Rheem tankless gas water heater always starts on HIGH!


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Old 01-19-16, 01:44 PM
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Rheem tankless gas water heater always starts on HIGH!

We had our failed electric water heater replaced with a Rheem RTGH-84DVLN Tankless water heater a few weeks ago. Couple of issues with it but the main one is:

When the hot water heater is at rest and even a tiny amount of hot water is requested the hot water heater starts on its highest setting. This is very loud (the hot water heater is located in a noise sensitive area), and a waste of gas and electricity and wear and tear on the machine. When it switches from the highest mode to the lowest mode there is a big air pressure change inside the tankless cabinet which causes the poor quality/flimsy front cover to do a big flex and give out an all mighty THUMP.

It wouldn't annoy me so much except that for some reason when any toilet in the house gets flushed it triggers the water heater to fire up! IN HIGH mode, THUMP, low mode, off, all in the period of 3 or 4 seconds. What a waste.

I called Rheem tech support at 800-432-8373 and spoke with a "senior" technician and he laughed when I asked if we could make it start in the lowest mode. "But it would take an extra few seconds to get the full hot water out of your taps! Why would you want that?". After that he didn't seem very helpful and just said "Nope, can't change that, always starts at 100%." Yay.

There's eight dip switches in this beast and I only know what one of them is for (DIP1#4 to unlock 140f max temp output setting).



So..... Anyone know what the rest of the dip switches are for? Ideally I would like to DELAY the activation of it by 1 or 2 seconds (to stop the toilet flushes from activating it) as well as make it start always on the lowest mode (i.e. be less aggressive trying to heat the water quickly).

Thank you for any help or advice you can provide.

-Jamie M.
 
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Old 01-19-16, 02:39 PM
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If rheem did not help and said no, then I dont think anyone here will help.. The manual says no dip switched should be touched .. except for the high altitude one stated in the manual..

Starting on high is no doubt required for safety.

Messing with them or if anyone here suggests to you to do so I will just close the thread..

Your best off calling rheem again or the installer to rectify your issue..
 
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Old 01-19-16, 02:43 PM
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Could you explain how starting on high would be a safety feature?

Thanks for all the information. I'm e-mailing Rheem with my request and also the high school kids that installed it to see if they have any ideas.

-Jamie M.
 
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Old 01-26-16, 02:45 PM
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Well, I put all that starting on high to good use now



Soooo nice.

Oh yeah, got the problem fixed with the toilets activating the water heater. Installed a backflow preventer (i.e. check valve) and an expansion tank and no more toilet activation!





-Jamie M.
 
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Old 02-13-16, 10:57 AM
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Toilet Startin hot water tank

Toilet Starting hot water tank hi I was wondering if you can explain where you put the check valve and expansion tank I am having the same problem when I flush the toilet when the toilet finishes filling my tank clicks for a second I seen this post wondering if you can help thanks
 
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Old 02-13-16, 01:27 PM
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This was the diagram sent by Rheem. It shows the location of the check valve. It fixed my problem perfectly!



-Jamie M.
 
 

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