Rinnai Combi Boiler

In my opinion Rinnai has always been an industry leader, their combi boilers exceed those same expectations.

2019 Product Updates

As time goes by companies update and re-invent their products, contantly changing and adding features and efficiency.  Rinnai combi boilers are no different, there have been a number of new models released.  Below are 7 models available in a complete wall hang-able package to provide all your homes hot water as well as heating needs.  All combi system models can operate on both Natural Gas or Propane fuel.

Rinnai I Series

Released in February 2019, the Rinnai I series combi boilers have a unique feature in that they can both heat your home and heat water simultaneously.

If someone is in the shower and your thermostat calls for heat the I series combi boiler can satisfy both demands. uniquely, if your home has more than one zone this combi system can heat them both separately and simultaneously as well.

The L series comes in 3 different sizes.

  • i060CN
  • i090CN
  • i0120CN

Rinnai M-Series

The Rinnai M Series combi boilers were released in 2018 and are able to provide both home heating as well as all hot water needs.  These systems are very similar to the Navien combi boiler systems available.

The M Series is available in 4 different sizes.

  • M060CN
  • M090CN
  • M120CN
  • M160CN

Below we will go though the various Rinnai combi boiler products and explain their general function and use. Some of the systems below have been discontinued.  Each combi system has been thoroughly explored in depth and you will find a link to individual pages and much more detailed reviews 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 thermostat 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

Rinnai E Combi Boiler from the C Series

Rinnai Combi Boiler Models

Listed below are the first generation of systems offered from Rinnai

  • E50C
  • E75C
  • E110C

The Current generation of Rinnai combi boilers

Rinnai Comb Boiler

Rinnai E combi boiler from CR series

  • E50CR
  • E75CR
  • E110CR

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 Combi Boiler

Q175C combi boiler from Rinnai

  • 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.


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