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tbarb

New Member

1

Tuesday, October 3rd 2017, 4:24pm

Blowing out Febco 765 PVB

I want to blow out my sprinkler system valves and lines during the next week and looking at the Febco 765-1" PVB that was installed this summer I see no way to close off this backflow preventer on the outflow side and connect the compressor hose after that in order to blow only towards the sprinkler valves and lines. Looking at the direction of flow the air hose connection/test cocks are on the supply side which has to mean I will be blowing air through the Febco unit as I can only close the lower valve (closing off the house supply) and blow through the Febco unit towards the sprinkler valves and lines. All the You Tube videos I've watched note NOT to blow through a backflow device. So though I should check here... ??
Thanks

This post has been edited 2 times, last edit by "tbarb" (Oct 4th 2017, 1:42pm)


Wet_Boots

Supreme Member

Posts: 5,133

Location: Metro NYC

2

Wednesday, October 4th 2017, 7:21am

Is there no drain for the supply plumbing anywhere?

tbarb

New Member

3

Wednesday, October 4th 2017, 1:42pm

There is one drain valve on the supply side line just inside the home just before it goes through the cement foundation on it's way to the Febco 765. It will the 3' or so of supply pipe from the drain to the Febco unit above, which of course is the high point and above ground by about 2 1/2 ft on the outside. If I only open from this supply line drain I think I will leave some water in the Febco unit as well as the supply line after the Febco to the underground valves and then forward to the sprinkler heads. I think you are asking if there is a supply line drain after the Febco unit and that answer is no.

There is no fitting for the compressor to attach to forward of the Febco backflow unit
- There are only two test cocks and are air compressor attachable, but they are both on the supply side of the Febco unit, which is how it is made. I don't know where else I can attach the air compressor except to these and send air through the Febco unit.
I
read a post of yours about the same Febco 795 PVB unit in which you responded that it was 'not a big deal with a "homeowner compressor'. Maybe it's not at 60 PSI, but I don't know and why I'm asking here.

This post has been edited 1 times, last edit by "tbarb" (Oct 5th 2017, 8:06pm)


Wet_Boots

Supreme Member

Posts: 5,133

Location: Metro NYC

4

Friday, October 6th 2017, 2:53pm

A system like yours was intended to be blown out from an air hose dragged into the basement. In a word, dumb. Go ahead and use the testcock for the air input, and drain the inside into a bucket.

AlL

New Member

Posts: 9

Location: NH

5

Sunday, October 8th 2017, 11:08am

Email sent to you.

Did you receive the email I sent you yesterday regarding the use of an expandable plug in the BFP? If you didn't please advise & i'll send you another or a PM.

Wet_Boots

Supreme Member

Posts: 5,133

Location: Metro NYC

6

Sunday, October 8th 2017, 4:59pm

No emails, please. Public posting shares the knowledge. There is no reason to disassemble the PVB.

AlL

New Member

Posts: 9

Location: NH

7

Monday, October 9th 2017, 9:11am

My apologies, no problem with that at all.

However, with no way to attach an airline before the BFP if one doesn't remove the internals & plug off the BFP then the poppet/retainer/check asm. will vibrate/flutter excessively when pressurizing the system from the test port & possibly cause damage to the BFP components as air is applied in the opposite direction from normal use of the BFP. An expandable plug prevents this damage.

Wet_Boots

Supreme Member

Posts: 5,133

Location: Metro NYC

8

Monday, October 9th 2017, 1:10pm

"Gee, I have to remove the bonnet on this PVB so I can winterize," said no professional ever.

The homeowner air compressor connects to the low point drain on your supply plumbing. If you do not have a low point drain, you need to correct this shortcoming.

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