Should I use a chemical cleaner on my 100 yr old system?

Maxbtu

Looking for advice from those of you who have experience cleaning very old systems.

I have 100 year old, gravity-fed hot water heating system with approximately 50 antique radiators and a new, 400K btu boiler. The system originally was a steam but converted about 50 years ago. Recently, a tech recommended a chemical cleaner to improve flow and efficiency through the system. It seems Fernox and similar products are effective but I'm concerned the removal of corrosion may expose leaks. This would be particularly problematic because the walls and floors are poured concrete so replacing a damaged pipe of fitting requires a lot of discovery and demolition.

So, my question to those of you with experience, would you use a chemical cleaner under these circumstances? If you've done so in the past, did leaks develop after flushing the system? If leaks did arise, were chemical sealers effective at fixing them?

Thanks in advance for any guidance you can provide!

EBEBRATT-Ed

I would not add anything

Jamie Hall

This doesn't happen to be in Dobbs Ferry, New York, does it?

I don;t think a thorough flush would hurt, but unless you know you have a problem with some kind of buildup somewhere, I'd be a little wary of doing more than that.

Mad Dog_2

Any pictures?  A Loss Loss Header with a Dirt/Steel magnet 🧲 is all I would do.  Mad Dog 🐕 

Maxbtu

Jamie Hall said:

This doesn't happen to be in Dobbs Ferry, New York, does it?

I don't think a thorough flush would hurt, but unless you know you have a problem with some kind of buildup somewhere, I'd be a little wary of doing more than that.

Thanks for your reply. The only evidence I have of buildup is uneven heating between radiators/rooms but I ran calcs on the boiler pumps I think they're underpowered for the size of the system. Other than that, we replaced a handful of radiators the past couple of years and the return pipes had buildup but not blockage. I'm inclined to replace the pumps and see if doings so improves performance before considering a chemical cleaner. I could add a magnetic separator at the same time. Does that seem reasonable? Also, property is near Chicago but sounds like it may have a long lost sibling in Dobbs Ferry.

hot_rod

The common hydronic cleaners are just a strong detergent. They will not dislodge metal particles.
The aggressive acid type like Hercules Sizzle will dissolve weak metals. I would not use that type. Acid based are generally for systems with a lot of lime scale, like excessive makeup water.