Replacing Press. Reducing Valve, Bleed Air


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Old 02-16-09, 10:27 AM
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Replacing Press. Reducing Valve, Bleed Air

Hello. I was wondering if someone could offer advice on a boiler project I have going on. I want to replace the old leaking pressure reducing valve (see pic below) using copper instead of the black pipe used previously. And also want to unhook and move a section of baseboard heater for my kitchen remodel. I'm OK with doing the removal/installation of new components but I'm a little lost as to how to bleed the air out. What is the proper method for re-charging the system and removing air.
I have a Weil McLain boiler, Single circulator and 4 isolation valves. My system uses a closed type expansion tank with an Airtrol vent mounted to the tank bottom. Also, there is a purge valve at the end of the 4 valve manifold on the return end of the loop. Thanks for any help you may offer.

Mike Klein





 
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Old 02-16-09, 04:09 PM
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I wonder about sumpin... that BX/MC cable tied to the black... I wonder if that could have contributed to the joint failure via electrolysis? just a thought... but ya might wanna re-route that cable... or at least put some tape around it ... I know it's a long shot, cuz bronze and black is not usually a problem. Is everything electrically bonded correctly?

If that purge valve on the end of the manifold is corroded, might as well use the opportunity to replace that with a BALL type boiler drain.

Mike, show us more of the piping around the boiler... for example, where does the water actually feed into the system? Can you step back and take some wider shots so we can see how it all fits together?
 
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Old 02-16-09, 06:01 PM
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My hunch is that the corrosion at the fill valve was caused by the leak, not the other way around.

Copper should be fine. But I wouldn't have used black pipe for the original make-up fill line. Galvanized pipe should have been used, I think. That line carries fresh water, probably loaded with disolved oxygen.

Black pipe is fine for the hot-water circulating pipes if there are effective air-removal devices.

It's difficult to tell from the photos, but I wonder if the line going to the airtrol fitting is sloped upwards toward the expansion tank. It needs to be.

One of my gripes with copper pipe installations, which yours seems to mainly be, is that there typically are no unions or there are insufficient unions. So, replacing valves, etc., often requires cutting pipes. As part of your project, you might want to add some unions.
Doug
 

Last edited by gilmorrie; 02-16-09 at 06:21 PM.
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Old 02-18-09, 10:17 AM
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More Picture Detail

OK. I got some more detailed pictures last night. I hope this helps show how to vent my system. I did check the airtrol line slope and it is sloped substantially up towards the expansion tank.

Interesting comments about the armoured cable. I will isolate it from the water feed pipe when I install the new valve and piping. Couldn't hurt. I'll also install the new boiler drain.





 
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Old 02-18-09, 05:25 PM
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With the additional pix, I'm pretty uncertain that the piping to the airtrol fitting is sloped up to the tank. But, you seem to say otherwise.

The whole piping circuit needs to slope, not just one segment.
Doug
 
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Old 02-19-09, 08:11 AM
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Airtrol

You are right. Only the one mid section of piping slopes up toward the tank. However, I have not encountered a problem with air in my system for 8 years or so (since I moved in), so I think that the system is working OK as is. My question is how to remove air once I crack the lines open and release water from the boiler. I'm thinking I can purge the bulk of the air through the boiler drain by isolating the loops with the gate valves, and pump water through the boiler until it flows clear. Do the same for each loop by opening one loop at a time and flow water through and out the boiler drain. Any comments on this approach? This can't be rocket science right? (famous last words)
 
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Old 02-19-09, 02:44 PM
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All ya need is a couple degrees of upward slope... doesn't take much.

As long as that check valve on the return line is functioning properly, you should just be able to do as you say, with only one return valve open at a time, and the drain on the end of the manifold open, the water should run through the zones and purge them. If that check valve is NOT working properly, very little water will flow through the zones, most will go past the check, and out the drain... the water will take the path of least resistance.

I don't know about Doug, but I can pretty much make ANYTHING into rocket science!
 
 

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