45° vs. Straight: Where Should the Backflow Ball Valves Sit After Winterizing?

Different companies finish differently. Some leave backflow ball valves at 45°. I exercise them and leave them straight (inline / fully open). Here’s what each position does, why I prefer straight, and why—big picture—this choice matters far less than making sure the backflow is vented and the drain has a path.

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Quick anatomy (30 seconds)

Ball valve: a drilled sphere rotates inside the body. Inline = port aligned (open). Perpendicular = closed. 45° = partially open/closed.
Two isolation ball valves live around your backflow—one upstream, one downstream—plus small test cocks used to vent the shell.
After a blowout, venting and draining the backflow is what protects it; handle position is a finishing preference.

What 45° does (and why some techs use it)

The idea

Leaving the handle mid-travel “signals winter” and, in theory, avoids seating the ball hard against either seal.

My take

At 45°, the port is partially aligned and can hold a cup of water inside the ball cavity. In cold weather that pocket can sit there and, in my experience, distort seals or leave moisture where we don’t need it. I’d rather not create a place for water to linger.

What straight (inline / fully open) does—and why I prefer it

Clear drain path: With the port fully aligned, any residual film drains through if we’ve opened the test cocks and provided a drain path.
No “cupping” in the ball: The cavity isn’t half-blocked, so there’s less chance of a trapped puddle.
Less springtime confusion: Handle position clearly shows open/closed. (Perpendicular = closed; inline = open.)

I still exercise each valve full-open/full-close during winterizing to keep it free, then park it inline.

What actually prevents winter damage (more than handle angle)

Vent the shell

Open both test cocks so the backflow body itself can’t hold water.

Give seepage a way out

Leave the drain plug off or partially threaded for 24–72 hours so if the main shutoff weeps, it drips out instead of refilling the line.

Blow zones to a mist

Use high airflow at modest pressure so heads/valves clear. A clean mist at the end means we moved water out instead of over-pressurizing parts.

Exactly what I do on site

Shut the irrigation supply, connect downstream of the backflow.
Run each zone until it finishes on mist (short, cool passes once mostly air).
Open both test cocks to vent the backflow shell.
Leave the drain plug off/partially threaded 24–72 hours.
Exercise both ball valves (full open, full close), then leave them inline (open).
Leave a paper Winterizing Report + text summary; ask you to peek at the drain in a day or two. Persistent drip = weeping shutoff (plan a replacement).

Is there a “right” answer?

Honestly, this is a shop preference topic. If a company loves the 45° look, that’s their method. My experience says 45° can trap a small pocket in the ball; I prefer straight. Either way works when the backflow is vented and the drain has a path. That’s the main thing.

Quick FAQ

Should I leave them closed instead?

You can, but closed seats harder against the seals. I exercise them and leave inline (open) so residual film can move if it wants to.

What if I already set them to 45°?

Don’t sweat it. Open the test cocks and make sure your drain is cracked. If you want to match my setup, just turn them inline.

Why might I see a drip later?

Usually a weeping main shutoff. That’s why I leave the drain cracked—so drip goes out, not back into the system.