Why my expansion tank keep failing?

[Navien Hater]

Hi there,
My first expansion tank with the Navien tankless water-heating system was leaking in about 2 years so I replaced it with a new Calefactio HGT-30-4.8 us gal tank 9 months ago. However, I just found out today, it is leaking again, not event last 1 year?!!!! I have no idea that is the problem of Navien water-heating system or just the low quality of the tanks?
I know I have to replace the tank, again, but just want to get some opinion if my Navien failed me again!!!

Thanks for reading!!!

 

[John Gayewski]

Hi there,
My first expansion tank with the Navien tankless water-heating system was leaking in about 2 years so I replaced it with a new Calefactio HGT-30-4.8 us gal tank 9 months ago. However, I just found out today, it is leaking again, not event last 1 year?!!!! I have no idea that is the problem of Navien water-heating system or just the low quality of the tanks?
I know I have to replace the tank, again, but just want to get some opinion if my Navien failed me again!!!

Thanks for reading!!!

Tankless heaters don't actually need expansion tanks. I didn't search the tank you had, but the ones that are used with tankless heaters are tiny, they look more like a hammer arrestor.

What do you mean fall? How are they failing? Your saying leaking, but where?

 

[Sponsor]

 

[Bannerman]

Post some photos showing the expansion tank connection and showing any tank support brackets, straps etc. Also include a diagram showing the location of the expansion tank in relation to the Navien unit.

Water source: Private well or municipal supply?

Was the expansion tank air pre-charge pressure adjusted in relation to the water pressure normally experienced in your home?

 

[Fitter30]

Tanks on heating or dhw side? Where are the leaks?

 

[Navien Hater]

Tankless heaters don't actually need expansion tanks. I didn't search the tank you had, but the ones that are used with tankless heaters are tiny, they look more like a hammer arrestor.

What do you mean fall? How are they failing? Your saying leaking, but where?

Sorry, it is "fail", my bad. A company installed the Navien combi-boiler. Its not a tiny system so they added a expansion tanks for me.

 

[Navien Hater]

Tanks on heating or dhw side? Where are the leaks?

Thanks for getting back to me. I found where the leak is...

 

[Navien Hater]

Tanks on heating or dhw side? Where are the leaks?

its on the top... I do not know what that part should be called... thanks for asking

 

[Navien Hater]

Post some photos showing the expansion tank connection and showing any tank support brackets, straps etc. Also include a diagram showing the location of the expansion tank in relation to the Navien unit.

Water source: Private well or municipal supply?

Was the expansion tank air pre-charge pressure adjusted in relation to the water pressure normally experienced in your home?

sure, photos are one the way... the green one is the old one which I replaced 9 months ago during the whole system down...

 

[Fitter30]

First test the boiler water for ph with litmus paper or another way. Ex tanks like other parts normally don't fail that way. Bladder yes not the tank especially two different brands.

 

[Navien Hater]

First test the boiler water for ph with litmus paper or another way. Ex tanks like other parts normally don't fail that way. Bladder yes not the tank especially two different brands.

You are right. It should last 5-10 years not 9 months! thanks