condensing boiler which make

Brad White_9

All products exposed to acids or alkalais will leach to an extent, the question is, how much and what of the fallout?

I have heard that about aluminum (the paste) but only in passing. Even condensate from SS boilers yields chromium, vanadium and other trace elements not directly a part of the gas itself. The contribution has to come from the metal. Even the Hydrotherm KN cast iron condensing boiler has a rust colored staining. The thick walls is what buys the time, over 30 years projected before reduction below ASME thicknesses are exceeded.

rich_42

condensing boiler

alluminum vs. stanless steel heat exchanger. better performance ad1- alumiunum is ok against carrosion stainless is good also what about heat exchange performance ?

Brad White_9

Stainless Steel is my First Choice

Both materials have a first-face reasonable resistance to corrosion especially in that they are compared to raw steel. Aluminum is sensitive to pH (acidity specifically). Aluminum is lower mass and is more conductive, but stainless at those temperatures is still respectable. You could not hold your hand on either of them

Ultimately, for performance, it is all in the published data. As a system both can be made to work equally well to a point of distinction without a difference.

The conundrum I have is, if one has to monitor the water-side pH to remain above 8.0 to an 8.0 to 9.0 range, then what does this say about the "fire-side" where pH's range in the 3.5 to 4.0 area under higher temperatures?

For this reason, I would go with stainless as a first choice.

Glenn Sossin_2

Leaching

Brad
I was meeting with people from Noritz yesterday, including a product design engineer. The are developing a SS modcon. They were asking lots of questions - likes, dislikes etc. When I started to discuss aluminum, he said they have seen evidence of aluminum leaching creating aluminum hydroxide. Supposedly over time this can attack other products in the heating system.

Ever hear of this ??

L'town radiant

MODCON GLYCOL

You may also consider that some aluminium modcon manufacturers require a special glycol product to be used in thier units that is quite expensive. Stainless boilers don't have this issue....can unexpectedly impact the price of a glycol job significantly!