The Mystery: Plastic rod with multiple holes in it inserted in hot water tank where hot water enters. Not an anode.

[rob49]

Plumbers came out to replace anode rod, but a pipe had been run directly over where old alum anode as installed and they would have to cut that pipe to get to the old anode. They said they could install anode rod directly into the hot water entry into tank at the top. They removed about a 30 inch long plastic pipe with multiple holes in it, which I assumed was for circulation of the water. I had requested a magnesium anode rod, so they installed what they called a "kit" which, in addition to the mag anode rod, had a couple 6 inch sections of pipe that coupled the anode in tank with the hot water line at top of tank. (This "kit" cost $340 which was about $270 more than a mag anode rod alone. This is before labor). So we have a mag anode rod installed (and the 4-5 year old aluminum rod still in tank). One more thing before asking my question.
After they left and my wife and I showered, we noticed that the hot water in bathroom farthest from the hot water heater in attic was about half as hot as before the plumbers did their work. I called plumber who said that removing plastic rod and installing the mag anode would not have affected the temp of water. (No one had changed the set temp of water at tank).
My questions:
What was the plastic rod with holes in it and its purpose?
Why did temp of water change after the installation of anode rod?
Thanks

 

[Twowaxhack]

Post pics of everything or it’s all a big guess.

 

[rob49]

The plumbers took the plastic tube with holes in it away, so no photo.

 

[Twowaxhack]

Sounds like they may have removed the dip tube. Who knows, it’s a guess. Sounds like you spent a lot of money for nothing. Good luck

 

[wpns]

Yes, sounds like the cold water inlet dip tube is now missing. That lets the cold water into the _bottom_ of the tank, so the hot water comes out the top. Now you have cold water going into the top of the tank and going back out the top of the tank, much less efficient, and lower temperature.

Those guys had no idea what they were doing.

 

[Jim Jensen]

this sounds like the picture-perfect warning, about vetting any "pro" you hire.....

 

[Twowaxhack]

Rheem makes a anode kit that installs in the hot side.

If they installled the kit on the cold side then they removed the dip tube.

It’ll never work properly without a dip tube if the cold is piped into the top of the water heater.

This would cause a temp change alright, you’d get very little hot water. Crazy temp swings also without touching it the faucet handle.

 

[rob49]

WPNS,

The part you call the dip tube was installed at the top of tank, not bottom, at the hot water entry. Installed just like an anode would be, hanging down in tank about 27-30 inches, so it should have hot water running down in it and then dispersed in tank through all the holes in it.

 

[rob49]

Sorry. Installed where hot water comes out of tank, not in. So it seems like cold water heats in tank then goes out tube with holes in it and to the rest of house. Still don't understand exactly what that part with the holes in it does.

 

[Twowaxhack]

Good luck with it. I’m done guessing

 

[rob49]

Thanks for trying.

 

[rob49]

I did some digging and found out what the dip tube does. The puzzler is that it supposed to be installed on cold water entry side of tank. The one they removed had been installed on hot water exit side of tank. Since its purpose is to guide incoming cold water toward the bottom of tank where heating element is, I don't see how it does any good installed on side where hot water comes out of tank. Seems the plumber who came out didn't think it was necessary to have a dip tube since they did not replace it. And it seems previous plumber did not know to install it on cold water entry side of tank.

 

[havasu]

Normally there is an "H" and "C" embossed at the top of the tank. If you have confirmed it, I'd call him back and have him explain why he did what he did.

 

[rob49]

Thanks. They are coming back tomorrow with a dip tube to install on cold water side.

 

[Steve_K2]

Let us know how this worked out.

 

[wpns]

This whole thing is very confusing, unless it’s a solar heated hot water tank, and it’s plumbed “sideways“ I’m not sure I know what’s going on. Let us know what you find out!

 

[rob49]

I will let you know how the installation goes. Thanks for your interest. I really appreciate it.

 

[JEG in Raleigh]

Interesting discussion for me as I'm learning more about plumbing. FYI rob49, I found this explanation of the holes on another site:

Originally it was possible to accidentally drain a water heater when the piping system was depressurized and opened during work. It still is if the dip tube which reaches into the bottom of the tank creates a siphon. If an electric water heater is not turned off at the power source and a siphon drainage occurs the elements could become exposed to air and will burn out if the thermostat closes the second leg of 120-volt power to one or both of them. A dip tube has a small hole in it that should be higher than the top element in the water heater. This hole is intended to break any siphon that occurs by allowing air to enter the cold water side. The hole is small however and not 100% to be relied upon as it could become plugged. If you are draining water from a cold water pipe during work and the water is hot or warm you are probably siphoning from the water heater and should power down the heater. Power it down before you try to stop the siphon, you should probably power it down when opening the piping in any case.

It sounds like the holes in the dip tube are intended to break a siphon.

 

[JEG in Raleigh]

Question for the pros on this thread. I'm on a well and (with good sediment and backwash filtering & softening) and I have a 6-year-old Rheem Marathon WH (all plastic) that has worked great. I was hoping to live out my days with only maybe needing to replace the heating elements, but now after reading this thread, should I replace the dip tube every 7-8 years or so to be on the safe side? Or, do I not need to worry about it? I don't want the thing breaking off inside and ruining my expensive, supposed-lifetime WH. With regard to anyone dealing with a broken dip tube situation, if the dip tube breaks off and settles in the bottom of the WH, is the WH toast or can you just replace the dip tube and keep on using it?

 

[wpns]

It sounds like the holes in the dip tube are intended to break a siphon.

Except it sounds like there were multiple holes? In my solar hot water tank, one of the dip tubes has multiple holes along the length, which I thought had something to do with the solar function. I no longer remember which one it was, sorry. There are two dip tubes to the bottom of the tank (cold water in and 'out to collector'), one to the middle ('in from collector'), and the usual hot water outlet at the top. The electric hot water boost only heats the top of the tank when it's on.