Installing Electric Tankless Water Heater: Why valves? Why 36" pipe?

I have an Iheart S16 Drakken electric tankless water heater to install.

The provided installation instructions say to "always install 36" of copper pipe to inlet and from outlet of the heater to insulate heater from any plastic pipe...not using will void warranty..."

Why does the heater need to be insulated from the plastic pipe? Certainly, CPVC can handle the heat.

Why would it need this 36" of copper pipe on the cold side?

The "installation kit" is 2 valves with taps and a pressure relief valve, which seems to only be available in 3/4 inch. (The heater has 1/2 inch connections.)
The tap on the hot valve is for the pressure relief valve.
But what is the tap on the cold valve for? On pictures of an installed heater, sometimes that isn't there.

The 2taps are provided for descaling the heat exchanger
You turn off the supplies and recirculate through the taps

I'm sorry but if you do not know about those two things or are even questioning it, maybe someone else should do your tankless. Especially about the descaling maintenance that is required. Not to mention some gas units require gas pipe to be upsized.

Good luck to the OP. A tankless whole house for a couple hundred bucks.

SHEPLMBR said:

I'm sorry but if you do not know about those two things or are even questioning it, maybe someone else should do your tankless. Especially about the descaling maintenance that is required. Not to mention some gas units require gas pipe to be upsized.

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What are you sorry about, criticizing someone for asking a question?

The questions (if you read) are about an electric unit, so why do you bring up resizing gas pipes?

And in the future, you might consider writing in sentences. If you're not acquainted with that convention, perhaps someone else should write your posts.

Nehmo said:

What are you sorry about, criticizing someone for asking a question?

The questions (if you read) are about an electric unit, so why do you bring up resizing gas pipes?

And in the future, you might consider writing in sentences. If you're not acquainted with that convention, perhaps someone else should write your posts.

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Hey guy no need to be nasty. The electric part was an oversight on my part. I wasn't criticizing. As far as my posts, I didn't think we were here to write a thesis. If you have a problem with the way I write, maybe you have too much time on your hands.
Again, I apologize for the oversight of the heater being electric. I was not trying to be rude.

Nehmo said:

And in the future, you might consider writing in sentences. If you're not acquainted with that convention, perhaps someone else should write your posts.

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Get over yourself bud

Gotta love it... ask a question then insult the professional answering it.

Not the way to get advice.

speedbump said:

Gotta love it... ask a question then insult the professional answering it.

Not the way to get advice.

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A damn shame. It's akin to biting the hand that is feeding ya.

Nehmo said:

What are you sorry about, criticizing someone for asking a question?

The questions (if you read) are about an electric unit, so why do you bring up resizing gas pipes?

And in the future, you might consider writing in sentences. If you're not acquainted with that convention, perhaps someone else should write your posts.

Click to expand...

F.in Troll

tanksnotanks said:

The 2taps are provided for descaling the heat exchanger
You turn off the supplies and recirculate through the taps

Click to expand...

Thank you for answering the question. The taps can't be for anything else. However, it's interesting most tankless heater manufacturers don't have the cold tap in their installation diagrams. Here's a pdf of Rheem's gas tankless piping installation diagrams.
Drakken customer support 888 816 4328 couldn't answer my question about the taps. The guy who answered (believe it or not) explained by saying he was "not a plumber".
Even though the installation kits all come with taps, the cold one must be somewhat optional. Most of the pics on the internet of completed installations do not show a cold tap.

Another question I have is about the GFCI recommendation on a sticker on the heater. It says to use one, however, the included electrical instructions don't mention it. Online installations of similar units don't seem to use one either.

The code says anything within 6ft of water needs to be gfci