9D backflow preventer leaking

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  #1  
Old 10-13-09, 08:14 PM
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9D backflow preventer leaking

After shutting off my house main water supply and turning it on, the 9D backflow preventer above the furnace starts leaking from the side port. It drips about one drop per five seconds. Is it because the dirt gets to the valve seat? I tried flush it by lift the lever of the pressure regulator valve but it didn't work. Can I remove the valve and clean it? Is there any procedure I need to follow? Please help! Thanks.
 
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Old 10-13-09, 08:24 PM
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Yes, you can remove the 9D and take it apart for cleaning. It may not be any better after re-assembly than it is right now but nothing ventured, nothing gained.

I don't know if rebuild kits are available for this or what their cost is compared to a whole new backflow preventer. It may be easiest to just replace it with a new unit.

Hopefully the guys that actually deal with these things on a daily basis will have a better answer.
 
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Old 10-14-09, 09:17 AM
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9D valve

Thank you, Furd.
Do I need to completely drain the water before I remove the valve? After I reinstall the valve how do I fill the water into the system and get the air out? Anybody know? Thanks.
 
  #4  
Old 10-14-09, 01:17 PM
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I'd bet that the backflow preventer can be isolated. On the inlet side, maybe you'll have to turn off the whole house supply? Downstream, I'd expect an iso valve ahead of the boiler. Assuming this is all correct, you shouldn't have to drain the system.

Watts sells a repair kit. I would probably opt for a new unit. Or, you might consider getting a repair kit and a new unit - you could then repair the old one and have a spare.
 
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Old 10-14-09, 04:59 PM
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Originally Posted by Mike Speed 30 View Post
I'd bet that the backflow preventer can be isolated. On the inlet side, maybe you'll have to turn off the whole house supply? Downstream, I'd expect an iso valve ahead of the boiler. Assuming this is all correct, you shouldn't have to drain the system.

Watts sells a repair kit. I would probably opt for a new unit. Or, you might consider getting a repair kit and a new unit - you could then repair the old one and have a spare.
Yes, there is an inlet shut off valve but there is no valve downstream the pressure regulator valve, so the 9D cannot be isolated. Now back to my original question: how do I refill the water into the system after replacing the 9D if I have to drain the water?
 
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Old 10-14-09, 05:05 PM
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Originally Posted by harryman View Post
Now back to my original question: how do I refill the water into the system after replacing the 9D if I have to drain the water?
You open the valve that feeds city water to the automatic fill valve - that's it.

The fill valve may have a lever that, when lifted, fills at a faster rate.

Then go to each heat emitter, and look for a bleeder valve on one end or the other. Bleed until you get water, not air.
 
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Old 10-14-09, 06:17 PM
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Originally Posted by Mike Speed 30 View Post
You open the valve that feeds city water to the automatic fill valve - that's it.

The fill valve may have a lever that, when lifted, fills at a faster rate.

Then go to each heat emitter, and look for a bleeder valve on one end or the other. Bleed until you get water, not air.
Thank you for replying.
I don't have bleed valve at each baseboard. There is only an air vent above the expansion tank. How does this valve work? How can it get rid of the air from upstairs? I am afraid after replacing the 9D, the air is trapped upstairs then I am in trouble.
 
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Old 10-14-09, 07:32 PM
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If your connection is city water shut-off valve>9D>pressure reducing valve> boiler system you can likely remove the 9D without having any significant amount of air entering the system or needing to drain any water from the system.

Close the city water valve and then disconnect any unions to allow removal of the 9D. The pressure reducing valve (PRV) will act as a check valve to prevent boiler system water from flowing backwards. After reassembling the 9D into the system open the city water valve and check for leaks. Ideally there should be a union just before the PRV and you can leave this slightly loose to bleed any air from the 9D with the city water valve only slightly open, then tighten the union and open the city water valve wide. Any air introduced should be caught by the air elimination device.
 
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Old 10-14-09, 08:03 PM
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Originally Posted by furd View Post
If your connection is city water shut-off valve>9D>pressure reducing valve> boiler system you can likely remove the 9D without having any significant amount of air entering the system or needing to drain any water from the system.

Close the city water valve and then disconnect any unions to allow removal of the 9D. The pressure reducing valve (PRV) will act as a check valve to prevent boiler system water from flowing backwards. After reassembling the 9D into the system open the city water valve and check for leaks. Ideally there should be a union just before the PRV and you can leave this slightly loose to bleed any air from the 9D with the city water valve only slightly open, then tighten the union and open the city water valve wide. Any air introduced should be caught by the air elimination device.
You are right. It is city water shut-off valve>9D>pressure reducing valve> expansion tank (air vent valve on top)>boiler system. It's good to know the PRV is also a check valve. This way I don't need to drain the water. Just shut off the water supply and replace the 9D. It's only a few inches between the shut off and PRV. I will buy a new 9D and try. Thank you.
 
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Old 10-17-09, 07:06 PM
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Update: I bought a 9D from Home Depot ($32) and replaced the old one. The old valve is very dirty, gasket of the secondary check valve is broken that makes it leak (there are two check valves in the 9D). My heating system works fine now.

Many thanks to furd and Mike Speed 30 for your help.
 
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Old 10-18-09, 04:28 PM
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Glad it worked for you and thank you for letting us know it worked out.
 
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