It is common knowledge that having one of your pipes freeze is NOT A GOOD THING.  A frozen pipe not only stops water from flowing, but in most cases a frozen pipe results in the following:

• Water Damage: Once a pipe thaws, pinhole leaks or even pipe bursts create water damage to the walls, floors, and/or ceiling. *Reminder, if you pipe freezes, shut off the water supply valve to prevent flooding/extreme water damage.
• Costly Pipe Repairs:  Frozen pipes need to be repaired prior to turning the water on and good plumbers will take the time to inspect the entire pipe and pipe fittings prior to thawing and reopening the supply valve.  The plumbers will replace any questionable pipe/fittings which may get expensive.

It seems that common wisdom is that pipes will not freeze if they are insulated.  Unfortunately this is not completely true nor completely false.  This blog post will explain what pipe insulation can and cannot do for eliminating frozen pipe issues.

Pipe Insulation is beneficial in many ways, it helps save energy, maintains pipe temperatures (both cold and hot), prevents condensation, and can slow down the freezing process of a pipe.   On that last item, we should emphasize that pipe insulation can SLOW down the freezing process of a pipe.  Most people assume that pipe insulation PREVENTS a pipe from freezing.  A key fact to remember is that pipe insulation does not add heat to a pipe, it only helps maintain its temperature.  

Pipe Insulation slows down the freezing cycle by extending the timeline for the heat loss of the pipe to reach the ambient air temperature.  What helps pipe insulation do its job is water flushing.  Water flushing is running the pipe so the water in the pipe is replaced occasionally.  The water flush will take the water which was slowly getting closer to freezing temps and replaces it with "warmer" water.  This water flush resets the freezing cycle and the pipe insulation will get to work.

TIME TO FREEZE

TTF or Time To Freeze is the number of hours that standing water in a pipe will reach freezing temperature (32°F) at a given ambient air temp.  The Time to Freeze Calculation is based off the following inputs:

• Water Temperature of fresh water in the pipe.  Most water comes from underground piping and will have a 45°F to 60°F ground temperature. (Many variables to this temperature)
  • The higher the water temperature the longer the TTF
• Ambient Temperature which is the air temperature of the location of the pipe.
  • The lower the ambient temperature the shorter the TTF
• Pipe Size: The size of the water pipe.
  • The larger the pipe the longer the TTF.  The smaller the pipe the shorter the TTF
• Pipe Insulation Thickness:  The wall thickness of the pipe insulation installed on the pipe (if any).
  • The thicker the insulation the longer the TTF
  • *Please contact us to run your TTF calculations for you.

TIME TO FREEZE EXAMPLES:

Example 1:  Ms. Smith is concerned her water supply line in her drafty unheated crawlspace will freeze.  She wants to add enough pipe insulation to keep the pipe from freezing at night before she wakes up and flushes the water line.

Water Temp: 55°F
Ambient Temp: 29°F
Pipe Size: 1" Copper

TTF with 1/2" thick Pipe Insulation:      4.1 hours

TTF with 1" thick Pipe Insulation:         6.1 hours

TTF with 1-1/2" thick Pipe Insulation:   8.3 hours

TTF with 2" thick Pipe Insulation:         9.8 hours

We recommend that Ms. Smith go with 1-1/2" and 2" thick insulation and in her scenario she will be able to flush the water out prior to it reaching freezing temperature.  Also please note that even at the hours listed above, the pipes may not actually freeze at that time, it will take longer to freeze completely however the pipe at this time would be at risk of freezing.  You can also see how each additional 1/2" wall thickness will add about 2 hours in this scenario.

Example 2: Mr. Patel has a small water line running in his unheated attic.  He is concerned that the pipe may freeze and cause water damage.  He wants to add pipe insulation to keep the pipe from freezing on the worst winter nights.

Water Temp: 55°F
Ambient Temp: 15°F
Pipe Size: 1/2" Copper

TTF with 1/2" up to 3" thick Pipe Insulation:  Less than 2 hours!

This example shows the limitations of pipe insulation alone in freeze protection of a pipe.  Because of the extremely low air temperature of the attic, Mr. Patel will have to add a heat source to his pipe prior to installing pipe insulation.  The heat source we recommend is a Pipe Heating Cable.

LEARN MORE ABOUT PIPE HEATING CABLES