It's coming soon - hot water recirculating system.
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URL: http://www.rpod-owners.com/forum_posts.asp?TID=5486
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Topic: It's coming soon - hot water recirculating system.
Posted By: wildfire305
Subject: It's coming soon - hot water recirculating system.
Date Posted: 28 Oct 2014 at 12:13pm
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Coming this spring, I intend to do a full hot water recirculating on demand system with temperature limiting control (since the water heater is set to 140). I am a licensed master plumber who hates to see water wasted down to the grey tank and out of the fresh tank waiting for hot water to reach the faucet all the way to the back of my 179. The recirculating system will be less than $100 and be fully automatic at the push of a button with no permanent modifications to the camper. The temperature control will cost about the same and will require modification.
I'm in the process of engineering it now and am looking for advice from others who have already done such a thing. After I make it I intend to do a full instructional post with pictures. I know you CAN catch the cold water in a pan and use it for tea/coffee. But, I must tinker. ------------- 2005 Dodge Durango 4.7 V8 OLD Tow Vehicle 2004 Honda Odyssey 2015 RP179 "73b" OLD 2005 Viking Saga 2480ST popup |
Replies:
Posted By: Sandpiper
Date Posted: 28 Oct 2014 at 12:30pm
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I added an instant hot water system in our home ( for one bathroom) and it was pretty simple. It was a WATTS system. A link to the description is http://www.watts.com/pages/whatsnew/IHWRS.asp I'm sure you would have no trouble at all installing this. I think I paid $160 or so and had a plumber install the pump for a small charge on the water heater. We love it and don't waste all that cold water waiting for the hot water to get to the faucet. |
Posted By: wildfire305
Date Posted: 28 Oct 2014 at 12:33pm
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Forgot to mention my system will be run on 12 volt not house power like most of the systems are made for. I don't always have hookups and that is when it is even more important not to waste any of the precious 36 gallons. ------------- 2005 Dodge Durango 4.7 V8 OLD Tow Vehicle 2004 Honda Odyssey 2015 RP179 "73b" OLD 2005 Viking Saga 2480ST popup |
Posted By: techntrek
Date Posted: 28 Oct 2014 at 1:50pm
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Interesting putting a recirc system into a camper, but definitely a benefit when boondocking. Although it would be cheaper to just carry an extra 5-10 gallons of fresh water with you, but I fully understand the need to tinker ( http://forum.solar-electric.com/showthread.php?t=12962 - see this link ). Someone around here mentioned an idea of using the WH to power a hydronic heating system (quieter than the furnace), add an extra 3-way valve and some extra hose, mix that water fairly cool, and you could get double-duty out of those parts you mention. ------------- Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual 
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Posted By: wildfire305
Date Posted: 28 Oct 2014 at 1:56pm
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Using the above idea with a loop under the mattress would make a heated bed. ------------- 2005 Dodge Durango 4.7 V8 OLD Tow Vehicle 2004 Honda Odyssey 2015 RP179 "73b" OLD 2005 Viking Saga 2480ST popup |
Posted By: fwunder
Date Posted: 28 Oct 2014 at 2:44pm
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I've wondered about using the HW system to fabricate a small radiant or forced air heating system. Here's one idea => http://www.go2marine.com/product/20172F/radex-hot-water-forced-air-heater.html - http://www.go2marine.com/product/20172F/radex-hot-water-forced-air-heater.html That said, I picked up a http://www.walmart.com/ip/Mr.-Heater-Portable-Buddy-Radiant-Heater/16622306 - Mr. Heater Buddy this past weekend and used it while camping. Wow, this thing throws off some heat! We used one pound of propane over four days just running it intermittently to take the chill off. fred ------------- 2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits 2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
Posted By: David and Danette
Date Posted: 28 Oct 2014 at 3:49pm
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Lance campers for their model 1575 have a instant propane hot water heater and you are able to dial the temperature you desire at the time you need hot water. I don't how well it has worked out but sounds like a good idea. Forget the manufacture of hot water heater. ( I have looked back at reviews and the tankless hot water heater has not been well liked by owners. I went to the Lance manufacture website and there was no mention of them, my guess they have been discontinued with the Lance 1575.) ------------- 2018 Vista Cruiser 19BFD (2018- 2012 Vibe 6503 (2014-2019) 2009 r-pod 171 (2009-2014) Middle Tn 2014 Ram 1500 Quad cab |
Posted By: wildfire305
Date Posted: 28 Oct 2014 at 4:03pm
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Instant water heaters usually produce a cold water sandwich every time you turn the faucet on and off. I had one for a week in my house and ripped it out. It drove us nuts washing dishes. That used a lot of water. Some, and I stress some, newer tankless heaters have a small tank in them to stop the sandwich effect. ------------- 2005 Dodge Durango 4.7 V8 OLD Tow Vehicle 2004 Honda Odyssey 2015 RP179 "73b" OLD 2005 Viking Saga 2480ST popup |
Posted By: techntrek
Date Posted: 28 Oct 2014 at 6:18pm
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Fred, interesting device. Doesn't sound like it has a pump or thermostat. You probably could go cheaper with a $50 transmission cooler and $5 computer fan. Add a 12 volt thermostat, relay, pump and you would be golden. ------------- Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual
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Posted By: fwunder
Date Posted: 28 Oct 2014 at 6:29pm
Yeah Doug! Junk Yard Wars!  I sorta got obsessed with this idea today.Wondering the relative efficiencies of using the HW heater as a boiler, plumbed with a 6,000 BTU cabin heater like http://www.amazon.com/Aqua-Hot-200-Series-Heater-EXE-200-200/dp/B007GR84FI/ - This Aqua Hot exchanger and a high efficiency circulating pump like http://www.absak.com/catalog/product_info.php/cPath/24_74/products_id/217 - This Jabsco . Would take a little plumbing engineering to prevent back flow into FW tank and allow HW to still circulate with on board FW pump, but I bet it could be done! Both the heat exchanger and the pump are very low power draw and the HW heater just seems to be much more efficient than the furnace. I bet it would be quiet too. Fun Stuff! fred ------------- 2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits 2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
Posted By: techntrek
Date Posted: 28 Oct 2014 at 8:12pm
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Quiet is the key - definitely would be quieter than the furnace. It should be more efficient than using a generator to run an electric heater, too. I'm not sure the FW tank would be a problem, just withdraw water from the WH tank on the hot side and feed the return line back into the WH on the cold side. The existing hot and cold water system would operate normally, unless I'm missing something you've thought of? ------------- Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual
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Posted By: dsmiths
Date Posted: 28 Oct 2014 at 8:35pm
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and then we could add a thermostat to the Fresh Water tank so if boon docking in temps below 30 or so some hot water could be circulated in a loop through the fresh water tank to keep it from freezing . Humm the possibilities are endless. ------------- Dane and Donna Smith 2011 RP-172 2008 Chevrolet Trailblazer 4X4 lift kit prodigy wireless brake controller |
Posted By: fwunder
Date Posted: 28 Oct 2014 at 8:43pm
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Dump 50 pounds of ice in the FW tank, throw the HW bypass valves and we got us a Air Conditioner!! Oh, don't forget that we could plumb more than one exchanger for zone heating and cooling! Somebody stop me!  fred ------------- 2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits 2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
Posted By: fwunder
Date Posted: 29 Oct 2014 at 9:04am
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Doug, I'm thinking we'll need an inline check valve on the cold water returns of the city water line and the tank line to keep the boiler/exchanger a closed loop system. I think you are right that there should be no issue or significant interference with on board FW system. I guess we could use the existing thermostat to turn on exchanger fan and circulating pump. dsmiths, that sounds like a great and simple idea also! A loop through FW tank (or anywhere else) would be just a matter of plumbing. Practically speaking, I'm really surprised this isn't done. Yes, I know http://www.aquahot.com - Aqua Hot systems are used in some large and expensive coaches, but the idea seems even more practical in a small space like the pod where we often heat 6 gallons of very hot water, use just a little and then let all that energy just fade away... I'm going to take some HW temperature measurements today. I know it's hot. fred ------------- 2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits 2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
Posted By: wildfire305
Date Posted: 29 Oct 2014 at 9:25am
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Suburban service manual says 140 degrees nonadjustable. That is hot enough to cause blisters in half of a second. ------------- 2005 Dodge Durango 4.7 V8 OLD Tow Vehicle 2004 Honda Odyssey 2015 RP179 "73b" OLD 2005 Viking Saga 2480ST popup |
Posted By: fwunder
Date Posted: 29 Oct 2014 at 9:39am
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Thanks wildfire! I looked for that spec but missed it. I turned on the propane HW just about 20 minutes ago. I'm curious what I measure with my smoker probe when it shuts off. After about 15 minutes w/ambient about 50 degrees it measures 105. @140 it would seem an efficient exchanger might offer a good deal of useable heat, no? Thanks again for giving me an idea for another winter project!  fred Edited to add: At 30 minutes, propane shut off and I measured 138 @ kitchen faucet, so I would say the 140 spec is pretty accurate. Thanks! ------------- 2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits 2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
Posted By: hogone
Date Posted: 29 Oct 2014 at 1:26pm
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fwunder: so you liked the "mr. buddy"! did you use disposable containers or a small refill one. seriously thinking of making this purchase. hogone ------------- Jon & Pam 2013 RP177 2023 F150 2017 HD Streetglide CHEESEHEAD |
Posted By: techntrek
Date Posted: 29 Oct 2014 at 1:59pm
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Dang, don't give me another project to consider! My to-do is already long enough. But it would be an interesting project to fiddle around with. Then there would be testing to compare propane used via the furnace vs. the WH given the same outside conditions (temp and wind). Then improvements to make it more efficient, then....  ------------- Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual
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Posted By: fwunder
Date Posted: 29 Oct 2014 at 3:00pm
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Hogone, The Mr. Heater portable buddy cranks some heat...quickly and quietly. We used a one pound bottle on this trip, but I do normally carry a one gallon refillable tank and hose that can be used with either my Weber Q or the Portable Buddy. Total burn time on low (which is hot) is about 5-6 hours per pound. Wife was a bit more skeptical and a bit uncomfortable with the heater than me. It has a small open flame pilot and glows bright red and is very hot directly in front and on top. It does have a built in oxygen sensor and auto shutoff if tilted more than 45 degrees. I don't think I would leave it running all night and you really do need to crack a window or two just in case. It's really great for sitting in front of under the dome or standing in front of after a shower! Doug, I tried to find my 45 year old Thermodynamics textbook to work out the energy equations...then laughed at the thought of me trying to understand that again! Ya know, we could probably find an old auto heater core, a small fan, a pump, a sink full of 140 degree water and do some testing in your kitchen! I won't tell my wife if you don't tell yours!  Seriously though, given the amount of heat the furnace throws outside and reading that the furnace is, at best, 70% efficient *and* I still got 6 gallons of 140 degree water; I gotto believe the hot water heating system would be more efficient. But...I was also positive we would have flying cars and a robot maid named Rosie! fred
------------- 2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits 2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
Posted By: techntrek
Date Posted: 29 Oct 2014 at 7:45pm
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LOL, that testing is exactly the type of thing I would enjoy on a Saturday afternoon when I should be outside doing my leaves. ------------- Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual
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Posted By: wildfire305
Date Posted: 29 Oct 2014 at 7:45pm
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12 volt solar hot water recirculating pump. 3 gpm @ 500ma draw. ------------- 2005 Dodge Durango 4.7 V8 OLD Tow Vehicle 2004 Honda Odyssey 2015 RP179 "73b" OLD 2005 Viking Saga 2480ST popup |
Posted By: fwunder
Date Posted: 29 Oct 2014 at 8:10pm
What brand? Sounds great. Thanks! fred ------------- 2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits 2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
Posted By: wildfire305
Date Posted: 29 Oct 2014 at 8:53pm
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http://www.amazon.com/gp/aw/d/B00E0FXR6K
I found it on Amazon. There was also one with brass ends for three times that. The specs looked good. ------------- 2005 Dodge Durango 4.7 V8 OLD Tow Vehicle 2004 Honda Odyssey 2015 RP179 "73b" OLD 2005 Viking Saga 2480ST popup |
Posted By: fwunder
Date Posted: 31 Oct 2014 at 1:45pm
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Pretty funny...parallel universe! http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27819530/srt/pa/pging/1/page/1.cfm - http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27819530/srt/pa/pging/1/page/1.cfm fred ------------- 2014 RPod 178 => https://goo.gl/CV446f - MyMods and Buying Habits 2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
Posted By: techntrek
Date Posted: 31 Oct 2014 at 10:40pm
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Ha! ------------- Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual
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Posted By: CharlieM
Date Posted: 01 Nov 2014 at 10:01am
Fred, As they say "There's nothing new under the sun". I've been thinking about recirculating HW from the WH for some time, but only on paper so far. I don't mind the furnace noise in my Camplite, but the Camplite has more exposed plumbing than the Pods so I've been thinking about using hydronics to keep pipes from freezing. This approach, vs heat tapes, would be especially good for dry camping and while in motion on the road. All I need is to wrap small tubing along the exposed piping and sense outside temperature to activate it. I've collected a file on small pumps and valves for the future. But right now I'm re-looking the pure electrical solution. For short runs between battery recharges it might still be practical and a lot simpler. ------------- Charlie Northern Colorado OLD: 2013 RP-172, 2010 Honda Pilot 3.5L 4WD PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD |