Replacing a 16 gal Water Heater with On Demand

[High5er]

Hey all. We bought a new 5th wheel last October and need to change our 16 gallon water heater over to a tankless/on-demand heater. Before people start telling my why I shouldn't, I've already made up my mind. We had one on our last trailer and know what we're getting into.

My question is this: Has anyone done this on their own trailer? Specifically replacing a tank this size. The opening is huge (I will need an 18 inch door). I ultimately want to get a 60k BTU or better and need to find a manufacturer who can cover that size of door.

I'm sure Truma has something, but we're looking at having to pack up and drag our house to the dealer then shell out $2500 for the unit and installation. I'm hoping I can get some recommendations for one I can install in an afternoon on my own.

[Mikendebbie]

I should probably PM you to avoid drawing fire - but we have a Suburban IW60 and it has worked well for us. I had one issue...September 2021 (~18 months into covid shutdown) we were getting ready to go on a 2 week trip. The Monte had not been used since December 2020. I was testing things out and the water heater did not work. Could not find much help on youtube to troubleshoot. I asked DW "Honey it will be just like when we were in the popup - we can use the campground bathrooms". The answer was "NO WAY!!".
So I pulled the trigger and ordered another one for $600 and installed it. The old one is in a box. Later I found a video about cleaning out a probable spider web in a certain orifice. Oh well - now I have a backup!

The install is easy - old wires hook up to new...control wires hook up easy...gas and water in and out - easy peazy. The back of the unit gets a small steel angle to anchor it to the floor. My unit is accessed by removing the basement wall...good access. Whatever unit you choose - make sure the outer cover is included...since your current outside cover will not work - they may sell the outside covers separately.

What the IW60 is missing is the plumbing apparatus/fittings/valves to descale it. I will install this after I retire in July...I have the instructions and the fittings are at Home Depot. For winterizing - I always drain the Monte after every trip. I blow the plumbing out with air. I have had no damage from the recent artic apocalypses and power outages that hit Texas (Feb 2021, Feb 2022, Jan 2023).

I have noticed that some of the new on-demand units have easier methods to descale built-in. LOTS of folks complain about waiting for the hot water to get to the shower head. No big deal for me. I leave it at 129* and temper with cold water rather than messing with the thermostat to get (say) 105* water with no tempering. Our unit has a full tub across the front. DW loves her bathtub. I think with any of the on-demand units - it will deliver (say) 103* water in the winter rather than 115* water because the city water coming in is colder. The unit can only raise the temp of the water so much - so if you start with cold water - the end result will be cooler. Again - no big deal to us.

Edit: screen shots below...
Actual temps I get from my heater from a thread last year I think.
Also pics of what the unit looks like behind my basement wall...red arrow pointing to the steel clip angle.

[High5er]

Thanks for the input. We had the same one in our last trailer, but had pretty frequent problems with it. We suspect it's because we didn't learn we needed to descale it until 18 months in and the water in our area is more mineral than it is liquid. I think by the time we figured it out, it was probably too scaled for vinegar or any other household chemical to cut through it. It's good to hear you've had a better experience.

My wife is leaning towards the Truma, but I'm hesitant because of the massive shower head they put in this thing and the ridiculous price tag. I'm sure our shower is pushing > 2 GPM, which would lead to problems in the winter with having colder water flow in as fast as the shower can push it out. I'm starting to lean towards the IW60 again (with plans to take better care of it) given you can set the temp to a max of 130 (Truma is 120-ish). I'm not sure if the extra 10 degrees is enough to maintain pressure when our hot will only be at 1.5 GPM. If you have a shower head that dumps buckets per minute and have used it in really cold temps, I would love to hear how it worked.

I just went through replacing our 3 glass shower doors with a retractible door and hated every minute of it. The last thing I want to do is replace that panel-mounted rain shower so that I can replace the water heater. I'm trying to reduce my projects around here

[High5er]

Originally Posted by Mikendebbie

Edit: screen shots below...

The opening your WH lives in is pretty big. Did you replace a 16 gallon tank with the IW60?

[Mikendebbie]

No - I put in a new IW60 to replace the original IW60 (which was not working after sitting un-used for 20 months - re: my sad story in post #2 above). But I have watched YouTube videos of people doing exactly what you want to do. Your water heater may be a bit harder to reach since it is behind the furnace. Take a basement wall down and make sure you can work on the back side of the water heater before you pull the trigger and decide to install it yourself.

Probably you most difficult task will be figuring out where to mount your control panel. I did not have to buy a new control panel - it was fine. Screen shot of a controller below. You will need to run 2 small wires from the heater to the spot where you want to mount this. I don’t know if your unit has any type of water heater controller. If you do - you can probably use the same wires.

[RMcNeal]

Ok. I have to ask...Why would discussing an on demand water heater draw fire?
It seems like it would be a good idea, especially if you full time.

[Mikendebbie]

DRAW FIRE? Maybe not so much here on this forum - but over on the Keystone forum they just don’t like on-demand water heaters and a thread like this will get 15 replies…waste of money…terrible option…wouldn’t have one of those things…I replaced mine with standard water heater…trash…they waste SO MUCH WATER…etc.
Maybe that is true for those guys - it has not been my experience.

If you boondock - these are not a good choice but they can be managed to work. We never boondock.

If the campground does not have good water pressure they don’t work very good.

The degree of heat produced varies with the temperature of the incoming city water.

Don’t plan to wash dishes at the same time someone is taking a shower. Two outlets reduce the water pressure or water volume too much for the heater to work well. Things don’t work in an RV like the do at home.

We bought this Monte because DW wanted a tub. In the old days every RV shower had a little baby tub - and she would have been fine with that…but RV manufacturers have turned 100% to showers. Nobody offers tubs anymore. The IW60 came installed in our unit for the tub. I knew nothing about it good or bad. It has served us well…so that’s my story.

Edit: winterizing story…in Feb 2017 we were staying at The Vineyards campground in Grapevine TX while I worked on a project. We had a Keystone Laredo travel trailer at the time. A guy pulled in to the space next to us with a beautiful new Montana they just bought and brought it to the Vineyards for a shakedown outing. It had a IW60 water heater which I knew nothing about. The weather forecast was for temps in the teens for 2-3 days - so they locked it up and went to their house in Grapevine to ride out the storm. The next morning I noticed a huge ice stalagmite coming out of the IW60 water heater. He should have taken time to winterize before leaving. They came back to a mess when things thawed out. They hooked up and left - I suppose with lots of damage to their plumbing and water heater.

[RMcNeal]

Gotcha! Kinda like talking about the weight and towing capacity of your tow vehicle. Lots of people take a very hard line on DRW vs SRW, etc.

[Bourbon County]

Fogatti makes an 18" X 18" outer door for their models.

I'm not sure if RV tankless models do this, but residential models all have a flow control valve. Temperature is always king, they will throttle the flow rate down to the point that it can maintain output temperature. Flow and pressure are 2 different entities. A 2 GPM shower head isn't really that much, if the flow rate upstream is restricted, that's all it can pass.

[High5er]

Originally Posted by Bourbon County

Fogatti makes an 18" X 18" outer door for their models.

I'm not sure if RV tankless models do this, but residential models all have a flow control valve. Temperature is always king, they will throttle the flow rate down to the point that it can maintain output temperature. Flow and pressure are 2 different entities. A 2 GPM shower head isn't really that much, if the flow rate upstream is restricted, that's all it can pass.

Thanks for the tip on Fogatti. I've seen some mixed reviews so need to research to see if the negative experiences are specific to certain models or more widespread.

From what I've seen, all these RV tankless models are fixed flow rate (only the input flow can reduce it below the maximum). It seems to me if the tankless is only allowing 1.5 GPM and the shower head is rated at 2 GPM or above, there will be a loss of pressure from what we're used to unless we mix in some cold. This is where I get concerned. The water temp will immediately drop when it leaves the tankless and continue to lose heat energy as it travels through the pipes. Mixing in cold will absorb even more of that heat energy resulting in even lower temps. I also understand many of these RV tankless units shut down when you start mixing in cold (Girard, etc.).

If we were just camping, I wouldn't really care much about this, but we're full time, so can't spend a bunch of money to take 95 degree showers every day.

[High5er]

Originally Posted by RMcNeal

Gotcha! Kinda like talking about the weight and towing capacity of your tow vehicle. Lots of people take a very hard line on DRW vs SRW, etc.

No doubt about it. I've been involved in those debates over SRW and DRW

Funny enough, it's weight that lit a fire under me to get this figured out. We were going to make this change anyway, but now it's more important. We hit the scales for the first time last weekend and the truck (SRW ) is fine, but we're over on what we have in the trailer. It occurred to me that with a 16 gallon water heater, we're toting around 133 lbs of water wherever we go. By making the switch to tankless, we stand to shed around 150 lbs (tankless are usually around 30 lbs, this tank weighs upwards of 50) and get endless hot water.

[Bourbon County]

I don't think that's the case with every RV tankless being limited to 1.5GPM, they are very reluctant to publish a curve or graph on delivery over a range of incoming water temperature. I would recommend giving PrecisionTemp a call. It's a small company that makes RV tankless and they are located in Cincinnati. They're small enough you can actually talk to an engineer. They make a model that seems very good on paper at least; they're about the same price as Truma but you can self install.

I would not be concerned with temperature loss in the piping between the water heater and shower head. If yours is like many fifth wheel models and has the bathroom at the top of the stairs, that's one of the shortest runs on the camper. That distance is the same regardless of what water heater you have.

[High5er]

Originally Posted by Bourbon County

I don't think that's the case with every RV tankless being limited to 1.5GPM, they are very reluctant to publish a curve or graph on delivery over a range of incoming water temperature. I would recommend giving PrecisionTemp a call. It's a small company that makes RV tankless and they are located in Cincinnati. They're small enough you can actually talk to an engineer. They make a model that seems very good on paper at least; they're about the same price as Truma but you can self install.

I would not be concerned with temperature loss in the piping between the water heater and shower head. If yours is like many fifth wheel models and has the bathroom at the top of the stairs, that's one of the shortest runs on the camper. That distance is the same regardless of what water heater you have.

You're right about the 1.5 GPM. That's the outflow rate of the Suburban Nautilus I initially intended to get. I finally called Truma and asked them point blank about their unit and they advised me not to buy it because it won't keep up with the shower. In the 3941FO the bathroom is in the rear, just forward of the bedroom, so the run is a bit longer. I'm trying to figure out if I can get a lower flow head for this Lippert "Shower Tower" to eliminate the problem without it looking too janky, but that's still a work in progress.

Thanks for the suggestion on PrecisionTemp. I haven't done any research on them yet, so it gives me another possible option. I appreciate your help.

[High5er]

So I've learned quite a bit about tankless water heaters from the guys at PrecisionTemp. For anyone with the Lippert shower tower (or anything with a flow over 2GPM), and living in the northern US there isn't good a plug and play tankless solution. I thought I had a solution with a unit claiming almost a 4GPM flow rate and learned it was "theoretical". It can produce that flow rate, but only at the southern tip of the Florida panhandle, or the southern third of Arizona where the groundwater temp is very high.

We absolutely need to reconfigure our shower before I can realistically consider any tankless water heater.

[Bourbon County]

I'm glad you spoke to PrecisionTemp, I talked to one of their engineers for nearly an hour some time ago when I was considering a tankless. He was very informative and honest about the shortcomings of an RV tankless. This conversation was what ultimately convinced me not to install one; it's just not a good investment for our style of camping.

It's good that you now understand how critical the groundwater temperature is when considering a tankless. Just a quick look and I see that the average groundwater temp in WA is about 50 degrees. That means to take a 100 degree shower you need to raise the water temperature 50 degrees. The smallest residential models which have burners twice the size of an RV model can barely do 4 GPM with those temps.

As far as reconfiguring your shower; take a look at Grohe Smartshower valve. It's a temperature control as opposed to pressure balance and they make a surface mount remodel unit. I installed the built-in version when we remodeled our bathroom a couple years ago. You can get one that controls up to 3 different heads or sprays, each outlet has on/off control and flow control for that spray. The temperature is adjustable but there is a detent stop on the control that you can adjust for your preference, and allows some adjustment up and down from that setting; they recommend 100 degrees. The temp control is common to all sprays.

[High5er]

It's really unfortunate that these aftermarket tank brands don't provide clearer information on their units. I don't think they're trying to hide anything. I've spoken with Truma, PrecisionTemp and RaneinRV and all were very forthcoming about the capabilities of the units they're selling. As you said, ground water temp is a critical component. On top of that, buyers need to understand the role that BTUs, flow rate and max temperature have. Without understanding all of it, there's a good chance of spending time and money on something you immediately regret.

The Grohe Smart Shower looks incredible. I'm afraid I don't have the know-how to replace this shower tower and not leave ugly patches where the supporting brackets are mounted. For now I've found a 1.5 GPM shower head that might work with it. It should be here Friday or Saturday so I'm hopeful I'll be able to re-evaluate the available tankless water heaters for our revised setup. Of course there's always the chance it either looks terrible or doesn't work well, in which case it's back to the drawing board.

I truly appreciate all the input and advice. This has been a real education.