During the pool winterizing process it is very typical to use air to blow out the water lines so that it doesn’t freeze in the pipe, expand it, and break it. After blowing out these pipes, winter plugs are used to ensure that no moisture accumulates in the pipe and to protect it during the cold weather months. Plugs are truly the perfect winterizing accessory as they work to protect your costly pool equipment from the harsh winter elements.
Winter plugs are also known as expansion plugs, freeze plugs, hole plugs, pool bugs or rubber plugs. They are basically tapered rubber plugs with two stainless steel washers and a bolt passing through the center, these plugs then expands as you turn the oversized wingnut. The wingnut is easy to grip even in cold water or cold weather helping to get a great fit and a full seal.
These plugs are made from quality rubber, a plastic or stainless-steel wingnut, marine grade stainless steel washers and bolt and will typically last a few winter seasons. Attention should be paid to any deterioration and replace plugs at your discretion.
Winter plugs are conveniently available in very common sizes to fit things such as return lines, skimmers, and cleaner lines as is needed. Rubber expansion plugs are also commonly used but only in the pool itself and not on things like the filtration system. Availability usually starts at ½ in. diameter pipes all of the way up to 2 ½ inches in diameter. The size of the winter plug is discerned by a number. These numbers range from 0 to 12 with specific numbered plugs typically having specific functions. Number 4 and number 5 plugs are compatible with ¾ in. wall returns like those which are typically found in gunite pools. Number 9 and number 10 plugs can be used for 1-1/2-in. threaded return fittings or skimmers.
Some common uses for winter plugs include:
- The 1½ in. threaded skimmer plug can be used in both skimmers and return fittings.
- The No. 4 rubber plug and the No. 5 rubber plug are usually used on gunite pools for ¾” angled wall returns.
- The No. 8 and the No. 9 pool plugs are for 1½ in. pipes that are non-threaded. These can be used on spa jets or in-floor cleaner system pipes. or to plug the main drain pipe, when connected to a skimmer. Where ever you use a regular #8 plug, the extended version is easier to work with and gives a better seal, further into the pipe. Also fits deep into 1.5" wall returns and skimmers.
- The No. 11 and the No. 12 plugs work with 2 in. pipes and fittings.
Winter Pool Plugs with blow-through valves allow you to insert compressed air into pipe lines. These plugs are also non-corrosive and range from ¾ in. all of the way up to a 4 in. fitting or tube. The blow out is very similar to a bike tire valve. These types of plugs work great to air block water lines. In winterizing all of your pool’s water pipes, you should always keep in mind, “wherever there is water, make sure there is air” just like a sprinkler system in your lawn. Getting this process correct will help you stay clear of any costly pipe repairs after the off-season. Keep in mind that the majority of the pipe systems are buried and to dig up and replace would be quite a project. Consult the chart below for sizes.