Heat Exchanger Zincs

[Capt. Rich]

I screw the zinc pencil into the plug with nothing on the threads. I then screw the plug into the heat exchanger dry as well. Does it isolate the zinc if you put thread lube on the plug itself before screwing into the heat exchanger? I have heard alot of different thoughts on this.

[psneeld]

Originally Posted by Capt. Rich

I screw the zinc pencil into the plug with nothing on the threads. I then screw the plug into the heat exchanger dry as well. Does it isolate the zinc if you put thread lube on the plug itself before screwing into the heat exchanger? I have heard alot of different thoughts on this.

not recommended or required if using brass/bronze plug into bronze heat exchanger.

[doug86]

I do mine dry, but if you want to lube the threads, use a conductive grease, like:

CP8-TP | Connectitwireless

[S/V_Surya]

I had thought about this myself when I replaced mine last week. I think it is important to maintain good conductivity in all elements. I used dielectic grease to coat pencil zinc to plug and used nothing on the plug itself.

When I pulled the plug originally there was plenty of zinc left from last year I then tried to unscrew the pencil zinc. Bad Idea, metal is soft and just broke off and I was then forced to replace plug as well as zinc.

[David M]

Don't worry about it. There is no sealant that prevents the male and female threads from touching each other. There is no sealant that does this. The acid test is in putting a multimeters continuity tester across the plug and the heat exchanger. You do want to put some sort of sealant in there to prevent leakage and to eliminate oxidation.

Always replace when it is more than 50% gone.

[doug86]

Originally Posted by S/V_Surya

I used dielectic grease to coat pencil zinc to plug and used nothing on the plug itself.

Why would you want to electrically insulate the zinc from the plug or the heat exchanger? A sacrificial annode needs to be electrically connected to the metal it is supposed to protect.

dielectric
–noun

1. A nonconductor of electricity, especially a substance with electrical conductivity of less than a millionth (10-6) of a siemens.

[S/V_Surya]

It is non-conductive, but when you slide the connectors together there is metal-to-metal contact and the grease gets displaced but the area around connector is protected from moisture.
Using a bit more grease is usually a wise idea, since it protects the connectors from corrosion by displacing water and reducing exposure to oxygen. If the contact between the two pieces is such that enough grease is between them to cause a problem—you've got other problems with the connection (that's when conductive grease saves the day). The connection should be tight enough that it forces the grease out of the way.

[doug86]

Ah, ok. I agree that the connection will be pretty tight if it's tight enough to prevent water escape; and really, that is all the tightness it needs.

[Capt. Rich]

Good thoughts all. I like the idea of using Copper Shield on the zinc and plug as well. It should still have current flow and yet make for ease of removal. I use Coppershield all the time but never considered this application.

[psneeld]

Unfortunately you really can't ohm check when all is assembled...it's neither recommended or necessary to use anything on zincs...bolt on zincs are better as they don't corrode at the threads...but the trick is to pull, check, unscrew and rescrew at intervals that before they break at the threads they can/should be replaced.