Flushing Toilet Starts Water Heater

[lenp]

Linda,

Did this rig come with this water heater or was it added later?  If added later, there may well be a water heater bypass installed that the dealer may have "activated" when they winterized and it never got de-activated.  

Since the heater comes on even when a cold water tap is opened there has to be a cross connect someplace.  

Len

[Kirk W]

8 hours ago, lenp said:

Since the heater comes on even when a cold water tap is opened there has to be a cross connect someplace.  

That is exactly what I was thinking when I asked if cold water would turn it on also. Have you taken a look at the plumbing behind the water heater? As I look at the Winnebago brochure, it seems that the tankless water heater was an option at the time yours was built, but that a 6 gallon was the standard. Based on that, even if the present water heater was factory installed, it is possible that there is a water heater bypass. I would sure take a look at that possibility. 

[LindaH]

10 hours ago, lenp said:

Did this rig come with this water heater or was it added later? 

It came with the rig.

[LindaH]

1 hour ago, Kirk W said:

That is exactly what I was thinking when I asked if cold water would turn it on also. Have you taken a look at the plumbing behind the water heater? As I look at the Winnebago brochure, it seems that the tankless water heater was an option at the time yours was built, but that a 6 gallon was the standard. Based on that, even if the present water heater was factory installed, it is possible that there is a water heater bypass. I would sure take a look at that possibility. 

If that were true, it seems it would have been a problem from the start, but this is a brand new problem which cropped up this year after we dewinterized it.

HOWEVER, we seemed to have solved the problem!  Kirk, when you asked whether or not the problem happened when we turned on the cold water to a tap, I turned on the cold water at the kitchen sink.  The heater came on (I'm not clear on whether or not it was actually the burner that came on or whether it was just the fan that came on -- we never went outside and opened up the door to the water heater to see whether or not there was a flame).  So I went to the bathroom sink and turned on the cold water.  It sputtered a bit, but then flowed normally.  Anyway, that seems to have cured the problem because now when we flush the toilet or turn on the cold water at the kitchen or bathroom sink, the water heater doesn't come on.

I have no explanation as to why turning on the cold water taps cured the problem, especially since when we dewinterized I'm positive I turned on both the hot and cold taps at each faucet and the shower.  As I mentioned earlier, we rarely, if ever, turn on the cold water...the single-lever handles are always in the hot water position.

[Dutch_12078]

Air in the cold water lines might have allowed enough expansion room to cause enough flow to trip the heater switch. When you opened the cold taps the excess air was vented, "fixing" the problem.

[ARGO]

Maybe it was a factory setup for the optional bidet ?

[Barbaraok]

Gremlins - when I can't figure why something strange happens in the coach, I know it is a Gremlins attack just to drive me crazy!

[Kirk W]

3 hours ago, LindaH said:

If that were true, it seems it would have been a problem from the start, but this is a brand new problem which cropped up this year after we dewinterized it.

My thinking was that if it were there, the tech who winterized could easily have changed the valve position, since that was when your problem began.

3 hours ago, LindaH said:

It sputtered a bit, but then flowed normally. 

That would sound like there was still some air in the system. Why did it cause the symptom? Some things are not worth the effort to figure out. 

[lenp]

Linda,

Glad you got it solved!!!!!

Len

[LindaH]

21 hours ago, Barbaraok said:

Gremlins - when I can't figure why something strange happens in the coach, I know it is a Gremlins attack just to drive me crazy!

Exactly! 🤪

[GR "Scott" Cundiff]

All I can say is that if flushing caused our water heater to come on it would be on all the time.

[Al F]

On 11/22/2020 at 10:43 PM, LindaH said:

Water pressure at all faucets is good.

We always run off the water pump from the tank even when we're in an RV park, which is rare.

The heater stays on the entire time...we can hear it running for awhile afterward, just like it does when using hot water at a faucet.

Both hot and cold are turned off at the outside shower.

We bought a new-to-us RV in 2018 that had a tankless water heater.  I think it was the same brand water heater that you have.  It did the same thing yours does. (turns on when toilet flushed)  Note, that the toilet water flush has no flow restrictor like sink faucets do.  So flushing the toilet causes a bigger water surge than the sinks do.  That may be what causes the water heater flow detector to trigger the gas flame.

We also boondock/dry camp a lot and also, as you do, only run our water system off the water pump and fresh water tank even when we have water hookups available. 

A second problem we found is that since we dry camp/boondock a lot we tend to only turn on the sink faucets a tiny bit to limit the amount of water we use.  That tends to fluctuate the water flow because the water pumps runs very slow and speeds up as the water pressure drops.  We have a variable speed water pump, so it doesn't turn off and on, but it sure does slow down and speed up under low flow conditions. 

The low water flow would cause the water heater to turn off the flame and the water heater would run its cool down cycle for probably 20-30 seconds (note: no gas flame to heat water).   

Bottom line I yanked out the piece-of-junk tankless water heater and installed the regular 10 gallon tank water heater that was originally in the RV.  

It only takes about 15 minutes on gas only to get the water in the water heater tank hot enough for washing dishes or shower.  Once it is hot it stays warm for quite a while.  If we have electric hookups I turn on both the gas & electric for about 10 minutes to get the water hot.

I think the tankless water heaters are only good for folks who have unlimited water/sewer access and can let the water run a full flow until you no longer need the water.   

[LindaH]

43 minutes ago, Al F said:

Bottom line I yanked out the piece-of-junk tankless water heater and installed the regular 10 gallon tank water heater that was originally in the RV.  

I've thought about doing the same thing because I really dislike this tankless water heater!  While I've learned to live with it, I would NEVER have another one.  

Would you be willing to let me know about how much it cost to replace the tankless with a tank (we'd probably only get a 6-gallon which has been more than sufficient in past RVs)?  You can PM me if you like.

[Al F]

57 minutes ago, LindaH said:

I've thought about doing the same thing because I really dislike this tankless water heater!  While I've learned to live with it, I would NEVER have another one.  

Would you be willing to let me know about how much it cost to replace the tankless with a tank (we'd probably only get a 6-gallon which has been more than sufficient in past RVs)?  You can PM me if you like.

I did the work myself so no labor involved.  The new Atwood 10 gallon gas/elect water heater was $540 on Amazon.   I bought the 10 gallon instead of the 6 gallon because that was the original size in the RV.

[LindaH]

19 hours ago, Al F said:

I did the work myself so no labor involved.  The new Atwood 10 gallon gas/elect water heater was $540 on Amazon.   I bought the 10 gallon instead of the 6 gallon because that was the original size in the RV.

I doubt we'd do the work ourselves, so labor would probably add another $500-$1000.  Probably not worth it considering we don't know how much longer we'll keep heading south for the winter.

[MarciaElkins]

On 11/23/2020 at 8:30 PM, LindaH said:

That's not the way this water heater is set up.  There's a temperature dial in the bathroom where you can increase or decrease the temperature.  We set it so that we can take a shower without turning on the cold water.

 

Yes, it does.  I'd never noticed it before since I almost never turn on the cold water.

Tell me about this temperature dial.  Did you all install it?  We are Newbies and I used a lot of water to get the hot and cold set for my first (and only so far) shower.  The cold would steal the pressure from the hot and cause it to go cold.  We have a tankless HW heater.

[Kirk W]

15 hours ago, MarciaElkins said:

Tell me about this temperature dial. 

Your 2020 Vista does not have the water heater which she has. It comes with a standard, 6 gallon RV water heater and they do not list a tankless water heater as an option. Therefore you do not have what Linda has described.

Edited December 2, 2020 by Kirk W

[LindaH]

16 hours ago, MarciaElkins said:

Tell me about this temperature dial.  Did you all install it?  

No, we did not install it.  It is part and parcel of the tankless water heater and was installed by the manufacturer.

I, too, looked at the brochure for the 2020 Vista and it does not list a tankless water heater as an option.  So, I don't believe that you have one unless you were able to get it specially installed by the dealer.  If you DO have a tankless water heater, you have to have means of controlling the temperature.

With the 6-gallon water heater that the Vista brochure says comes with the RV, you can do some experimenting with leaving the water heater turned on for "X" period of time, turning it off, and then testing the temperature to see if the temperature is satisfactory for you to take a shower without turning on the cold water.

[Al F]

4 hours ago, Stephen Ryan said:

We bought Eccotemp water heater for our RV, and it has been a dream! We fulltime in our RV, and use it on a daily basis. The only time we have issues is when the water pressure is too low, not a fault of the heater. We read reviews that complained about the freezing issue, we mounted the unit on an inside wall perpendicular to the outside wall to where it was vented. This kept the coils away from the colder outside wall, and yes it got cold this winter, and we never had one issue with freezing.

Do you dry camp/boondock with it?  How well does it work with very intermittent water flow Such as running the water for 2-4 seconds then off for 10-15 seconds then on for 2-4 seconds and repeat.  We do this when washing hands, or washing dishes.  

When dry camping/boondocking you very severely limit the amount of time you let the water run. 

The one we had, (not the one you have) the heater would start during the 2-4 seconds run time, turn off and run the 20-30 second cool down cycle, but not heating water.  When we turned the water back on the heater was still in the cool down cycle so it wouldn't re-light for a while.