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I have a Rinnai tankless HW Heater (flow activated). Can I use a Closed Loop Circulating System on hot water line downstream of the Rinnai?

by LiveModern Webmaster last modified Jan 04, 2012 02:04 AM
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by last modified Dec 29, 2010

The goal is to minimize the cold water flow when the HW Spicket is opened. It seems to me that the water circulating in the HW Closed lop will not activate the Ranni until a HW Spicket is opened. I would thing I would need a Check valve between the Ranni and the Loop. The problem is I'm just not sure how much water I save with this arrangment?



You can have a recirculating pump on a tankless, but you need to purchase a recirculating pump that will actually activate the tankless heater.

  • Check with the tankless manufacturer.
  • I have also heard that some tankless manufacturers are voiding warranties when a recirculating pump is connected, so you need to verify. Rinnai might be one of those companies.

It would defeat the purpose to have the recirculating pump running 24/7, so please make sure your install a recirculating pump that is on a timer or on a point of use switch. The timer would run the pump for one or two hours in the morning for showers. The point of use switch can be turned on a few minutes before a shower and turned off after the shower.

I have been installing Rinnai's for a few years and feel the recirculating pump is worth the effort, but I do not have any hard numbers.




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