FIDISP 8Pcs 3/4 Inch IPS Isolator Tankless Water Heater Valve Kit with 2Pcs 3/4" NPT to 1/2" FNPT and 2Pcs Brass Pipe Fitting, Tankless Water Heater Flushing Kit with Pressure Relief Valve, Clean Brass

Why this kit matters

Tankless water heaters are fantastic until the day you have to service them. Isolation valves with flush ports are the difference between a one-hour maintenance task and an afternoon of wrestling with hoses and improvised fittings. I installed the FIDISP tankless service valve kit on a recent heater swap at my house, and it hits the right notes: straightforward installation, solid build, and the small extras that keep a Saturday project on schedule.

What’s in the box

FIDISP ships the kit in a tidy foam-lined box, and everything arrives separated and protected. In the set you get:
- Hot and cold isolation valves (500 WOG) with color-coded handles
- A pressure relief valve rated 150 PSI/205,000 BTU
- Two 3/4-inch NPT-to-3/4-inch NPT brass couplers
- Two reducer bushings (3/4-inch MNPT to 1/2-inch FNPT)
- A roll of PTFE thread-sealing tape

The core valves—the hot, cold, and the relief valve—are forged from certified lead‑free brass. That matters both for safety and longevity. A clear note in the kit states the other included brass fittings (the reducers and couplers) are low‑lead and not for potable water connections, which is the right way to present it: use those where code allows or swap to lead‑free alternatives for any potable path.

Build quality and feel

The valves are reassuringly stout with clean machining on the NPT threads. The levers have the right resistance—easy to move with one hand but not loose. Inside, they’re conventional quarter‑turn ball valves with smooth actuation and positive stops. The finish on the bodies is consistent, and there were no burrs or casting flaws on the pieces I received.

The pressure relief valve is a standalone component, not an integrated assembly, which I prefer. If it ever weeps or reaches end-of-life, you can replace just that part rather than the entire valve stack. It threads cleanly into the cold side and seats well with standard sealant.

A pleasant surprise: the included thread-sealing tape is thicker than the usual throwaway roll you get with budget kits. It doesn’t shred or tangle, which makes it suitable for the job if you don’t keep PTFE tape on hand.

Installation experience

My heater uses 3/4-inch NPT connections, so the kit’s standard thread spec matched out of the gate. If you’re stepping down to 1/2-inch supply lines, the included 3/4-inch MNPT to 1/2-inch FNPT reducers are handy and thread nicely without galling. I used three wraps of tape on each male thread and a light coat of pipe dope where I wanted a bit more insurance. Everything came together square without fuss.

A few notes from the bench:
- Orientation: Mount the color-coded valves so the red lever is on the hot outlet and the blue on the cold inlet, with the relief valve on the cold side where your local code specifies. Keep the service/drain ports accessible; you’ll thank yourself during the first flush cycle.
- Support: These valves add mass. If your heater has rigid copper or CPVC directly attached, add a hanger or bracket to relieve strain on the heater stubs.
- O-rings: If your service port caps use O-rings, confirm they’re seated before pressurizing. It’s an easy miss when unpacking, and a quick check avoids a drip.

Once pressurized, I had no leaks at the unions or relief valve. Lever action stayed smooth under pressure, and the handles are easy to distinguish at a glance.

Using it for maintenance and flushing

With isolation valves, annual descaling becomes routine instead of a project. Close hot and cold, open the service ports, circulate your cleaning solution, then flush and return to service. The quarter‑turn operation on this kit makes that sequence quick and unambiguous; the handles align clearly with flow direction, and the ports are easy to access with standard hose connections. Flow through the ports is adequate for small utility pumps commonly used for descaling.

The 500 WOG rating on the valves is more than sufficient for residential systems. The pressure relief valve’s 150 PSI rating is standard fare and connects cleanly to a discharge line. As with any relief device, don’t test it against a closed system—verify operation per manufacturer guidance and local code.

Compatibility and fitment

The thread spec is 3/4-inch NPT across the main pieces, which matches most tankless platforms from Rheem, Rinnai, Navien, Noritz, Ecosmart, and Takagi in North America. If you’re integrating with PEX, copper, or CPVC, you’ll need the appropriate transition fittings (not included). The two 3/4 x 3/4 couplers help if you’re tying into short stubs or need a clean extension, but they are straight couplers, not union fittings.

One consideration: this kit does not include union ends on the isolation valves. That’s not a deal-breaker, but it means future removal of the heater or rework may require unthreading plumbing rather than cracking a union. If you anticipate frequent swap-outs or very tight spaces, a union-style kit might be worth the extra cost. For most residential installs, these threaded connections are perfectly serviceable.

Safety and compliance

FIDISP lists the service valves and relief valve as forged from certified lead‑free brass and CSA‑approved. That’s what I want to see on components that live directly in the potable water path. The low‑lead adapters and couplers should not be used in potable lines where code prohibits them; use them on non‑potable loops or keep them in the kit as “get out of jail” parts and source lead‑free versions for final connections. Always check your local code on relief valve placement, discharge piping, and dielectric isolation.

What I liked

• Clean machining and robust feel: The valves thread smoothly, seal easily, and operate with a crisp, predictable action.
• Thoughtful extras: The reducers saved a supply run on one install, and the PTFE tape is actually usable.
• Clear orientation: Color-coded handles minimize mistakes during hookup and service.
• Replaceable relief valve: A separate PRV reduces long-term maintenance cost and hassle.
• Honest materials disclosure: Clearly distinguishes lead‑free vs low‑lead components.

Where it could improve

• No union connections: Adding union ends would make servicing or replacing a heater simpler in tight mechanical rooms.
• Documentation: The kit is straightforward, but a one-page quick guide with torque guidance, thread seal recommendations, and a schematic would help less experienced DIYers.
• Lead-free across the board: Including lead‑free versions of the couplers and reducers would make the kit fully potable-ready in all jurisdictions.

Who it’s for

If you’re installing or retrofitting a tankless water heater and want an affordable, capable service valve setup without hunting for matching pieces, this kit hits the mark. It’s approachable for confident DIYers and perfectly suitable for pros who want a no-drama option that threads up cleanly and doesn’t leak. If your workflow demands union valves or you’re working in a jurisdiction that requires lead‑free fittings everywhere in the potable path, factor in substitutions or consider a union‑style set.

The bottom line

The FIDISP tankless service valve kit delivers solid build quality, smooth operation, and genuinely useful extras at a sensible price. Installation is straightforward, the valves seal up without games, and the separate pressure relief valve is easy to place and replace. I’d like to see union ends and all lead‑free accessories, but those are manageable trade-offs given the performance and value.

Recommendation: I recommend this kit. It’s a dependable, well-matched set for isolating and servicing a tankless water heater, with good materials where it matters, clear orientation, and the adapters most installs need. Plan your transitions to meet local code—especially around lead‑free requirements—and you’ll have a clean, maintainable setup that makes annual flushing as painless as it should be.