Section 13.2
Sizing example: two-shower propane cabin in Colorado at 8,500 ft
A two-bathroom cabin near 8,500 ft in Colorado, on a propane tank with no gas utility, needs 4.0 GPM at a 63 F rise. Rinnai's map shows 37 to 52 F across Colorado, with the coldest water in the high mountains[1]. This example uses 42 F.
- Fixtures at the same time
- Two 2.0 GPM showers, 4.0 GPM in total
- Rise
- 105 F minus 42 F = 63 F
- Altitude
- about 8,500 ft
| Model | Flow at 63 F rise | Against 4.0 GPM | Manufacturer requirement |
|---|---|---|---|
| Rinnai V75eP (propane) / V75eN | 4.3 GPM | Delivers 4.0 GPM | 180,000 BTU/h, outdoor (external) |
| Eccotemp SmartHome SH12-A-LP (indoor) | 2.2 GPM | Short by 1.8 GPM | 80,000 BTU/h, indoor |
| Rinnai V53DeP (propane) / V53DeN | 3.1 GPM | Short by 0.9 GPM | 120,000 BTU/h, outdoor (external) |
| Eccotemp SmartHome SH22-LP (outdoor) | 3.8 GPM | Short by 0.2 GPM | 140,000 BTU/h, outdoor |
| Eccotemp SmartHome SH22-ILP (indoor) | 3.8 GPM | Short by 0.2 GPM | 140,000 BTU/h, indoor |
| Rinnai V65eP (propane) / V65eN | 3.5 GPM | Short by 0.5 GPM | 150,000 BTU/h, outdoor (external) |
13.2.1 Altitude approval
Rinnai approves the V53De, V65e and V75e up to 10,200 ft[1][2][3]. Eccotemp's SmartHome pages list no altitude approval[4], so an approval for 8,500 ft has to come from Eccotemp in writing. Only the Rinnai V75e delivers 4.0 GPM at a 63 F rise, and it has a listed altitude approval. The Eccotemp SH22 is next at about 3.8 GPM.
Propane line sizing, the regulator, venting and clearances follow the manufacturer's manual and local code. A licensed gas installer or plumber does the work.
Notes and sources
- Rinnai, non-condensing tankless brochure with United States Ground Water Temperature Map and V53De table, 06/2022 (PDF hosted by Woodstove Pro)
- Rinnai, V65e specification sheet with water flow curve (PDF)
- Rinnai, V75e specification sheet with water flow curve (PDF)
- Eccotemp, SmartHome SH22-LP outdoor product page