How to Seal Hot Water Tank

[Dano57]

OK, I've seen elsewhere that silicon caulk doesn't stick to aluminum, is that true? If so what should I use around the hot water tank, I am removing it to re-plumb the trailer so.....plumber's putty or something else?

Dan

[GreatPumpkin]

Use Vulkem from Vintage Trailer Supply (or elsewhere) for sealing outside seams. Are you removing and not replacing the water heater? What exactly are you trying to seal?

[CaddyGrn]

List the brand of your hot water tank, do you know how bad and where the leak is? Post a photo as well and maybe you will get better answers. If the tank is under pressure when the water is being used, so sealing could be a problem. Also need to know if you are using a water pump when you turn the water on or do you have a pressurized system that runs off a compressor? Answering these questions might give you more answers than questions in return.

We removed our original 1963 hot water tank, and took it to a professional welder who made sure all was sealed and perfect!

Mrs. NorCal Bambi (traveling in S Tardis)

[lewster]

Originally Posted by Dano57

OK, I've seen elsewhere that silicon caulk doesn't stick to aluminum, is that true? If so what should I use around the hot water tank, I am removing it to re-plumb the trailer so.....plumber's putty or something else?

Dan

Dan,

The Airstream factory uses SikaFlex polyurethane sealant (and so do I) on just about all of the large seams and caulking jobs on the newer models. It is incredibly tenacious on just about any material (even glass). The smaller seams are filled with Acryl-R.

Lots of people on the Forum use Vulkem. It is a lot cheaper than SikaFlex. The choice is a little like engine oil......pick what you like!

[wahoonc]

Dan,
I you are talking about the flange where the water heater mounts to the trailer, they used a butyl tape orginally. It is availble at any RV supply house, however a big fat bead of Vulkem or Sikaflex will work fine too. FWIW both the Vulkem and the Sikaflex are polyurethane based caulks with very similar properties. NP-1 is another one. Also apparently the vulkem name is going away. The new stuff just says Tremco on it.

Aaron

[Dano57]

My bad, I didn't clearly state the issue, my apologies. I am removing the hot water tank so I can re-plumb with PEX pipe. I guess the previous owner had some freeze damage and patched it up but didn't do a good job so I redoing all the piping with PEX.

So to get to the hot water tank connections I am going to pull the tank from the side as it is easier than drilling the inside cover off. When I go back with the tank I need to reseal the flange that screws to the trailer. I have been reading about using vulkem and such but didn't know if it was good around heat sources such as the hot water heater. It appears that it or one of the similar products will be fine.

Gladly accepting any other ideas, and thanks for the responses so far.

Dan