A mechanical switch only makes and breaks a contact. A smart controller measures pressure, ramps the pump up gently and protects it against dry running and over-current.
In most buildings a mechanical pressure switch still decides when the pump runs. It is cheap and simple, but what it does is not quite what a domestic water system needs.
What a mechanical pressure switch does
A spring and a diaphragm make and break a contact at a set pressure. That is all. The device does not know how much current the pump draws, whether water is reaching it, or how hot it has become.
In practice that means:
- The pump starts abruptly at full power and creates water hammer in the pipework.
- If the water runs out, the pump runs dry until it burns.
- Pressure noticeably fluctuates on the upper floors.
- Pressure is set with a screw and a spring, which is not precise.
What a smart controller changes
An electronic controller measures line pressure continuously and decides accordingly.
| Aspect | Mechanical pressure switch | Smart controller |
|---|---|---|
| Pressure setting | by spring, approximate | numeric and precise |
| Pump start | abrupt | soft and gradual |
| Dry running | not detected | detected, pump stopped automatically |
| Over current | no protection | pump stopped, fault displayed |
| Over temperature | no protection | pump stopped, resumes automatically |
| Status display | none | four-digit display |
| Automatic retry | none | automatic, at a set interval |
Why soft starting matters
When a pump starts suddenly, the column of water in the pipe accelerates and water hammer follows. Over time that loosens fittings, wears valves and stresses the pump itself. Soft starting spreads that acceleration out.
On HYDROSET the soft-start and soft-stop times are set with parameters F11 and F12.
Dry-run protection
The commonest reason a domestic pump burns out is running without water. A smart controller detects that in two ways: a drop in the pump's current, and pressure that fails to build. In either case the pump is stopped and the unit retries at the interval you set.
Is replacing it difficult?
No. The controller takes the place of the pressure switch directly: the sensor screws onto the pipe after the check valve, and the incoming supply and pump output go to the unit's terminals. Factory settings suit most installations without change.
