Underground lawn irrigation system Winterization and frost protection
Table of Content
I had really done something good for my lawn this summer with the installation of my Hunter automatic and retractable lawn watering system. According to the weather, my lawn could and can be watered and I have no problems with bare or burnt spots in the lawn even during longer periods of drought.
Nevertheless, every gardening season ends at the latest at the end of autumn when winter is approaching. And with lows in my region ranging from just below zero to -25 C° in recent years, the irrigation system must be prepared accordingly for the cold season.
That means – water out!
Why drain the lawn irrigation before the frost?
Freezing and re-thawing water poses the greatest risk to water pipes and water sprinklers. The ice crushes the ABS plastic or the PE it bursts.
If the system is then put back into operation in the spring, the long search for the broken parts as well as the costs for the repair remain in the room.
To prevent this, it is important to completely empty the irrigation system before winter.
Is a drain valve sufficient for frost protection?
This is possible, for example, by installing drain valves. These valves allow the water to drain from the sprinklers and pipes as soon as the pressure drops below a predetermined level.
- Verhindert Frostschäden: Durch automatische Entwässerung bei Außerbetriebnahme des Sprinklersystems, Ventil öffnet bei einem Wasserdruck von unter ca. 0.2 bar im System
- Einfache Montage: An das separat erhältliche T-Stück 25 mm x 34 Zoll Innengewinde (Art.-Nr. 2790)
- Ideale Installation: Entwässerungsventile werden idealerweise an der tiefsten Stelle der Bewässerungsanlage montiert
- Drainage: Zur sicheren Drainage in eine Packung aus gewaschenem Grobkies einbauen
- Lieferumfang beinhaltet: 1x Gardena Entwässerungsventil
The advantage is virtually automation. The system is in fact permanently draining itself and does not provide any attack points for frost. A small disadvantage, however, is a certain waste of water since the water from the pipes gradually seeps into the subsoil after each sprinkling.
However, in my opinion, it is much more serious that an accurately planned and even better executed installation of the entire irrigation system must take place, since all pipes and sprinklers require a slope to the valve.
This would have been possible in my garden only at insanely high cost.
In the end, however, I also decided against installing drain valves because these valves can quickly get dirty and jammed and this therefore brings more trouble than benefit.
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Blow out lawn irrigation with compressed air
I decided to blow out the irrigation system with compressed air. In my view, this method is simple, efficient, not very time-consuming and, above all, safe!
In order to blow out my irrigation system with just under 75 meters of pipe and 12 sprinklers at the time (currently it is over 100 meters with 18 sprinklers), I had to install a compressed air adapter in a suitable location.
And although my Hunter valve box as well as my Rainbird valve box provide for a connection point, I decided to install the transition right after the water meter on the house wall. I would also be able to drive there later with my compressor without any problems in order to connect it to the system.
I screwed the adapter to the ¾ female thread of a Gardena 25 T-connector via a reducer. This part of the line is shut off via a tap placed in between.
Please note that some compressors run oil-lubricated and the compressed air is therefore oily. In this case, either use an oil separator or a compressor without oil.
- Druckluft Kupplungsstecker mit Außengewinde - NW 7,2 - inkl. Dichtungsring
- Gewinde außen: 1/2"
- Werkstoff: Messing
- Max. Betriebsdruck: 0 - 35 bar sowie Grobvakuum
- Temperaturbereich [°C]: -20 bis +100
Video tutorial on how to blow out the irrigation system
In the following video I show you how I blow out my lawn irrigation system with compressed air. Another video, on the construction of the compressed air connection, can be found further down in this entry.
I have posted a variety of other videos on my automatic garden watering playlist.
I captured the modifications for the compressed air connection to the lawn irrigation system in the following video.
- Einsatzbereich: Mit seinem 50 Liter Kessel und seinen 412 L/min Ansaugleistung verfügt der Kompressor stehts über genügend Reserven für Anwendungen in Haus und Garage. Durch die Schnellanschlusskupplungen kann der Kompressor je nach Bedarf einfach umgerüstet werden
- Kraftvoll: mit einer Leistung von 2200 Watt kann man den Kompressor hervorragend für verschiedene Zwecke einsetzen. Des weiteren ist ein Druckminderer für optionale Regulierung des Arbeitsdrucks vorhanden
- Variabel und langlebig: der Kompressor ist geeignet für Arbeiten wie zum Beispiel: Reifen befüllen, das Arbeiten mit Nagelpistolen oder auch für Lackierarbeiten
- Lieferumfang: 1 x scheppach Kompressor HC53DC, Gewicht: 42,6 kg
How do I blow the water out of the water pipes?
At the end of autumn, the water pipe from the house exterior connection is shut off, vented and drained.
I then connect my compressor to the piping system of my lawn irrigation system and open the individual valves by hand.
The compressor provides enough air at a pressure of 5 bar to blow the water through the individual circuits until it reaches the Hunter I20 lawn sprinklers. Hunter MP rotators are also easily blown free and drained.
I go about emptying each circuit one at a time and wait until there is no more water or spray coming out of the sprinklers.
The whole process takes me a good two hours – once a year.
What is the system separator all about?
When operating a lawn irrigation system, and ultimately when operating any water lines outside the building, you must ensure that no water can flow back into the building’s mains.
This could carry bacteria, germs, and other contaminants from outdoor service water into the drinking water system.
Make sure that the air does not press the water back into the house network!
The water pipe should have a system separator. All shut-off cocks to the house mains must be closed.
Shut-off valves or a downward slope are NOT sufficient because (theoretically) certain factors could cause negative pressure in the house network. Then there would be the (theoretical) possibility that the water from the irrigation system would be sucked back into the house network.
The water in the outside pipes is “basically” considered contaminated and must not be allowed to come into contact with your home’s drinking water system – and consequently the next largest water supply pipe. come. By the way, the same applies to the water in the outdoor faucet or the garden hose that supplies the pool.
All these water-bearing pipelines must be technically separated from the house network. Special system separators are available for this purpose. Before installation, however, find out what requirements your water supplier has!
- Systemtrenner Typ BA mit Monoblockkartusche zur Normgerechten Befüllung von Heizungsanlagen
- Entzinkungsfreies Messing-Gehäuse. 3/4“ ÜW für den Anschluss an ein vorhandenes Zapfventil
- Mit Schlauchanschluss und eingangsseitigem Schmutzsieb
- Zertifiziert nach EN 12729 und Beschluss 4/2007
- Max. Betriebsdruck: 10 bar. Max. Betriebstemperatur: 65°C
By the way: In my playlist on the topic of automatic garden watering, I have already posted a variety of videos on my garden watering. You can find more projects in my Youtube channel.
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