Should cold water pipes against an outside wall in the basement be covered in insulation sleeves or just the hot water pipes? My husband said the insulation will only keep them colder. It is to be subzero tonight with wind chills to -35 tomorrow. I think the insulation would keep them from getting colder so which is the best solution?

Hi splummer and welcome, Insulate both pipes. Good luck

Well you are both right and you are both wrong. You need to realize that insulation does not make things hot or cold. Insulation only slows down the transfer of heat. Insulation without a source of heat is useless. You are correct that if the pipes are insulated it will take longer for them to reach the point of freezing. It will not keep them from getting cold or freezing, only take longer. Hubby is correct that they will stay cold longer.

The real question you should be asking yourself is, will the basement temperature drop below freezing if the overnight temperature is 0 degrees. The wind chill is only a factor in that the high winds will take heat away from the house faster.
Most basements do not reach freezing when the upper floors are at normal living temperatures. Of course, that all depends on how tight the basement is sealed and whether there is insulation and how much, between the basement and the upper floors.

You should also know that hot water pipes freeze quicker than cold water pipes.

The fact that the pipes are along an exterior wall is not of great significance as long as the pipes are exposed to the basement air temperature.

If you are worried about freezing, open a faucet, hot and cold, and let the water trickle. That way the water in the pipes is constantly being replaced with warmer water.

I drained mine! It's worth the grief.

Unless this is a normal occurrence (sub-zero temps) that your pipes have survived before, you should consider letting water run. Both hot and cold water lines. The cost of the water including fuel for water heater will be miniscule in comparison to having busted pipes repaired, damage from water leaking, and the disruption of you losing your water suplly in these extreme weaher conditions. My region is forecast for record breaking cold tomorrow night (Monday night), and it is warming up to +35 tonight. Go figger.

Good luck. PS Disconnect hoses from outside faucets also, if they are still screwed on. I paid thru the nose for that idiotic mistake 2 years ago.

Yup! I am in 100% agreement with NOT insulating the pipes. Insulate the space between the outside wall and the pipes, but leave the pipes so they are getting the warm air from the basement (as I think Hkstroud suggested).

Leaving the water trickling, as has also been mentioned here, is cheap insurance, for sure!!

Mark

Hot freezing faster than cold never made sense to me but it can happen, its called the Mpemba Effect. Pipes do not feel chill factor so don't worry about that part. If your pipes have frozen in the past a cheap way to prevent it from happening tonight is to slightly open your tap for both hot and cold at the end of this pipes run. It is wasting water but water is cheap compared to replacing a broken pipe. Just a trickle will take care of the freezing, moving water will not freeze as fast as water standing in a pipe.

ballenger,

"Hot freezing faster than cold never made sense to me but it can happen, its called the Mpemba Effect."
This "below" is the explanation I have heard for many years, and that is- distance between molecules.
I did an experiment once a long time ago with hot and cold water just in ice cube trays and the hot did start to solidify slightly ahead of the cold.
Mpemba noticed the effect when he made ice cream. Seems simple to prove, but hard to explain. The guy in this video does a pretty good job.

Why does hot water freeze faster than cold water? - YouTube

The reason it doesn't make sense to me is when you start with hot water, lets say 120degrees, and you put it in the freezer the water temp drops as expected. Once it drops to room temp then the other container of water should act just like to once hot water. At some point they are both room temp.