Quick answer: For a FibroPool heat pump, the matching model-specific bypass kit (BA120/220, BA135, BA235, BA255, BA270, or BA285 depending on your unit) runs $99.99-$119.99 and bundles CPVC 3-way diverter valves, unions, and a check valve in one hand-assembled US-made package, according to FibroPool’s own product listings. Pentair MasterTemp 175-200 owners can add manual bypass with the Pentair 77707-0001 kit (about $39.50), or step up to Pentair’s motorized 462048 Smart Heater Automatic Bypass Valve Actuator Kit (about $449.99) for a bypass that adjusts itself. Hayward H-Series Millivolt ED1 heaters (pre-September 2004) use the HAXBPK1932 kit (about $65-$66) — confirm the ED1-vs-ED2 millivolt/IID variant against your rating plate before ordering, since Hayward has sold more than one bypass kit under closely related names.
A bypass kit solves the same flow-rate problem our bypass valve guide covers — keeping water flow through the heat exchanger inside the manufacturer’s rated GPM window — but it’s a different product form. Instead of sourcing a generic 3-way valve and unions separately and sizing them yourself, a kit ships as one pre-matched package for a specific heater or heat pump model, with the fitting sizes and valve capacity already worked out by the manufacturer.
Kit vs. valve: which one you actually need
If you’re troubleshooting short-cycling or a high-limit trip on a heater that already has a bypass valve installed, that’s a diagnosis-and-repair job — start with our bypass valve guide and not-heating troubleshooting table. A bypass kit is what you buy when there’s no bypass in the plumbing yet: a new heat pump install, an older heater that was never fitted with one, or a full pad re-plumb where you want a matched, model-specific package instead of assembling generic parts yourself.
| Kit | Fits | Type | Price |
|---|---|---|---|
| FibroPool BA-series (BA120/220 through BA285) | FibroPool FH120/220, FH135, FH235-i, FH255, FH270, FH285-i heat pumps | Manual 3-way diverter + unions + check valve | $99.99-$119.99 |
| Pentair 77707-0001 | MasterTemp 175-200 | Manual bypass valve kit | ~$39.50 |
| Pentair 462048 | MasterTemp/Sta-Rite (Smart Heater compatible) | Motorized automatic bypass actuator | ~$449.99 |
| Hayward HAXBPK1932 | H-Series Millivolt ED1 (pre-9/2004) | Manual bypass valve kit | ~$65-$66 |
1. FibroPool BA-Series — Model-Specific Kit for Every FH Heat Pump
FibroPool Bypass Kit (BA120/220, BA135, BA235, BA255, BA270, or BA285)
- FibroPool sells six separate kit numbers, one matched to each heat pump model in its lineup — a BA135 sized for the FH135 isn't interchangeable with a BA270 sized for the larger FH270, since the union and valve sizing changes with the unit's plumbing ports.
- Each kit is described by FibroPool as hand-assembled in the USA and includes CPVC 3-way diverter valves, unions, and a check valve — the same three components a technician would otherwise have to source and size separately for a scratch-built bypass loop.
- The FH120/220 kit is the cheapest at $99.99; every other model in the line runs $119.99 regardless of heat pump size, so the price difference between models is minimal once you're above the entry-level unit.
- This is the direct companion part to the FH255/FH270 heat pumps this site already recommends in its sizing guides — if you're installing one of those new, budgeting for the matching bypass kit up front avoids a second order later.
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2. Pentair 77707-0001 — Manual Kit for MasterTemp 175-200
Pentair 77707-0001 MasterTemp 175-200 Bypass Valve Kit
- The cheapest kit on this list by a wide margin — a manual, hand-adjusted valve rather than the motorized version below, and sized specifically for the smaller MasterTemp 175-200 models.
- Pentair's larger MasterTemp 250/300/400 models use different bypass and manifold hardware, covered separately by this site's manifold guide — confirm your exact model number before ordering rather than assuming every MasterTemp shares the same kit.
- A straightforward retrofit for anyone adding bypass capability to an existing MasterTemp installation that was plumbed without one, without the cost of the automated actuator kit.
3. Pentair 462048 — Motorized Smart Heater Automatic Bypass
Pentair Smart Heater Automatic Bypass Valve Actuator Kit (462048)
- More than ten times the price of Pentair's own manual 77707-0001 kit, because this version replaces manual valve-cranking with a motorized actuator that opens and closes the bypass automatically as flow conditions change.
- Automating what Raypak's own technical blog calls "the long lost art of bypass valves" — rebalancing flow for optimal heat transfer without a manual crank — aimed at owners who've automated the rest of their pad (variable-speed pump, salt system) and don't want the bypass to be the one manual step left.
- Overkill for a simple new-install bypass need; this is the pick for someone specifically chasing hands-off flow tuning rather than a one-time fix.
4. Hayward HAXBPK1932 — For H-Series Millivolt ED1 (Legacy)
Hayward HAXBPK1932 By-Pass Valve Kit
- Retailer listings for this exact part number aren't fully consistent — some describe it as fitting the older ED1 millivolt style specifically, others list it more broadly against the H-Series/Low NOx/ED2 range — so treat the ED1-vs-ED2 distinction as something to verify against your heater's rating plate or with the retailer before ordering, not something to assume from the part number alone.
- This is the same Universal H-Series family this site's igniter and pressure switch guides already cover — if a technician is on-site replacing one of those parts on an older H-Series unit, that's a natural time to check whether a bypass is already plumbed in.
- Mid-priced relative to the other three kits here — pricier than Pentair's manual kit, cheaper than FibroPool's, and far below Pentair's motorized version.
The bottom line
A bypass kit earns its keep on a new install or a heater that was never plumbed with bypass capability — it’s the pre-matched, model-specific alternative to sourcing a diverter valve, unions, and a check valve separately and sizing them yourself. FibroPool’s per-model BA-series kits ($99.99-$119.99) are the clearest example of that approach for heat pump owners, while Pentair offers both a budget manual option (77707-0001, about $39.50) and a premium motorized one (462048, about $449.99) depending on how hands-off you want the bypass to be. If your heater already has a working bypass and you’re chasing a short-cycling or high-limit-trip problem instead, our bypass valve guide and troubleshooting table are the better starting point than buying a whole new kit. Installing a heat pump new and want to see where a bypass fits into the rest of the plumbing sequence? Our installation guide covers that, and our parts guide rounds up every other component that’s worth budgeting for alongside it.
Sources: FibroPool — Pool Heater Bypass Kits, TC Pool Equipment — Pentair MasterTemp 175-200 Bypass Valve Kit 77707-0001, Pentair — The Long Lost Art of Bypass Valves, Vita Pool Supply — Pentair Smart Heater Automatic Bypass Valve Actuator Kit 462048, EZ Test Pools — Hayward ED1/ED2 Bypass Valve Kit HAXBPK1932