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Propane Tankless water heater for tiny house?

F

falgsc-al

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Joined
Sep 9, 2020
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76
Howdy folks

I am trying to find a decent tankless water heater for my off-grid tiny house. Has to be propane, and will only serve to back-up my custom 24v 50gal electric tank water heater when the sun doesnt come out for a few days at a time. I know Amazon and a bunch of other retailers are fudging their reviews as Ive been offered money myself to remove a 1-star review from a water filter. When I sort the 1 star reviews out of any tankless lp heater on amazon the reviews become appalling.

Anyone using an LP tankless that can run a min 3gpm hot? Reliable? That you would recommend? My water reserve totes live in my greenhouse so my water rarely drops below 50 degrees.
 
I was a little concerned about being off topic posting this in the tiny home subsection but completely overlooked the offgrid living advice subsection.
 
My neighbor at my camp lives off grid 24x7 and he swears by the EZ-202 Tankless Water Heater that he's had installed for a few years. The screens tend to clog up from his spring but he says he's had great support from the company getting troubleshooting and parts help.

The only catch seems to be that the water and gas fittings were British BSP and he had to get adapters to fir his NPT piping, but that was about $20 for everything he needed.
 
Takagi. I've been using a direct vent propane fired T-H3M DV for almost 6 years now. It is the backup or alternate heat (alternate is when I want to take a break from loading the outdoor wood boiler) for domestic water heating and infloor for 2000 sq ft of house. Works great.
 
Rinnai is good, kind of the Victron of on demand water heating.

I’ve installed many Rinnai water heaters with few problems. In fact the only issue I can think of was one developed a bee hive over a summer of no use.

They would have the water heater you need with the reliability you want. 3gpm, propane etc.
 
Groscout said:
Rinnai is good
Click to expand...
And expensive

I’ve been using one of these for almost four years. Fantastic. You do what is in your mind safe and I’m not recommending you do what I do but I have this mounted inside with a 12V-3VDC power supply, and plumbed to my RV’s water system- no other water heater.

I’ve had some issues but I’ve accommodated for them and it’s been great for me.

DO NOT USE this without installing a 20-micron water filter on the ‘suction’ side of the water pump or ahead of the water heater. Silt, debris, whatever will mess up the waterflow sensor and the unit will either not turn on the gas- or worse: will not turn off the flame until it starts to boil and the over temp safety kicks in. Those were my issues. Steam will blow plastic pipe in a rather spectacular fashion. So I run mine with the 3V supply on a timer so it can’t “fault” and start/ignite when I’m not home or whatever (both the water pump and heater are through the rotary 20-min timer).

This thing used to go all summer on one portable propane tank although now I have a 120gal propane tank so it makes no difference to me- consumption is very low.

With lowered water flow (it’s adjustable) and the propane (also adjustable) flame knob turned 50/50 straight hot no cold is almost too hot for a shower. If your incoming water temp is warm this makes water hot enough to scald you bad. I’d suggest a temperature-controlled valve.

This works for me. I’m relating what I did. You should only do what you’re competent and comfortable with. Not what I did.
 
I have a Takagi TH-3-M which is used exclusively for my Radiant Heating system (uses Glycol) and it is a wonderous beast that works incredibly well. I have an EccoTemp On Demand (they also own Marey) unit for my Hot Water provisions. It is a PITA because it has a high cutin switch so regulating low flow (not full open tap) is a pain in the worst sense. It is also not that efficient... no it is an older FVI-12 model and they have since come out with much better direct vent models that do not have teh same cut-in issues.

It is really important to install the system correctly, no short cuts ! Use a proper installation valve kit like this below:
iu

There is also TWO Types of Mixing Valves which can be used.

The "Pre-Mix" valve will allow a small amount of the hot water coming out to flow back in with the intake to raise the incoming water temps. This reduces the amount of heating energy required as it is a higher temp to raise to raise. This has minimal effect on output PSI.

The PostMix Valve is more commonly used, that is similar to a scalding prevention device like the scald preventing faucets.

TIP, for Tiny House sized small units do yourself a HUGE FAVOUR ! Whatever one you go with (real & credible reviews help) ensure that it has a digital temp setting system. Not just a dial to set the temp, but programmable to not exceed XX Temp so if you set it at 115F that it never puts out more than that regardless of water pressure. As incoming water temps change (from what is in the pipe to pressure tank to direct from deep underground), it immediately impacts the On-Demand heater which could slow the water flow or make it too hot for a few moments as it readjusts, This CAN BE A DANGER especially if you have children present... it really only takes a second to go from 115 to 130+ F and sometimes just the change in incoming temps dropping can do it and only takes moments. NOTE you will also NEED to install a Water Hammer Arrestor on your incoming water line ! It's no joke and you don't want to learn the hard reasons why... you can pop valves, pex connections and depending on water heating usins, seams and welds can also pop over time.

I am an offgrid Cabineer and involved with many others living it, my involvement on this site is uniquely with regards to the solar stuff. Don't get into such here as this is not the venue for it.
 
I’ve installed tankless for 30 years… aquastar, myson, Rinnai, navien, wonderful technologies.
I like the navien most right now.
On a tiny home, I’d suspect any would handle showers, and hand washing.
The aquastar unit is 100% mechanical. No electricity needed for operation. It uses water pressure and flow to determine output and temp. Kinda nice… but has a standing pilot, so either you leave it burning all the time, or you light the pilot when you need hot water.
 
Groscout said:
Rinnai is good
Click to expand...
We have two. One for my mancave, the other for our second dwelling (granny flat). Work really well. They are plugged into a mains power for the ignition/controller. So they do need electricity to operate.

Granny flat has one elderly occupant who showers daily. One 45kg propane tank lasts her ~ 18 months. Hot water not required for clothes washing machine or dishwasher as they heat their own water. The 45kg tank on my mancave has been there for over three years and still has 1/3rd left in the tank.

What you need to work out is how much hot water you need at the same time (flow rate) and how cold the supply is. That will help set the specs for a suitable unit.

Our home has 315 litre electric resistance HW storage tank.
 
We have a smaller Camplux model (1.32 gpm) but it has worked flawlessly for our cabin.
Hooking up the shower this upcoming season, but piping hot water for the kitchen.

They make larger models:
camplux.com

Camplux Instant Indoor Tankless Gas Water Heater 3.18 GPM | Black

Find reliable and affordable Tankless Gas Water Heater options at Camplux. Our Constant Water Heater with a 3.18 GPM flow rate delivers instant hot water with easy installation and modern design features. Safety is a top priority with 6-in-1 protection standards. Buy now for comfortable, endless...
camplux.com camplux.com

Our 1.32 gpm model just uses a 20lb LP tank. Easy to hook up and use right away.

The key thing you need to make sure it works properly is the water pressure.
We have a 65 psi water pressure pump so the water heater is fed with enough.
If you want 3+ gpm, you'll need more than that for water pressure.
 
12VoltInstalls said:
And expensive

I’ve been using one of these for almost four years. Fantastic. You do what is in your mind safe and I’m not recommending you do what I do but I have this mounted inside with a 12V-3VDC power supply, and plumbed to my RV’s water system- no other water heater.

I’ve had some issues but I’ve accommodated for them and it’s been great for me.

DO NOT USE this without installing a 20-micron water filter on the ‘suction’ side of the water pump or ahead of the water heater. Silt, debris, whatever will mess up the waterflow sensor and the unit will either not turn on the gas- or worse: will not turn off the flame until it starts to boil and the over temp safety kicks in. Those were my issues. Steam will blow plastic pipe in a rather spectacular fashion. So I run mine with the 3V supply on a timer so it can’t “fault” and start/ignite when I’m not home or whatever (both the water pump and heater are through the rotary 20-min timer).

This thing used to go all summer on one portable propane tank although now I have a 120gal propane tank so it makes no difference to me- consumption is very low.

With lowered water flow (it’s adjustable) and the propane (also adjustable) flame knob turned 50/50 straight hot no cold is almost too hot for a shower. If your incoming water temp is warm this makes water hot enough to scald you bad. I’d suggest a temperature-controlled valve.

This works for me. I’m relating what I did. You should only do what you’re competent and comfortable with. Not what I did.
Click to expand...
And that's the small one, which I should have probably used on the outhouse. I've got an 18L version of those run of the mill "vevor" etc. chinese made propane heaters (also come in nat gas).

First pic was years ago and second is current. So far reliable enough for weekly and guest use. It got daily use at the beginning of 2020, for about 9 months...
 

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This is the unit I have for the mancave:

IMG_0600.JPG

Ignore the (non-compliant) hanging 9kg propane bottle, that was just a stop gap to check it was working until I got the 45kg tank delivered and mounted on the concrete paving pad (the chains go round the tanks as a topple prevention measure).
 
BuffaloTrace said:
And that's the small one, which I should have probably used on the outhouse. I've got an 18L version of those run of the mill "vevor" etc. chinese made propane heaters (also come in nat gas)
Click to expand...
My first one was bigger. It had issues sensing water flow- I replaced with this tinier one which i theorized would be ‘relatively faster water flow. image.jpg
 
12VoltInstalls said:
My first one was bigger. It had issues sensing water flow- I replaced with this tinier one which i theorized would be ‘relatively faster water flow. View attachment 80735
Click to expand...
This set-up looks very similar to mine. Probably the same DC water pump as well. I added a 5 gallon pressure tank to keep the pump from running every time I open the faucet.
 
Thank you all for the suggestions so much! For those who are using 20lb bottles, how often do you find yourself swapping it?
 
For the money, you can add more batteries and solar for less cost and a better payback?

I have calculated that for one day at a time recharge batteries hold more energy then the same cost in a tank heater.
 
falgsc-al said:
Thank you all for the suggestions so much! For those who are using 20lb bottles, how often do you find yourself swapping it?
Click to expand...
I used <56 gallons for 5 weeks (or ~11gal/week) with a lot of well-below freezing days and colder nights.
Which is like a couple or so smaller tanks/week for heat and cooking and hot water.
Summers a 20# will go a few months but that includes cooking.
 
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