Stainless steel hot water cylinders

Hedgecutter · 17-01-2024 11:38AM #1

Hi all.

I need to replace my hot water cylinder. Its a solar copper cylinder.

I cant source a solar copper cylinder and will have to go with a stainless steel one. One of the suppliers mentioned that if im in an area with lime and use a water softener i should think about buying a marine grade stainless steel cylinder as apposed to a 316 grade cylinder. We have lime in our water but its doesn't cause trouble.

He said the 316 grade will start to break down in two to three years. Has anyone experienced this. Thought 316 stainless would have been more robust.

Dr.Tom · 17-01-2024 11:47AM

https://www.boards.ie/discussion/2058331783/stainless-steel-hot-water-cylinders

I work with all different grades of stainless steel daily. Id like to hear what the supplier refers to as "marine grade" stainless steel.

We have various products going through our 316 SS manufactured parts that the hobs of hell wouldn't shift so Id say a 316 SS cylinder will be just fine.

Calahonda52 · 17-01-2024 12:05PM

https://www.boards.ie/discussion/2058331783/stainless-steel-hot-water-cylinders

I think they are mixing it up: the base level, IIRC, is 303 or 304 and 316 is next

trouble if they are making both how to they ensure you are not being stuff with 304 for 316 prices

For waht its worth the 316 is really only marine splash proof, not full contact 24/7

Hedgecutter · 17-01-2024 12:11PM

This is the brand of cylinder he recommended.

https://aquatech.ie/cylinders-2/

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Dr.Tom · 17-01-2024 12:24PM

That's a 1.4521 grade stainless which is very similar to 1.4404 which is 316 stainless.

What they seem to show in their comparison table is a comparison to 304 stainless (1.4301) which is maybe why he us recommending it.

Hedgecutter · 17-01-2024 12:37PM

So do you think he got his grades mixed up and it a 304 grade Vs a 316 grade?

Dr.Tom · 17-01-2024 01:01PM

https://www.boards.ie/discussion/comment/121628569#Comment_121628569

I cant say that for sure. The tank you linked doesn't have a 316 option.

I have a Joule cylinder myself which is a duplex stainless steel (1.4462) and has better wear and corrosion resistance than 316 (1.4404).

I cant see there being any issues with 304

gw80 · 17-01-2024 01:06PM

https://www.boards.ie/discussion/comment/121628688#Comment_121628688

I would say that is what the guy meant by marine stainless,as duplex is used for a lot of marine applications, ie:offshore rigs and the likes,

Mellor · 17-01-2024 01:14PM

https://www.boards.ie/discussion/comment/121628569#Comment_121628569

Yeah, sounds like he got mixed up.

304 is basic (most common) stainless. Marine grade is a marketing terms, but 316 or 316L is most often used for those applications.

The product above is 444 grade. Which is very similar to 316 and has similar pitting resistance. I wouldn't pay a premium vrs 316. Don't go 304 obviously