Anti-freeze or no

Wayco Wayne

I am currently installing a system in an old house in D.C. The boiler is a munchkin. I have a primary /secondary loop feeding an indirect, a pre-existing radiator loop, and a radiant floor loop. The radiant floor loop heats the kitchen, the master bath and a powder room. The powder room is where the question comes in. It is located on a porch and has wide open spaces beneath it. It will be insulated of course but is relatively exposed. Under normal operating conditions the loop will never freeze. The Tek mar controller will begin circulating at 60 F and below. I am worried in the event of an extended power outage such as we had 4 years ago during an ice storm that knocked power out for 3 days. The Powder room is only 6 x 10 and I would feel foolish installing a flat plate and circ for such a small space. I am considering putting boiler antifreeze in the entire system. The radiator loop is the most significant volume and is from a pre existing gravity system with large stately column radiators. Of course the Munhkin holds hardly any volume at all. What are the pros and cons to the anti freeze solution. (no pun intended). Thanks in advance.

Bob Bona_4

In a perfect world

antifreeze is installed in precise proportions, with proper inhibitor balances. All piping is tight and no joint ever leaks. The system will never need service or purging. The Ph of the boiler water is spot on. The home is visited at least once a year by a tech fluent in antifreeeze maintenence, and thouroughly checks and adjusts the fluid content.

*POOF!* In reality, I have seen far too many hydronic systems dying a slow and horrible death due to antifreeze corrosion from lack of maintenence, over charging, weeping joints. I liken it to a poison. I would say to avoid ruining the rest of the system just for a dinky zone. Can you insulate the heck out of the under-exposed portion? Advise a generator? Last resort of course is to install that plate HX. BTW this is in no way a detriment to your workmanship, it is the aftercare that is unknown?

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Jamie Hall

oh boy

I have to admit I quite agree with Wayco Wayne... in principle, antifreeze is fine, preferably ethylene glycol type with inhibitors. In practice... he's quite right. You do have to maintain the stuff (ever read your car's owner's manual on the subject?) or disasters will occur. A generator or a way to drain easily suggest themselves...

If you are inclined to plow ahead, keep one other thing in mind: antifreeze, of all sorts, is toxic. Very Toxic. Your boiler fill line must either go through an air gap (unrealistic in a pressurized hydronic system) or through what is called a Reduced Pressure Zone backflow preventer (your local plumbing code may be even more restrictive). Don't even think of connecting through a check valve, or even two check valves...

Jamie Hall

oops.

I meant to agree with Bob...

By the way, we do use such systems, now and then (Cape Breton, NS, Canada) but only where they can be maintained.

John@Reliable

Anti-freeze

I would consider adding ball valves and drains just for that part of system,anti-freeze like other posts said is not always maintain

hr

Toxic glycol??

Propylene glycol is actually used in the food industry. It is both a flavor and scent enhancer. Kraft foods in Springfield, Missouri actually uses about 6000 gallons a month in various cheese products. It is also listed a one of the first ingrediants on many baked goods. Check those gooey blueberry muffins at your supermarket some day.

As various inhibitors are added to "food grade" glycol the toxicity does go up a bit. Corrosion inhibitors and O2 scanvenger chemicals are added to hydronic glycols, rasing the toxicity a bit over the food grade base product. But still considered low toxixity by the FDA. RV antifreeze can be used in the domestic water lines and holding tanks without human harm.

Truth be known ethylene glycol actually bio degrades easier than propylene, as it has two carbons compared to propylenes three carbons. EG is what they generally on airplanes in the winter. It drains to bio ponds, is held for a period of time and then discharges into the public sewer system. As glycol breaks down (biodegrades) it consumes lots of O2. This is why is should held in ponds before it is discharged into the streams or aquifers where O2 depletion would compromise the fish or aquatic plants.

EG is a better heat transfer fluid than PG due to lower viscosity.

Ethylene glycol is very sweet. This is what attracts dogs to it. If they consume large quantities it will make them sick or kill them.

Most codes will allow you to use a simple dual backflow preventor for "low toxicity" cross connections. A Watts 9D will meet this requirement, under all the codes I know. A RPZ would add extra protection if this is a concern.


If glycol is overheated (above 250 or so) it can turn into glycolic acid. Much more corrosive than plain water. After it turns I imagine the toxicity may increase. I sure wouldn'd drink that smelly stuff.


hot rod

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Jamie Hall

Propylene glycol, as you say, is non-toxic. Ethylene glycol, unfortunately, causes permanent, irreversible kidney damage. How bad that is depends on how much kidney you have left... but it is a much better heat transfer fluid than propylene, which is why it is used as an antifreeze.