Quick answer: A pool heater’s gas valve is the electronically-controlled component that meters natural gas or propane into the burner tray, and it’s one of the only parts on the heater we don’t recommend swapping yourself. For Raypak Digital heaters the OEM part is the 003900F natural gas valve (roughly $230-$390); for Pentair MasterTemp and Max-E-Therm heaters it’s the 42001-0051S combination gas control valve kit (roughly $200-$435, with unusually wide retailer variance); and for Hayward Universal H-Series units it’s the FDXLGSV0001 natural gas valve kit (roughly $275-$400 typically, though we’ve seen it as low as $164 on sale). According to Angi’s 2026 pool heater repair data, a professionally installed gas valve replacement runs $175-$600+ including labor — and that installed price, not the parts-only number, is what you should actually budget for.
Why we’re not showing you how to install this one
Every other OEM-parts guide on this site — igniters, pressure switches, capacitors, heat exchangers — covers parts most owners can swap themselves with a screwdriver and the right part number. The gas valve is different. It sits directly on the gas supply line, and replacing it means disconnecting and reconnecting a live gas connection. In most U.S. jurisdictions, that work legally requires a licensed gas-fitter or plumbing contractor and a permitted inspection — California’s licensing board, for example, requires a C-36 plumbing contractor license specifically for gas line work on pool equipment, and heaters themselves are built to ANSI Z21.56, the gas-safety standard that inspectors check against. Beyond the legal side, a bad gas connection risks a leak, and most manufacturers will void the heater’s warranty if a valve was swapped by anyone other than a licensed technician. This guide exists so you know what part your technician is quoting and whether that quote is reasonable — not so you can order the part and do it yourself.
Pool heater gas valves at a glance
| Gas valve | Fits | Fuel | Parts price |
|---|---|---|---|
| Raypak 003900F | Digital 206A-406A (IID ignition) | Natural gas | $230-$390 |
| Pentair 42001-0051S | MasterTemp / Max-E-Therm | Natural gas | $200-$435 |
| Hayward FDXLGSV0001 | Universal H-Series / Low NOx (H150FDN-H400FDN) | Natural gas | $275-$400 |
Propane (LP) versions exist for all three brands — Raypak’s propane valve is a different part number (004306F for IID ignition, 003899F for millivolt), and Pentair and Hayward both sell LP-specific valve kits rather than a universal one. If your heater runs propane, give your technician the fuel type up front so they order the right kit the first time.
1. Raypak 003900F — For Raypak Digital Heaters
Raypak 003900F Electronic Combination Natural Gas Valve
- The OEM combination gas valve for Raypak's Digital line, the same models covered in our best Raypak pool heater roundup.
- Combination valve means it handles both the safety shutoff and the modulating gas flow in a single unit, rather than two separate components.
- A propane version exists under different part numbers (004306F for IID ignition units, 003899F for millivolt) — don't order this natural-gas part number for an LP heater.
- This is the part your technician will source and install; use it to confirm you're being quoted the correct component before authorizing the repair.
Have your pool heater’s spare parts on hand before the technician visit? Try Amazon Prime free for 30 days and get your pool heater delivered in two days.
2. Pentair 42001-0051S — For MasterTemp and Max-E-Therm
Pentair 42001-0051S Combination Gas Control Valve Kit
- The OEM valve kit for Pentair's MasterTemp and Max-E-Therm lines, the same heaters reviewed in our Hayward vs Pentair comparison.
- Pricing on this exact part varies unusually widely between retailers — we've seen it listed under $200 at some pool-equipment suppliers and over $400 at others, so it's worth getting your technician's parts markup itemized separately from labor.
- Comes as a kit rather than a bare valve, which typically includes the gasket and mounting hardware needed for a clean install.
- Fits both the residential and commercial-adjacent versions of these two model lines, so confirm your exact model number before ordering.
3. Hayward FDXLGSV0001 — For Universal H-Series
Hayward FDXLGSV0001 Natural Gas Valve Kit
- The OEM natural gas valve for Hayward's Universal H-Series and Low NOx lines, spanning the H150FDN through H400FDN models.
- Listed directly on Hayward's own parts site as well as third-party pool-parts retailers, which makes it easier to verify you're getting a genuine OEM part rather than an aftermarket substitute.
- Retailer pricing has a wide spread on this part too — we've seen sale pricing as low as $164 and list pricing above $460, so it's worth comparing two or three listings if you're sourcing it yourself for your technician to install.
- A separate LP kit is sold for propane versions of the same heater lines; the part number above is natural-gas-only.
What a fair quote looks like
Angi’s 2026 pool heater repair data puts a professionally installed gas valve replacement at $175-$600+, with labor typically billed separately at $80-$120/hour. A quote that’s well above that range isn’t necessarily a scam — travel fees, emergency/same-day service, and older or harder-to-source models can all push it higher — but it’s worth asking your technician to itemize the part cost against the ranges above before agreeing to it. If the total quote starts closing in on half the price of a new heater, our repair cost guide covers the 50% rule pool pros use to decide when replacing the whole unit beats repairing it.
The bottom line
A pool heater gas valve isn’t an expensive part on its own — $200-$435 depending on brand — but it’s the one repair on this site we don’t recommend doing yourself, since it means working on a live gas connection that most jurisdictions require a licensed technician to handle. Knowing the OEM part number and price range for your brand — Raypak 003900F, Pentair 42001-0051S, or Hayward FDXLGSV0001 — mainly protects you from an inflated quote, not from doing the job yourself. If your heater is showing ignition problems, start with our not-heating troubleshooting guide to rule out the free fixes first, and check our parts guide for the components that genuinely are DIY-friendly if you want to handle some of the repair yourself and leave just the gas-side work to a pro.