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Topic ClosedConcept for cold weather use of rPod water systems

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Direct Link To This Post Topic: Concept for cold weather use of rPod water systems
    Posted: 23 Jan 2019 at 5:10am
Skirting and heating is not a good solution unless you're parking the trailer for a long period. If you're on the road in cold weather or camping for a couple of days between moves its not going to be very practical. The recirc system is going to cost all of about $50 to do at most so its really going to be cost effective if it works well.  But to each their own. 

texman, you have the operating theory correct, Just one clarification,  the thermostat on the water heater operates independently of the one on the recirc system. The water heater will turn on when its thermostat calls for heat, which might or might not be when the recirc system is operating. 

The purpose for adding the new thermostat on the water heater is only to be able to set the water temp lower than the 130 deg non adjustable setting of the standard thermostat. By setting the temp down around 102-110 degrees (whatever feels comfortable to you) you don't ever get scalded, you don't need to fiddle with adjusting the water temp, and you waste less water. So, you won't need to change the recirc system back to its normal hot and cold setup in order to use the water in the winter. 

In my case, when I do the recirc mod I don't think I'll ever change it back to allow separate hot and cold line function, even in summer. As I don't drink or rinse food with the trailer tap water (I don't trust the water in the tank so I use bottled water for those purposes and for brushing my teeth),  I really have no need for the cold water function. 

I think you shouldn't need to set the recirc thermostat setpoint anywhere near as high as 60 degrees. If its temp sensor is located at the coldest low point of the system its probably OK to set it more like 35-40 degrees. Some testing will probably be required to dial that in. The temp sensors on the little thermostat boards are thermistors so if the wires to them are too short you can cut them and splice in longer wires without causing a problem.  The boards are supposed to have a temp calibration adjustment but the one I bought didn't, so I had to use a separate thermometer to set up mine the first time. Just immerse both the temp probe and a known good thermometer in a glass of water and record the temp difference for later use. 

Re your earlier question about whether the water recirc freeze protection will work for the risers up to the trailer appliances from the water lines in the floor, I would assume that it doesn't until proven otherwise. So, there should be a way for maintaining the interior of the trailer above freezing at all times unless you winterize. I'd also leave the cabinet doors open a bit under the sink and by the new cutoffs you would install for the outside shower. 

That being said, since those appliance lines are risers, it is very likely that the water in them will warm somewhat just from natural convection from the heated lines in the floor. You'd have to experiment a bit and maybe take some temp measurements to determine how warm the interior of the trailer needs to be to keep them from freezing. It might be a pretty low temp.
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Direct Link To This Post Posted: 22 Jan 2019 at 8:41pm
One other question.  If I just use one thermostat to control the solenoid and keep the hot water at the130 deg, wont I have to open the valve on the cold supply to keep from getting scalded?
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Direct Link To This Post Posted: 22 Jan 2019 at 8:05pm
I remember one time somebody just put a skirt around the bottom of the trailer and put a little buddy in there on low. Seems like an elegant simple solution.
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Direct Link To This Post Posted: 22 Jan 2019 at 7:02pm
So the solenoid is triggered by thermostat A.  The opening of the solenoid relieves pressure which triggers the pump to come on and cause recirculating water to flow through system.  Thermostat B controls the water heater and triggers the water heater to come on as the recirculating water is cooled by running through the lines and fresh water tank. At this point the water heater is on, the pump is running and the solenoid is open. The water heater will reach the set point temp and turn itself off according to set point of thermostat B. Thermostat A will cause the solenoid to close at the set point.  Thermostat A should be a low temp like 60 deg, for instance. Thermostat B should be normal hot water temp of say 125 deg. The pump will continue to run until pressure is restored to system.  Correct?
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Direct Link To This Post Posted: 22 Jan 2019 at 6:14pm
Yep, and you raise a good point on the city water. I really never use that so I hadn't considered it. You'll want that disconnected for the recirc system to work correctly. That shouldn't be a problem because that connection would be the first to freeze up in the winter anyway. Just refill your fresh water tank with the city water if you run out. 
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Direct Link To This Post Posted: 22 Jan 2019 at 5:44pm
am i on the right track ?Confused

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Direct Link To This Post Posted: 22 Jan 2019 at 3:35pm
I'm not familiar with the plumbing arrangement on a 182g but if its anything like the 179 FR conveniently runs the hot and cold lines together. My endpoint is at the hot and cold low point drains by the fridge. 

I would suggest doing away with all the low point drains and sealing the holes with closed cell foam insulation. If you want to winterize with antifreeze just open the valve at the far end and run the antifreeze through the whole system that way. You'll want cutoff valves for your outside shower too. 

The second valve is just an inline valve to cut off pressure from the pump to the cold water line, a tee isn't required. Then the solenoid goes between the cold water line side (not the pump side) of that valve and drains into the fresh water tank. When the thermostat calls for heat the solenoid valve will open and the pump will pump water out of the fresh tank, through the hot water heater and out the hot water line. The hot water will return via the cold water line from the far point, run through the solenoid valve and back down into the fresh tank, thereby completing the loop and warming everything up in the process.  Hope that makes sense. 
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Direct Link To This Post Posted: 22 Jan 2019 at 3:12pm
Originally posted by offgrid

If you just use the solenoid and thermostat it you shouldn't need to do anything else. Add a shutoff valve so you can redirect water between the hot and cold lines at the far end of the water system from the pump.  This is just a connection of the hot and cold lines together with a valve to shutoff like at the water heater correct? probably located at the garage sink since i have a 182g  or low point drain? That valve will be open in winter and closed in summer. Add a second shutoff valve between the cold line and the water pump(solenoid or pressure pump in the trailer?) which will be open in summer and closed in winter to make sure the pump feeds only through the hot water line in winter.  a little fuzzy on the second cuttoff, a T valve ?if closed how does water from the fresh tank reach the pump? wouldn't i just add a T to the hot water line to feed the solenoid input? The solenoid can go between the cold line and the fresh tank overflow line so it runs hot water back into the fresh water tank. Or you can run it back into the fresh tank drain, that might use less heat because you won't be trying to heat the bottom of the fresh tank from the top. 

 I used one of the little Chinese thermostats in another project to provide a precise temp control for the water heater. There is a thread on it on the forum.  It runs on 12Vdc which is available at the water heater controls and should be able to run a 12V solenoid valve just fine. The temp probe for the thermostat can go on the lowest place in the system (bottom of the fresh water tank or on the bottom of the pump feed line at the tank).  You can get 2 thermostats for $8 on Amazon and have a second one to adjust the water heater temp. 

https://www.amazon.com/HiLetgo-Temperature-Controller-Thermostat-One-channel/dp/B07CH7W3XP/ref=pd_sim_328_2/145-8709395-3663044?_encoding=UTF8&pd_rd_i=B07CH7W3XP&pd_rd_r=c892e5d4-1e83-11e9-8739-9941e184f583&pd_rd_w=85MgR&pd_rd_wg=JxkeJ&pf_rd_p=18bb0b78-4200-49b9-ac91-f141d61a1780&pf_rd_r=WXCJRBAXMZMVQD4HQMAY&psc=1&refRID=WXCJRBAXMZMVQD4HQMAY  do they come with a cover? 

A solenoid valve like this should work OK. You'll need some plumbing parts to connect it up. 
https://www.amazon.com/SNS-2W025-08-Electric-Solenoid-Normally/dp/B0794XJGBF/ref=sr_1_5?crid=1SJGTGMTXP1KO&keywords=12v+solenoid+valve&qid=1548188854&sprefix=12v+solen%2Cfashion%2C261&sr=8-5. 

CharlieM did this mod on another brand of trailer and has a link to it on this thread. i have studied charlie's thread and i am trying to go by his schematic of the flow and pump location. 


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Direct Link To This Post Posted: 22 Jan 2019 at 2:37pm
If you just use the solenoid and thermostat it you shouldn't need to do anything else. Add a shutoff valve so you can redirect water between the hot and cold lines at the far end of the water system from the pump.  That valve will be open in winter and closed in summer. Add a second shutoff valve between the cold line and the water pump which will be open in summer and closed in winter to make sure the pump feeds only through the hot water line in winter. The solenoid can go between the cold line and the fresh tank overflow line so it runs hot water back into the fresh water tank. Or you can run it back into the fresh tank drain, that might use less heat because you won't be trying to heat the bottom of the fresh tank from the top. 

 I used one of the little Chinese thermostats in another project to provide a precise temp control for the water heater. There is a thread on it on the forum.  It runs on 12Vdc which is available at the water heater controls and should be able to run a 12V solenoid valve just fine. The temp probe for the thermostat can go on the lowest place in the system (bottom of the fresh water tank or on the bottom of the pump feed line at the tank).  You can get 2 thermostats for $8 on Amazon and have a second one to adjust the water heater temp. 

https://www.amazon.com/HiLetgo-Temperature-Controller-Thermostat-One-channel/dp/B07CH7W3XP/ref=pd_sim_328_2/145-8709395-3663044?_encoding=UTF8&pd_rd_i=B07CH7W3XP&pd_rd_r=c892e5d4-1e83-11e9-8739-9941e184f583&pd_rd_w=85MgR&pd_rd_wg=JxkeJ&pf_rd_p=18bb0b78-4200-49b9-ac91-f141d61a1780&pf_rd_r=WXCJRBAXMZMVQD4HQMAY&psc=1&refRID=WXCJRBAXMZMVQD4HQMAY

A solenoid valve like this should work OK. You'll need some plumbing parts to connect it up. 
https://www.amazon.com/SNS-2W025-08-Electric-Solenoid-Normally/dp/B0794XJGBF/ref=sr_1_5?crid=1SJGTGMTXP1KO&keywords=12v+solenoid+valve&qid=1548188854&sprefix=12v+solen%2Cfashion%2C261&sr=8-5. 

CharlieM did this mod on another brand of trailer and has a link to it on this thread. 


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Direct Link To This Post Posted: 22 Jan 2019 at 2:29pm
offgrid and/or charlie,

a few questions on this: 
1.  this will require a tap into fresh water tank for return correct? what is the best way to do that?

2. concept question: what about the water lines at a sink for instance? no water actually circulates say the last foot unless you open the sink valves.  Does the water actually circulate enough within the line to accomplish the necessary heat distribution ?  or is this moot since these areas are in heated living areas?  for instance in Charlies schematic of the water lines, the hot and cold to the shower?

3. Is the manual valve on the solenoid pump just for pressure and flow limiting ?

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