Low Prop Glycol % ......... or not at all

DaveL

Curious if any radiant pro's have comments to share - fellow wetheads getting bored in the stay at home mode perhaps?

My home application will have ~3000' Rehau in gypkrete, this single story above conditioned well insulated crawl space, manifolds in crawl and boiler room in the home/side of the attached garage.

Using Lochinvar Knight firetube, so currently thinking that "if" I use antifreeze I am really only doing so to protect boiler and the copper pipe in there; seems to me the pex can do fine if it gets slushy. Only thing to protect is from the highly unlikely multi-day power outage occurring at same time of a multi day winter freeze when I am gone and unable to plug it into gas generator.

It would take 5+ days, I think, for the pex embedded in floor of house to drop to freeze temp, and if the pex fluid is at 32F then likely the copper in boiler room will be frozen solid long before that..........agree or not so much?

I'll use distilled water to fill system, so thinking I'd be smart to use maybe ~25% PG? Strictly as insurance to a remote what if. Or is this a real overkill is my head argument going on!

Also, curious if anyone knows, if I do add PG, and it was Hercules cryo-tek AG, it has pH 9.5-10.
So if I only use at only 25% concentration and rest is distilled water then seems my resultant system pH will be well within the pH 6.5>9.5 stainless boiler needs.....agree?

Thank you in advance to anyone sharing experiences and/or thoughtful replies!

Jamie Hall

On the pH (I'm not going to comment on whether or not -- out of my area!). pH doesn't work like that. I'm not sure what the glycol uses as a buffer, but something -- and the way pH works is nothing like normal dilution. The resulting pH would be only slightly less than 9.5, if any -- more likely not any. At that concentration of glycol plus distilled water, I'd bet on it being right about 9.6 or 9.7.

pecmsg

Use the lightest concentration you need.
25% is about 15° Freeze -1° burst. Is it going to get neat -1°?

hot_rod

If you use glycol the ph will be higher than water, of course.

I'd only use glycol if absolutely necessary, it reduces heat transfer, messy to keep inside joints.

3 temperatures with glycol:
Freeze point where ice crystals form
Slush point, no longer pump-able with a centrifugal pump
Burst point

Some manufacturers list all 3, some just freeze and burst. Also check with the manufacturer on the lowest % they suggest. The inhibitor package gets too low and you lose protection, possible bacteria growth also.

Do you know the systems capacity? if so get undiluted PG and just add enough to get the % you want.

Zman

If this is a full time home and the the tubing is held back from the garage doors with good insulation, I absolutely would not use glycol at all.
If you decide to use glycol, don't use less than 25% or so, it is not recommended. I believe this is because it will breakdown to quickly at low concentrations.
As for the Lochinvar boiler, it is stainless and should not require inhibitor. If you want the extra protection, why not use inhibitor without glycol. Be sure to flush the system before adding anything.

pecmsg

Zman said:

If this is a full time home and the the tubing is held back from the garage doors with good insulation, I absolutely would not use glycol at all.
If you decide to use glycol, don't use less than 25% or so, it is not recommended. I believe this is because it will breakdown to quickly at low concentrations.
As for the Lochinvar boiler, it is stainless and should not require inhibitor. If you want the extra protection, why not use inhibitor without glycol. Be sure to flush the system before adding anything.

Ive never heard of that. (I Do Chilled Water Systems)

Any Documents to back it up?

hot_rod

Some good info here
https://www.dow.com/content/dam/dcc/documents/en-us/app-tech-guide/180/180-01286-01-engineering-and-operating-guide-for-dowfrost-and-dowfrost-hd.pdf?iframe=true

Zman

@pecmsg
I did not realize this for many years either.

pecmsg

hot_rod said:

Some good info here
https://www.dow.com/content/dam/dcc/documents/en-us/app-tech-guide/180/180-01286-01-engineering-and-operating-guide-for-dowfrost-and-dowfrost-hd.pdf?iframe=true

Zman said:

@pecmsg
I did not realize this for many years either.

Thank You

Something to research tomorrow.

Fortunately the systems I work on are generally 30% but always willing to learn!

kcopp

I agree.
I would not use ANY glycol unless you a super sure that they will lose power for an extended period of time.
I cant stand the stuff.
I just worked on a system this week w glycol in it and it damaged the system pretty well.

hot_rod

You can go lower if you notify the blender, they boost the inhibitor package they blend. I had a local provider that taught me that.

GroundUp

kcopp said:

I agree.
I would not use ANY glycol unless you a super sure that they will lose power for an extended period of time.
I cant stand the stuff.
I just worked on a system this week w glycol in it and it damaged the system pretty well.

What did the glycol damage, exactly? 95% of my work is radiant that includes a garage only heated to slightly above freezing, which in my opinion, would be foolish not to run glycol as I get at least a dozen calls every winter with frozen garage loops from people running water. Many systems I work on have 20+ year old PG in them and the system is still clean as a whistle. Honestly I've seen much more damage caused by filling with domestic water than any other variety of fluid, just can't understand the hate for PG

hot_rod

If the inhibitors get consumed or break down the glycol can turn into glycolic acid.
Also blending with anything other that DI or RO water can cause it to break down. Weak solutions can also have bacteria growth.

Temperature is a factors also, glycol at the boiler wall can see 300F temperatures. Beside you upsize the circulators to get adequate flow thru the boilers.

Sight, smell, and Ph are good indicators of the glycol condition.

kcopp

It killed this expansion tank.. also note the fittings and the mix valve. 1 year old tank and fittings. The glycol probably has not been looked after but unfortunately it becomes a service issue. This was a large system. 4500 Sq feet and 8 zones.

SuperTech

Yup. That nasty black crap is often found on systems with bad glycol in them. I would avoid using it unless absolutely necessary. Checking the glycol every year for freeze protection and acidity is necessary. If the customer doesn't want to pay for the new glycol it's on them.

hot_rod

I think the biggest mistake with glycol is not cleaning the system first, both new and old installations.

Solder flux, pipe dope, manufacturing oils and lubes all have an effect on glycol. As does hard or high TDS blend water. Most glycol systems don't start out well.

Jamie Hall

There is a reason, folks, why in engines there is a recommendation that the antifreeze be drained and flushed at regular intervals. It's glycol. Granted, Ethylene rather than Propylene, but still a glycol. Also granted that an engine is a harsher environment than a heating system.

But... the recommendation is not just to make money for the shop.

pecmsg

kcopp said:

It killed this expansion tank.. also note the fittings and the mix valve. 1 year old tank and fittings. The glycol probably has not been looked after but unfortunately it becomes a service issue. This was a large system. 4500 Sq feet and 8 zones.

That's not the Glycols fault.

If they don't change the oil in there cars engine is that the companies fault?

GroundUp

Yeah, that was a maintenance problem not a glycol problem. Obviously it hadn't been looked after and turned acidic (which can happen with straight water also) but judging by the mud inside the valve, it was filthy too. Certainly not a fault of the glycol itself, just a lack of care.

hot_rod

GroundUp said:

Yeah, that was a maintenance problem not a glycol problem. Obviously it hadn't been looked after and turned acidic (which can happen with straight water also) but judging by the mud inside the valve, it was filthy too. Certainly not a fault of the glycol itself, just a lack of care.

I'm not sure water in hydronics can go bad or turn acidic?

When you see sludge and lots of corrosion it indicates O2 ingress breaking down the ferrous metals. That can happen regardless of the fluid or blend. Glycolic does tend to cause more problems than water when it goes bad.

pecmsg

hot_rod said:

GroundUp said:

Yeah, that was a maintenance problem not a glycol problem. Obviously it hadn't been looked after and turned acidic (which can happen with straight water also) but judging by the mud inside the valve, it was filthy too. Certainly not a fault of the glycol itself, just a lack of care.

I'm not sure water in hydronics can go bad or turn acidic?

When you see sludge and lots of corrosion it indicates O2 ingress breaking down the ferrous metals. That can happen regardless of the fluid or blend. Glycolic does tend to cause more problems than water when it goes bad.

Maintenance!

hot_rod

> @pecmsg said:
> (Quote)
> Maintenance!

Better yet find and stop the cause of the problem. maintenance may be just treating symptom?

GroundUp

hot_rod said:

GroundUp said:

Yeah, that was a maintenance problem not a glycol problem. Obviously it hadn't been looked after and turned acidic (which can happen with straight water also) but judging by the mud inside the valve, it was filthy too. Certainly not a fault of the glycol itself, just a lack of care.

I'm not sure water in hydronics can go bad or turn acidic?

When you see sludge and lots of corrosion it indicates O2 ingress breaking down the ferrous metals. That can happen regardless of the fluid or blend. Glycolic does tend to cause more problems than water when it goes bad.

Any pH less than 7 is acidic, and will degrade system components. I run into quite a few untreated water systems with a pH under 5. Again, it rolls back to maintenance in most cases.

kcopp

Yes there are situations where it is prudent to use glycol in systems. When you do so I certainly agree that the system MUST be clean.
However more often than not it is injected into systems as a maker of course. Just saying in probably most cases it just is not needed.
As to the maintenance of the system.... we need to do a much better job of educating our customers of that. 99% of the public has not a clue about that at all.
Still don't like the stuff...

hot_rod

GroundUp said:

hot_rod said:

GroundUp said:

Yeah, that was a maintenance problem not a glycol problem. Obviously it hadn't been looked after and turned acidic (which can happen with straight water also) but judging by the mud inside the valve, it was filthy too. Certainly not a fault of the glycol itself, just a lack of care.

I'm not sure water in hydronics can go bad or turn acidic?

When you see sludge and lots of corrosion it indicates O2 ingress breaking down the ferrous metals. That can happen regardless of the fluid or blend. Glycolic does tend to cause more problems than water when it goes bad.

Any pH less than 7 is acidic, and will degrade system components. I run into quite a few untreated water systems with a pH under 5. Again, it rolls back to maintenance in most cases.

Ph below 5 in copper tube? Seems like that would pinhole ida a very short time? Is the potable water below 5 also?

GroundUp

Ph below 5 in copper tube? Seems like that would pinhole ida a very short time? Is the potable water below 5 also?



Potable is typically around 7 here, some slightly less and some slightly more. Seems a certain area in particular is most prudent to the lower pH, and yes I run across probably 4 or 5 systems a year on straight water with a pH under 5. Some copper, some pex, some PB, some black, some galv, and surprisingly little pinholing aside from the galv sections. Have definitely cut out some type M that was paper thin and VERY close to pinholing, but have yet to actually see a pinhole on site. I will say that 3 of those 4-5 a year are atmospheric OWB systems and not pressurized indoor systems, so that surely plays a role, but not saying it doesn't happen to pressurized systems also.

Come to think of it, I bought a rental home in July of '18 that had the original Sears boiler in it from 1966 when the house was built and a single series loop of steel pipe & fin baseboard through the house aside from one copper section in the bathroom (added later maybe?) and I'm guessing the original B&G 100 series circ. I was going to convert it to underfloor radiant with a mod/con anyway, but did some testing before I started cutting and the water smelled like pure battery acid so I tested it and pH was at 3.8 at the boiler drain. It wasn't circulating so I don't know if that was just localized or not, but it was a real mess inside the system once demo started with all the magnetite and whatnot but I didn't see a single repair in any of the piping, unless possibly the bathroom was a repair but I find that unlikely due to the age of the copper in there.