Design and installation guide for Rinnai tankless water heater systems, covering plumbing, pump sizing, water quality, and pressure loss.
This manual provides detailed information for designing and installing hot water systems that use Rinnai tankless water heaters. It includes plumbing schematics, MSB kit configurations, water‑quality guidelines, pump‑sizing calculations, and pressure‑loss curves for both non‑condensing and condensing models.
Key sections cover MSB kits for multiple heaters, water‑quality limits, pump sizing for circulation and storage‑tank recovery, additional installation guidelines, and pressure‑loss data for each heater model. The document is intended for designers, engineers, and installers who need to size components and ensure reliable operation.
| Maximum total water hardness | 200 mg/L |
|---|---|
| Minimum pump flow for circulation loops | 3 gpm |
| Allowed pump construction materials | Brass, bronze, or stainless steel |
The water should have a total hardness of up to 200 mg/L.
A minimum circulating flow rate of 3 gpm is required.
Pumps must be made of brass, bronze, or stainless steel; iron pumps are not allowed.