# Indoor Vs Outdoor Tankless Water Heaters



## Bob Mariani (Dec 1, 2008)

Indoor will work better since it is not working against the cold outside air. How would the pipes to connect this unit not freeze if it is outside.


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## vsheetz (Sep 28, 2008)

I would think the outdoor units are meant to replace existing tank water heaters that are presently located outside. Desert areas such as Las Vegas have water heaters located outside. 

The washer/dryer may also be located outside...


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## Thurman (Feb 9, 2009)

Bob, and others, please remember that there _could be_ local codes involved with this issue also. Here for instance, *IF* you have a natural gas, tankless water heater installed it must be installed outside of the _living area_ of the home. And--the local City's Water/Gas/Light Department is the only way to obtain natural gas, even in some areas of the county. Now, if you would want one which operates using LP gas, these are not permissible within the City Limits ( they supply the Natural Gas remember), and the same rules apply as to where it is mounted by County Ordinance. What about an electrically heated unit? Hmm, as long as the rated current draw does not exceed 30% of your main breaker within the panel, you may have an electric unit. And--YES, you have to obtain a permit to install any of the above mentioned units, City or County, AND-you must be a State Licensed Electrician to wire one, or a State Licensed Gas Fitter to plumb one up. Want to know why the apron stores here don't sell them, or why they are not so popular around here? Thanks, David


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## limitdiy (Apr 26, 2009)

Thurman said:


> Bob, and others, please remember that there _could be_ local codes involved with this issue also. Here for instance, *IF* you have a natural gas, tankless water heater installed it must be installed outside of the _living area_ of the home. And--the local City's Water/Gas/Light Department is the only way to obtain natural gas, even in some areas of the county. Now, if you would want one which operates using LP gas, these are not permissible within the City Limits ( they supply the Natural Gas remember), and the same rules apply as to where it is mounted by County Ordinance. What about an electrically heated unit? Hmm, as long as the rated current draw does not exceed 30% of your main breaker within the panel, you may have an electric unit. And--YES, you have to obtain a permit to install any of the above mentioned units, City or County, AND-you must be a State Licensed Electrician to wire one, or a State Licensed Gas Fitter to plumb one up. Want to know why the apron stores here don't sell them, or why they are not so popular around here? Thanks, David


Gotta love the state, just reminding us all who's boss.

What is LP gas?

nevermind...liquid propane, right?


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## jbfan (Jul 1, 2004)

One of the reasons to mount outside and not inside is the venting.
If mounted outside, the vent just vents, and inside you must use the special vent pipe, which is costley.
Since an electric unit does not need venting, it makes no differance where it is mounted.


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## limitdiy (Apr 26, 2009)

jbfan said:


> One of the reasons to mount outside and not inside is the venting.
> If mounted outside, the vent just vents, and inside you must use the special vent pipe, which is costley.
> Since an electric unit does not need venting, it makes no differance where it is mounted.


if i have a tank water heater that runs off of gas that is inside right now...do you think the venting is already in place?


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## pyper (Jul 1, 2009)

limitdiy said:


> if i have a tank water heater that runs off of gas that is inside right now...do you think the venting is already in place?



There could be more than one answer, depending on which tankless heater you have.

The one I have required a 5" double wall pipe. The existing tank heater had a 4" single wall pipe. So I had to put new venting in. The tankless also has a minimum rise requirement, that complicated matters, and it needed 5/8" LP supply lines, meaning a new regulator.

The one saving grace is that it shouldn't ever wear out.


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## vsheetz (Sep 28, 2008)

pyper said:


> There could be more than one answer, depending on which tankless heater you have.
> 
> *The one I have required a 5" double wall pipe. The existing tank heater had a 4" single wall pipe. So I had to put new venting in.* The tankless also has a minimum rise requirement, that complicated matters, and it needed 5/8" LP supply lines, meaning a new regulator.
> 
> The one saving grace is that it shouldn't ever wear out.


I had the same pipe change to make - which nessitated an enlargement of the roof opening and reflashing. Was not a big deal to do.


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## spollock (Jan 13, 2014)

*install outdoor unit indoors?*

What is the difference between the indoor and outdoor gas hot water heater units. Is it just insulation? I would like to install it in an unheated outdoor closet that gets very cold in the winter. Which one should I use?


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## James444 (Oct 5, 2019)

Different manuf of tankless have different ways of dealing with indoor/outdoor units. Find out the model/make of the unit, go to their website and read the install manual. It should detail the manuf requirements.


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## Contra (Jan 8, 2018)

I want to add a unit to my 220 in the garage, the current location of my 50 gallon tank, because me and my wife love to take long showers.


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## georgemcq (Feb 19, 2018)

Be careful choosing an electric tankless water heater as it may require an electric service upgrade. Many electric tankless require two 80 amp breakers (more or less) and can quickly overwhelm a 100 amp service. Just check out all the facts and requirements before jumping on board.


I have not seen any of the big box stores stock gas and/or electric tankless water heaters that are suitable to run a medium size house or larger....they are way undersized for most needs. Check carefully the recovery rates, gallons per hour flow and other items.


My house required a 180,000btu gas tankless (I installed a 199,000btu) so that I could take the long showers and have dishwasher, washing machine operating at the same time. I installed a Takagi tankless and have been very pleased.


Next question to be answered is should I get a condensing or non-condensing water heater. The condensing are more efficient and cost about 5% more but they use schedule 40 PVC as the exhaust vent.


Good luck but do your homework before you buy.


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## Calson (Jan 23, 2019)

Different requirements for electric and natural gas on demand hot water heaters. With gas there needs to be outside air brought in and the exhaust heat vented outside. On the other hand if the tank is outside then running the supply lines is more difficult if they are not already in place. Easiest to mount where your existing hot water heater is located. 

As a side note, I would not buy something like this from Home Depot but from a local dealer who will do the installation and provide warranty servicing on site if there are problems. I would also research the brands as the reliability varies widely as does the number of years some of these have been manufactured. 

Where places like Lowe's and Home Depot and Amazon may be helpful is in learning how good the warranty support is by the various manufacturers and the number of people experiencing problems with their water heaters. 

In many areas there is no choice as to whether to go with a non-condensing and less efficient hot water heater. In my county a condensing hot water heater is not required but only Sears actually sells this type and neither Lowe's or Home Depot do. 

With the standard tank type hot water heaters there is still an electronically controlled damper flap to improve energy efficiency and these often fail and then the hot water unit shuts down and it is a $500 repair. 



https://www.energystar.gov/products/water_heaters/water_heater_whole_home_gas_tankless


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## Old Thomas (Nov 28, 2019)

Our house in central FL has the gas water heater hanging outside on the exterior wall. It is usually hotter there than anywhere indoors. Of course, our NY house has it inside.


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