The Marey Power Gas Indoor series is the brand\'s indoor-rated propane and natural gas tankless water heater lineup — engineered for permanent residential installation with sealed combustion venting. Distinct from Marey\'s portable L-series (outdoor only) and ECO Electric (whole-house electric), Power Gas Indoor units are the residential primary water heater offering.
Power Gas Indoor model lineup
- Power Gas Indoor 5L: 1.5 GPM, 35,000 BTU/hr, apartment-scale
- Power Gas Indoor 10L: 2.6 GPM, 75,000 BTU/hr, 1-2 bath residence
- Power Gas Indoor 14L: 3.7 GPM, 105,000 BTU/hr, 2-3 bath residence
- Power Gas Indoor 18L: 4.8 GPM, 140,000 BTU/hr, larger residential
Available in propane (LP) and natural gas (NG) variants. Verify the correct fuel type matches your installation before ordering — conversion between fuel types is possible but requires manufacturer-specific conversion kits.
Indoor installation requirements
Unlike Marey\'s L-series portable units, Power Gas Indoor models require permanent indoor installation with:
- Sealed combustion concentric or twin-pipe venting (per Marey specifications)
- Outdoor termination of vent with proper clearances from windows, intakes, and grade
- 120V electrical for controls and ignition
- Properly sized gas line (verify with Marey\'s pipe-sizing chart based on line length)
- Water connections (typically 3/4" cold inlet and hot outlet)
- Optional condensate drain (for high-efficiency variants)
Marey Power Gas Indoor vs major US tankless brands
vs Rinnai
Rinnai dominates US tankless market share with the longest warranty terms (10-12 year heat exchanger) and most extensive installer network. Marey advantages: significantly lower upfront cost (often 40-50% less). Marey disadvantages: shorter warranty, narrower service network, less robust customer support.
vs Navien
Navien NPE tankless is the premium Korean-engineered competitor with 15-year heat exchanger warranty and NavilinkWiFi connectivity. Marey is meaningfully less expensive but lacks the engineering refinement and warranty depth of Navien.
vs Bosch Greentherm
Bosch Greentherm condensing tankless delivers premium German engineering at higher prices. Marey is the budget alternative with simpler design and reduced features.
vs Eccotemp i-Series
Direct competitor in the budget propane/gas tankless market. Marey and Eccotemp are functionally similar at similar price points. Eccotemp has slightly stronger US customer service; Marey has slightly longer heat exchanger warranty on premium models.
Common Power Gas Indoor concerns
- Cold-water sandwich: like all tankless units, brief cold patch when hot draws stop and restart. More noticeable with longer pipe runs between unit and fixture.
- Gas line sizing: Marey\'s higher BTU models (105,000-140,000) typically require 3/4" gas line or larger. Verify before installation.
- Temperature stability at low flow: below 0.5 GPM, some units cycle, creating temperature fluctuation. Open fixtures wider for stable temperature.
- Service quality: warranty service through Marey direct (no broad dealer network), which is less responsive than major brands.
Installation specifics
Power Gas Indoor installation considerations:
- Mounting: typically wall-mounted via included bracket; verify wall strength can support unit weight
- Vent path: shortest practical route to exterior, properly sealed concentric or twin-pipe
- Gas piping: verify line size; black iron or CSST per local code
- Electrical: dedicated 15A circuit; verify GFCI requirements per local code
- Water connections: shutoff valves and service ports (strongly recommended for future descaling access)
- Drain pan: required if installed above finished space
Annual descaling requirement
Hard-water installations require annual descaling to prevent heat exchanger scale buildup. Without descaling, performance degrades and eventually triggers fault codes. Verify your water hardness (test kits at hardware stores) and schedule descaling accordingly:
- Under 5 grains/gallon: descale every 18-24 months
- 5-10 grains/gallon: descale annually
- Over 10 grains/gallon: descale every 6 months OR install softener upstream
Lifespan
Power Gas Indoor units in proper service typically achieve 8-12 year lifespans — shorter than premium brands (Rinnai, Navien at 15-20 years) but reasonable for the price point. Heat exchanger is the most expensive failure mode; replacement typically pushes toward whole-unit replacement decision.
Who should buy Marey Power Gas Indoor
Right buyer: budget-conscious whole-house tankless replacement, smaller home with moderate demand, willing to do annual descaling, comfortable with online/Marey-direct warranty service.
Wrong buyer: premium home install where service depth matters, cold-climate primary residence where temperature rise capacity is critical, household needing simultaneous high-flow demand (multi-shower).
Total cost of ownership reality
Marey saves money upfront ($800-1,500 vs Rinnai\'s $1,800-3,500 for similar capacity). Total cost of ownership over 15 years depends on:
- Service reliability (Marey may need more service calls)
- Operating efficiency (similar across brands at similar capacity)
- Replacement timing (Marey may need replacement at 10 years vs Rinnai at 18)
For tight-budget installations where the immediate cash flow matters more than long-term cost, Marey wins. For primary residential where long-term ownership is planned, premium brands typically pencil better despite higher upfront cost.