instant hot temp fluctuates

[kevfra]

Precept with instant hot water. heats fine but the temperature fluctuates wildly about every thirty seconds, from cold to hot. if I only use the hot side it stays hot, but adding any cold side causes the fluctuations. thoughts?

[Jopopsy]

With instant hot water heaters, you're not supposed to use the cold water side at all. Regulate your water temperature by playing w/ the hot water supply side knob and the hot water heater dial on the wall.

If your hot water is cycling, its not getting enough flow through the heater and its likely tripping at the cutoff temperature until everything cools down a bit.

[Cycledoc675]

I almost exclusively boondock, which makes regulating the temperature a bit more challenging. The freshwater tank is prone to really heating up when its quite hot outside and the generator is running. During the summer, I'll take showers with ONLY the cold faucet open and I'm comfortable. Otherwise, I typically set my temperature closer to the LOW setting (mine is the 2nd gen Girard WITHOUT the electronic temperature gauge) and open the HOT faucet wide open. If you slow the flow, the water temp will get even hotter because the water passes through the water heater slower, allowing it to heat up the water even more. If the temp is too hot, then simply turn the dial down even more toward LOW. As Jopopsy mentioned above, if the heater overheats it will cycle. By using the cold water dial, you are actually reducing the flow from the hot water intake to the Girard and causing it to overheat both the water and the water heater. The water pump simply doesn't have enough pressure to meet both demands.
Now if you are hooked to a water supply to the "CITY FIXTURES" 2 & 6 setting with good water pressure, you can get away with using the cold side as well.

[kevfra]

Well heck, that's a dumb design. so people can't take a shower while someone else uses the kitchen sink. silly.

[bansai]

Originally Posted by Jopopsy

With instant hot water heaters, you're not supposed to use the cold water side at all.

Only if your system is broken.

My tankless system at home operates *exactly* like the tank system it replaced from an end user perspective. There's no way people would buy into a hot water system that only supported 1 temp on demand. Mixing cold water into the 'stream' has nothing to do with the hot water system anyway... with the exception that you are perhaps limiting the amount of flow available to it.

They don't expect people to take 140 degree showers just because that's what you use when doing dishes.

[NickM]

Originally Posted by bansai

Only if your system is broken.

My tankless system at home operates *exactly* like the tank system it replaced from an end user perspective. There's no way people would buy into a hot water system that only supported 1 temp on demand. Mixing cold water into the 'stream' has nothing to do with the hot water system anyway... with the exception that you are perhaps limiting the amount of flow available to it.

They don't expect people to take 140 degree showers just because that's what you use when doing dishes.

You should read up on the Girard RV tankless heaters. Adding cold water to the hot side will cause the heater to needlessly cycle. Set the temp you want in the controller and use only the hot side of the shower. Yes, I agree, probably a poor design but it is what it is.

[kevfra]

No question about it - I got ahold of a Generation II Rev 5 manual and it is quite clear that No Cold Water is to be used with this system.

The hot water valve controls temperature by regulating how long the water spends in the heating chamber. To reduce temperature you simply open the valve more. To increase temperature you close the valve some which naturally restricts flow and thus the water spends more time getting hot. No cold water side is involved.

So finding the right temp setting is a matter of setting the water control properly, and then setting the flow correctly.

Looks like I don't have a problem, just have to get used to a new way of using water. Can't say I like it, would prefer a good old tank that I can heat with electricity or gas.

[RyRoRyan]

This is primarily the reason why I did not buy locally and went out of state for my 16' Seneca. The ones made later had the gen III TWH in it. Now, I have to correct you a litle on the Gen II. From what I understood from Gerard the dial controls the BTU output of the burner. If I recall correctly it can be dialed from I think around 12000 BTU to 30000 BTU or somewhere along those lines. The flame though is constant, no matter what water flow is going through it. This is why when you flow slower, the temp is hotter, but when you flow faster the temp is lower. The good news is that the space that the TWH takes is the same as a standard tanked water heater. Many people have swapped out the Gen II for a tanked system because of this problem. I have also heard of someone complaining to Jayco about this system (on this forum) and somehow Jayco sent him a Gen III. The Gen III solves the problem because it is computer controlled and changes the flame on the fly based on the flow, keeping a constant temperature not a constant flame level.

[MadDad]

Just use the hot water valve, open the shower valve about 3/4 of the way, the set the temp control to get it just right. If need be during the shower use the hot water valve to make more or less flow. Not hard to do once you get used to it.

[Robbbyr]

And by the way, forget about reducing the flow to a trickle when you shampoo or soap up, that wreaks havoc with temperature regulation. Also makes saving water (and grey tank space) more challenging when not on full hookups.

Consistent hot water shouldn't be so difficult like it is with the older Girards! And even the new ones cycle when you reduce the flow to a trickle. That is why I swapped mine out for a 10-gallon Atwood XT. Low flow, no problem. High flow, no problem. Water is kept at a consistent temperature and the XT technology allows it to seem like it is even a bigger than 10 gallon tank. An added benefit to this heater is that I also keep the water hot using campground electricity when plugged in. I seldom need to even turn the propane burner on in a campground. I have never run out of hot water even with multiple people showering consecutively.

Jayco should give buyers the option. But I heard it straight from the factory when I complained about my original Girard that they were less expensive and weighed far less (with water) than a traditional tank heater. But the 83 pounds of water mines carries is inconsequential to me. I can understand in another type of RV it might not be. But in their premier Class A's and Super C's I would have thought true performance and ease of use might have prevailed.

I have never looked back since changing mine over.

[dgantz]

This is our first experience with the tankless heater and we love it. Set temp at 110 and use the hot water side only......works great. 2017 Greyhawk 29MV

Sent from my VS986 using Tapatalk

[Arniesports60]

I have mixed (no pun intended) results/water temp
with my Girard v1 on my 2015 31ul. From my complaints to dealer
they said I Jayco would pay for a replacement if I desired.

I haven't made decision yet based on last trip that had no issues.
On last trip i did the following -
ONLY use Hot water valve in shower (Per instructions by Girard)
Remove water reducer in shower
Change shower head to Oxygenics
use Adjustable Water flow regulator at connection (to get min 50 psi)

These seem to help.

If I do decide on replacement, I wonder what is best solution???
a) Replace with Standard system (assume no charge)
b) Replace with VIII of Tankless system (not sure if charge)
c) Replace with Truma Aqua system (not sure of costs)
(a few have replaced with this and had Glowing Reviews)

Mike

[bansai]

Crazy... well you guys taught me something today. My residential system doesn't work like the ones you guys are talking about. Anyway, thanks for the education on using the 1 tap only... I personally wouldn't buy one with that knowledge.. just seems weird.

[Arniesports60]

Bansai,

I agree. The tankless system and usage of only 1 valve is
different from normal house usage and seems counter-intuitive...

[Vicr]

Here's something told to us by the salesman at our awesome dealership Blade RV in Mt. Vernon, WA. Put some water in your tank if you are on city hook-up. Turn on your water pump. Go to each fixture and open the hot, close; open the cold,close. Run toilet water. Turn off pump. This will purge air out of all the water lines allowing for a constant pressure. It works, not perfect but a huge difference from when we didn't do this. We have the Oxygenics showerhead and set hot water to 110 to shower and wash dishes with hot water only.

[Robbbyr]

Originally Posted by Arniesports60

If I do decide on replacement, I wonder what is best solution???
a) Replace with Standard system (assume no charge)
b) Replace with VIII of Tankless system (not sure if charge)
c) Replace with Truma Aqua system (not sure of costs)
(a few have replaced with this and had Glowing Reviews)

Mike

When Jayco and I discussed a replacement to my erratic Girard they were only willing (at that time) to install a 6-gallon Suburban non-electric (but DSI) water heater. The 6-gallon Suburban would reportedly fit in the exterior opening with only a little "massaging". I wanted more capacity and an electric element, so I opted to do it myself rather than continue the battle. Fortunately my unit was easily able to accommodate the larger opening required of my Atwood XT. And running a new 110-volt electric circuit was also easy in my unit. Those issues may be large stumbling blocks for other types of RV's.

Girard did not yet offer the newest version with the digital display which actually measures the water flow and outlet temperature. That has to be a big step up from the version I had, which only adjusted the flame size regardless of water flow. Online reviews of the Truma have been good and they (Truma) claim to be able to compensate for small flows without scalding or create wild cold/hot fluctuations. Perhaps some actual Truma owners, if they are part of this forum, could verify that claim.

Good luck in your pursuit!