Time: 20–30 minutes. Skill: homeowner-comfortable with a screwdriver and able to isolate the circuit at the breaker. Cost: the price of one replacement capacitor (NZD incl GST).
Why your Davey pool pump capacitor fails
If your Davey pool pump hums but won’t spin up, trips the breaker, or starts only when you nudge the fan, a tired capacitor is the usual suspect. The capacitor gives the single-phase motor the rotational “kick” it needs to start, and on a poolside pump it lives a hard life: heat, vibration and the occasional splash all shorten its lifespan. Davey ProMaster and Silensor models are workhorses on Kiwi pools and spas, so it’s common to need a replacement after a few summers rather than scrap an otherwise healthy motor.
The good news is that swapping the cap is one of the most satisfying, money-saving repairs a confident DIYer can do — provided you respect the safety steps below.
Safety first — read before you touch anything
A capacitor stores a dangerous electrical charge even after the pump is switched off and unplugged. Treat it with respect.
- Switch off and isolate the power at the breaker or the pump’s isolator switch. Don’t rely on the pump’s own on/off button.
- Before handling, discharge the capacitor by bridging its two terminals with a bleed resistor (around 10–20 kΩ, 5 W) or a proper capacitor discharge tool — a bare insulated-handle screwdriver across the terminals also drains it but sparks violently and can pit the terminals, so use that only as a last resort. This drains the stored charge safely.
- In New Zealand, fixed mains wiring legally requires a licensed electrician. If your pump is hard-wired or you’re at all unsure, get a sparky in. There’s no shame in it, and the swap itself is quick for them.
Where the capacitor sits on a Davey motor
On most Davey ProMaster and Silensor pumps the capacitor lives under a small cover on top of, or on the side of, the motor housing — often a black or grey cylindrical can held by a metal clamp. On the quieter Silensor units it can be tucked under the shroud, so you may need to remove the fan cover first.
What you’ll need
- The replacement run capacitor — match the µF (within ±5%) and equal-or-higher voltage to the one fitted now.
- Phillips and flat screwdrivers.
- An insulated screwdriver, or a 10–20 kΩ bleed resistor with insulated leads, to discharge the old capacitor safely.
- A multimeter, if you want to confirm the diagnosis before swapping.
- Your phone — to photograph the wiring before disconnecting anything.
Steps
1. Isolate the power
At the breaker/isolator and confirm the pump is dead by trying to switch it on.
2. Wait, then discharge
— give it a minute, then bridge the capacitor terminals with a bleed resistor or a proper discharge tool (a bare insulated screwdriver also works but sparks — last resort) to drain any stored charge before touching the wires.
3. Open the housing
— unscrew the capacitor cover (or the motor end shroud on Silensor units) to expose the capacitor and its clamp.
4. Photograph and label the wiring
So you know exactly which spade terminal goes where on reassembly.
5. Read the old capacitor
— note the printed µF rating and voltage. Many single-phase pool pumps use a run capacitor in the roughly 20–50µF range at 400–450V, but you must confirm from your own capacitor or the motor nameplate — fitting the wrong capacitance can damage the motor.
6. Remove the old capacitor
— loosen the clamp, slide it out, and unplug the spade connectors.
7. Fit the new capacitor
— match the µF exactly and use a voltage rating equal to or higher than the original (never lower), push the connectors firmly onto the matching terminals, and re-secure the clamp.
8. Reassemble
The cover/shroud and double-check nothing is pinched or loose.
9. Restore power and test
— switch back on at the isolator. The pump should start crisply and run quietly. If it still hums, switch off and recheck your connections.
Choosing the right replacement
Match three things: microfarads (µF), voltage rating, and physical size/terminal type. A higher voltage rating than the original is fine; a different µF is not. If you can still read your old cap, you’re sorted. If it’s burst or illegible, use the motor nameplate or our find-your-capacitor wizard to narrow it down. Browse compatible options on our pool pump capacitor range or filter the pool capacitor shop. Browse all Davey pump capacitors by model to match your exact unit.
Tips specific to Davey owners
- Silensor shrouds clip back tightly — make sure the fan spins freely before you power up.
- If the pump tripped the RCD when it failed, have the wiring checked; a failed cap can sometimes take an insulation fault with it.
- Keep the old cap until the new one is proven working, so you can compare ratings if needed.
Get the right part, first time
Not sure which capacitor your Davey takes? Run our quick find-your-capacitor wizard or browse the pool capacitor shop and the full pump capacitor range.
Every order is shipped tracked, around 2 weeks via NZ Post or courier, prices in NZD incl GST, backed by a 90-day DOA guarantee. NZ-owned and here to help you keep your pool ticking over.