Swimming Pool Blog

Your Pool, the Cold, and How to Protect it

by Myles McMorrow, November 10, 2009

Pools are great during the hot summer months, but what about the cold months?
Swimming pools do not like the extreme cold. There are so many things that the cold can do to damage you pool and equipment. That is why most of the USA and all of Canada close their pools during the winter months. Let’s face it, you cannot count on the weather man ( or woman) to be accurate on predicting the weather or when a freeze might hit. So let's talk about what a freeze can do to your pool and what you can do to protect it.
The system and plumbing:
      Ice and plumbing don’t mix. Most plumbing on pools now a days is made of PVC plastic and is subject to cracking as the water expands as it turns to ice. This can cause major damage in the lines for the returns and suction side of your system. Most inground pool plumbing is under ground and the depth it is buried depends on the frost line in your area (see chart below). Here in the Washington DC area most builders go about 3 feet, but when I worked in Santa Cruz, California they were about 4 inches to a foot.
underground pool plumbingunderground pool plumbing
Plumbing depth differs due to frost lines in your area
      The last thing you want is to have a freeze break in the plumbing under the nice concrete deck around your pool. This will cost a lot of money to replace and matching an old deck with a patch is hard to do. It can also be difficult to locate the exact point to start digging. And tunneling under the deck? Ugh - been there, done that!
pool plumbing freeze damage #1pool plumbing freeze damage #2pool plumbing freeze damage #3pool plumbing freeze damage #4
      What’s worse than that is an inground plastic skimmer that is sunk in concrete and rebar on all sides. The only way to fix them is to jack hammer it out and that takes about a day because the concrete is about a foot thick on all sides and you have to cut through rebar. Normal cost to replace a skimmer is about $1200 to $1700, so it is not something you want to have happen.
      Your pool equipment is the “heart of you pool” as I call it, and it can become damaged too. I have seen pumps and filters freeze and split in half. When this happens you are better off buying a whole new filter. This is because most manufactures charge just as much for a filter tank as a whole new filter. They make the tanks in limited production runs and will take apart a whole filter to sell you just the tank.
      I have seen a pump freeze and break the impeller inside but the unit looks fine on the outside. This was after I replumbed the whole system due to cracked plumbing from an early freeze. I was so happy to be done with the job, until I turned on the pump and the shell of the housing cracked from the broken impeller being wedged on the inside of the pump housing. Not a fun thing to find out after doing all that work.
Pool heaters are a whole different game. They have 3 things that can be damaged from ice:
1. The exchanger, this is the most expensive part in the heater and can run as much as $1400 to replace. This is the copper tubing that is use to transfer heat from the flame to the pool water.
2. The headers, these are cast iron or high tempeture composite material at the ends of the exchanger that redirect the water flow to the pool and back to the exchanger. A low spot in the heater, the headers will freeze before anything else usually.
3. The pressure switch tube. This is a tube that water gets pushed through and operates a switch that tells the heater that there is enough water flow to operate the heater. It is only a 3/8th inch copper tube that is very prone to freezing.
The pool shell:
        Pools come in all types of materials from Fiberglass, concrete, to metal or composite liners pools. All pools are made for all climates when it comes to the structure to a point. If the weather gets to freezing they must have the water lowered. The reason for that is the ice expands and if it start to push on the side at the top that can cause damage from popping off tiles and cracking the bond beam behind them to breaking the top rail supports on an above ground pool. It is best to plan ahead to  winterize  your pool before this happens.
freeze damage aboveground poofreeze damage inground pool
         Above ground pool freeze damage               Inground pool tile and bond beam damage
So what can I do to prevent this?
The best thing to do is to winterize your pool before you get a freeze but when a freeze will hit is up to Mother Nature and you may not have time to do so.
What do you do if you know it is going to freeze? It is a fact that moving water has less of a chance to freeze. Take off your timer trippers if you have a timer or turn on your switch to set the pool to run 24 hours a day. The water flowing through your pipes will help protect your plumbing and system. If you have a heater, set it to the lowest setting to heat your pool. This will stop the surface of the water from freezing against your pool shell or tiles.
The good news is that they have what they call freeze protectors for your pool (if you have a computer controller you might have one already, just make sure it is on and set). These systems are not a lot of money and can save you hundreds of dollars in repairs. They will turn on your pool equipment when you are a few degrees above freezing to protect you plumbing and system. You can even get one with built in timers to run your pool too. These are must if you live up north or in an area that is prone to freezing, and you tend to keep your pool open later in the fall.
For a list of pool freeze protection products click here
dual clock freeze protectorfreeze protection devicesfreeze sensor for pooljandy aqualink controller includes freeze protection
Dual timer with freeze protect         Single timer/ freeze sensor        Stand alone freeze sensor    Controllers have Sensors
This is a Frost line map that shows the depth the ground can freeze to, much has to do with moisture levels in the soil, soil type and weather patterns. This chart is the maximum found depth averaged over the years.
freeze map

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