Question about Rheem Tankless Hot Water Heater Rtg-74pvp-2 7.4 Gpm

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What sort of lpm rate would suit a normal home with fairly good water pressure

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This is just what I would say for an average family of four during hours of peak usage. You should be okay with a flow rate of twenty to twenty four lpm,assuming you have rapid enough recovery. This is based on one shower at a time and not running dishwasher or clothes washer at the same time.If you are using hot water from multiple fixtures then increase accordingly.Hope this helps. Thanks

Posted on Nov 10, 2010

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Will the Grundfos RCP-96 model work with my Rinnai tankless heater model # C85e-1?


Grundfos RCP-96 has Flow range: 0 - 27.5 U.S. GPM
According to Amazon spec sheet:
http://www.amazon.com/Grundfos-RCP-96-UP515-55SFC-Recirculator-Timer/dp/B00128BJAO

Most tankless require .4 GPM to start burner and .25 GPM to maintain burner
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http://www.rinnai.us/tankless-water-heater/
Sample manual from Rainnai mentions 'minimum flow rate' several times but doesn't give specific number. Yet promotion blurb on page 1 says "Ultra operates at a lower minimum flow rate."
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It might seem that tankless promoters are CTA by failing to mention specific flow rate numbers.
I think tankless promotion is a definite overachiever, and vague flow rate is one tiny example.
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All performance numbers are based on new products in ideal circumstance, and not based on a 4 year old product located in your home.

Your flow rate may vary, especially over time, and especially if water in your area is not crystal clear, and you are not diligent with correct water softener and filter.
Many factors can affect flow rates: water pressure, number of elbows, clogs in the line, sediment, size of pipe, aireators, water-saving shower heads, local water conservation policies, water well pressure, MUD district pressure issues, your home located near end of a water main, etc.

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    Major changes in flow rate can adversely affect the output water temperature of the heater. Increases from one major fixture running to multiple fixtures running at one time can cause the temperature to fluctuate. Stay within the heater's specifications. See: TWH E2-03 Outlet temperature vs. flow rate [PDF].
From the Bosch website.

Good Luck,
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My Atwood 6 gal. water heaters pressure relief valve starts dripping shortly after (8 or 10 min.) heat is called for, and dripping gets stronger until a full flow. I have checked all four hi-limits and...


If the water seems hotter than normal, then a faulty thermostat would be a good bet.
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usually 2 things cause that, too much pressure coming in, or thermostat faulty and not cutting out when normal temperature reached, thus higher temperature, and pressure. If both them check out, replace valve.

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1 Answer

The water pipes that carry the water throughout the house makes a loud humming noise every three seconds


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Sincerely,
Shastalaker7

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