Quick answer: For Raypak R-Series heaters (R185A, R265A, R335A) and the P-R406A-EN-C, the Raypak 006737F 1.75 PSI Direct Mount Pressure Switch is the correct OEM replacement. Pentair MasterTemp 125 through 400 (NA and LP versions) use the Pentair 42001-0060S Water Pressure Switch. Hayward Universal H-Series Low NOx heaters (H150FDN through H400FDP) take the Hayward FDXLWPS1930 Water Pressure Switch, and Jandy JXi ASME-compliant heaters use the Zodiac/Jandy R0013200 Water Pressure Switch Kit. All four do the same job — proving water flow before the burner or compressor is allowed to fire — and all four are among the more common failure points on a heater past the 3-5 year mark, according to our own parts-lifespan breakdown. Prices below were re-checked against current retailer listings as of September 2026.
A pressure switch failing (or just getting fouled with scale) is the single most common cause of a heater that refuses to fire even though water is clearly circulating fine — the switch itself is what’s lying to the control board, not the flow. Because Raypak, Pentair, Hayward, and Jandy each use a different mounting style, PSI rating, and connector, ordering the wrong switch for your model is the most common mistake here. We’ve matched each part below to the model lines it actually fits.
Pool heater pressure switches at a glance
| Pressure switch | Fits | PSI rating | Price |
|---|---|---|---|
| Raypak 006737F | R185A, R265A, R335A, P-R406A-EN-C | 1.75 PSI | $50-$70 |
| Pentair 42001-0060S | MasterTemp 125-400 (NA/LP) | Manufacturer-set | $65-$112 |
| Hayward FDXLWPS1930 | Universal H-Series Low NOx (H150FDN-H400FDP) | Manufacturer-set | $50-$68 |
| Zodiac/Jandy R0013200 | JXi ASME-compliant heaters | 2 PSI | $80-$105 |
1. Raypak 006737F — For R185A, R265A, R335A & P-R406A-EN-C
Raypak 006737F 1.75 PSI Direct Mount Pressure Switch
- Direct-mount design that threads straight into the water manifold, rather than needing a separate tubing run to a remote-mounted switch.
- Raypak sells pressure switches in more than one PSI rating across its lineup (the Digital and 5100-series families use different part numbers entirely) — confirm the 1.75 PSI rating and model match on your heater's rating plate before ordering.
- A fouled or failed switch on Raypak heaters commonly shows up as a "low water flow" or "pressure switch open" lockout code even with the pump running normally and the filter clean.
- Installs with a wrench for the water fitting and a plug-in or screw-terminal electrical connector, depending on model year — no gas line work involved.
If your Raypak heater trips a flow-related lockout despite a clean filter, full pool water level, and a pump you can hear running at normal speed, the pressure switch is the next part to check before assuming it’s the pump itself.
2. Pentair 42001-0060S — For MasterTemp 125-400
Pentair 42001-0060S Water Pressure Switch
- The pressure switch Pentair specifies across the entire MasterTemp size range, from the smallest 125,000 BTU model up through the 400,000 BTU unit.
- List prices on this part vary unusually widely between sellers — we've seen it priced from around $65 on sale to over $110 at full retail, so it's worth comparing a couple of listings before buying.
- Wired in-line with the heater's control board and threaded onto the water side of the plumbing manifold; expect a barbed or threaded fitting plus a two-wire connector.
- MasterTemp's "Service" light combined with a flow-related fault code is the classic symptom of this switch failing or fouling with scale.
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3. Hayward FDXLWPS1930 — For Universal H-Series Low NOx
Hayward FDXLWPS1930 Water Pressure Switch
- Covers the full Universal H-Series Low NOx ("FD") size range — H150, H200, H250, H300, H350, and H400, in both natural gas (FDN) and propane (FDP) versions.
- Same OEM family as the Hayward igniter kit covered in our [igniter guide](/best/best-pool-heater-igniter/) — if one flow-adjacent or ignition-adjacent part is failing from age on a Universal H-Series unit, it's worth checking both while the cabinet is already open.
- Typically the least expensive of the four OEM switches here, and one of the more straightforward swaps — a barbed water-line fitting and a plug-in connector.
- Hayward's older non-Low-NOx H-Series and HeatPro models use different pressure switch part numbers, so match the "FD" designation on your model number before ordering.
4. Zodiac/Jandy R0013200 — For JXi ASME-Compliant Heaters
Zodiac/Jandy R0013200 Water Pressure Switch Kit
- Designed for Jandy's ASME-compliant JXi heaters — Jandy's own parts diagrams list more than one pressure-switch variant across the JXi line (including a siphon-loop version), so cross-reference your exact model number rather than ordering on the JXi name alone.
- Rated at 2 PSI, in line with JXi's low-flow-resistance design compared to older Jandy Lite2 and Hi-E2 heaters.
- A companion part worth checking at the same time: the flame sensor, which our [parts guide](/guides/pool-heater-parts/) notes fails on a similar timeline from the same heat-cycling stress.
- Availability on this exact part number fluctuates between specialty pool-parts sellers more than the other three brands here — check stock across two or three retailers rather than assuming a single listing is current.
How to confirm it’s the pressure switch before you buy
Rule out the free fixes first: a dirty filter, a closed or partially closed valve, a low pool water level, or an undersized pump for the heater’s flow requirement will all trigger the exact same “low flow” lockout and cost nothing to fix. Our pool heater not heating guide ranks these causes cheapest-to-rule-out first — flow and valve issues sit near the top of that list precisely because they’re mistaken for a bad pressure switch so often. If the filter is clean, the pump is confirmed running at its rated flow, and the lockout still appears, the switch itself (or scale buildup inside it) is the likely cause.
Always cross-reference the exact part number against your heater’s specific model and size, not just the brand — Raypak, Pentair, Hayward, and Jandy all sell multiple pressure-switch variants within a single product family, calibrated to different PSI thresholds for different burner sizes. The rating plate inside the heater’s access panel is the source of truth here, not the model name alone.
The bottom line
A pressure switch is one of the more common — and most misdiagnosed — pool heater faults, since a fouled or worn switch produces the exact same symptom as an actual flow problem. The Raypak 006737F, Pentair 42001-0060S, Hayward FDXLWPS1930, and Zodiac/Jandy R0013200 each cover their respective brand’s mainstream heater lines at roughly $50-$112 in parts — cheap insurance against paying a technician’s diagnostic fee to find a part you could have swapped yourself. If the switch is one of several components failing at once on an older unit, our pool heater lifespan guide can help you decide whether it’s still worth repairing versus replacing the whole heater.