Water heater connection. What is this?

[2002sheds]

Hi All,
I was given a Takagi tankless water heater by friend of mine. The heater was functioning just fine, but he needed to switch to a different type.

When I got the heater home and looked at it more carefully, I saw that the water inlet was nearly completely clogged with some sort of corrosion or deposits. I removed the “collar” where the deposits were built up, and found that the pipe beyond that (into the inlet screen and beyond) was quite clean.

I have been soaking the “collar” in vinegar and the vast majority of the stuff has come off. I am left with the question of what this stuff is, and is the collar made of a metal that attracts elements from the water so that they don’t get further into the guts of the heater? Picture below.


Thanks,
David

 

[Two60zCowboy]

Looks like half a water heater dialectric union to me. The junk is the plastic that has corroded.

 

[Sponsor]

 

[Smooky]

You are so close on it I can't tell for sure. . . . That looks like part of the isolator valve; it might be one of the flush ports. That type of heater has to be flushed out to prevent minerals from building up and reducing efficiency.

 

[2002sheds]

Hi 260, Smooky,
Thanks for your responses! Yes, it is a very close shot. There are only three fittings on the whole unit — the gas inlet, this water inlet and the hot water outlet. I removed the inlet piece (the one in question) and soaked it in vinegar after breaking out as much of the crap as I could. The comment that it might be what is left of a dielectric union sounds right, as the threads do not go all the way to the end and there is a ring at the end that seems like it had retained something at some point...

Since the piece is removed from the tankless heater, my picture (which I will post in around 30 minutes) will be of the fitting only. As far as I can see, there is no corrosion past that point. I already have a Noritz tankless heater on another building on our property, and understand the importance of routine maintenance, including flushing the heater to prevent the buildup of water deposits

Thanks very much — I think you guys are helping me get on the right track!

 

[Terry]

Can you pull up the installation manual for that tankless and see what their suggested installation is for that unit?

 

[Fitter30]

Agree that looks like half of a dielectric with some galvanic corrosion.

 

[2002sheds]

Hi Terry,

Can you pull up the installation manual for that tankless and see what their suggested installation is for that unit?

Sure. The suggested installation is indoor and vented to the outside via a 4 inch vent.

My friend changed out the heater because he had vented it into a 30 foot tall light shaft (I am guessing that it is an opening between buildings. The inspector wanted him/the plumber to change the vent. He chose to go with a different heater.

Thanks,
David

 

[2002sheds]

Agree that looks like half of a dielectric with some galvanic corrosion.

Hi Guys,
Here are two pics of the water inlet fitting after removal and some cleanup. I cannot tell if it is Takagi or not...


Thanks,
David

 

[2002sheds]

Hi Guys,
Here are two pics of the water inlet fitting after removal and some cleanup. I cannot tell if it is Takagi or not...


Thanks,
David

Hi Guys,
I think I am slowly catching up... so the picture is the “fixed” half of a union, correct? The supply line would have the nut on it, I am assuming. And the whole thing is missing the plastic/rubber sleeve insert, correct?

Thanks,
David

 

[2002sheds]

Hi Guys,
I think I am slowly catching up... so the picture is the “fixed” half of a union, correct? The supply line would have the nut on it, I am assuming. And the whole thing is missing the plastic/rubber sleeve insert, correct?

Thanks,
David

One more picture, this one of the stock unit. Clearly, the piece I wrote in about is not part of the original setup. All signs point to that fitting being a dielectric union...