Connections to exterior tankless water heater

[Wayne Whitney]

Hello,

I'm planning to install a tankless gas water heater on the outside of my house, and I'm unclear on the best way to make up the various connections to the unit: gas, hot water, cold water, and electrical. In an interior installation, I'd use flexible gas and water supply lines and an electrical cord and plug to a receptacle.

Are stainless steel flexible gas and water lines rated for exterior use? Or should I run rigid supply lines and make the connections with unions? That would be a bit more difficult but is doable.

As for the electrical supply, can I still use a cord and plug with an exterior receptacle? That would allow easy physical and electrical disconnection. Would a GFCI receptacle be required? That seems undesirable on a water heater.

Thanks, Wayne

[thrugoodmarshall]

What brand/model is the heater?

Is the heater rated for outside installation? (I'm thinking freeze protection and weather proofing.) There should be installation instructions.

Here are some installation instructions for "a heater", but you really should find the ones for yours!

[SQLit]

Your location is a bit blurry from where I can see. If your in the SW USA. Anything but metal and concrete fails in the sun light over time. There are methods of connecting your water lines with pipe that do not require flexible connections, and yes still removable, check into a union. From what I read on my investigation into tankless heaters, outside installs are extremely sensitive to cold and freezing. Personally it the exterior installation is just to ugly for my taste.

Dedicated circuits to equipment do not usually require a GFCI. Do not use a duplex outlet use a single outlet. Outside subject to weather you will need a weather proof cover that can be closed with the plug in the outlet. Those covers are pricey. Your going to need to find a cord that is sunlight resistant.

Better check with your local building department or trades people to be sure.

[Wayne Whitney]

I'm currently leaning toward the Noritz N-063S. Mainly because it is the least expensive of the 175K-199K BTU/hr heaters, and because it requires only 0.5 GPM flow to operate (for models manufactured in June

2005 or later).

Yes, it is rated for outside installation when used with an exterior vent cap. It doesn't freeze in my climate (at least not in the last 5 years), and the water heater has electrical freeze protection for the fluke freeze.

The Noritz N-063S direction don't specify how to make up the connections themselves. One example does show using rigid pipe and unions for the gas and water, but nowhere does it say it is required.

Looking into flexible water supply lines some more, I see that in addition to the plastic/braided stainless steel lines I'm used before, there are also corrugated stainless steel and copper supply lines. As long as I get a corrugated metal supply lines rated to max the T+P valve, it should be fine.

So I guess my only remaining questions are about the electrical supply, is a plug and cord OK to use outside?

Thanks, Wayne

[Wayne Whitney]

Berkeley, CA. It pretty much doesn't freeze here.

I'm familiar with unions, in theory not in practice. What are the pros and cons of using rigid copper and unions versus using a corrugated flexible copper supply line?

Absolutely, everything will be done with permitted. I just like to be educated before I talk to the inspector.

Thanks, Wayne

[SQLit]

It will take more time to make up the metal connections with unions. But there will never be a problem with them from sunlight or any other outdoor situation other than physical damage.

Anything below 40F runs the risk of freezing. If your unit had a standing pilot light that would probably be enough heat to keep it from freezing. But then again you would not need the 120v there would you?

[Doug]

Wayne Whitney wrote in news: [e-mail]:

I personally wouldn't use a plug and cord outside for a fixed appliance like this. I think you'd want to do what's typically done for an air conditioning compressor. Outdoor rated junction box with a disconnect of some type for servicing then conduit to the unit. Air conditioners usually use liquid tight flexible conduit since they vibrate. Your heater shouldn't vibrate so you could use metal or PVC. PVC would probably be easier to work with and weatherproof.

Doug

[Wayne Whitney]

Excellent, thanks for the suggestion! I was looking for a flexible electrical connection, so the liquid tight flexible fits the bill.

Cheers, Wayne

[Wayne Whitney]

It does get below 40F here sometimes. How can it freeze above 32F? The unit has electric freeze protection, and I plan to insulate the water pipes, which will be on the exterior for a very brief run. Given the rarity of weather below 40F, hopefully that will be sufficient.

Cheers, Wayne