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Why does my Rinnai model # v2520ffuc tankless water heater…

Why does my Rinnai...

Why does my Rinnai model # v2520ffuc tankless water heater cycle short cycle on and off constantly when calling for hot water. Hot water discharge line temperature fluctuates dramatically when this happens..what are some of the things that need to be checked? Heat exchanger has been thoroughly flushed

Contractor's Assistant: How long has this been going on? And how severe is the problem?

It’s been ongoing for at least a year... when showering the water temperature fluctuate after approx. 5 mins

Contractor's Assistant: Do you plan on doing the work yourself?

No, I plan on hiring an technician to trouble shoot , however, I want them to do a thorough investigation as to what the problem is , and not just tell me the unit will need to be replaced.... I need to confirm that all the steps are followed up

Contractor's Assistant: Anything else we should know to help you best?

The remote controller display did not indicate any error code

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Answered in 55 minutes by:
3/24/2018
Phil
Phil, Mechanical Engineer.
Category: Plumbing
Satisfied Customers: 9,822
Experience: Retired mech. contractor, shop owner, 51 yrs experience.
Verified

Hello, a dirt cold water inlet strainer will cause that problem... remove and clean it, if it was clogged you will have most likely solved the problem/

IF the cold water inlet strainer was not clogged, then it is likely that you have a 'water saver' shower head, those restrict the water flow, and thus the hot water flow, and that can also cause the short cycling you are talking about.

To test that, turn on the hot water tap in the bathroom sink while taking a shower, as a test.

If that solves the problem then remove the shower head and remove its flow restrictor.... if its not removable buy a full flow shower head.

.

Its time to rate my input for the day, that gets me paid, locate the "finish and rate your expert" link near the top of the page and click on it. I will appreciate that very much.

I am in every day from 9 am to 11 pm west coast USA time to do any follow up, including coaching, training and repair advice as needed at no additional charge.

Phil
Phil, Mechanical Engineer.
Category: Plumbing
Satisfied Customers: 9,822
Experience: Retired mech. contractor, shop owner, 51 yrs experience.
Verified
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