Installation Guide

Rinnai Tankless Water Heater Installation and Operation Manual 91
COMBINATION SPACE HEATING/POTABLE WATER SYSTEM
(For Use In Commonwealth of Massachuses)
When the system requires water for space heating at temperatures higher than required for other uses, a means such as a mixing valve shall be installed to temperature the water for those uses in order to reduce scald hazard potential.
Air handler
Use Only in Commonwealth of Massachusetts
Electronically controlled pump timer. Activates every 6 hours for 60 seconds. Wire to product approved pump. (or built
- in pump)
Hot Water Supply and Return to Heating Coil
Tempered water to plumbing fixtures. Must meet temperature requirements of 248 CMR
Automatic Tempering Device Must be installed below the top of the water heater as per manufacturer's recommendations.
Check Valve
Cold Water
Supply
Shut Off Valve
Check Valve with 1/8in. Hole Drilled in Clapper Optional
Expansion
Tank
Product Approved Water Heater
100'-00" maximum distance from water heater to fan coil and back. (Developed length) not including coil in heating unit.
Piping loop between water heater and fan coil shall be in compliance with 248 CMR.
NSF-61 Product Approved Pump
Check Valve
Gas supply
Min. 2' developed length Type L copper from water heater
Air handler
Combination Space
Heating/Potable
Water System
All water piping should be insulated in accordance with 780 CMR (Massachusetts Energy Code)
Hot water coil
System installed with reverse acting aquastat to shutoff fan. Suggested but not required by 248 CMR.
Figure 102