Rinnai RL75 - need hot water faster

by Tom
(Toronto, Canada)

I have bought a house recently which has a tankless water heater made by Rinnai that doesn't have a manual and I never seen or run one before. It is an indoor Rinnai RL75i.

My two-story house has three bathrooms and the hot water we are getting from the water heater at the most distant shower is OK but it takes time to get it.

My question is: how can I get it faster... do I have to buy a special pump? Any suggestion would be appreciated.


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Jul 14, 2013
Recirculating pump and plumbing tips
by: Zak plumber

In order to get the hot water fast I would suggest installing the external recirculating pump. The best way to do is to install the 3/4 inch hot water return line, a recirculation loop, with the pump installed in return line and after the hot water fixtures with the check valve after the pump.

For your Rinnai RL75i, the requirements for the pump are 120 V and 60 Hz with the 2 amps maximum. Also the pump should be sized for water flow of 2.5 gallons per minute. This particular model has a feature called Circ-Logic which has the ability to control the pump. The wire harness for the pump goes back to PC board. 4 Amp fuse must be added to the wire of the pump.

There are two modes in recirculation mode: economy and comfort. While in economy mode the pump cycles less and less energy is consumed while in comfort mode pump cycles more often, therefore consumes more energy. By setting the DIP switch properly you will choose one of the two modes.

The recirculating mode on your Rinnai RL75 is activated only when hot water is used and according to Rinnai cannot be used with the Bath Fill controller or with multiple models installed.

Hope this helped.

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