mrgoat
52 main st, Goshen MA
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Using a LP gas tankless system intended for a house in an RV or Camper trailer
This may seem like a bad idea to a lot of people out there but I am only considering this option. I have spent the last hour searching on the web and have been unable to find anyone who has tried this. I understand installing a a home system in a way that is not intended for use will most likely void a warranty. If you tell them. I have been researching two RV systems, one being the Girard RV system, which is cheaper ($350-$800 on eBay) but has bad reviews. It seems to need 1 gallon per Min (1gpm) before it kicks on, so RV-ING somewhere where water can not be wasted people complain that it is kicking on and off. In an RV the water pumps are not very accurate, when you open the faucet the water pressure tends to fluctuate, especially when its running very slowly. I like to travel across country and often find myself holding down the camp at a truck stop for several days while waiting for a check to clear, so I know the importance of not wasting water and if I'm doing dishes I don’t want 1gpm of water being wasted nor do I want the small stream of water being cold. In my shower I use a household water head on a water saver setting, I would say it sprays at least 1gpm but maybe not if I have the cold water on as well. So that might not work for me in the shower either. Then there is the RV-500 by precision. ($1000 on web, not on eBay right now) It has much better reviews and seems to kick on at 0.4gpm. It also seems to have a higher BTU for better hotter hot water.
Why don’t I just replace my leaking 6 gallon water heater with another one you may ask? For one, when I’m at a campground or plugged in somewhere where I am living and have unlimited water I am sick of only being able to take 7 min showers while turning the water on and off in-between soaps. Two, I run out of hot water when doing a sink full of dishes. Three, I want to sit in the little bath tub filled with hot water while more hot water is spraying down on top of me. Four, I live in an 87 royal diamond 35 ft camper trailer, I have done lots of work and carpentry. I have significantly added weight to the poor trailer, so loosing the 6 gallon water tank would be a nice change and reduce weight substantially. Other then the high price of the RV-500 another issue is that you need to get a winter package ($100) if you often camp somewhere cold. (Right now there is snow outside) This adds a fan to blow against wind gusts and also adds some type of heated wires that go around the water pipes inside the burn area I guess, because the RV models separate the RV from the flame by mounting from the outside. I'm sure the heat package must use at least 200-400 watts and when your running everything off one 120 volt plug that's a lot.
I don’t see why I can't pull the old water heater out, cut the shelf off that it rests on under my counter. Frame in the existing hole and mount a home unit for $200-$300 bucks and drill a hole in the plywood for the vent. If their safe enough to use in your house why cant you use it in a small house / RV. That would also reduce the need for the heat tape and crap. It could also be wired to a switch so it can be shut off when not around. As long as its mounted properly and checked after stopping somewhere, What the big deal? You could even screw a simple cage around it to keep something from falling against it. I do understand that the trailer would have to be pretty level to maintain peek performance, and I doubt being slightly unlevel would really be dangerous for I bet all tankless systems have sensors that shut them off if overheating is detected. Has anyone tried this? What do you think? Thank you!
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edited 02/02/12 11:41pm by mrgoat *
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mobeewan
Hampton, Va
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From what I have seen the household type units still needs a metal exhaust pipe to be installed at the top to vent carbon monoxide out of the house just like the traditional household gas water heater.
Outdoor camping and cabin models vent out the top using a heat shield to reflect heat away from the wall and sometimes have a short metal chimney that has a cap to keep rain out of the exhaust port. Enclosing any OD gas water heater that vents out the top is dangerous to install inside a cabinet or under a counter due to the possibility of a fire. If there really are units that are made to be used in a house or apartment and do not vent directly to the outside those places are a lot more voluminous than a TT. You mentioned that you do like long showers so CO could be a problem.
That said there are ways to properly vent an indoor unit. One would be to mount it where you could pipe exhaust through the roof or side of the trailer either of which would be shielded with a secondary pipe and properly mounted and insulated. This is common with buck stoves that are mounted and used in houses as well as mobile homes. There will also be a problem with a TT as the exhaust pipe will either need to be removable and the hole sealed while in transit unless it can withstand highway speeds.
There are also coal and wood burning stoves that are made for use in boats with the proper insulated exhaust pipes that go up through the deck. So there is technology existing for boats that could be applied to TTs.
A member of this forum did mount a low volume top vented unit in his storage bay on a fifth wheel trailer. He also added a vent through the side of the trailer with an exhaust fan to remove heat and CO. He posted pictures. I don't know if it was used successfully for any length of time to say it was successful or not in the long term.
I have thought about adding one on the bathroom wall above the toilet and piping it through the ceiling but haven't needed to yet. I have learned to take navy showers and turn the water off and on as needed when washing dishes. I have a double sink and wash all the silverware and utensils first and lay them in the drain basket which is in the left sink half as I wash them in the right side, then I rinse them all at once. I do similar with smaller items increasing to the larger ones as I go. As I wash larger items I rinse the outside then when rinsing the inside I pour the rinse water over smaller items as I go. Works pretty well and I never run out of hot water while washing a lot of dishes. I do need to partially empty the right sink a couple times though as it is the smaller side and does catch some of the rinse water as I rinse larger items.
I have an outdoor OD water heater rated for 2.8 GPM. I have it mounted to a piece of plywood and prop it up when using it when tent camping and using my pop up. I can also bungie it around a tree. One thing I can do with it is that I have added male garden hose fitting with quick connect ball valves to my outside low point drains and can connect it to the the TT through them if needed. But that would be for warmer weather camping in the spring and fall not winter as the water heater might freeze up when not in use.
Watch out, put on your fire suit and hold on it's going to get hot and bumpy. The water heater police and nay sayers are comming and will think we are nuts.
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rpegram
Eastern NC
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I've seen this before on here and the biggest issue with any of the house style tankless system is the gas requirement for it to run. The supply line has to be 3/4", your camper is currently 1/2" or smaller. Your current 30 lb. cylinders cannot supply the volume needed for the heater to run. I've installed these heaters where I work, and we have to use cylinders larger than 100 lb., can't even use multiple 100 lb. tied together. My experience is with the Rinai, so it is limited to these units.
As far as installing the unit, I see no reason the unit could not be mounted in an RV safely. The outside units work very similar to your current LP heater, gas comes in, ignited and exhaust out the unit into the atmosphere. The only requirement for safety is that no flammable material be near the exhaust. If one was used that required a vent stack through the roof, then the requirements for distances are greatly reduced. You would most likely have to use triple wall flue pipe, but that can be in direct contact with wood.
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sdianel
Tampa, FL
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Girard makes an LP Tankless Water heater for RV's. www.pplmotorhomes.com has them. They also have an optional winterization feature.
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ng2951
Louisiana, USA
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If you aren't dry camping it might be worthwhile. If you are dry camping, water gets critical so people need to limit their HW usage.
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dougrainer
Carrolton, Texas
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1. There are 2 makers of Tankless LP Water Heaters for Rv's.
2. NONE do a good job for continous adequate hot water.
3. The LP regulator on Rv's is rated at 210,000 Btu's so the LP regulator is not factor in the installation.
4. The LP piping size may be a factor. It all depends on the Install directions and requirements.
5. I installed 1 Girard unit last year in a 2006 Jayco fifth wheel at the customers insistance. It does NOT perform as well as a standard LP RV water heater.
6. I would never install a tankless LP Water Heater in a RV. The Diesel powered units in Motorhomes perform flawlessly. Doug
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dougrainer
Carrolton, Texas
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rpegram wrote:I've seen this before on here and the biggest issue with any of the house style tankless system is the gas requirement for it to run. The supply line has to be 3/4", your camper is currently 1/2" or smaller. Your current 30 lb. cylinders cannot supply the volume needed for the heater to run. I've installed these heaters where I work, and we have to use cylinders larger than 100 lb., can't even use multiple 100 lb. tied together. My experience is with the Rinai, so it is limited to these units.
As far as installing the unit, I see no reason the unit could not be mounted in an RV safely. The outside units work very similar to your current LP heater, gas comes in, ignited and exhaust out the unit into the atmosphere. The only requirement for safety is that no flammable material be near the exhaust. If one was used that required a vent stack through the roof, then the requirements for distances are greatly reduced. You would most likely have to use triple wall flue pipe, but that can be in direct contact with wood.
The RV LP regulator can supply 210,000 Btu's of gas for a RV system. Yes, the size of the Piping is a significant factor, but the LP system CAN supply the volume of LP as long as the piping is the correct size. Doug
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cpaharley2008
york,pa
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I have the Girard unit in my Lance 1575, you operate it using only the hot water side, the temperature is controlled by the flow, low flow is very hot, higher volume is cooler. It uses very little water, is quiet and you do not need to drain or fill it. Winterizing it involves turning off a switch, simple.
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Gdetrailer
PA
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mrgoat writes "I understand installing a a home system in a way that is not intended for use will most likely void a warranty. If you tell them."
The issue isn't the warranty but it is due to many factors such as clearances to combustibles.
The shear BTU size of the burner (120,000 BTU- 200,000 BTU).
The oversized exhaust flue required (5" class B gas vent for 120,000 BTU).
Correct square inches of air intake.
The min required flow to turn on burner.
Something most sellers of tankless water heatersdon't talk about is REQUIRED periodic cleaning of the tubing. This is a must when dealing with well water or any water system that has a high mineral content. The process of heating the water at such high temps will create mineral deposits inside the water tubing and over time it will clog.
Some manufacturers even suggest special mineral removal prefilters too boot.
Water pressure drop across the water heater, since it uses a lot of tubing that creates a lot of friction (IE resistance) to the water causing you to have less pressure on the outlet.
And then the last piece of the puzzle the unregulated water temp according to flow and input temp of the water.
All those factors need to be taken in account as to why it isn't a real good idea to adapt a home tankless water heater to a RV.
As far as weight reduction, I think you will be suprised at how little of that will happen, smaller tankless heaters can have at least a gallon (maybe more) of water internally inside, there is a lot of tubing inside of the unit and that will hold some water.
"Frame in the existing hole and mount a home unit for $200-$300 bucks and drill a hole in the plywood for the vent. If their safe enough to use in your house why cant you use it in a small house / RV."
I don't know where you will find even a new small gas fired home unit for $200-$300, right now new home pilot tankless water heaters are starting at $750, if you want electronic ignition you will be around $1000.
"That would also reduce the need for the heat tape and crap."
Actually with a home unit you will be risking having the entire unit freezing since it must have enough fresh air for the large burner. In a RV that air for the burner would have to come from the outside.
Remember, once the burner shuts off, there is no more heat in the unit and the water will freeze faster than a tank unit.Basically risking a trashed unit in freezing temps between uses.
I had looked into buying a tankless unit for my sticks and bricks after having to replace THREE tank heaters in 4 yrs. But after weighing out the pros and cons, the cons won and I bought yet another tank unit.
Do yourself a favor, either stick with a regular tank water heater or buy a properly designed RV tankless water heater.
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mrgoat
52 main st, Goshen MA
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great post, I appreciate everyone’s help!
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