Converting to an on-demand water heater

Topic: Converting to an on-demand water heater (Read 2900 times) previous topic - next topic

Converting to an on-demand water heater

October 24, 2011, 09:39:40 pm

Seems I can't stop finding things I want to improve/change on my coach.

Currently under consideration is ditching the 6 gallon Atwood LP heater for a Precision Temp RV 500 on demand LP heater --> PrecisionTemp.com: For Recreational Vehicles and Boats. Several reasons for this:

1. The one in there is a replacement, is 14 years old, and lacks electronic ignition, electric, or a heat exchanger. So when I want hot water I have to go outside with a lighter and futz around trying to get it lit. Not a happy thought on a cold, windy, rainy day.

2. I don't expect to use a lot of hot water, but when I want it, don't want to wait 1/2 an hour for it to heat up.

3. Seems wasteful to keep heating the water all the time to have it available when I need it. I plan to boondock a fair bit, and this system makes more sense to me in conserving energy.

4. If I'm connected to city water, a long hot shower is readily available.

Wondering if anyone else has done this, and if they're happy with it. The PT unit is a direct swap for a 10 gallon unit, and will require some cutting of the vertical space with a 6 gallon unit (as in my case). I don't think FT has ever installed these; looks like Aquahot is king. There is one other make of tankless water heater out there that I could find (Girard), but has a bad rep due to numerous usability issues.

Still thinking about it - would appreciate any feedback you may have. Thanks.

Steve

Re: Converting to an on-demand water heater

Reply #1 – October 25, 2011, 10:47:27 am

Steve,

Had thought about exactly the same thing as I have an intermittent igniter problem. Most the time it lights but sometimes not. Have checked and dbl checked all connections, etc. Plus, we dry camp 100% of the time so always looking for something more efficient.

I like the stock heater for several reasons. It heats going down the road from the engine. It has a plug-in electric heater (aftermarket) so I can heat from the generator or plug in at home and I can also bypass the propane ignition unit if the electric rod completely fails so I am not stuck without hot water out in the middle of nowhere.

It is convenient to just flip the switch next to the sink and have it light almost instantly. It does heat water for a shower in about 10 minutes if I don't take a long one. Nice to shut easily shut it off when we don't need it and don't want to listen to the racket it makes. With the heater on one side and the two furnaces on the other, it's a real noise polluter. Generator not too campground friendly either.

Re: Converting to an on-demand water heater

Reply #2 – October 25, 2011, 11:13:50 am

Thanks for the reply. I've read of many instances of electronic ignition issues. Something I remember from a recent journey on the web is a gentleman who pointed out that often the ground path for the ignition is through the sheet metal and fasteners, and as corrosion develops problems abound. He grounded his ignition with a wire to a good chassis ground, and that was that.

I've always thought the heat exchanger is brilliant. Hot water when you get where you going, for free. The electric as a secondary heat source is also a good thing. With the system I'm looking at, if it doesn't light, no hot water. While I'm pretty confident I can service and repair the unit, getting parts in the boons can be a problem. I like the idea of a tankless heater relative to not using much hot water. Have concerns about water stagnating in the tank.

My backup solution at this point, and primary in good weather, is a pair of Swiss Army 5 gallon solar water bags, I plan to hang somewhere in the sun when camped. In years past I've taken many a warm or hot shower in the woods with these. Here's a good unit to order --> Swiss Military 20L (5 Gallon) Water Bag, 2 pack [445301] - $24.95 :: Colemans. The only downside is the waiting time.

The secondary backup system is a campfire with a pot of water on a grill.

The more I think about, the more it appeals to me. I guess at this point I'm looking for reasons not to convert.

Steve

Re: Converting to an on-demand water heater

Reply #3 – October 25, 2011, 11:29:22 am

After a recent meltdown I replaced my original 3 way Atwood with a new one. Remarkable improvement in insulation, and the electric element control design is much improved. We had to install the optional adjustable thermostat because it was so hot the mixing valve in the shower didn't work! The propane lights in an instant, and is nearly silent. Hot water from engine heat used to be available for 6-8 hours. Now 12. The insulation is now a banded styrofoam molded shell. Using the electric this trip, the propane has not lit once... I had thought of doing what you are contemplating at one time. No more.

Re: Converting to an on-demand water heater

Reply #4 – October 25, 2011, 11:57:55 am

Dave, if you don't mind, what was the installed cost? Is your a 10 gallon or a 6 gallon?

Re: Converting to an on-demand water heater

Reply #5 – October 25, 2011, 12:02:00 pm

Quote from: Merle Hench – October 25, 2011, 11:13:50 am

My backup solution at this point, and primary in good weather, is a pair of Swiss Army 5 gallon solar water bags, I plan to hang somewhere in the sun when camped. In years past I've taken many a warm or hot shower in the woods with these. Here's a good unit to order --> Swiss Military 20L (5 Gallon) Water Bag, 2 pack [445301] - $24.95 :: Colemans. The only downside is the waiting time.

The secondary backup system is a campfire with a pot of water on a grill.

The more I think about, the more it appeals to me. I guess at this point I'm looking for reasons not to convert.

Steve

I have used one of these in my prior camping adventures. Zodi Hot water heater

Zodi Instant Water Heater and Hot Shower - Walmart.com

Re: Converting to an on-demand water heater

Reply #6 – October 25, 2011, 12:29:32 pm

Mine is a 10 gal. Best online price was Adventurer RV in Sevierville TN... I had a leak in the back and had to contract a tech to help with a shark bite fitting. As I recall it was about $650 plus 150 labor. 10 gal three way aren't cheap!

Re: Converting to an on-demand water heater

Reply #7 – October 25, 2011, 05:00:50 pm

Quote from: Rick – October 25, 2011, 12:02:00 pm

I have used one of these in my prior camping adventures. Zodi Hot water heater

Zodi Instant Water Heater and Hot Shower - Walmart.com

That's pretty cool Rick. Does it use a lot of propane?

Steve

Re: Converting to an on-demand water heater

Reply #8 – October 25, 2011, 05:17:06 pm

Quote from: Dave Head – October 25, 2011, 12:29:32 pm

Mine is a 10 gal. Best online price was Adventurer RV in Sevierville TN... I had a leak in the back and had to contract a tech to help with a shark bite fitting. As I recall it was about $650 plus 150 labor. 10 gal three way aren't cheap!

Hi Dave,

Your 10 gallon is still a lot less than the unit I'm looking at, which seems to be in the $1K range. A 3 way 6 gallon is around $450 if I remember right. I've read where a 6 gal unit mandates Navy showers, while people with a 10 gallon unit were satisfied with their hot water availability.

I just wonder how much electricity these units use, and how that compares with burning propane only when hot water is needed. Using 120v to heat the tank is fine when plugged in, but off an inverter the batteries will run down sooner, requiring more frequent charging, which means more generator run time, which means I'm burning LP either way. If I had real world numbers I could make a better decision. I am planning to add solar panels in the spring, which will help keep the batteries charged.

The fridge has been changed out for an electric, so the only LP I'll be burning is the water heater, gennie, the stove, and the furnaces, which in milder climates wouldn't be used.

More reading and thinking to do, I guess. Thanks for your feedback on this.

Steve

Re: Converting to an on-demand water heater

Reply #9 – October 25, 2011, 06:03:31 pm

Our three way water heater will not run on 120VAC from the inverter. It is wired to run from generator or shore power only. The same is true for refrigerator, hot water dispenser, air conditioners, vacuum cleaner, and block heater. That is how the coach was wired from the factory.

Re: Converting to an on-demand water heater

Reply #10 – October 25, 2011, 08:14:49 pm

1400 watt element

Re: Converting to an on-demand water heater

Reply #11 – October 26, 2011, 06:20:00 am

Quote from: J. D. Stevens – October 25, 2011, 06:03:31 pm

Our three way water heater will not run on 120VAC from the inverter. It is wired to run from generator or shore power only. The same is true for refrigerator, hot water dispenser, air conditioners, vacuum cleaner, and block heater. That is how the coach was wired from the factory.

Yessir - mine too. I am redoing the electrical system with the addition of an inverter, which requires a subpanel. In my case, I'm looking to replace the original panel with two smaller ones. The block heater and ACs will still run on shore or gen power only. The vacuum was removed, and everything else will be powered through the inverter subpanel. The inverter will pass AC power through to the subpanel when AC power is available, and also charge the batteries. The water heater as originally supplied was an LP only model with electronic ignition and a heat exchanger.

Steve

Re: Converting to an on-demand water heater

Reply #12 – October 26, 2011, 06:29:38 am

Quote from: Dave Head – October 25, 2011, 08:14:49 pm

1400 watt element

Thanks Dave.

That's a lot of watts... no worries when plugged in, but that's a lot to draw from an inverter when camped. I know it isn't on all the time; the question being how many watts a day would it take, and I don't think anyone can answer that, with so many variables involved.

Need to do some more digging, methinks. Operating costs and fuel consumption are the biggest factors for me in making a choice, moreso than upfront costs.

Steve

Re: Converting to an on-demand water heater

Reply #13 – October 26, 2011, 12:02:05 pm

Quote from: Merle Hench – October 25, 2011, 05:00:50 pm

Quote from: Rick – October 25, 2011, 12:02:00 pm
I have used one of these in my prior camping adventures. Zodi Hot water heater

Zodi Instant Water Heater and Hot Shower - Walmart.com

That's pretty cool Rick. Does it use a lot of propane?

Steve

Steve,
I used to share propane bottles between the stove and the shower so I don't know how many showers you can get out of a bottle. It is very efficient and will heat the water very quickly. I would go thru a couple of bottles in a season. I used to just let the water heat and recycle into the tub until the temperature was good for me and then shut off the burner and just use the pump to pump the hot/warm water. There is a stove top version that they used to make where you put the heat exchanger on a stovetop burner and heat water that way. See link for details and additional research.

enjoy hot water anytime anywhere with zodi on demand hot water and portable hot

Re: Converting to an on-demand water heater

Reply #14 – October 26, 2011, 12:36:39 pm

I just got an instant-on called a Hoter Instant Water Heaters HOTER-series by Shimron Energy LTD. its a 4000 watt, gonna plumb in between gas water heater and hot supply. I'm gonna add its own cord to plug in at pedestal, only when we are on campground water. Just to save wear and tear on gas water heater.

Re: Converting to an on-demand water heater

Reply #15 – October 26, 2011, 08:09:47 pm

Thanks folks.

I'm seeing a number of these smaller portable type units out there.

I keep thinking I'm seldom going to plug in anywhere, but at this point I really don't know. Am working towards a mostly self sufficient coach, at least one that can stay boondocked for a time. The less energy (and water) I use day to day, the longer I can stay put.

Still leaning toward a tankless system, but undecided at this point. There are those who love their tanked water heaters, and those that love their tankless heaters. More thinking to do...

Steve

Re: Converting to an on-demand water heater

Reply #16 – October 27, 2011, 09:23:39 am

I find that even when I don't turn the water on and off at the shower head while showering, the 6 gallon tank is sufficient for a nice long shower and recovery is very fast. When mine dies I intend to get a 6 gallon 3-way so I don't have to use propane when A/C is available.

Re: Converting to an on-demand water heater

Reply #17 – October 27, 2011, 11:04:20 am

If you're willing to spend $70 along with some time, aftermarket 120V electric elements are available to convert almost any RV water heater. Mine was done a couple of owners ago. When connected to shore power or generator, it brings the water up to temp in about 45 minutes. Can be used at the same time as propane to cut recovery time a little. Here is the ebay site: lightning rod rv | eBay Sold under several names and prices but made you know where.

Re: Converting to an on-demand water heater

Reply #18 – October 27, 2011, 12:04:48 pm

And since atwoods don't need sacrificial anodes, it's a "no problem" upgrade...

Re: Converting to an on-demand water heater

Reply #19 – December 15, 2011, 07:21:10 am

Greetings,

Finally decided what to do...

From what I have learned, adding an aftermarket heating element to your water heater will void most warranties. I guess it doesn't matter if the warranty is up anyway.

After further reading and searching, and much deliberation, I've decided to forego the tankless heater. One of the key issues is a single point of failure, with a product that has a limited track record. Parts availability is also a big concern. I also won't have to break out the Sawzall and cut a larger hole in the side of the coach.

I have settled on replacing the existing bare-bones Atwood 6 gal unit with another one, only this one has the electronic ignition, heat exchanger, and 120 volt heating element. No more standing outside with a lighter trying to get the pilot lit.

The original heater in the coach had electronic ignition only. However, the coolant hose does come through the floor right behind the heater with the shutoff valve, so should be a relatively simple matter to hook up to the heat exchanger. I am in the process of installing an inverter, so will be removing the converter. The 120 volt circuit feeding the converter just happens to run right past the water heater, through the floor, and then along the storage bay wall to an outlet the converter is plugged into. Disconnecting the feed, pulling it back to the water heater and adding an outlet box with switch provides a dedicated circuit for the heating element, which will be active only when I have shore or gen power happening.

Done deal.
Steve

Re: Converting to an on-demand water heater

Reply #20 – December 15, 2011, 09:37:23 am

Steve,

Not sure you want your newer inverter/charger (I assume that is what you are adding) with its higher amp draw than the OE converter AND a high amp electric heating element for the new water heater on the same circuit. Each should have its own breaker in the 120 VAC breaker box and you should verify that the wire is sized for the new load.

Brett

Re: Converting to an on-demand water heater

Reply #21 – December 15, 2011, 11:40:17 am

Converted to a Girard unit, love it.

Re: Converting to an on-demand water heater

Reply #22 – December 15, 2011, 11:58:21 am

Can you post the model number and maybe a link? Is it a tankless unit?
Thanks, Don

Quote from: Alfred – December 15, 2011, 11:40:17 am

Converted to a Girard unit, love it.

Re: Converting to an on-demand water heater

Reply #23 – December 15, 2011, 12:10:18 pm

Quote from: Alfred – December 15, 2011, 11:40:17 am

Converted to a Girard unit, love it.

Alfred, I had not heard of the Girard unit, so I Googled around a bit (thinking to have the information tucked away should we ever need to replace our Atwood). Like Don, I would interested in hearing more about your experience.

A good description of models and costs in on the PPL website (appears to be between $800-900 for a winter use version with replacement door): RV Tankless Water Heater from Girard - PPL Motor Homes

I then found a rather informative post from last March on RV.net and learned a bit more about controlling the temperature (I'll paste the post below). Now... not so sure... but will be interested to hear Alfred's experience.

The Girard Tankless Hot Water Heater tips are:

Operating Tips - Girard Products, LLC | Tankless RV Water Heater Operating Tips

In Summary,

* Turn the Power switch to ON
* Set the Mode Switch to Auto
* Open a hot water faucet
* Adjust the flow to achieve the desired temperature
* Gradually DECREASE the Water Flow to RAISE the temperature.
* Gradually INCREASE the Water Flow to LOWER the temperature.

*By manually setting the MODE switch to automatic, the model GSWH-1 automatically senses and adjusts the flame level (High or Low) depending on the temperature of the inlet cold water (the water coming into the GSWH-1). The flame will change from High to Low if the temperature of the inlet water goes above 70°F and will switch back to High when the inlet water goes below 65°F. Manually switching the Mode switch from AUTO to LOW overrides the automatic function and forces the flame to stay in LOW even if the inlet water is less than 65°F. This can be desirable when the cold water inlet temperature is very cold and the inlet water pressure is below 1.0 gpm which could result in limiting (see Notice below). The system will remain in Low until manually switched to Auto.

Basically the puppy delivers two differing amounts of heat energy to the water - a fixed but low level of heat energy to incoming water whose temperature is over 70F, and a different & higher, but still fixed, amount of heat energy when the incoming water temperature is under 65F.

A user varies the temperature as delivered from the shower head by increasing or decreasing the flow rate of the delivered water, not by changing the settings of the cold and hot water settings on the shower control.

I.e., forget about getting a high volume of hot water for a nice relaxing shower in a Wildcat Sterling 5th wheel, or any other RV with a Girard tankless hot water system. It won't happen. You can get only a moderate or low flow of hot water, though you can get the hot water as long as the propane holds out.

I have read posts (perhaps on this board) explaining how to get a decently long hot water shower with a hot water heater which uses both propane and electricity to heat the water. You just have to turn both heat sources on simultaneously, right before the shower. The two heat sources will rapidly heat up the incoming replacement cold water entering the hot water tank. You must, however, remember to turn off one of those heat sources after your shower is over.

Basically we're stuck with "Navy" type showers in RV's. Wet yourself up, turn the water off, lather up, turn the water back on to rinse off, and then turn the water off. Soaking in a nice long hot shower requires not merely an external water hookup, but also either some effort and possible mistakes with the controls of a hot water tank, or a relatively low flow of water from a tankless hot water system. Both will eat a lot of propane.

Re: Converting to an on-demand water heater

Reply #24 – December 15, 2011, 12:13:20 pm

Here's the Link;
Girard Water Heater - Girard Products, LLC | Tankless RV Water Heater | On

Be sure to connect the engine hot water hoses together and turn off valve.
Use adjustable water pressure regulator set at 50-55psi.
Install Oxygenics Body & Spa Shower Head
After messing up my back several days ago, I find a lenthy hot shower to be needed these cold mornings to get going.
I love this heater.

Affiliate Notice