Serious Question on antifreeze

[webie]

What or why is the reason that you should not use ethylene glycol in your boiler. When I first installed my old steal king boiler nearly 30 years ago My heating guy recommended that I put antifreeze in my system and off we were to buy a 55 gallon drum of Durex auto antifreeze .... My heating guy says that's all they used . Then back in 2001 when I had my Tarm put in The same heating guy says I have to use this High dollar Polyethylene glycol , which looks like the same stuff I put in my camper only about 4 times as much .
What gives ?
Its time for me to change my system out ......... I am thinking about going back to green as its alot more economical .

 

[stee6043]

I've heard it said that the "high dollar" forms of anti-freeze will survive under much higher temps than the standard glycol green stuff. I wonder if there is also a difference in how toxic they are? Perhaps the expensive stuff is more safe for the fish? ha.

 

[PJF1313]

Are you also heating your DHW?
The only reason I ask is in case you have a leak in your HX, you can drink (or so "they"[whom ever they are;-) ]) Poly with no ill effects. I do know the Poly will evaporate quicker than the green stuff in an open air condition. We now use the Poly (blue) stuff to winterize our out buildings at work, but by spring, the traps (in the toilets, urinals, sinks) are bone dry, but the "old" green stuff would still be there, and not cause a spring start-up problem - a few flushes and it'd be gone. The blue stuff leaves a film and has to be scrubbed out.

 

[tom in maine]

Propylene glycol should be used since it is non-toxic. In many states it has to be used by law.
Considering the volume a heating system might hold and the fact that there is always a possibility of direct contact with
potable systems, it makes sense.

Heating glycol is more expensive than RV antifreeze since it is a higher concentration and has corrosion inhibitors as well as the
ability to stand up to high temperatures.

It ain't cheap but it is used for good reasons.

 

[Tarmsolo60]

check your pH, you may be able to add inhibitor to "recharge" corrosion protection.


cut and paste from http://www.raypak.com/afreeze.htm


While high quality glycol solutions may last in excess of 20 years, hard use, improper maintenance or chemical contaminants will significantly shorten fluid life. Fluid pH serves as a good barometer for the condition of the glycol and is best measured with a field pH meter. This method is significantly more accurate than litmus paper tests.

Although glycol fluid pH is primarily a function of the corrosion inhibitor, and therefore, will vary from product to product, a few rules of thumb will be helpful in determining what constitutes proper pH. Most concentrated inhibited glycols have a pH in the 9.0 to 10.5 range. When diluted in a 30% to 50% solution, the pH falls to between 8.3 and 9.0. A pH reading below 8.0 indicates that a significant portion of the inhibitor has been depleted and that more inhibitor needs to be added. When the pH of the mixture falls below 7.0, most manufacturers recommend replacing the fluid. A pH value of less than seven indicates that oxidation of the glycol has occurred. The system should be drained and flushed before severe system damage occurs. For additional product specific information, contact the applicable chemical manufacturer.

 

[Gooserider]

What or why is the reason that you should not use ethylene glycol in your boiler. When I first installed my old steal king boiler nearly 30 years ago My heating guy recommended that I put antifreeze in my system and off we were to buy a 55 gallon drum of Durex auto antifreeze .... My heating guy says that's all they used . Then back in 2001 when I had my Tarm put in The same heating guy says I have to use this High dollar Polyethylene glycol , which looks like the same stuff I put in my camper only about 4 times as much .
What gives ?
Its time for me to change my system out ......... I am thinking about going back to green as its alot more economical .

Automotive antifreeze is SERIOUSLY deadly stuff - if it gets into your potable water (i.e. a leak in your HX) it can easily kill you or make you majorly ill - but it doesn't have a bad taste that would warn you off - some reports say that it tastes sweet... There are also concerns about it's environmental impacts, etc, which is why your gas stations are now required to recycle it as opposed to pouring it down the drain like we used to...

The polyethylene is less toxic as mentioned, with the boiler stuff being more expensive because of the increased strength and additive packages.

If you care about such things, most places it's quite illegal to put automotive glycol in a heating system...

IMHO though, while I think doing some water conditioning is useful (see some of the other threads on this) if you can safely NOT run anti-freeze, I wouldn't... The only real virtue of anti-freeze is that it doesn't freeze, otherwise it does nothing good... It has lower heat capacity than straight water, so you need to move more of it through your system to get the same heat output. (bigger pumps, more electricity) It is harder to pump than water (again more electric) It can break down and become corrosive much more easily than water... And as you noticed it's expensive...

If one can arrange decent freeze protection in some other way, I figure you are better off without it.

Gooserider

 

[webie]

Thanks guys for the responses. I am thinking that my heating guy either by laws or other reasons is required to tell me to use propylene glycol rather than ethylene glycol , plus the fact of good additives for hydro heating systems verses automotive antifreeze . Thanks Tarmsolo for the raypak link that was good reading and information . Gooserider altho it would be nice to try and maybe able to get away with no antifreeze I do remember my heating guy telling me that One call out to thaw and possible fix broken heating pipes will easily pay for the added protection of running antifreeze . I have one area of concern in my system and that is my sun room as during really cold weather or during the week we try to maintain just above freezing temp in the room ( 35 ) . It would make me uncomfortable to run just plain water ( just to big of a chance ) Of course I could raise the room temp but at what point is it safe to say it wont freeze ( don't know ) This is especially true with since when the slab temp is up to say 90 it takes several days for the room to drop too 35 where the wall heaters kick in and the radiant in floor set at 40 start running again . I would be scared on the perimeter runs that they could be frozen . I actually had a chance to try this and the coldest area away from my in floor sensor and my thermostat I placed a coffee can with about a half inch of plain water on the floor between the hot tub and the wall . The radiant in floor had still not run yet as it was at 42 , my wall heaters were running at 35 I had a little bit of ice in the bucket , later it thawed and I never seen it again , Temps were near the zero mark out side.
That same day I had placed outside a 5 gallon bucket with about a 1/2 inch of my boiler water outside on my front porch and after about 12 hours there was no sign of freezing altho it did look about the consistency of a light motor oil .
This all said and done I do believe I should run some antifreeze BUT I think I could easily reduce my concentration to about 20% rather than probably about 40% I am running now . This I think would benefit me several ways I still have a bit of protection yet would be more easily pumped through my system and also still benefit from the additives in the antifreeze .
I have some changes that I am planning this summer and that being said I probably wont add anymore antifreeze in to replace whats loss and I will just let my soft water re-place whats loss and re pressurize the system .
I have had thoughts about changeing my storage and adding a 500 gal pressurized storage along with my 1200 unpressurized storage and doing a completely seperate loop heated through a coil in my unpressurized storage just for heating my sunroom wall heaters , radiant infloor and hottub . And then just use plain water in the rest of the house .
The added cost of controls , pipeing , pumps , tank and insulation , versus actual benefits have me pondering on whether its worth it or not ? Still got to think on this one .
Thanks all
Webie

 

[greg in MN]

It has lower heat capacity than straight water, so you need to move more of it through your system to get the same heat output. (bigger pumps, more electricity) It is harder to pump than water (again more electric) .


Sometimes I am gone for a couple days at a time so I used antifreeze in my system. About 65%, 50% protection is about 5 above. I heat 5100 square feet, main floor of house and basement, with an Econoburn 150 with a grundfos 15-58 set on low speed. Even at 20 below and windy had plenty of heat. Do not know how much more wood it uses as never burned before.

 

[jebatty]

With 1000 gal storage, antifreeze was not even an option. What I have done is plumb in a 12kw instant hot water heater, added bypass ball valves, and then put in a low temp aquastat. The aquastat closes on temperature falling to the setpoint, which energizes a relay to turn on the circulator(s), and energizes a contactor to turn on the instant hot water heater. When the water temp rises above the setpoint, the whole system shuts down. It is only once or twice a winter when I am gone long enough to be concerned about freezing, so electric use is minimal. And I will never have to deal with maintaining or disposing antifreeze.

 

[in hot water]

Actually Ethylene glycols (EG), the hydronic types like DowTherm, are more common in large systems. It is less expensive, and a bit better heat transfer fluid than Propylene glycol. It's common to see EG in large commercial and industrial jobs. But EG does have a higher oral toxicity and double walled heat exchangers are required when used around potable water.

EG actually breaks down quicker in the environment as it has two carbons, PG has three. EG was once used as a de-icer fluid for planes as it would breakdown faster in the bio-pond and could be dumped into the sewer after. Looks like PG is used for de-icing now, I always look when I see the de-icer trucks and tanks.

You never want to use automotive antifreeze in hydronic system, even the PG stuff like Sierra. It has silicate inhibitors that will sludge up your pumps and valves. .

PG can be as pure as a food grade and is used in many food products as a flavor and scent enhancer. That always strikes me as odd because glycol comes from "cracking" down a barrel of crude oil!

As they start to blend chemicals in for hydronic use, technical grade, it gets more and more toxic. Allegedly the real high operating temperature solar fluids really don't meet the "non"- or low oral toxicity standard. Not many AHJs are aware of that, however.

Unless you really, really need freeze protection I would stay away from any glycols. They are expensive, leak prone, need higher head circs to move it, require maintenance, and a poor heat transfer fluid compared to plain water.

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