Could I use one of these to fill a mini bathtub on my patio? I would just like to soak every so often. Many of them produce 2 gallons of hot water a minute...the question is how hot. Anyone know?

Never heard of them. BUT, can you not find the specs at their website? I doubt a portable 120 on demand can produce 2 gallons of water hotter than 110 degrees. Doug

I had a 220 vac 7KW tankless that a plumber installed. It didn't work (southwest florida!) so I measured temp. rise. It was right on spec at 30 degrees F. I put in a 15 KW and it works great in SWFL. The spec on any tankless is temp rise for a given flow rate. Slow down the flow and temp rise increases. Thinking outside the box I wonder if you could put a submersible water pump in the tub and pump from a full tub into the tankless until the temp rerached your goal. The water gains a few degrees rise with every trip from the tub to the tankless to the tub.

Roadpilot wrote:Thinking outside the box I wonder if you could put a submersible water pump in the tub and pump from a full tub into the tankless until the temp reached your goal. The water gains a few degrees rise with every trip from the tub to the tankless to the tub. Most tankless heaters will not work with preheated water, but some will--they are intended, IIRC, to deal with water coming from a rooftop solar water heating system that may need additional heating. Check the specs.

I use an Eccotemp L5 I bought about 8 - 10 years ago when tent and pop up camping. With outdoor temp in the 50's to 70's connected to the campgroung spigot with 50 feet of garden hose I can get 55 degree well water at the camp ground warm enough to wash dishes or take a warm shower. That would be burner on full and water flow throttled.At home connected to the spigot outside and using city water in summer I had to turn the burner down and increase the water flow to keep from scalding my hand and the Chihuahua when giving her a bath.I bought it through Sportsmans Guide. It is an outdoor model with a heat deflector to divert the exhaust when mounted to an outside wall. I mounted mine to a piece of plywood and use bungie cords to strap it to a tree.An L7 or L10 might be better for filling an outdoor tub.

Roadpilot wrote:Thinking outside the box I wonder if you could put a submersible water pump in the tub and pump from a full tub into the tankless until the temp rerached your goal. The water gains a few degrees rise with every trip from the tub to the tankless to the tub.You could do something like that with one of the inflatable hot tub units (Lay-Z-Spa or similar; it appears that a fair few are the same basic models with different brand names and colors). I suspect the heater/circulator unit could be adapted to a different tub fairly easily, it just being a matter of hooking up a couple of hoses. I'm not sure if the heater units are available separately; I suspect not.

Portable tankless water heaters.... | Good Sam Community

dclark1946
Explorer
May 22, 2017
We use the Coleman Hot Water On Demand portable system which I think is still available. It uses the one pound propane tanks and a rechargeable battery to power a water pump and the burner igniter. The pump attaches to a Coleman 5 gallon water bag but you can also buy an accessory that attaches to a water hose. The burner ignites when you turn on the water. Our kids used this in the National Park for showering (using shower attachment that attaches to the faucet)and it worked fine.
mobeewan
Explorer
May 16, 2017
The Eccotemp L5, L7 & L10 are all very portable outdoor units using 20 lb propane cylinder or smaller. It requires 2 - D cells for the automatic electronic spark ignition.
DrewE
Explorer II
May 14, 2017
drsteve wrote:
Lantley wrote:
d needs power.

Mine has a standing pilot, with a mechanical spark ignitor to use if it happens to go out. But yeah, power is required for units that have automatic ignition.

I have a rather vague recollection of seeing some available that used some sort of a little turbine thingy in the water to generate power for ignition, perhaps in combination with a battery or supercapacitor or other device to store the charge.
drsteve
Explorer
May 14, 2017
Lantley wrote:
drsteve wrote:
Wild Card wrote:
You can take a Renii or Bosch tankless and make it portable. All they need is gas, water flow and 110v to run

The tankless Bosch in my house doesn't need electricity. I don't believe any of the propane powered units do.

The best setup I ever saw was years ago while at a rustic campground frequented by dirt bikers. Guy had a portable shower stall like you'd see at a hazmat cleanup site, with a residential propane tankless and a gas powered water pump. Throw the supply hose in the lake, fire it up, and take a nice hot shower, with loads of pressure. Waste water went to a blue tote and got dumped into the campground's vault toilet.

Unless there is a pilot light it has electronic ignition and needs power.

Mine has a standing pilot, with a mechanical spark ignitor to use if it happens to go out. But yeah, power is required for units that have automatic ignition.
Lantley
Nomad
May 14, 2017
drsteve wrote:
Wild Card wrote:
You can take a Renii or Bosch tankless and make it portable. All they need is gas, water flow and 110v to run

The tankless Bosch in my house doesn't need electricity. I don't believe any of the propane powered units do.

The best setup I ever saw was years ago while at a rustic campground frequented by dirt bikers. Guy had a portable shower stall like you'd see at a hazmat cleanup site, with a residential propane tankless and a gas powered water pump. Throw the supply hose in the lake, fire it up, and take a nice hot shower, with loads of pressure. Waste water went to a blue tote and got dumped into the campground's vault toilet.

Unless there is a pilot light it has electronic ignition and needs power.
drsteve
Explorer
May 14, 2017
Wild Card wrote:
You can take a Renii or Bosch tankless and make it portable. All they need is gas, water flow and 110v to run

The tankless Bosch in my house doesn't need electricity. I don't believe any of the propane powered units do.

The best setup I ever saw was years ago while at a rustic campground frequented by dirt bikers. Guy had a portable shower stall like you'd see at a hazmat cleanup site, with a residential propane tankless and a gas powered water pump. Throw the supply hose in the lake, fire it up, and take a nice hot shower, with loads of pressure. Waste water went to a blue tote and got dumped into the campground's vault toilet.
westend
Explorer
May 14, 2017
Put a black barrel or bladder in the air, high enough for gravity flow. Put it in the sun and report back the water temperatures. I guarantee it will be too hot, in most cases, if left to achieve maximum temp. The differential then becomes time left in the sun rather than temp rise/flow of a gas unit.
dougrainer
Nomad
May 14, 2017
MrWizard wrote:
Most 'portable' tankless heaters are propane, and can turn COLD creek water into hot shower water

Portable camping water heaters are NOT electric

i don't see why what the OP asked will not work

use a barbecue LP tank the portable heater connected to the outside water tap
and fill his tub/sauna/whatever for a hot soak on the patio

The LP models state a 30 to 35 degree temp raise from inlet water temp. So, COLD creek water(lets be generous at 60 degrees) would be 90 to 95 degrees output. THAT is NOT hot water. Now, they are designed for quick showers at Campsites. NOT designed to fill mini-bathtub to soak in. Once you start attempting to fill a Bathtub the water will quickly cool down(not much) but enough to nullify the type temps you want to soak in. Now the Larger L10 model may be large enough to do the job but it is not as portable as the L5. Doug
Wild_Card
Explorer
May 14, 2017
You can take a Renii or Bosch tankless and make it portable. All they need is gas, water flow and 110v to run
MrWizard
Moderator
May 14, 2017
Most 'portable' tankless heaters are propane, and can turn COLD creek water into hot shower water

Portable camping water heaters are NOT electric

i don't see why what the OP asked will not work

use a barbecue LP tank the portable heater connected to the outside water tap
and fill his tub/sauna/whatever for a hot soak on the patio

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