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Small Cabin Forum / Off-Grid Living / Tankless water heater at high altitude
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Gnerd
Member
# Posted: 12 Nov 2022 11:41
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I'm looking to use a tankless propane water heater at 7500 feet altitude. The heaters I look at online say they're "not recommended" at high altitude (some say above 2000 feet, some say 5000). As I understand it, there's not enough air for the propane burner to run well and heat the water up enough at high altitude.

I was wondering if it might be possible to make some kind of air induction system with a blower to give it enough air. Has anyone tried something like this?

frankpaige
Member
# Posted: 12 Nov 2022 13:15
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No experience my self. Have heard that changing the orifice can help. Also a big concern is the water temperature at the cabin. Low temps will not help in having warm water.

gcrank1
Member
# Posted: 12 Nov 2022 13:34 - Edited by: gcrank1
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If there 'isnt enough air' it means that there will be 'too much gas (lp)', so whatever the device the choices are increase the air (thus your idea), or, if that isnt possible you reduce the gas, thus the smaller orifice. Any local propane supplier should be well familiar with that.
Does the device have replaceable, or better yet, adjustable jetting (orifice)?
The difference between the ambient water temp and the required rise in temp to your desired use (typical water heater is 120*f) is what you will be looking at; ie, if the water heater has a 60*f rise potential it can make 120* if the water starts out at 60*. That will mean dont use 40* water unless you want a body temp shower!.

ICC
Member
# Posted: 12 Nov 2022 14:43
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The air gets less dense with altitude. That means less available oxygen to burn the fuel. The burner will probably work but soot up the burner. More CO will be produced which could be a bad thing depending on whether or not the heater is a direct vented type or not. If a pilot light is involved the pilot may not stay lit reliably.

FYI, the water heaters in most RV's have an altitude limit of about 4000 to 5000 feet. Above that, they usually work okay at providing hot water but the burners do get sooty if used at high altitudes a lot. They also often have a bad odor when burning as not all the propane gets burnt.

The RV water heaters I am familiar with do not have a simple used changeable orifice. They are a press fit and not designed for adjustment or change out. These burners often do have an air adjustment collar so there is a chance of maybe being able to help the situation. If the air adjustment sleeve is set to slightly restrict the airflow, then opening that up may allow sufficient extra air to enhance the combustion.

Propane or natural gas heaters of all types will also produce less heat at higher altitudes, even when equipped with the altitude correct orifice. Less oxygen in the lower density high altitude air means less fuel can be turned into heat. Same reason your naturally aspirated motor vehicles lose power in the mountains.

Nobadays
Member
# Posted: 12 Nov 2022 15:43
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I did some searching, I wish I remembered where, and ended up buying a Marey 3.1gpm thankless WH as I got a couple of responses from folks at high elevation.... one at 9,500' as we are that said it worked well for them.

All that said I have not used the one I bought. We have a tank style WH that is still working.

gcrank1
Member
# Posted: 12 Nov 2022 16:44 - Edited by: gcrank1
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If you have a supply water tank inside with you in the interior heat you could have a small pump pressurize delivery (specs should say min. del. pressure) to the on-demand unit so the temp rise required would be minimal.
Even if the delivery tank runs dry if there isnt del. pressure the WH is supposed to shut off the burner.
I never tested that out on ours......

Gnerd
Member
# Posted: 13 Nov 2022 14:00
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OK, I think I have a better idea now. I might try a small 7 gallon Bosch electric water heater like this. I can get it nice and hot during the day when there's plenty of solar power, then turn it off. In the evening it will still be fairly hot, and I can set it to a lower temp and run it minimally (if at all) without putting much drain on the batteries.

gcrank1
Member
# Posted: 13 Nov 2022 15:16
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Fwiw
We have a 30gal elec WH at home, on grid, just the two of us. Ive run through 2 or 3 elec timers in our 35ish years here. Last one I realized a couple months ago had died but I dont know just when.....the timer died in the On position.
So, I started running it with the manual lever (on its own box) a couple hours in the morning and a couple at night, pretty much only about 4-5hrs a day. It holds the heat well that way, we can turn on a tap and have 'good enough' hot water through the day, and if we really need HotHot I throw the lever and in 15min. its Hot.
Not quite an 'on demand' unit, but way better than running 24/7 switching itself on/off. Looks like this way it saves us about $20/mo.
Just a confirmation that using an elec WH for your time schedule and demands can work.

Steve_S
Member
# Posted: 13 Nov 2022 18:05
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If this is a Full Time residential setup you should probably have a look at the info below. No Fossil fuel, just 120VAC to run the circulation systems (minimal power) and no stress on a solar system or other.

Note that several companies now make these but Rheem is a top quality product with excellent suport.

Unmatched Savings & so Much More​
The Rheem® ProTerra® Hybrid Electric Water Heater draws heat from the air around it to deliver unmatched savings and works like a standard electric water heater when the air is too cold. Either way, you enjoy worry-free hot water.

ProTerra - Rheem Manufacturing Company
Global Leader and Manufacturer of Heating, Cooling, and Water Heating Products
https://www.rheem.com/heatpumpwaterheaters/

Good article with several links:
Rheem Releases 120V Plug-In Heat Pump Water Heater That Can Be Plugged Into Typical Outlet
They’re finally here! Rheem released its 120V ProTerra(R) Plug-in Heat Pump water heater (HPWH) in July and everyone is excited!

https://cleantechnica.com/2022/09/26/rheem-releases-120v-plug-in-heat-pump-water-heat er-that-can-be-plugged-into-typical-outlet/

Various Rebates are also applicable in USA, also through the IRA initiative.

snobdds
Member
# Posted: 14 Nov 2022 11:07
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I use one at my cabin at 9,500 feet. Never have had a problem.

Nobadays
Member
# Posted: 14 Nov 2022 13:11
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Are you here in CO snobdds?

snobdds
Member
# Posted: 14 Nov 2022 14:05
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Wyoming.

Snowy Range Mountains.

Nobadays
Member
# Posted: 14 Nov 2022 15:56
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Sweet! Beautiful area!

Howdy
Member
# Posted: 11 Oct 2023 12:05 - Edited by: Howdy
Reply 


@snobdds which brand are you using? I am looking at eccotemp. Thanks

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