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

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Posted on Jul 19, 2017
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No warm water from Rheem tankless

We just had the mother board replaced, and have found we can't get warm water in the shower. We get hot, we get cold, but we can't get it to mix. When we try to cool the hot by turning the knob to cooler, it just shuts off the hot. I will call the plumber on Monday, but was wondering if it is something that just didn't get set right when he replaced the motherboard. Its a propane, direct-vent.

  • dana_larkin
    dana_larkin Jul 30, 2012

    Thanks for the comments. I am embarrassed to say it was low flow caused by a clogged shower head. When we would turn the handle to cool, the flow of hot was too low to maintain and it would shut off. I feel stupid for posting, but brilliant for figuring it out!

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1 Answer

Gene Haynes

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  • Rheem Master 5,391 Answers
  • Posted on Oct 29, 2017
Gene Haynes
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5 Related Answers

Anonymous

  • 61 Answers
  • Posted on Sep 19, 2009

SOURCE: warm water only

You can eliminate the shower control knob possibility by turning on your hot water anywhere else in the house. If you get hot water in other places, then it could be the knob causing it. A substantial lime buildup in the tank can also cause poor heat transfer from the elements to the water.

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Anonymous

  • 248 Answers
  • Posted on Oct 31, 2009

SOURCE: rheem tankless water heater error code C4 13??

check diaphrapm valve or micro/switch best of luck

Anonymous

  • 2 Answers
  • Posted on May 08, 2010

SOURCE: Hi, I have a Rheem RTG-74PVN-2 tankless hot water

there will need to be a recall, everyone is having the same problems across the country. Rheem is finally taking notice. Call your dealer and they may replace unit.

Douglas Jensen

  • 494 Answers
  • Posted on May 15, 2010

SOURCE: Rheem Power Vent 2 water heater is flashing 4

The flashing light is a trouble sequence light. Find your manual to see what 4 flashes means. It's usually attached to the side of the water heater tank. Try a quick fix by unplugging the power vent and see what happens.

Anonymous

  • 760 Answers
  • Posted on Jul 04, 2010

SOURCE: I have a rheem hot water tank when you turn on the

Could be your thermostat but it might be your inlet dip tube. Your water heater has a plastic pipe that carries the cold water to the bottom of the tank. When you open your tap, it takes the hot water from the top of the tank, the cold goes to the bottem and gets heated. If this tube breaks, or comes loose, it will short circuit the cycle. The tank is hot but as soon as you start using water, cold water comes in at the top and mixes with your hot water, giving you just warm water. If you have room above your tank, you can remove the union on the cold side , screw out the pipe nipple, and look inside and see if there is a tube. If not you can buy one from home depot or lowes for just a few dollars. Also a water heater should be partially drained annually to remove any solids from the bottom, which will allow better heat transfer.If you find bits of plastic when you do, then you know where your dip tube went. Also if you've had a hot water faucet stop up and it looked like plastic there it is.

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Related Questions:

0helpful
1answer

I went to take a shower this morning and the water was ice cold. For more than twenty minutes the water ran and never warmed up. Are there common things to check my hot water heater for in this situ

There is an adjustment knob to control how hot the water can become. There might be a problem at the tap (however, if this is the case, you would still get hot water everywhere in the house). If the entire house isn't getting hot water, and the knob is set at the hottest water, you probably need to get the hot water tank replaced.
0helpful
1answer

I just replaced the circuit board, and the water gets warm, but not hot.

Problem might be crossover from failed single-handle faucet cartridge:
http://waterheatertimer.org/Crossover.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

0helpful
1answer

Error c4-15 what does that mean

Before calling service technician, copy following link for troubleshoot resources:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

C4 can range from failed PC Board to lime build-up inside heat exchanger
Error 15 is 'heat exchanger is too hot', clogged heat exchanger, restriction in cold water inlet, temperature set point too high.
If you recently changed temperature setting, then that might be cause.
Tankless require monthy-to-yearly maintenance to avoid common error codes.
Delime tankless and clean water filter, keep temperature low.
Never install tankless water heater is best way to avoid complications of expensive water heater that is maintenance heavy, hard to diagnose, expensive to fix, etc.
Never expose tankless to more than 11 grains hard water.
http://waterheatertimer.org/pdf/Rheem-CondensingTankless-maintenance-2012.pdf
http://waterheatertimer.org/pdf/Rheem-De-lime-tankless.pdf

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1helpful
1answer

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

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

0helpful
1answer

My Rheem tankless water heater has been flashing a C8 and 76 code. I can turn off the heater using the power button on the unit, but my hot water will only last for a shower or so. Any suggestions? ...

Before calling service technician, open following link for troubleshoot resources including Rheem chat and contact, possible manual, error codes, etc.:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

C8 76 is generally bad PC board. Call 800-432-8373
Just like a motherboard on your computer, the tankless PC board is operational center of tankless water heater.
Various sensors gather information from water pipes, gas line, vent pipe, and air supply to determine when to activate burner.
Most people understand that when their computer motherboard needs replacement, that computer will probably not work reliably again.

Tankless is basically connecting a complex computer to your plumbing and electrical lines and to a gas burner with a vent pipe to outdoors, despite knowing that plumbing lines, vent pipes, gas burners, and household electrical systems have plenty of problems on their own.

Age factor: When tankless is new and everything operates perfectly, the tankless works correctly.
And each tankless manual recommends yearly and monthly maintenance, just to maintain operation, the cost of which can exceed the expected 1-8$ monthly savings. And who wants to clean the water filter each month and delime the exchanger every year?
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf

Don't buy a tankless water heater because the only folks promising unlimited hot water and effortless water heating experience while saving money with a tankless are the tankless promotors.

Solve most tankless problems yourself, same day, any brand for about $350.
http://waterheatertimer.org/How-to-install-gas-water-heater.html
2helpful
2answers

Have a Rheem PTG-74PVP tankless water heater. Shuts off after a few minutes while taking a shower. Get a code 76 C8

Before calling service technician, open following links for troubleshoot resources including error codes and rheem chat, and typical scheduled maintenance:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf

Error 76 can mean communication failure between tankless and remote control, which can include bad remote control, bad wire, bad wiring connector, or PC board failure.
Disconnect remote control and see if tankless will work.
http://waterheatertimer.org/pdf/Rheem-error-code-C7-76.pdf

Error C8 76 can mean PC board failure.
Contact Rheem and/or service technician.

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And take advantage of fixya expert assistance live.
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0helpful
1answer

Hi, I have a Rheem water tankless heater and there was a storm lastnight so suddendly I have no hot water. What can It be?

1) All tankless water heaters require voltage to operate electronic sensors and circuit board.
This is true for gas and electric tankless.

2) Check that circuit breaker is not tripped. Push circuit breaker all the way one direction and then all the way back other direction.

3) There are fuses located inside the tankless unit, so check your manual for location of each fuse.
Manual is filled with useful maintenance and troubleshooting steps.

4) Before calling service technician, open following link for troubleshoot resources including manuals, Rheem on-line chat, and useful links for maintaining tankless water heater.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

5) If you had nearby lightning strike, I don't know if your tankless is protected from surge.
I recommend whole-house surge protector for tank and tankless water heater electronics, and household circuits. Surge protection is installed in main breaker box, and is replaced after each surge event. Separate protection needed for co-ax TV satellite, co-ax surge protection can be found on some ordinary power strips.
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#surge
3helpful
3answers

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 :)
1helpful
1answer

I have a Rheem tankless pronto unit. I had a

is there any type of surge portection for tankless water heaters mother boards??????
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