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How do I have hot water?

bobkatmsu
Explorer
Explorer
I have a new to me, 2010 Newmar Dutch Star 4369. It comes with an on-demand tankless water heater. It has been parked the past week, hooked up to a 30 amp service. I have had both the electrical and propane switches to the water heater turned off. Just for the heck of it I turned on the hot water at a faucet and got...hot water. How does that work?
2010 Newmar Dutch Star DP
2014 Jeep Wrangler Sahara
23 REPLIES 23

gonesouth
Explorer
Explorer
I've got to say thanks to Doug for taking the time and effort to figure this out. I like to think I'm an expert on Aquahots and I've repaired one that had been frozen and left as a box of parts, but I sure didn't see this one coming at the start of the thread.

Kudos, Doug!
Currently planning for retirement.....planning to build a small home in Nova Scotia for summers and someday year-round. Trying to sort out a good way to spend winters in central Florida as I can't drive anymore.

bobkatmsu
Explorer
Explorer
jorbill2or wrote:
It’s obviously that the oasis died as Doug said and they decided to save a few bucks putting in the precision temp in its place. You have a puzzle to figure out how they wired it .. hopefully with a breaker somewhere. Hydronic heat has registers that are normally in baseboard cabinets etc. I’d bet they used the oasis original ones and just plumbed them in.
Are you the second owner? If you are the guy who sold it to you was playing dumb.
yes, second owner.
2010 Newmar Dutch Star DP
2014 Jeep Wrangler Sahara

jorbill2or
Explorer II
Explorer II
It’s obviously that the oasis died as Doug said and they decided to save a few bucks putting in the precision temp in its place. You have a puzzle to figure out how they wired it .. hopefully with a breaker somewhere. Hydronic heat has registers that are normally in baseboard cabinets etc. I’d bet they used the oasis original ones and just plumbed them in.
Are you the second owner? If you are the guy who sold it to you was playing dumb.
Bill

bobkatmsu
Explorer
Explorer
dougrainer wrote:
bobkatmsu wrote:
Does not have a furnace! I hadn't even looked for it yet as it hasn't been an issue living in Florida. Used the heat pump a few times and that worked fine. Do not know if it had hot water heater. Newgle is telling me it could have been made with a 10 gal hot water heater or the Oasis system.


If NO furnace, it came with the Oasis system. At sometime he must have frozen the Oasis and replaced it with the Precision Temp system. When you freeze a Hydronic system, you have destroyed it and will need replaced. The Precision and Oasis will utilize the same hook ups. The only difference will be how the system is controlled from inside the RV. If you had a Hot Water Heater, Sorry, no such thing. If you had a (cold):W WATER Heater, then you would have a HOLE in the side of the RV, usually on the drivers side in a DSDP. Hole about 15 to 18 inches square. As I stated, The Precision temp website is horrible as it does NOT show operation or the remote wall switch. If the website DOES show it, it is very difficult to find it. Doug
Nothing like that on either side of motor home.
2010 Newmar Dutch Star DP
2014 Jeep Wrangler Sahara

dougrainer
Nomad
Nomad
bobkatmsu wrote:
Does not have a furnace! I hadn't even looked for it yet as it hasn't been an issue living in Florida. Used the heat pump a few times and that worked fine. Do not know if it had hot water heater. Newgle is telling me it could have been made with a 10 gal hot water heater or the Oasis system.


If NO furnace, it came with the Oasis system. At sometime he must have frozen the Oasis and replaced it with the Precision Temp system. When you freeze a Hydronic system, you have destroyed it and will need replaced. The Precision and Oasis will utilize the same hook ups. The only difference will be how the system is controlled from inside the RV. If you had a Hot Water Heater, Sorry, no such thing. If you had a (cold):W WATER Heater, then you would have a HOLE in the side of the RV, usually on the drivers side in a DSDP. Hole about 15 to 18 inches square. As I stated, The Precision temp website is horrible as it does NOT show operation or the remote wall switch. If the website DOES show it, it is very difficult to find it. Doug

bobkatmsu
Explorer
Explorer
Does not have a furnace! I hadn't even looked for it yet as it hasn't been an issue living in Florida. Used the heat pump a few times and that worked fine. Do not know if it had hot water heater. Newgle is telling me it could have been made with a 10 gal hot water heater or the Oasis system.
2010 Newmar Dutch Star DP
2014 Jeep Wrangler Sahara

dougrainer
Nomad
Nomad
https://precisiontemp.com/wp-content/uploads/2018/03/Twin-Temp-2-and-Jr-Installation-Manual.pdf

Click and look at the install. You will have numerous Hot water lines run thru out the RV for the Furnace zones. IF those hose parts are not used at the units and blocked off, he spent a LOT of money for a Water heater. Do you know if the original unit had a Water Heater or the Oasis system? He may have had the Oasis and replaced with the Twin Temp which would work with the Zone furnace radiators of the Oasis. IF you have a LP powered Furnace, then the unit did not come with a Hydronic system. Doug

bobkatmsu
Explorer
Explorer
I do not see anything that would lead me to believe I have hydronic heating and the previous owner says no, but I have learned he did not know much about his unit. What should I be looking for if I had hydronic heating. Also there IS NOT a twin temp switch in the motorhome, but there is one on the side of the unit.
2010 Newmar Dutch Star DP
2014 Jeep Wrangler Sahara

bobkatmsu
Explorer
Explorer
I do not see anything that would lead me to believe I have hydronic heating and the previous owner says no, but I have learned he did not know much about his unit. What should I be looking for if I had hydronic heating
2010 Newmar Dutch Star DP
2014 Jeep Wrangler Sahara

rogerddd
Explorer
Explorer
What Doug said. "TRUE Tankless RV water heaters CANNOT utilize 120 volts to give continuous HOT water." Mine starts warm then cycles between warm and cold. That's if we are hooked up. Dry camping presents different (worse) issues.

dougrainer
Nomad
Nomad
bobkatmsu wrote:
dougrainer wrote:
I just checked Newmar's archives. They list ONLY a Standard 10 gallon water heater or the upgrade optional Oasis type LP powered System hydronic zoned system.
So, that points to one of the problems with forums. The OP has just purchased a 8 year old Motorhome and has questions. BUT, he has no way of knowing what the previous owner/s did to that coach. They may have added a Tankless system and wired it in such a way that it does indeed stay on when he thinks he has turned it off. When he checks, he will post the Brand and hopefully model of his Tankless system. We can then give him more accurate info. Doug
After reading your post I checked my Newgle account and again agree with you, a tankless water heater was not an option in 2010. The previous owner must have installed this to replace the 10 gallon water heater.
I was at my mh this morning and found that the manufacturer is Precision Temp, the model is a Twin Temp Jr. Hydronic Heating/Water Heater. I could not get to the model number. Thanks for all your help.


OK, don't need model number, your model is what you stated. Now, I went to precision temps website and the install/operation instructions are HORRIBLE. They list NO remote On/Off panel. They seem to indicate that the system switch is ON the unit itself. Now, Adding a Hydronic system is NOT easy or inexpensive. So, if you do indeed have the COMPLETE Hydronic HEATING and Water Heater system, you got a good deal on your used motorhome. They may have installed just the Water Heater part. Now, the odds are it had the standard OLD OEM water heater switch for turning on the LP or 120 system. THAT wall switch would not really work for the Twin Temp. So, if you turned the OEM Water Heater switches OFF, but did not turn the Twin Temp OFF at the Twin Temp unit, that would be why you had Hot water after a week. Do you have a Precision temp inside remote switch? Do you have the Hydronic radiators for Furnace heating? Doug

bobkatmsu
Explorer
Explorer
dougrainer wrote:
I just checked Newmar's archives. They list ONLY a Standard 10 gallon water heater or the upgrade optional Oasis type LP powered System hydronic zoned system.
So, that points to one of the problems with forums. The OP has just purchased a 8 year old Motorhome and has questions. BUT, he has no way of knowing what the previous owner/s did to that coach. They may have added a Tankless system and wired it in such a way that it does indeed stay on when he thinks he has turned it off. When he checks, he will post the Brand and hopefully model of his Tankless system. We can then give him more accurate info. Doug
After reading your post I checked my Newgle account and again agree with you, a tankless water heater was not an option in 2010. The previous owner must have installed this to replace the 10 gallon water heater.
I was at my mh this morning and found that the manufacturer is Precision Temp, the model is a Twin Temp Jr. Hydronic Heating/Water Heater. I could not get to the model number. Thanks for all your help.
2010 Newmar Dutch Star DP
2014 Jeep Wrangler Sahara

bobkatmsu
Explorer
Explorer
dougrainer wrote:
1. TRUE Tankless RV water heaters CANNOT utilize 120 volts to give continuous HOT water. Even HOME 240 volt systems must be designed for AC operation and will NOT function as well as LP or Natural Gas Tankless Water Heaters.
2. Even the LARGE Aqua hot with 2- 120 elements, will only give about 4 gallons of hot water before the 120 elements cannot keep up with the demand--Aqua hot states to utilize the Diesel burner for continous
3. Most RV TANKLESS water Heaters are LP powered or Diesel powered(Aqua Hot)
4. Lets say the OP came back after a week and had Hot water. He needs to then run the Hot water and see HOW long/much hot water he had. I doubt more than a gallon if his switches were indeed turned off. But, if he does have a 120 system also, then that would account for the hot water he had but just not much hot water. Doug
I'll try that tomorrow, good idea. At least, then I would know what the source is. As you stated the electric is only for things like washing your hands, doing a small load of dishes, etc. I you are going to take a shower, you have to use the LP.
2010 Newmar Dutch Star DP
2014 Jeep Wrangler Sahara

dougrainer
Nomad
Nomad
I just checked Newmar's archives. They list ONLY a Standard 10 gallon water heater or the upgrade optional Oasis type LP powered System hydronic zoned system.
So, that points to one of the problems with forums. The OP has just purchased a 8 year old Motorhome and has questions. BUT, he has no way of knowing what the previous owner/s did to that coach. They may have added a Tankless system and wired it in such a way that it does indeed stay on when he thinks he has turned it off. When he checks, he will post the Brand and hopefully model of his Tankless system. We can then give him more accurate info. Doug