I was told " there are no dumb questions"

[FLnative]

Well here goes, I had a Keystone Montana, with an actual Hot water tank. I never had this problem. The instant hot water in my 2024 Grand Design has me stumped. I set the temp for 100 and as I turn on the hot water the numbers are like a slot machine. Temp goes from 100 to 115 to 105 to 122 to 107 and on occasion during a shower back to 100 but not for long. What would cause this constant change in water temp while the water is running ?

 

[WhittleBurner]

​That's wacked out, must make for an uncomfortable shower. Are you running it continuous or stopping and starting the flow?

 

[DougW9876]

I set mine for 100 and turn the hot on full open. It will fluctuate kind of wild for a few moments, then it settles down to 100 and stays comfortable. If I turn it off then back on it will fluctuate a bit again then settle down. It is just another of the things I don’t like about the demand water heater.

 

[FLnative]

​That's wacked out, must make for an uncomfortable shower. Are you running it continuous or stopping and starting the flow?

I never let the water run continuous. Regardless of where I set the temp, the temp fluctuates when the hot water is flowing. But thanks for the response. With your time at this I can only assume "I got a problem" with a 7-week-old unit.

Now I must say this if I turn the flow down so that it barely has enough to spray outward then it remains constant at 100 but then you must stand directly under the slow flowing water. The water pressure is showing on a gauge below the recommended 45psi.

 

[WhittleBurner]

The Low water pressure might be part of the problem, does the paper work say anything about required pressure

 

[FLnative]

I will try that. Just leave the water flow and not interrupt it. I may be the problem. THANKS !

 

[FLnative]

I'll try that. Constant flow may be what I need to do. I just thought I would save some propane and shut it down after getting wet.

 

[RatLordDad]

Our Grand Design RV's use a Tankless water heater (as does my home). That means it does not store and maintain hot water. When you turn on the hot water faucet the tankless system compares the incoming water temperature with the temperature you've set on the controller. If hotter water is needed it fires up the propane burner to heat the water--as needed. The benefit is endless hot water, low propane usage, less weight (no stored hot water). The offset is it takes a few seconds to heat up the water when one first turns it on, and low usage will result in the tankless heater turning on and off "as needed".

The colder the water coming into the RV, the faster the tankless generates hot water and the more likely it will stay hot.

If you take a shower and only use a little hot water, the tankless will slow down making hot water (which is why the temp reading decreases).

With higher water pressure coming in, and high usage in the shower, the tankless will be pretty consistent.

Hope this helps.

 

[WhittleBurner]

Our Grand Design RV's use a Tankless water heater (as does my home). That means it does not store and maintain hot water. When you turn on the hot water faucet the tankless system compares the incoming water temperature with the temperature you've set on the controller. If hotter water is needed it fires up the propane burner to heat the water--as needed. The benefit is endless hot water, low propane usage, less weight (no stored hot water). The offset is it takes a few seconds to heat up the water when one first turns it on, and low usage will result in the tankless heater turning on and off "as needed".

The colder the water coming into the RV, the faster the tankless generates hot water and the more likely it will stay hot.

If you take a shower and only use a little hot water, the tankless will slow down making hot water (which is why the temp reading decreases).

With higher water pressure coming in, and high usage in the shower, the tankless will be pretty consistent.

Hope this helps.

That's what I don't like about the tankless. Especially in the sink. You can't get a lukewarm low flow, it will turn cold. To keep a steady flow of hot water you have to turn the hot to high. Which means the water can go anywhere. Between how long it takes to get hot water when you first turn it on and having to keep it turned on high I think it wastes a lot of water.

 

[robmcqueen]

I see most people do not like the Tankless water heater Why do they keep putting them in unit ? What type of water heater do you all like

 

[Hoopy Frood]

I see most people do not like the Tankless water heater Why do they keep putting them in unit ? What type of water heater do you all like

My opinion is the RV builders don't really care what people want, or don't want. They build it and figure people will buy them because if one builder does it, the rest follow right behind. So pretty soon there are no choices. Witness the residential refrigerators, which while they work well to cool, seem to have issues having the insides stay in one piece going down the road. Or the solid steps that aren't universally accepted because of the issues with them. Or the proliferation of electronic controls that absolutely no one asked for, but you get them anyway.

Personally I would not want the tankless water heater due to the issues with them. Most are minor issues, that are not present with the tank water heaters. We never run out, but I can see why they would be more popular with smaller tank sizes.

 

[ddepew]

We have found the variation of the hot water temperature is due to the temperature and flow rate of the incoming water. Outside, on the water heater there is a flow rate control, so if the temperature coming in is too hot, you increase the flow rate so it is not over the flame so long. What you are describing sounds like your incoming water hose has been in the sun, and the incoming temp is high for a period then cools off. When we go to the beach in the summer, the incoming temp before the water heater is 84 degrees. We have increased the flow to maximum, set the heater temp to 95 but can not get the temp below 115, which is impossible to shower. So we go to the shower house or take a cold 84 degree shower. Where the incoming water tempurature is below 70, the instant works great and you can acutlly control it usually just inside with the thermostat, but can get the initial too hot if the hose has been in the sun. I agree the instant on is a water waster. Hope this helps.

 

[Daren-n-Leah]

I see most people do not like the Tankless water heater Why do they keep putting them in unit ? What type of water heater do you all like

I see the same on these forums,,, but everyone I know and have met that has the tankless heater love it, as do we.... I set mine on 120 degrees,,, in the shower I turn both the hot and cold water on full and it's perfect. As soon as it comes on the numbers on the controller bounce around for a couple seconds, but always settles in at 120...and when I get in the shower I use the cutoff on the shower head instead of the control knobs... when I turn it back on it is a little cooler for maybe 5 seconds but then goes right back to perfect, every time. no way I would even think about going to a water heater tank....
I will also add that I have run up with people that are looking to replace their old style water heater with a tankless heater, but never met anyone with a tankless heater wanting to replace it with an old style heater.

Another edit, after seeing ddepew's post above about the water hose being in the sun, we always hook up to city water and fill our fresh tank and just use it instead of leaving it on city water. Keeps the fresh tank fresh, and we get better water pressure using the unit's water pump than we do using city water with a pressure regulator. It also protects in case a of a water line failure,,,if that should happen it will stop when the tank runs empty...plus it makes it easier to cut the water off when going to bed or being away from the camper,,, just push a button....

 

[robmcqueen]

I see the same on these forums,,, but everyone I know and have met that has the tankless heater love it, as do we.... I set mine on 120 degrees,,, in the shower I turn both the hot and cold water on full and it's perfect. As soon as it comes on the numbers on the controller bounce around for a couple seconds, but always settles in at 120...and when I get in the shower I use the cutoff on the shower head instead of the control knobs... when I turn it back on it is a little cooler for maybe 5 seconds but then goes right back to perfect, every time. no way I would even think about going to a water heater tank....
I will also add that I have run up with people that are looking to replace their old style water heater with a tankless heater, but never met anyone with a tankless heater wanting to replace it with an old style heater.

Another edit, after seeing ddepew's post above about the water hose being in the sun, we always hook up to city water and fill our fresh tank and just use it instead of leaving it on city water. Keeps the fresh tank fresh, and we get better water pressure using the unit's water pump than we do using city water with a pressure regulator. It also protects in case a of a water line failure,,,if that should happen it will stop when the tank runs empty...plus it makes it easier to cut the water off when going to bed or being away from the camper,,, just push a button....

How long does it take to get hot water to the kitchen sink ? My parents refection 31mb takes about 30 sec. Thats a lot of wasted water when you don't have hook ups. I hear people say things like you can save it in a jug and use it for the toilet ect. Lets be honest that a pain in the butt. I still think if you boondock the gas/electric is still best. Plus when you do have hook ups you can run it off electric and save propane.

 

[Daren-n-Leah]

It takes less than 10 seconds to get hot water to the sink. Just guessing but I would say it is actually closer to 5 seconds... the water heater is directly below the sink in my 2500RL. It takes about 2 seconds for my tankless heater to fire once you turn the spigot on. Other than that it will take the same amount of time to get hot water to a faucet regardless of the kind of heater you use if they are mounted the same distance from the faucet. Propane efficiency has been amazing. We've had our 2500RL since last July and have been on 9 trips, 3 of which were 2 weeks or more, and that includes a week at the beach last Thanksgiving where we had to run the heat and a 17 day trip over Christmas/New Years over the North GA mountains, NC Mountains, and with the last 7 days being in Pigeon Forge Tenn... it snowed 3 times on us and that last week was down in the 20's every night... I've only refilled 3 20lb tanks since we bought the camper and still have a full bottle on the camper that hasn't been tapped into yet... wife and I shower every day without worrying about propane usage and we use both the burners and the oven probably more than the average people. I have been super impressed with propane usage. Never boondocked tho....

 

[dougjolie]

We upgraded to a new oxegenics shower head that hsa a shut off valve on it. My had the same problem you are describing and I found out that the valve was partially shut off causing low water flow. Temp was all over the place.

 

[mvermett]

RV tankless and home tankless aren't alike

We've had a tankless at home for years and never had the same experience as we do with our first Grand Design tankless.

The RV tankless will actually reduce heating when the outbound water pressure slows or stops, so turning on cold water or stopping flow altogether will reduce the hot water coming out of the tank and the temp you get at the faucet or shower will adjust accordingly.

The best way to keep temp stable is set the temp you want and don't stop the flow. It's one of the few things I don't like with our new Grand Design. That and the Furrion A/C units and where Furrion puts the temperature sensors for those. Topic for another forum.

 

[huntindog]

We've had a tankless at home for years and never had the same experience as we do with our first Grand Design tankless.

The RV tankless will actually reduce heating when the outbound water pressure slows or stops, so turning on cold water or stopping flow altogether will reduce the hot water coming out of the tank and the temp you get at the faucet or shower will adjust accordingly.

The best way to keep temp stable is set the temp you want and don't stop the flow. It's one of the few things I don't like with our new Grand Design. That and the Furrion A/C units and where Furrion puts the temperature sensors for those. Topic for another forum.

That practice makes the unit useless for boondocking.