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.

Javelin

@Maxbtu - Any update for us? Did you add any cleaner to your system?

I'm in a similar situation, though not quite as large a system - still have about 25 rads with a 250 k BTU boiler. As far as I know, things have been humming along.. Not sure how efficiently, but certainly get heat from everywhere - honestly, I never really even thought of cleaning.. I'm SURE it wasn't done in the 25 years before I moved into this house, so being in here 12 now, I figured don't rock the boat.

The only think that gives me pause recently is I just had a Danfoss RA2000 thermostatic valve lock up on me on one of the 3rd floor rads (I put them in about 10 years ago and others on the floor are fine). The locked up radiator was ice cold, so I took off the thermostat off the valve, massaged the pin a bit and pulled it in/out again and it seems like it's heating up again.

@hot_rod - you've been SO HELPFUL to me in the past and I know you weighed in above… Do you think it would be time for a flush/clean of my 100+ year old system? I don't want to do more harm than good. If you did put in a gentle cleaner - which one/brand would you recommend me investigating.

THANK YOU BOTH (All)

hot_rod

that us a tough call on an old system

Many if the hydronuc cleaners are a strong detergent. Ut cuts grease, oil, flux, pipe dope, etc. It doesn’t really strip rust off old cast radiators or steel pipes really

However just disturbing or power flushing an old system will move any sediment through the system.

I would definitely add a good dirt/ mag sep

The Caleffi XF is unique in that it is a Y strainer and mag dirt sep in one. Rotate the collar and brushes wipe the fine screen clean. So it gets particles on the first pass. A dirt separator takes 20 passes or more to pull out all the particles