Rinnai Combi Boiler
Below I will go though the various Rinnai combi boiler products and explain their general function and use. I have thoroughly explored each combi system in depth and you find a link to individual pages and a much more detailed review with specifications should you be interested in a specific system.
The Rinnai E series of combi boilers is most like your standard Navien NCB or Ecoking C series combi systems.
A Rinnai Combi Boiler consists of three heat exchangers. The primary one is the largest and heats your water up to the exact temperature you request. The second, (or secondary) is simply used to take excess heat out of the exhaust gases and preheat your incoming water increasing efficiency. In the Rinnai combi boiler there is a third heat exchanger that is used to completely isolate your potable water system. This enables you to use glycol in your heating system (radiant floors, forced air, thin fin baseboard, etc) should the need arise. That third heat exchanger is an additional step and does reduce the amount of hot water produced compared to a comparably designed tankless water heater. You would be looking at a reduction of around 0.5 gallons per minute, so it’s definitely not a deal breaker.
Combi boilers are a furnace and tankless water heater all in one unit. Your homes hot water is used very little throughout the day so that takes priority over home heating. I use one in my house and ill give an example of how it works. The house thermoatat is set at 21 Celsius and dips to 20, so the furnace kicks on and the fan starts pushing hot air though all the duct work (it’s a forced air hydronic system). I decide to turn the tap on to wash my hands while the furnace is running. The Combi boiler instantly senses a call for hot water and stops the hot water flowing to my furnace diverts it to my tap. As soon as I shut that tap off the combi system directs the hot water back to the furnace. My furnace fan doesn’t shut off during this transition, there is no noise or delay in hot water, it is incredibly seamless.
Rinnai Combi Boiler Models
Listed below are the first generation of systems offered from Rinnai
The Current generation of Rinnai combi boilers
With our Canadian temperatures I would really try to steer home owners into investing into a minimum E75 or a much better suited E110 with access to much higher Btu’s should it be needed.
Whats the difference between a C and CR?
As mentioned the CR is the new generation of Rinnai combi boilers so there have been a few upgraded and changes. The CR has had the expansion tank removed allowing the contractor to install it where needed. Venting has been upgraded to allow for 2” as well as 3” venting. A new fully modulating Grundfos pump has been added where the C series only has a 3 stage pump.
Benefits of a Modulating System Pump
- More adaptive system matching for more forgiving installation (ease of pump matching)
- Reduce electricity use
- Optimize water flow through radiators
- Improve boiler efficiency
- Increase pump and zone valve life
- Reduce pump noise
Rinnai Q175C Combi Boiler
- Rinnai Q175C
In addition to the E series combi boilers there is the Rinnai Q175C system to look at. This combi boiler employs an on board 25 liter hot water tank. If your home has a boiler with a separate indirect water tank this may be the system you seriously consider. The Q175C is a full boiler and water heater in a wall mountable unit, saving space and increasing efficiency.
Rinnai is an industry leader for tankless water heaters I wouldn’t be surprised to see them lead the charge in reliability for combi boilers as well. You won’t be disappointed in their products.