Noisy pipes - how to purge air

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Old 11-25-13, 12:12 PM
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Noisy pipes - how to purge air

Hi,

I'm the homeowner of a 50 year old house, with the original furnace, 5 zones. Pipes on the top floor were "banging", I imagine air in the pipes.

I tried this site's How to purge air from hot water boiler. There doesn't seem to be much pressure, it never reached the point where water was flowing. The meter dropped to zero psi after I opened the "pressure valve", after a few minutes it returned to 5 psi.

Am I turning the wrong knobs?

I also found some YouTube videos that show removing the air on the return side of the hot water boiler. Please advise if this is a better approach.

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  #2  
Old 11-25-13, 12:41 PM
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First, you never bleed your system through the pressure relief valve. That valve is there for safety reasons.
Next 5 psi is way to low. Your automatic feed valve, that's the one between your main shut off and your pressure relief valve if working is preset to 12-15 psi.
Make sure your main valve is open. If you lift up that lever on top you can manually feed water into the boiler and get the pressure up to 15 psi. to start.

One of the first things to do is make sure your pressure gauge is working correctly.
When and if you have to bleed the system it will be done by the return line, zone by zone.

I'm sure more pics of the supply and return piping will be needed to move forward.
For now at least make sure your gauge works and get some water in there.
 
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Old 11-25-13, 01:09 PM
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Thanks!

I increased the water pressure to 12 psi. I hesitated going higher, there is a red line for the "altitude" units at this level. Here is the current reading:
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Here are pictures of the supply side:
This shows two of the five zone pumps and valves. The text "connect hose here" in the picture, I now believe is incorrect.
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The return side:
picture return-A
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picture return-B
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Best regards.
 
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Old 11-25-13, 01:26 PM
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Yes connect hose there as you show... You also need to close the valve below the hose bib where you hook up the hose...

Try that, and as you bleed each zone try to lift the fill valve lever and keep the psi up. Dont let get higher then 30 psi or the relief valve will trip..

Additionally you need to replace that air vent thats ontop og the air seperator above the expansion tank... And any others you may have...

Also you may need to open the flow control for each zone as you purge.. They are in picture A return side pic. One is red the other 3 I see are brass.

Turn the knob CCW all the way out... When your done purging make sure you close them again.
 
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Old 11-25-13, 03:03 PM
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Regarding the pics are you saying the pumps are on the supply or return.
Also the first pic with the expansion tank says return line, and those check valve also say return.

First check the arrow on the back of the pumps to see which way they're pointing. I believe that is your return line andthe line with eexpansion tank is your supply. The air scoop with the vent also has an arrow to tell the direction of flow.

Unless I'm reading the pics wrong I think you have the two lines confused.
You have the hose bib marked as wrong but in fact is right.

Let's clear this up first before we go on.
 
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Old 11-25-13, 03:51 PM
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Correction:
1. The arrows on all five circulator pumps point toward the boiler.
2. The arrows on the five flow control valves (near the expansion tank) point away from the boiler.

With this new understanding, the pictures are:

Supply side (picture A)
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Supply side (picture B)
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Return side
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Did I say, I'm very grateful for your help?
 
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Old 11-25-13, 04:31 PM
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Dont matter where they are IMO... ...

Purge the zones as I stated in post #4....
 
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Old 11-25-13, 04:31 PM
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I increased the water pressure to 12 psi. I hesitated going higher, there is a red line for the "altitude" units at this level.
No, check your photo of the pressure gauge again. The units for the altitude are in ft of head, not psi. The red line starts at 30 psi and 70 ft. Jacking up the pressure to, say, 25 psi should be fine, and would help bleeding air.

The relief valve is set for 30 psi. If it were to lift when the gauge indicates 25 psi, then the gauge is probably wrong.
 
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Old 11-25-13, 04:34 PM
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First, the advice you've gotten so far is correct.

Hook the drain to each of the hose bibs and CLOSE the valve below it.

You shouldn't have to do anything with the flow control valves because the water will be flowing the proper direction.

Lift the 'fast fill' lever on top of the pressure reducing valve to get as much flow as you can without going over 28-30 PSI so you don't open the relief valve and make a mess.

It appears that there are two pumps, two returns... so you may want to figure out which 'set' of supply lines go to each of the two returns, and when you are purging operate the valves on the supply side so that you go through only one loop at a time.

Continue for each loop until no more bubbles out the hose end.

Let's talk about maintenance...

Mike mentioned the air vent on top of the air scoop. Needs replaced.

On that one pump, that flange has been 'weeping' for a long time. Needs new flange gaskets... hope the flanges aren't rusted to bad it will still leak... might want to use a thin layer of 'gasket maker' when you reassemble.

You should service the expansion tank before doing this process. Read this for steps on how to recharge the air in the tank.

http://www.doityourself.com/forum/bo...sion-tank.html

Also, it really helps when troubleshooting to KNOW that your gauge is accurate, so read this also:

http://www.doityourself.com/forum/bo...ure-gauge.html
 
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Old 11-25-13, 04:37 PM
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Regarding the pics are you saying the pumps are on the supply or return.
Look at the pump volutes. The flow is going from the top connection to the bottom connection of the pumps. Presumably, the boiler return is at the bottom of the boiler, so the pumps are on the return - like many millions of successful installations before "pump away" was advocated, including mine.
 
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Old 11-25-13, 04:40 PM
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there is a red line for the "altitude" units at this level.
Gil touched on this while I was posting... that red needle means basically 'nothing'.

The pressure in your boiler will vary from MINIMUM of 12 PSI (for a 2 story home, slightly higher if the home is taller) on a COLD BOILER, up to perhaps as high as 25 PSI, but if the expansion tank is the proper size for the system probably not more than 20, and perhaps even less, when the boiler is HOT.

Also, it's a good idea to change a pressure relief valve every 5 years or so... but nobody ever does... it's still a good idea.
 
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Old 11-25-13, 04:47 PM
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By the way, one last thing...

You said the pressure in the boiler was 5 PSI when you started... was this with the manual water feed valve in the ON position?

If so, this means one of two things:

Either your pressure gauge is not reading correctly (which is more than likely)

OR, your pressure reducing valve is also defective (which is equally likely)
 
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Old 11-25-13, 05:11 PM
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Also, it's a good idea to change a pressure relief valve every 5 years or so... but nobody ever does... it's still a good idea.
I do. Also, I replace the pressure reducing valve every 5-10 years, or so - performing throttling service, the seats can become wire drawn, I fear. I stock a spare Taco pump cartridge, too. But, I'm neurotic.

I replace my boiler every 75 years, whether it needs it or not. I've got 15 years left - that's for my boiler, not me.
 
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