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How To Winterize A Pool Heater

heater gas valve If you want to learn how to winterize a swimming pool heater you need to accept that if you make a mistake with this process you are likely going to have a broken heater come spring time. While it is not especially hard to winterize a pool heater, there are a number of steps to the process and missing any one will likely be a problem. If you are interested in learning how to properly close your heater for the winter season then the information on this page will help you accomplish this.

Above all else, if you forget to do everything else listed on this page, just be sure to close the gas valve going to the heater. Your heater actually has two gas valves - one inside the heater that will have "on", "off" and "pilot" designations usually. You will also have a second valve, usually a brass ball valve, somewhere on the gas line that feeds to the heater. Most commonly this should be directly beside the heater itself, however it is sometimes located directly after the gas meter on the line feeding your heater. Either way there is a gas valve somewhere and you need to find it and make absolutely sure that it is closed once you shut down your heater for the winter. Why do you need to close both gas valves for your heater? If one of them fails, or has a slow leak, this could result in enough gas building up in the heater that a spark could ignite an explosion.

pool heater gas valve

While most internal gas valves in pool heaters are very easy to read in terms of on and off, the style of gas valve shown here from a Hayward ED2 (a popular Canadian model, uncommon in the USA) is a little ambiguous as to which direction is "off". The valve as pictured here is currently in the "on position" for reference. As gas valves can fail as they age always be sure to close the primary valve on the gas line in addition to this internal valve.

gas heater valve

This picture shows the main gas line valve that is installed on the feed line just adjacent to the heater. Most commonly this will be a brass ball valve with a handle. When the handle is parallel (in line) with the pipe this indicates the valve is open. When the handle is perpendicular ("T") to the pipe this indicates a closed position. There are also gas valves without a handle that require a large wrench in order to close. As with ball valves, the orientation of the lines on these types of gas valves will indicate closed when the lines are perpendicular to the gas line, and open when the lines are parallel to the gas line.

Steps Involved With Winterizing A Pool Heater

There are many different brands, makes and models of pool heater on the market: Raypak, Rheem, Jandy, Hayward and Pentair just to name a few of the most popular brands. Each of these brands has multiple heater style models, as well as multiple sizes of each model. In total there are simply too many to have one definitive guide. Instead of a definitive guide simply follow these steps that apply to all pool heaters - the actual location of each of these items will be different depending on which heater you have.

Turn the gas valves off - I know we already discussed this, but it warrants mentioning again. Triple check the gas valves are all closed.

Turn the power off to the heater - Not every heater requires power but if yours does be sure to turn off the electrical breaker before you start to winterize your heater.

gas heater pressure switch gas heater pressure switch Open the pressure switch - Not every pool heater has a pressure switch but some do. If your pool has one then you need to open the connection to the pressure switch to prevent this sensitive (and expensive) piece of equipment from breaking when the water trapped inside it freezes. The pressure switch is normally located inside the heater and is connected with a 1/4" copper tubing.

There will be two nuts that connect to the top of the pressure switch and this is where you need to open it. The two styles that exist are either 7/16" or 1/2" in size. Use wrenches to open these carefully to avoid damaging the nuts or the pressure switch itself. You do not need to remove the switch completely. Opening the copper tube connection and letting the pressure switch hang from the wires is standard in the pool industry. The copper line will drain water when you open the connection port.

The remainder of the water will be pushed from the tube when you blow through the heater so no further interaction is needed with the pressure switch. Just open it and leave it - but be sure to reconnect it in the spring!

gas heater winterizing port Open the winterization ports (drain cocks) - Every pool heater has winterizing ports, or drain cocks, in multiple locations on the heater. The number of ports that you have will depend on which heater you have but you will be looking for between 2 to 4 ports in total. The first place to look, as pictured here, is under the header of the heater where the pipes connect to it. Most commonly you will find one, or two, drain cocks in this location. In addition to the ones on the header there is usually a drain cock or two on the opposite side of the heater. The drain cocks will either be a standard thread plastic plug or a brass bolt style. For the purposes of winterizing the heater you want to remove every drain plug that you can find. To avoid losing these very important plugs you can store them in the pump strainer basket while you are winterizing the heater.

The plastic plug heaters like with Pentair or Hayward are easier to winterize than Jandy heaters which use brass drain cocks. The problem with the brass ones is that the heater case and the plug are made from different metals. This can encourage corrosion in this location. Since the threads on the drain cock are so fine this can sometimes cause difficulty removing the plug. Brass will strip easily so be sure to use a 9/16" wrench, not an adjustable wrench, pliers, pipe wrench or channel locks as these will all damage the brass. Additionally these brass drain cocks are usually seized in place and require a fair amount of force to remove. It is also fairly common for these to break when you try to remove them. If this happens to you then you will need to tap and thread chase this location which requires drilling and a tap set. Plastic drain plugs from heaters can be left out for the winter similar to all other winterizing plugs on your equipment. Brass drain cocks should be reinstalled after winterizing the heater. If you leave the brass drain cocks out over the winter then rust will form on the exposed threads of the heater making a water tight seal much more difficult in the spring.

Blow through the heater - Pool companies use specialty tools to blow the water out of the lines in your pool such as the Cyclone Blower. These provide much more air flow than a shop vac for example. You can also use a leaf blower if you have one though this would involve some custom modification to make a hose attachment on the end of the blower. If you are a pool owner and you want to close your pool every year then you might want to use the Cyclone blower but if all you have access to is a standard shop vac this can work also so long as it is at least 5 horsepower in size.

If you have unions on the inlet and outlet ports of the heater this is ideal for opening the system and isolating the heater as you blow through it. Not every pool heater will give you this option however. If you do not have union ports on your heater then you will need to open the system in the closest place to the heater in order to blow through the lines. It is not ideal to blow through a filter to get to the heater so consider adding some winterization unions into your system by your heater if you don't have any. Almost all of the water will blow out of the heater in the first few seconds once you turn the blower on. Despite looking empty continue to let the blower run through the heater for a minimum of 5 minutes. After 5 minutes blow through the heater in the opposite direction for another 5 minutes just to be absolutely sure you have all of the water out of the system. Be sure to reconnect the unions after you are finished to prevent an access point for rodents to get into your heater or plumbing lines in the off season.

Tips For Winterizing Pool Heaters

This video talks about how to properly winterize a swimming pool heater. This is video 7 in my series on swimming pool winterization. If you would like to see the other videos that discuss how to winterize each component of your pool - pump, filter, heater, skimmer, returns and pipes - you can find this here: Pool Winterization Vlog.

While you can winterize your pool with mostly items you have around your home already there is one pro tool that you should consider getting and that is this cone adapter. Traditionally used for connecting pool vacuums to the skimmer port of pools, this cone adapter is perfect for blowing out pool pipes and ports of all different sizes. Getting a good seal on the pipe with your blower is key to having enough power to evacuate all of the water from the system. This small adapter will help greatly with this process. If you have a pool vacuum hose you can use one length of the pool vacuum hose to perfectly connect into this adapter. You would then use duct tape to connect the vacuum hose to your blower - Cyclone, shop vac or leaf blower.

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