Quick Answer: “Tankless water heater cover” search results split into two unrelated products. Most homeowners want a universal fabric weatherproof wrap (roughly $25-$40) that shields an outdoor unit’s cabinet from rain, UV, and dust — the HONITANO and moonoom covers below are the picks. A smaller group needs a rigid OEM pipe cover ($65-$230) that Rinnai and Rheem sell separately to enclose exposed water/gas pipe connections and venting stubs, a completely different part for a completely different job. Neither product is freeze protection — per our freeze protection guide, that’s a powered electric-heater function built into the unit itself.
Outdoor tankless units are already built to handle weather — Rinnai’s outdoor V-series and similar Rheem and Noritz models ship rated for direct rain exposure with no siding or enclosure required, as our best outdoor tankless water heater guide covers. A cover is an optional second layer of protection, and which one you need depends entirely on what part of the install you’re trying to protect: the cabinet itself, or the pipe connections underneath it.
Two products, one search term
The confusion is easy to fall into because both products are called a “cover” and both attach to a tankless water heater. A cabinet cover is a soft, zippered fabric wrap — Oxford cloth, waterproof film, and insulating layers — that goes over the entire unit body between uses or for the off-season, reducing sun-fade on the plastic housing and keeping dust and pollen out of the intake grille. A pipe cover is a rigid, brand-specific enclosure that Rinnai and Rheem sell as a factory accessory to shield the exposed water, gas, and venting connections that sit below or beside an outdoor unit — the part of the install that’s actually plumbing, not appliance. If your unit’s connections are already routed through a wall or protected alcove, you likely don’t need a pipe cover at all; if your cabinet just sits exposed to weather, the fabric wrap is the $25-$40 answer, not the $150+ OEM part.
Our top picks at a glance
| Cover | Type | Protects | Best For | Price |
|---|---|---|---|---|
| HONITANO Tankless Water Heater Cover | Fabric wrap | Cabinet — rain, UV, dust | Most outdoor units, standard size | ~$25-$40 |
| moonoom Tankless Water Heater Cover | Fabric wrap, 6-layer | Cabinet — rain, UV, dust | Extra insulation layer, magnetic/zip closure | ~$25-$40 |
| Rinnai PCD07-Series Pipe Cover | Rigid OEM enclosure | Exposed pipe connections + vent stub | Rinnai RC80/RC98/SE+ series outdoor installs | ~$65-$230 |
| Rheem RTG20330AJ Pipe Cover Assembly | Rigid OEM enclosure | Exposed pipe connections | Rheem RTG-series outdoor installs | ~$150-$165 |
1. HONITANO Tankless Water Heater Cover — Best Overall
HONITANO Tankless Water Heater Cover
- Built specifically for tankless cabinets rather than a generic tarp — the zippered fit and insulated layer are sized around a standard outdoor unit's dimensions instead of draping loosely.
- The straightforward pick if you just want to stop sun-fading and wind-blown dust from reaching the housing and control panel during the off-season or between uses.
- Not a substitute for the unit's built-in freeze protection — remove it before the unit runs so combustion air intake and exhaust termination stay clear.
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2. moonoom Tankless Water Heater Cover — Best Extra-Insulated Option
moonoom Tankless Water Heater Cover
- The thickest fabric build in this roundup — six layers versus the single-layer waterproof shells most generic covers use, which matters more in genuinely cold, wet climates than mild ones.
- Sold in more than one size and closure style (zipper or magnetic/touch-fastener), so check the listing's exact dimensions against your unit before ordering rather than assuming one size fits every outdoor cabinet.
- Same rule as any fabric cover: it's a weather layer for an idle or off-season unit, not something left zipped over an actively running gas unit's air intake.
3. Rinnai PCD07-Series Pipe Cover Enclosure — Best OEM Pipe Cover (Rinnai)
Rinnai PCD07-Series Pipe Cover Enclosure
- This is not a cabinet cover — it's a separate factory accessory that encloses just the plumbing and venting hardware exposed at the base of certain Rinnai outdoor installs, protecting connections from pests, debris, and weather the way the unit body itself is already protected.
- Model-specific: Rinnai sells multiple PCD07 variants by finish and by which series they fit, and pricing varies widely between them (roughly $65 for a bottom panel piece up to $230+ for a full enclosure) — match the exact part number to your unit rather than assuming any PCD07 fits.
- Only relevant if your install actually has exposed pipe connections that need shielding; a typical wall-mounted outdoor unit with connections routed cleanly often doesn't need this part at all.
4. Rheem RTG20330AJ Pipe Cover Assembly — Best OEM Pipe Cover (Rheem)
Rheem RTG20330AJ Outdoor Pipe Cover Assembly
- Rheem's equivalent to Rinnai's PCD07 line — a factory-matched enclosure for the plumbing connections on RTG-series outdoor installs, sold as a standalone accessory rather than bundled with the unit.
- Priced in a narrower, more predictable band than the Rinnai PCD07 lineup, since Rheem sells fewer finish variants of this specific part.
- Same caveat as the Rinnai option: confirm your exact RTG model is a listed fit before ordering, and skip it entirely if your install doesn't have exposed connections that need enclosing.
How to choose
- You just want to protect the cabinet from sun, rain, and dust: either fabric wrap works — HONITANO if you want the simpler standard-size option, moonoom if you’re in a harsher climate and want the thicker 6-layer build.
- Your install has exposed pipe or vent connections that need shielding: you need the OEM pipe cover for your brand — Rinnai’s PCD07-series or Rheem’s RTG20330AJ — not a fabric cabinet cover.
- You’re trying to protect against a winter power outage: none of these products help — see our freeze protection guide and winterization guide for what actually addresses that risk.
- You’re not sure your outdoor unit needs any cover at all: check our best outdoor tankless water heater guide — most outdoor-rated units are weatherproof by design, and a cover is a discretionary extra rather than a requirement.
The bottom line
“Tankless water heater cover” search results mix two unrelated products, and buying the wrong one either wastes $150+ on a part you didn’t need or leaves exposed plumbing connections unprotected. Most owners want the $25-$40 fabric wrap — HONITANO or moonoom — to protect the cabinet during idle periods or harsh weather. Only buy a Rinnai PCD07 or Rheem RTG20330AJ pipe cover if your specific install has exposed water/gas connections that need a rigid enclosure, and confirm the exact part number fits your model first. Either way, remember a cover is a weather layer, not freeze protection — for power-outage risk, see our freeze protection and winterization guides instead.