Isotherm water heater

[sean9c]

I'm replacing my water heater and figured I'd spring for a good one and picked an Isotherm. The ones sold by both Fisheries Supply and Sure Marine, the 2 suppliers that I use, come with a factory installed mixing valve, seems like there is a base model sold elsewhere without the mixing valve. Pretty cool now I don't need to worry about plumbing in my own mixing valve. I get the w-h installed and it leaks where the combo cold water inlet and drain valve connects to the pipe coming out of the tank. Bizarrely, imo, they use a compression fitting to connect the valve to the tank. I fight that for a while trying to get it to seal, no luck. Return the w-h to my supplier and get another w-h, the same model Isotherm. Install that and it leaks. This time at the mixing valve where they have an adapter that goes from whatever, likely metric, thread on the valve, to, again bizarrely, BSP thread. The other 3 threaded connections on the w-h are NPT. Why they would have one BSP thread, who knows. You then need a BSP to NPT adapter. I fight that for a while trying to get it to seal with no luck. That's where I am right now. I pulled the second w-h out last night, and sent a text to my salesman. I've spent too much time looking at Isotherm water heaters. IMO things like the tank, heat exchanger, insulation all look like they are top quality. But using compression fittings to attach the valves and having to have adapters to get to something usable just seems like a bad idea.
If it wasn't for those compression fittings I'd just pull those valves off and do my own inlet, outlet and mixing valve. I think maybe Isotherm needs better quality control.
Rant over

 

[rslifkin]

When I installed mine I had slight leaks at the compression fittings. As best I could tell, it was from stuff getting rotated slightly during installation (they weren't super tight). I pulled them apart, put some thread sealant on the olives and reassembled, allowing the sealant to cure before pressurizing. Hasn't leaked a drop since I did that.

The adapter on the mixing valve on mine was NPT on the output, so they likely offer it both ways.

 

[Comodave]

It is all in how you do it. I replaced a shower faucet on our last boat. I carefully put the fittings together. Had a drip. Took it apart and redid it 6 more times. Still drips but slower. I had a plumber come in and I watched how he did it, exactly like I did. He took it apart and put the fittings back together just like I did and no leaks…

 

[mvweebles]

Several years ago I stopped using Teflon tape in favor of pipe dope. Much better results for me.

Good luck. I feel your pain and frustration.

Peter

 

[Mac2]

Several years ago I stopped using Teflon tape in favor of pipe dope. Much better results for me.

Good luck. I feel your pain and frustration.

Peter View attachment 132890

Totally agree. I would also add that the difference between tape and pipe dope is to make sure you pay attention to cure times with the dope. Also, they make dope for water and for fuel. Diesel will break down the teflon in dope and teflon tape if not designed specifically for fuel.

 

[mvweebles]

Totally agree. I would also add that the difference between tape and pipe dope is to make sure you pay attention to cure times with the dope. Also, they make dope for water and for fuel. Diesel will break down the teflon in dope and teflon tape if not designed specifically for fuel.

I reached out to Steve D'antonio a few years ago for thread sealant for pipe fittings on a diesel tank. He recommended Leak Lock.

Highside Chemicals 10004 Leak Lock 4 Ounce Brush-Top Plastic Jar https://a.co/d/fLSUBm5

PermaTex also makes a product that is popular

Peter

 

[tiltrider1]

Several years ago I stopped using Teflon tape in favor of pipe dope. Much better results for me.

Good luck. I feel your pain and frustration.

Peter View attachment 132890

+1 for Rector 5.

Now when it comes to Teflon tape there are 3 kinds. Cheap white crap. Yellow which is formulated for fuel lines. Pink, which is much thicker and works great but costs more.

https://www.amazon.com/PROCURU-10-P...wicXNhIjoiMi43NiIsInFzcCI6IjIuNzUifQ==&sr=8-4

If you prefer the convenience of Teflon tape over Rector 5 then at least use the 4 mil thick pink stuff. I have never had leaking issues with it.

 

[sean9c]

Tony Athens uses Rectorseal 5, so I started using it years ago. Probably the weirdest thing is that you can find it at Home Depot.
With my issues in both cases the seal is created by metal to metal contact and you're not intended to use goop. I tried anyway, no luck. The valves are connected using a compression fitting and with the leak on the mixer valve adapter when I took the adapter off it was interesting to see that it's a straight thread on the valve and the adapter has a sealing surface that seats on the valve. It looks to be a one time use sort of thing, once it's on you don't take it off or it won't seal again. On the compression fitting I even took it apart and tried lapping the sealing surface together using valve grinding compound.

Several years ago I stopped using Teflon tape in favor of pipe dope. Much better results for me.

Good luck. I feel your pain and frustration.

Peter View attachment 132890

 

[rslifkin]

The compression fittings are supposed to be a metal to metal seal, but for whatever reason, they seem to weep slightly in some cases. It's just not a good enough seal under pressure. The tiny bit of thread sealant (I used Loctite 592) was enough to make up for whatever slight imperfection and it's held up to 60 psi just fine so far without any hint of leakage.

 

[sean9c]

Thanks for that tip. I'll give it a try.

The compression fittings are supposed to be a metal to metal seal, but for whatever reason, they seem to weep slightly in some cases. It's just not a good enough seal under pressure. The tiny bit of thread sealant (I used Loctite 592) was enough to make up for whatever slight imperfection and it's held up to 60 psi just fine so far without any hint of leakage.

 

[Comodave]

I was watching some Seaboard Marine videos the other day. Tony was having them put Rectorseal #5 even on hose barbs to seal them on the hoses. Great videos BTW.

 

[sean9c]

I do that. Probably the best benefit is that it helps when you try to get the hose off.

I was watching some Seaboard Marine videos the other day. Tony was having them put Rectorseal #5 even on hose barbs to seal them on the hoses. Great videos BTW.