How to purge my hot water baseboard heat (pictures added)


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Old 10-13-07, 02:03 AM
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How to purge my hot water baseboard heat (pictures added)

When the heat came on upstairs for the first time this season I could hear the water moving through the system. I'm assuming this means I have air in the system.

I would like to know based on my system how to properly purge air from that one zone. We have 3 zones.

http://i84.photobucket.com/albums/k1.../boiler001.jpg

http://i84.photobucket.com/albums/k1.../boiler004.jpg


From what I've read in other posts this is what I would assume I would do.

**Turn off the boiler**

1. Close the yellow valve right below the red handle on the return side.

2. Close the 2 yellow handles on the zones not in questions on the feed side

3. Fill my system to 25psi, open up the red valve and let the water drain, keep an eye on the psi to make sure it doesn't go above 30psi or get too low. Once I see major air bubbles come out it should be purged.


About how long would you guess it would normally take to purge a zone or how many gallons before I know I've made it through the entire loop? Our house is a 36X26 cape cod.
 
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Old 10-13-07, 06:14 AM
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Purging Air

The first mistake you are making it to turn off the boiler. By turning off the boiler, the zone valve will not open. Without the zone valve open, no water is going to flow thru the zone & push out the air. Make sure all thermostats except the one for the zone you wish to purge are turned all the way down & the one for the zone on which you are working is turned all the way up. The type of zone valves you have are not instant opening. They can take up to a minute to open or close so don't get in a big hurry.
 
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Old 10-13-07, 07:00 AM
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The Taco Control Zone Valve has a lever that I can manually open up the zone, can't I just do that?

I just purged the system and these were my steps...please someone correct me if I'm wrong.

1. Turn off boiler
2. Turn off yellow handle on return
3. Turn off 3 yellow handles on feed
4. Open yellow handle for zone you want to purge
on feed
5. Hook up hose to faucet above yellow handle with
red faucet.
6. Manually open up Taco Zone Control Valve for zone
to be purged.
7. Turn on faucet, make sure psi stays around 25 psi
when bleeding system
8. Manually add water to the system as itís being
purged. Use the small gold lever on the feed to
add water, if pressure gets too low turn off red
handle and allow time for psi to recover
10. When air is purged
11. Open all yellow handles back up.
12. Manually close Control Valve on zone being purged
13. Turn boiler back on.
 
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Old 10-13-07, 07:32 AM
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I should think that manually opening the zone valve would work OK.

A couple observations, and a question:

Keep in mind that when you add fresh water, you are actually also adding air entrained in that water, and after the boiler heats up, that air will be driven out. Your air scoop and valve should eventually take care of small amount of air that it catches. The little cap on top of the air valve on top of the air scoop needs to be left loose to allow that air to escape.

What is that object mounted on the box hanging off that bent piece of EMT tubing coming off the boiler shut off switch box ? Is that some sort of 'roll out switch' ? Or smoke/fire/CO sensor ? Just curious...
 
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Old 10-13-07, 07:41 AM
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I'm not sure that the air scoop works but it's the 2nd one installed so hopefully it does.

I'm not sure what that extra box is, from just looking at it underneath it looks like it has a button on it to push. Maybe if you are working on the water heater and need to quickly shut off the boiler not sure though.

So I should purge the zone with the boiler running and the water hot? I heard that can crack the boiler? Is that true?
 
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Old 10-13-07, 08:00 AM
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If you have a hot boiler and you add massive amounts of cold water suddenly, you could certainly run into trouble. You don't want to replace any more water than necessary to get rid of the air. Are there any vents on the upstairs baseboards ? You might be better off taking a look for those and vent the air from there if you can. You might have a lot less air in the system than you think. A little bit of air can make a lot of noise. The less fresh water you add, the better off you are. By flushing out the entire loop and adding fresh water, you could well be adding more air to the system than you already have.

How much pressure is normally on the system ? How high is the highest point in the system ?

You had the scoop replaced ? The big black thing ? If so, why ? I can't imagine how that could fail. The VENT (the thingy on top of the scoop) is a 'maintenance item', they can and do leak. Like I sed, that cap needs to be loose for it to work.
 
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Old 10-13-07, 08:20 AM
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We remove about 8 gallons of water to the system...a ton of air came out. I turned on the heat and it sounded good...tiny pings/bangs but we've always had that when the system starts to heat up once the pipes are hot the noises stop. It was the constant sound of water running that actually kept me awake last night.

How high is the highest point in the system? Not sure what you mean but it's the second floor heat that makes the noise and we have regular height ceilings on the first floor.

We don't have any relief valves on our baseboards.

When purging a system does the air usually shoot out right away?

We had that tiny shiny metal piece on top replaced. With the screw on it. Not the big black thing.

We run our pressure around 20psi. That's what it has always been set to.
 
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Old 10-13-07, 08:36 AM
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Originally Posted by nicole12 View Post
How high is the highest point in the system? Not sure what you mean ...
How high above the boiler is the highest baseboard piping... from what you said, with the boiler in the basement, and a two story house, I'm guessing around 20' or so. Reason I asked that is because if the pressure in the system is not high enough to keep the highest point pressurized, you will constantly have air problems. But you said 20 PSI and that should be more than enough.

Originally Posted by nicole12 View Post
When purging a system does the air usually shoot out right away?
It depends on how far the air is from the drain point. If the air is coming from upstairs to the basement, it could take like maybe 30 seconds or so, maybe a bit longer.

Originally Posted by nicole12 View Post
We had that tiny shiny metal piece on top replaced. With the screw on it. Not the big black thing.
once again, make sure you keep that screw or cap in the open position to vent the air it catches from the fresh water that you just added.

Sounds like you got it fixed up now...
 
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Old 10-13-07, 08:43 AM
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Yeah now you got me nervous about putting more air into the system. Will it ever end?

We saw a bunch of air about 30 seconds into it, the hose almost jumped out of the bucket and then after another 30 seconds a big air bubble came out. I wish then I had just stopped but I went for about another minute to make sure we did the entire loop.

I have the top to that relief valve almost all the way unscrewed.
 
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Old 10-13-07, 09:14 AM
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naahhhh, you'll be fine.

You sure there's no vents upstairs though ? Look at the ends of the baseboards, under the covers, mounted on an elbow or a tee fitting. They will be small, probably silver color, and have a little screwdriver slot in the top of them that you can open and close with a dime (or screwdriver).

If you get air later, and you do find those are there, just crack 'em open and let the air out. This is best done with the boiler off, and after it's been off for a while to allow the air to collect in the high spots, and a wad of paper towels in your hand.

Also remember that if you hear only a little bit of air, that you should give the scoop and vent (black thingy and shiny thingy) a chance to do their job first, before you start purging again.

Is this a repeat problem with this system ? like every year ?
 
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Old 10-13-07, 12:53 PM
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No, what happened was last year there was a leak in the basement and everyone on a different forum was convinced it was the baseboard heat, which I knew it wasn't because my pressure never dropped so they had me drain the boiler and it emptied therefore allowing air into the system.

This happened at the end of the winter, I purged the system used the heat only 2 or 3 more times so I'm assuming (hoping) that's why the air didn't have a chance to get out.
 
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Old 10-13-07, 03:12 PM
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Hmmmm... you have an automatic feedwater valve on the boiler. If you _did_ have a leak in the system, that valve would always add water to keep the pressure constant. That's what the valve with the gold handle is, a pressure regulator. The gold handle is a bypass for the regulator that allows you to 'fast fill' the system.

Do you still have a leak ? or did you find that ?

You might want to close the manual valve (either the blue one or the black one, or both) on the feedline and see if your pressure drops. If the boiler is hot now, it will drop a few PSI as it cools, but if it continues to drop, then guess what?

This is a problem with those autofeed valves / regulators, they do their job, BUT they can hide a leak. If you leave the valves open, and you have a leak, it may not be detected for a while. If you close them, and you have a leak, and your boiler goes low on water, then you have even bigger problems.

Life's a crap shoot anyway you look at it.
 
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Old 10-14-07, 05:47 AM
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I found the leak, it was the vent pipe that goes out the roof when they glued the PVC together in the kitchen wall going to the basement, they did an awful job and the pipe was put in crooked and leaked. We had to open up the kitchen wall and seal it with silicone. Leak stopped. Took lots of detective work on my part, became a full time job but I finally found it and fixed it.
 
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Old 10-14-07, 06:10 AM
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silicone?

Originally Posted by nicole12 View Post
I found the leak, it was the vent pipe that goes out the roof when they glued the PVC together in the kitchen wall going to the basement, they did an awful job and the pipe was put in crooked and leaked. We had to open up the kitchen wall and seal it with silicone. Leak stopped. Took lots of detective work on my part, became a full time job but I finally found it and fixed it.

Should of cut the joint out and reinstalled new pipe and cuplins.
Silicone can break down after time.
 
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Old 10-14-07, 08:44 AM
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Originally Posted by nicole12 View Post
I found the leak.
Good... in that case, don't bother to close those valves and see if the pressure drops, cuz obviously it ain't necessary.

So continue on, you should be in good shape now.
 
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Old 10-14-07, 10:07 AM
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OK--I'm lost

What does a leaking PVC vent pipe have to do with air in the heating system???
 
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Old 10-14-07, 10:23 AM
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Originally Posted by Grady View Post
What does a leaking PVC vent pipe have to do with air in the heating system???


read back a few messages, the problem started when there was a leak, they were told the heating system was leaking, they drained it, didn't need to, leak wasn't in the boiler/baseboards, etc ...

 
 

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