Compatible with Rinnai Tankless Water Heaters: RL94, RL75, C199, RU199, RU180, RU160, RU130
The MSB kits can electronically connect up to 25 water heaters
Up to 5 water heaters can be connected together using the MSB-M and MSB-C1 kits
When over 5 water heaters are connected together, MSB-M control boards are connected using MSB-C2 kits