Glycol and Corrosion

Thunder

I am wondering if there is a way to test which type of glycol has been used in a system.

I am also wondering if orange boiler water and tiny floating particles within that boiler water that "shine" under lights are caused by corrosion in the heat exchanger.

EBEBRATT-Ed

Two types of glycol. Ethylene which is similar to auto antifreeze is generally green. Polypropylene glycol (like rv antifreeze) is usually clear or pink.

Both change color as they degrade in the system and become acidic.

Thunder

Should the condensate on a condensing boiler be clear or would it also be orange/rust colored?

Jamie Hall

Thunder said:

Should the condensate on a condensing boiler be clear or would it also be orange/rust colored?

That would depend on what it's corroding... ! Initially it would be clear, though.

pecmsg

My chilled water glycol is Blue.  

The color really doesn’t matter, they can tint it any color. 

hot_rod

Thunder said:

I am wondering if there is a way to test which type of glycol has been used in a system. I am also wondering if orange boiler water and tiny floating particles within that boiler water that "shine" under lights are caused by corrosion in the heat 

If you send it to the manufacturer they can test for PG or EG. Why would you want to know. On small systems it’s best to flush suspect glycol out, clean the system and start fresh. If the system generates DHW with a HX or indirect, you want to use PG. DowFrost for example

EG, DowTherm is still used in larger systems and systems without DHW. Be sure to label any system that has glycol, and disconnect any auto fill valves.

Check the ph if the fluid, that tells the most about condition of the inhibitors, if it dropped into the 7’s, smells harsh, looks like coffee, get it out.

Thunder

I have a Noble fire tube that hasn't worked right from the start. Lots of issues with the install.

About 3 months ago, a tech noticed what appeared to be alcohol-based glycol in the system. I was getting alot of percolating. The system was flushed and filled with just plain water.

It does have a side warm DHW tank.

Since the flush, the percolation is gone, but now we are having issues with sediment plugging up the mixing valve screens and very poor flow.

It also has orange/rust colored condensation with some flakes in it. When we removed the burner to inspect the heat exchanger, there is also some of the rust colored flakes there along with a greenish scale. When we poured clear water into that to flush it, it came out rust colored. My condensation y trap is also stained.

And the clear water that we added in the boiler is now the color of rust as well and has a metallic smell to it.

I want to prove what the glycol was and whether or not that has caused rust inside the heat exchanger. I also want to prove if the sediment that is blocking the screens and causing poor flow is rust particles.

Any other ideas?

Solid_Fuel_Man

Have any pics of the system? 

Fire side and water side of the HX are two completly different things.

hot_rod

True glycol is oil based, from petroleum, or corn based. There are technical and food grade glycols. It's odd knowing petroleum products are used in food flavoring and preservatives

Some of the RV antifreezes are alcohol products, not really glycol base. More like windshield washer fluids.
I visited Douglas Products years ago, they blended the corn based solar fluids for Caleffi. They also blended RV fluids both from PG and methanol. Price driven choice for automotive stores.

A boiler should have ONLY hydronic glycols, not automotive, not RV stuff. When the fluids are new you can smell the difference, it may take a lab to analyze after corrosion has contaminates the fluid.

No empty containers around, I suppose?

I would run a hydronic cleaner in the system for a few days. That will cut the crap. Then flush with good water, pressure test, then add the final fluid.

If you really need glycol, either buy pre-blended or blend the 100% with only deionized water. Blending with hard or high TDS water pretty much ruins the glycol day one.

HomerJSmith

Ya! I had a sys that I had to flush 5 times with cleaner over time to get a decent fill. Boy, was the original installation a screw-up. Whether anti-freeze or not, clean is the mean.

hot_rod

What type of system do you have? Any rubber hose or non barrier pex in the piping.

Those would be tough on glycols, as O2 ingress also breaks down the inhibitors.