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[Jackman]

 Do you have antifreeze in your boiler water?   If no antifreeze what protects boiler from freeze up during down time?

[Bull]

I don't use antifreeze, I keep the pump running 24/7 and during heating season keep a fire going.

[oldchenowth]

Would antifreeze be better for the pump and metals in the system?  I have thought to replace the water with 50/50 to curb corrosion as I am not as diligent about testing my ph as I should be.

[MattyNH]

Non antifreeze user here...Antifreeze is only use to prevent the pipes from freezing if the fire goes out in the dead of winter with no pump running...Really nothing to do with the pump since its sealed..Antifreeze is very expensive plus is robs heat....If my fire in my owb boiler goes out..The oil boiler in my basement is the back up from pipes freezing as long as the owb pump is still running..Few yrs back major ice storm hit the area of New England  in Dec..Had no power for 32 hrs..Never had a freeze up problem..

[boilerman]

Ditto on what Matty said. Plus a good corrosion inhibitor water treatment is way cheaper than boiler antifreeze. Most companies say you can't use RV or automotive antifreeze, but only boiler rated antifreeze...Can buy it in 55 gallon drums for anywhere from $10.00-$15.00 a gallon. Too expensive for me! Inhibitors that most OWF dealers sell should balance both PH and Nitrite levels protecting your furnace and all inline components.

[Hydronix]

Glycol is more corrosive, much more. It transfers less btu's and requires a larger pump. All negatives, it voids some manufacturers warranties as well. Some people install a small 007 pump to run when the system is down and its below freezing, this is not for long periods of time tho, just temporary safety. If something is freezing then something needs more protection. Stagnate Hot water always freezes faster than cold water.

[martyinmi]

 Stagnate Hot water always freezes faster than cold water.

How and why?? I understand the Mpemba Effect. We played with that theory in high school using dry, sealed vessels(soda bottles) and found that 40* liquid always froze faster than 100* liquid. We did find that if the temperatures were closer(40* vs 50*) that it was harder to determine which vessel solidified first. Experiments have been done for many years showing how warmer water can indeed freeze faster under certain circumstances than cooler when certain controls aren't in place. I've never heard that it's possible for hot boiler water(185*) to freeze faster than cold water(ambient ground temperature).
   We did find that warmer water would freeze faster in an open container....sometimes, but that was attributed to many variables (steam,frost,etc., and the resulting lower volume) associated with it.

[MattyNH]

 Stagnate Hot water always freezes faster than cold water.

How and why?? I understand the Mpemba Effect. We played with that theory in high school using dry, sealed vessels(soda bottles) and found that 40* liquid always froze faster than 100* liquid. We did find that if the temperatures were closer(40* vs 50*) that it was harder to determine which vessel solidified first. Experiments have been done for many years showing how warmer water can indeed freeze faster under certain circumstances than cooler when certain controls aren't in place. I've never heard that it's possible for hot boiler water(185*) to freeze faster than cold water(ambient ground temperature).
   We did find that warmer water would freeze faster in an open container....sometimes, but that was attributed to many variables (steam,frost,etc., and the resulting lower volume) associated with it.

              One thing I do know for a fact is..You take a pan full of hot water and throw it in the air on a sub zero freezing cold day..Instant snow..Ive done it before..Pretty amazing..

[Hydronix]

What the physics exactly are, I couldn't tell you exactly. But after many many repairs of frozen pipes, it is what is always is...... I have had boiler zones freeze while no other pipe near it froze. The last one was an occupied home at 68 degrees, 2nd floor fin tube on the outside wall froze solid, split and made a mess. Within 2 feet were the bathroom pipes just fine running in the same area.   Even when they were insulated, many a dishwasher lines frozen this year, yank off the insul and everything is fine. You only have to have  1 square centimeter of exposed pipe to freeze the whole thing, common find on the 1/2" cap on an air chamber being exposed. Obviously if water is moving its not going to freeze.  Its something to do with phase change and the required energy exchange is less. Just ask any plumber which he repairs most.

[DmdJoe]

Would antifreeze be better for the pump and metals in the system?  I have thought to replace the water with 50/50 to curb corrosion as I am not as diligent about testing my ph as I should be.

pH does not mater if you are using the correct chemical. You need to be worried about passivation, not pH. As long as the pH is above 8 you are fine with passivation. Becareful using RV Antifreeze found in local stores, it claims to protect to -40F. But it does not! Find pure propylene glycol or inhibited propylene glycol and mix it yourself. This way you the exact dilution, not some fake number stamped on an RV bottle....