Swamp Cooler connected to sprinkler backflow

[Jeffro]

I connected my swamp cooler to the the test port on my FEBCO 765 backflow preventer. It has a 1/4 flare connection. When I was buying parts the "resident plumbing expert" kept telling me it was the "last thing I'd ever want to do". He didn't have an reason, so I marched ahead. Is this bad?

Here is the manual:
http://media.wattswater.com/IOM-F-765.pdf

I connected it to testcock#1 (before the seal breaker). I did this because the swamp cooler is 20' higher than the backflow preventer, so it would not prevent backflow properly. I figure it is the same as installing a TEE before the BF, but less work.

He also insisted the test ports were drain valves, so I felt OK disregarding. But, I do prefer to do things right, not a DIY hack. So, am I OK?

Thanks.

[phishfood]

IF I am understanding you correctly, you have some type of water using fixture that is quite a bit higher than the backflow attached to the water main on the input side of the backflow. This is definitely not how you should be plumbing this in. If there were to be a break in the city main, water from this swamp cooler could backsiphon into the city main and potentially contaminate with who knows what kind of nasty little critters a considerable amount of piping.

[Jeffro]

Yes, a fixture on my roof is attached to the input side of the backflow preventer. Most people seem to just attach it to a hose bib. No backflow prevention. The water inlet in the cooler is higher than the water reserve pan, so it cannot siphon that water. Just the water in the line.

That said I am happy to add a separate backflow device for the cooler. Any suggestions for one? I haven't seen one for this application.

[Reedwalker]

The proper backflow device for this application is a RPZ (Reduced Pressure Zone Valve).

From what your describing you have successfully created a cross contamination hazard. You and your family are subject to drinking your irrigation system water. Your PVB is also experiencing positive pressure from the elevated line (a column of water = 0.43 psi/ft). Actually your holding open the backflow preventor with an added 8.6 psi, allowing your sprinkler system to backflow into your drinking water as well. This is why when using a PVB it must be a minimum of 12" above the highest fixture it serves.

I strongly recommend installing a RPZ and having it tested upon installation by an ASSE Certified Tester. Then get it tested at least once every 3 years.

Not to get to alarmist here but waterborne illnesses are deadly.

[Jeffro]

Water column to cooler holds BF preventer open, allowing sprinker and swamp cooler line to backfeed. That makes sense. In my defense, the same exact thing would happen if I had connected to a hose bib as mr. ace hardware expert said. The column of water would have just taken a round about way holding the PVB open.

On to drop some coin on a RPZ. As said, I intended to do it all proper.

Cheers, Jeff

[phishfood]

It sounds as though a lot of people are putting themselves at risk in the exact same way by hooking their cooling system to their potable water system. I am glad that you were concerned enough to dig a little deeper and get the real answer.