Question about Rinnai Webstone The isolator EXP tankless water heater Service Valves WRIK

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I have a Rinnai Tankless Water Heater that will turn to cold water 10-15 minutes into a shower. The explanation has been that the water pressure on the hot water has to be so many Gallons per minute, but this does not make sense to me when the water spout setting is not being adjusted. Any other ideas what could be causing this? Could it be a GPM sensor gone bad?

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  • Rinnai Master
  • 5,089 Answers

Bad PC board.
Bad sensor.
Don't buy a tankless because the problems can be endless.

Before blaming the tankless however.
Perform the yearly required maintenance on burner
Delime the unit.
http://waterheatertimer.org/pdf/Bosch_Descaling-heat-exchanger.pdf

Remove and clean aerators, replace low-flow shower heads with large water-wasting shower heads.

IMPORTANT check all your single-handle faucets for crossover.
Water getting cool after 15 minutes could be bad cartridge on another faucet.
http://waterheatertimer.org/Crossover.html
http://waterheatertimer.org/pdf/No-Error-Code.pdf

Posted on Oct 25, 2012

6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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Posted on Jan 02, 2017

CRTN
  • 716 Answers

SOURCE: No water flow from hot water tap with a rinnai tankless water hea

Its A Possibility The Left Over Water In The Hot Is Frozen. If Your Line Is Exposed Outside Somewhere It Can Easily Freeze Up. Turn On The Hot Water Everywhere In The House And If Accessible Check The Lines To See Where The Warmth Ends. You Can Leave One Off Over Night In Hopes That It Will Eventually Defrost.

Posted on Jan 16, 2009

  • 152 Answers

SOURCE: No hot water

The code # 11 is a code that warns of "no ignition" and the causes of this error code are too many to list. I would suggest that a qualified tech. perform a diagnostic test and repair.

This is not a task for the "do it yourselfer"

Posted on Mar 25, 2009

  • 11 Answers

SOURCE: takes too long for hot water.

You need a recirculating line. You will have to hire a plumber to run a water line from the farthest fixture or to the fixture you are concerned about on the hot side and return it back to the water heater. this will cause hot water to constantly run throught the hot water line (via the recirculating line) and when you want to draw water from the fixture, you will already have hot water right at the line.
I know this works with standard tank water heaters, but it is a lil trickier with rinnai units(but very possible) if your plumber pleads the 5th and tries to sell you another unit call the Rinnai manufacturerand ask them how.

Posted on Jun 20, 2009

  • 45 Answers

SOURCE: My Rinnai tankless water heater cycles up and down

You need to first make sure is the tankless who do the “up and down”! . If the problem manifest on more then one faucet then the problem is the unit. Have a thermometer (we use a infrared gun wich we train on Hot water pipe !) and see if actually the unit is the culprit.
If the problem is only on one shower It is possible also to be a “antyscalding valve” If the trigger valve on your shower is being adjusted too low then it trigger a splash of cold water now and then on regulate intervals. Try to adjust the temperature lower at the unit (say 110F ) and see if the problem change. If it does, then the problem is for sure in the faucet. If it does not change , then you have a problem with the water flow sensor . It is simply getting stuck. Bad bearing or even a piece of Teflon tape. I believe you will need a certified technician for that so no issues with your warranty will appear.

Posted on Jan 13, 2010

  • 3 Answers

SOURCE: Our Rinnai tankless water heater is producing water as hot as pre

Power outage will reset Rinnai unit to that temperature. Read manual for more info.

Posted on Jan 26, 2010

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Rinnai RL94i - Produces hot water for 3 minutes, then stops


I just had this exact problem. It kept getting worse until we had no water. Our Rinnai tankless hot water heater started the same way though, with hot water for a few minutes and then would shut off with an error code 10. We just had to shut the hot water off and then back on, wait a minute or so and we had hot water back for a few minutes. Our unit would come on with a loud vibrating noise and remain until it shut off with an error code 10 (air flow fault). The solution was to remove the blower fan and blow out the squirrel cage. Ours had moths in it. We also vacuumed out the fan housing. Be careful to mark any wires you disconnect and take pictures before removal. Our unit is now almost silent when it comes on and supplies endless hot water.
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Water temperature fluctuates with tankless


Have you ever tried to pump water for a fountain... It is so tough and you need larger and larger pumps to get it to go 7 feet high to let's say 10 feet high. Having the on demand water heater in the attic dramatically drops it's pressure. It's best to feed it with a 1 inch or at least 3/4 inch pipe downstairs before it splits the hot and the cold to get the best pressure everywhere then the least pressure will be when it reaches the 2nd floor. but the heater won't cut out because the pressure it even greater downstairs.

Nov 30, 2013 | Rinnai Water Heaters

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I have a recently installed richmond water heater. When the shower is running and someone turns the faucet on in the kitchen the water gets drastically colder in the shower. We didnt have that problem with...


Which type Richmond water heater?
Is this a tankless water heater or tank-type?

Tankless are notorious for 'cold water sandwich' under exact conditions you describe. You might need tankless with larger BTU burner.
Don't install a tankless.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

If you have tank-type water heater, then I suspect a clog in the hot water line, or single-handle faucet cartridge in show is going bad.
Same problems can contribute to tankless problems.
http://waterheatertimer.org/Low-hot-water-pressure.html

Aug 06, 2012 | Rheem Richmond

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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
Rinnai does not show C85e-1 so you will have to consult your manual to see minimum water flow requirement.
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."
http://www.rinnai.us/documentation/downloads/U290-665x0200_Condensing_Manual_EN_FR_1-2010.pdf
Another rinnai manual mentions flow rate several times in troubleshoot section yet fails to define what that rate is:
http://www.rinnai.us/documentation/downloads/U287-1833_VB_Series_R75LSi_R94LSi_R98LSi_Manual_EN_FR_EN_FR.pdf

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.
It proves the necessity of reading whole manual and asking questions before buying a tankless.
There's another factor to consider:
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.

Read tankless efficiency vrs water softener
http://waterheatertimer.org/Battelle_Final_Report.pdf
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Bradford White tankless vrs tank side by side
Lime scale does not flush out of tankless
Tankless must have water conditions with less than 11 grains hardness
"Savings falls far short of a payback," 'without comparing service costs'
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Rinnai Infinity 26 hot water system set to 55 degrees with remote temp adjuster. Water only luke warm for showers. Burnner working, water & gas pressure ok. Any thoughts ... Stephen


If you aren't getting any error codes, then the heater is probably doing its job. Your problem is probably somewhere in your plumbing system. The most common reason you get this sort of problem is due to cold water mixing in the hot water system. There are a number of causes for a "cross connection" :

-Faulty check valve
-Missing check valve on reciculation return line
-Faulty shower cartridge
-Thermostatic mixing valve set too low
-Faulty thermostatic mixing valve
-Faulty anti-scald valve

The easiest way to confirm a cross connection is to: 1) shutoff the cold water entering the tankless heater 2) open hot water valves around the house. If you still have water flowing at your hot water fixtures, then you have a cross connection.

Jul 09, 2010 | Rinnai Digital Remote Water Heater Control...

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Water turns cold very quickly


I had the EXACT same problem (installed my tankless last winter and worked fine, now this summer it fluctuates, have to turn the shower completely off and then on again to get any hot water and then it only lasts for a couple of minutes!) Argh - it is frustrating!

Here's what I found: the demand for hot water is lower during the summer (hot) months because the "cold" water coming in is already quite warm. You don't need as much hot water to make the shower temp comfortable. SO, my tankless was shutting off due to low flow demand. I've removed the flow restrictor from my shower head and it helped alot but didn't completely solve the prob. Next step is what has been recommended to me by several people but is much more expensive - change the pressure valve on your shower to a temperature valve. Or just wait til winter and it should work ok again :)

Jul 06, 2010 | Bosch & Tankless LP Hot Water Heater

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I have a Rinnai system. Good cold water pressure, little hot.


What type of pipes are install on this heater?

Mar 13, 2009 | Water Heaters

2 Answers

Runs out of hot water


I wonder if you have this problem below caused by a drop in water pressure from someone flushing a toilet or a washing machine. I would call the company to remedy this issue.

17. What is a cold water sandwich effect? The term “cold water sandwich effect” is a term that is used to describe the introduction of cold water into the hot water supply line during frequent on/off operation of an instantaneous water heater. The cold water sandwich effect, when present, appears as a momentary drop in hot water temperature as it is discharged from a hot water supply outlet (i.e. shower, tub, or faucet). This phenomenon is present in the operation of all instantaneous, tankless style, water heaters, but is minimized with the high tech design of Rinnai water heaters.
The technology built into the Rinnai water heaters is designed to minimize the cold water sandwich effect. Rinnai water heaters are microprocessor controlled and when water flow through them ceases, they remain in a “ready to fire state” for approximately 1 minute. If water flow through a Rinnai water heater begins within the first minute following water flow stoppage, the water heater will fire back up within 1 to 2 seconds. This minimizes the cold water sandwich effect that would otherwise be experienced with a low tech tankless water heater. It should be noted that the cold water sandwich effect cannot be removed completely from tankless style water heaters. The safety standards developed to insure the safe operation of water heaters require a delay in the ignition sequence of all gas water heaters.
While the cold water sandwich effect cannot be completely eliminated from standard plumbing systems, it can be eliminated from plumbing systems that have a supply and return hot water circulating system. Rinnai has developed 2 methods to eliminate the cold water sandwich effect in residential hot water circulating systems.
The first (and preferred) method to remove the cold water sandwich from circulating systems utilizes a small electric tank water heater (powered up) that is used with a dual purpose. The small water heater acts as a mixing tank to eliminate the cold water sandwich effect from the Rinnai water heater and it uses its electric heating element to offset the heat losses from the hot water circulating system.
The second method to remove the cold water sandwich from circulating systems utilizes a small 2 to 6 gallon storage tank installed on the hot water outlet of the Rinnai water heater. This tank acts as a mixing tank to blend the cold water sandwich with hot water and eliminating its effect at fixtures.

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Rinnai tankless water heater


where the pipes are laid out it may run along an outer wall and the cold weather is cooling the water before it gets to the shower try to track the pipe from your water heater to your shower and insulate it where it is coldest

Dec 11, 2008 | Water Heaters

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