Freezing Irrigation Protection
Protect Your Irrigation System From Freezing Conditions.
Frost damage to irrigation systems is something that we witness on several occasions each year. The unwanted repairs can prove costly and difficult to manage (along with unseen damage that can add to further problems during the season).
Here we have some information and advice on how you can protect your irrigation system against sub-zero temperatures, along with tips that can prevent damage and reduce the winterization Process.
Over the next couple of weeks and months we are expecting long periods of sub-zero temperatures.
In areas where these freezing temperatures can access e.g. pump houses, exposed pipework, valves or irrigation equipment (and/or below ground installed pipes), you must consider the need to drain the irrigation system to prevent freeze damage.
Drip irrigation and sprinkler systems all use valves, filters, plastic fittings, PVC pipe or PE pipe, that can easily burst, break and split if water freezes inside any of these components.
Draining down a drip or sprinkler irrigation system will take around 1 hour. In extremely cold winters, freezing temperatures can severely damage your irrigation lines, components, pipelines and even pumps and filtration systems. Spending a short time carrying out these tasks can save you a lot of time, money, and stress in the busy spring time.
In draining your irrigation system, you are aiming to drain most of the water out of all of the system, components, and pipes. On some occasions it is a good idea to blow air through the system using a compressor. This will blow out most of the water and allow air pockets to build up in smaller nozzles that will allow for the frost to expand (reducing the impact of damage).
- Automatic Drain Valves can be a quick and easy way to drain your system (although make sure Air valves are installed across your system to allow air into the system and preventing pipes collapsing under suction).
- For design tips and advice
There is some controversy as to whether this is necessary in systems consisting of polyethylene pipe: some feel polyethylene systems will survive the expansion of water during a freeze. The manufacturers of polyethylene pipe agree it is not necessary to evacuate the water, but they do caution that the pipe must be buried, otherwise, the pipe can be broken if struck or flexed while full of frozen water.
Even so, enduring the stress of repeated water expansion over several years weakens the pipe and can lead to fractures. There is also a question of stress if the fittings and pipe do not expand and contract at the same rate during temperature changes.
More Information on Pipe Specifications
With PVC pipe, there is no question PVC @ -5°C behaves more like brittle glass. If PVC pipe more than half full of water is frozen, it will crack, and cracks caused by freezing are most often from fitting to fitting; that is, along the length of the pipe. In addition, closed-case heads installed above ground must be drained, regardless of their composition.
Find out more about PVC pipe and where it should be used.
Pumps should be turned off (by the controller) before you start draining down any system, however, they should be a part of the system that is drained down too. As they are one of the more expensive components on an irrigation system, special attention should be taken in making sure all of the water is drained from the pumps.
- Do Not switch off from the isolation switch. Leave the controllers switched on to prevent humidity building within the controller and electrical boards.
Valves and Valve Assemblies
All valves, by the nature of their design, when closed hold water. This makes them susceptible to damage when left closed during a frost. All manual valves should be left open (or at least ¾ open).
- If you have any Non-Return or Check Valves anywhere in your system, they should also be removed.
Solenoid valves are best winterized by leaving them open for the winter. You should also open and close them several times to release any trapped water in the chambers. Most valves now come with drain valves. These can be opened and left to drain.
- If your solenoid valve does not have a drain valve you can loosen the bonnet (top of the valve) and allow space for the water to expand.
Automatic Solenoid/Control valves (pressure reducing, pressure relief) usually come with PE external control tubing, pilots, and other parts.
- If the complete valve can be easily removed this is recommended.
- If not, all tubing should be removed (ensure you know the pipe connections for reconnecting). Remove any external parts (pilots, manual Valves, or battery controllers).
Carry out the same procedure as the solenoid valves.
Remove Drip line connections.
- Remove drip line end caps to allow water to be drained to the lowest part of the system.
If the lowest part is in the middle of a run, you should install a quick release connection that can be removed and used as the drain point.
Remove all anti drain valves or/and open any online valves to ensure all water is released from the dripper lines.
In some cases of long period of Sub-Zero conditions, it is good practice to used compressed air to blow out the system. This will not only blow out any parts of the dripline that have not properly drained, it will also allow small air pockets to accumulate in your nozzles that will allow for any frost to expand into, preventing breaking nozzles.
- Along with preventing frost damage, blowing out the dripper/sprinkler lines, will also flush out any debris within the lines, preventing blockages and extending the life of your dripper or sprinkler nozzles.
Even though your main filtration may be made of Steal, they can also be prone to frost damage.
Most filtration systems are manufactured with a drain point.
If this not the case, removing the locking nut or loosening the bolts will allow the filter to drain.
If the filter has an automatic flushing system, these usually come with external piping and hydraulic components. If the filter is easily removed it is a good idea to move into warm conditions.
- If not – As we do with the control valves, remove all piping and components (ensuring you remember how it is reconnected), and valves or connections should be drained and/or loosened.
Most systems are manufactured with drain points. If not, loosen all connections and allow for this system to be drained.
- Feeding systems are usually an expensive part of the irrigation system and are mostly bespoke built. This can result in replacement parts not being available, difficult to install, or in some cases, require a rebuild or retro fit which can prove expensive.
- Pay special attention when draining expensive feeding systems.
Control systems should be de-programmed and left switched on. This will keep the controller warm and stop moisture and/or humidity building inside the controller.
- Although your controller may be waterproof and rated, this does not mean moisture and humidity cannot affect the internal components of a control system.
- Moisture or humidity damage may result in the controller no longer working.
In pumphouses that have an electricity supply it is advised to install a thermostat controlled heater or radiator to keep the frost to a minimum.
(Alternatively, a small wood burner could be placed in or near the pumphouse when sub-zero temperatures are expected).
- Remember that the gluing of PVC pipes and fittings in sub-zero conditions is not recommended. Most glue manufacturers recommend that the gluing of PVC pipes and fittings should only take place in temperatures above 5°C.
- PVC pipe should not be moved or transported in temperatures less than -5°C
- All the information and advice above is from personal experience and the solutions recommended are those that have proved most successful for myself, based on a range of trials and manufacturers data. Some products and manufacturers may advise other of different practices.
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