behind a wall.

CHAPTER CHECK

• I can explain the purpose and failure mode of each item in this chapter. • I know which manufacturer limit or water-quality claim controls my choice. • I added the valve, access, drain, measurement or maintenance task to my drawing/checklist.