Affect of Glycol

[Jackfre]

This seems to come up a lot and I just found the formula for BTU/HR with a glycol base.

BTU/hr(water@68*)=GPMx500xDelta T
30% E Glycol=GPMX445XDelta T (Ethylene Glycol)
50% E Glycol=GPMX395XDelta T "

30% P Glycol=GPMX465XDelta T (Propylene Glycol)
50% P Glycol=GPMX420XDelta T "

FREEZING POINT ETHYLENE PROPYLENE
55% -50f -40f
50% -37f -28f
40% -14f -13f
30% +2f +4f
20% +15f +17f

 

[Rookie2]

Please be aware that Ethylene glycol is not for boilers !

 

[sixty4]

Try removing an old ****** or pipe with a system that has it in there. It will crumble like a month old cookie. Plus no one ever or rarely checks once a system is filled with the stuff. With that being said I don't know another way around it for driveway radiant heat, other than that keep it.

 

[BadgerBoilerMN]

Ethylene may be used for boilers, chillers, and is in the majority of "commercial" applications. It should never be use for residential applications however, as it is moderately toxic and used to taste sweet before bitter additives were introduced to discourage domestic animals and kids.

Ethylene glycol has half the heat capacity of water so a 50% mix gives you about 75% of the heat transfer of plain water. That means 25% more pumping. It also discounts the heat transfer efficiency of your heat source.

All of this is basically true of propylene glycol except PG is not toxic.

Naturally you have to get an MSDS from each manufacturer for each product to assess the compatibility of any product for your application.

In any case automotive anti-freeze should not be used in any heat transfer application be it heating, cooling or heat pump applications since it is specific to engine cooling and contains additives incompatible with boilers such as silicas that will tend to foul up hydronic systems in a hurry.

Inhibitors are added to control pH and system component corrosion. All hydronic system anti-freeze must be maintained thus testing pH, tends to go acidic, and the inhibitor concentration is essential to assure freeze protection and general heat transfer efficiency.

Finally, freeze and burst are not the same thing.
In our heated driveways here in Minneapolis we size for operation during design conditions. Here we limit it to zero Fahrenheit. This means that we size the pump to the added load of all the components including a certain mix of PG. We must also specify the PG concentration to protect the exposed system components from the outdoor design temperature, more specifically to the extreme mean. For this we use the "burst" rating for the anti-freeze we choose.

With PG the "burst" is often a negative 30-40°F below the "freeze". For systems that are not called on to operate from a dead freeze start, e.g. snow melting we use burst to protect without having to use high concentrations that cost more to install, maintain and operate. See Rookie's Camco chart...

 

[Bondo]

Ayuh,.... I put in-floor in my rental unit, 'n used antifreeze, just because if a tenant took off, the system wouldn't be turned to junk, from freezin' solid,...

I'm now expandin' the system to another floor, 'n will continue to use antifreeze,...

The slight loss in heat transfer is a small price to pay, to preserve the entire system,...

I went through the same sorta thing years ago, when a tenant thought she'd help me out, 'n shut the heat off in 1/2 of the house,...
Luckily, it was baseboard radiation, so it was "Fixable",....

With in-floor, to much of it is "Untouchable", to fix it,....

 

[BadgerBoilerMN]

If "slight" is 10% in fuel and another 10 in electrical load, I'm with you. Still the poison is in the dose. So a burst solution is my SOP for residential systems that must have freeze protection.

I personally use WiFi thermostats where power is reliable.

 

[pacemade]

Ethylene is an alcohol base and Propylene is a gelatin base. Propylene was created because kids and pets would get into the coolant.
In the automotive application coolant should be replaced every 3 years or 30,000 miles. Correct PH prevents most oxidizing but your detergence and other protective chemicals will break down too.
Coolant has many jobs it doesn't just keep the engine cool, it regulates the heat.
If your oil is sludgy you may need a coolant change because the chemicals have broken down and are not dissipating the heat correctly.
for example;
You know when water drops onto a hot service it beads up and rolls around until it evaporates. Coolant is designed not to do that, because it will create hot spots inside of you engine.