Replacing Air Bleeder Valves on Hydronic Baseboard

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Old 04-03-12, 08:26 AM
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Replacing Air Bleeder Valves on Hydronic Baseboard

We just moved into a 1950's cape and I am replacing all the old rusted baseboard heat skins on our house with new ones while leaving all the original copper fin. The existing air bleeder valves are corroded and calcified. They also seem to extend way too far off the copper 90's and will not fit under the new skins. Here is a picture of what I'm dealing with.

http://i255.photobucket.com/albums/h...-00-39_167.jpg

I want to replace them with new, lower profile, bleeder valves like these

Coin/Key Hot Water Air Valve-A957 at The Home Depot

Here is my plan.

1.turn off boiler
2. have new bleeder wrapped with teflon tape-ready for install
3. hit the old bleeder with with some PB Blaster
4. While holding the 90 with pliers, attempt to back off the old bleeder
5. clean the fitting and screw the new one on.

Is that all? Is it possible to switch out the old ones without draining the system as long as the circulator pump is off?

Any advice is greatly appreciated!
Thanks in advance.

Jon
 
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Old 04-03-12, 11:01 AM
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Hi Jon,

A few more points:

CLOSE the manual water feed valve to the boiler.

Hook up a hose or use a bucket to drain the pressure from the boiler using any convenient boiler drain.

DO NOT drain any more than necessary in order to drop the system pressure to ZERO.

If you don't do this, you will have water under pressure (15 PSI) coming out the fitting. By closing the water feed and draining the pressure you should be able to remove the old, put a thumb over the hole, grab the new and quickly screw it in. You will still get some water, so have some old towels or a wet-dry shop vac ready to catch the dribbles.

Don't let the teflon tape wrap over the end of the fitting, keep it 1-2 threads back from the end. On small fittings such as these, more then one wrap of tape is too much!

It appears that someone adapted those fittings so they could bleed without removing the covers.

Read this thread too:

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

If you've got the kind of expansion tank that looks like the gas grill type, then when you have the pressure off the system is an excellent time to check the air charge on that tank.

There may be some other minor service points that should be addressed. Post some pics of the boiler and stuff around it ... we'll take a look and advise.

By the way, do NOT 'flush' the system, no matter what you hear. It is NOT necessary nor is it a 'good thing' to do so. It will only introduce more air into the system and make more work for you.
 
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Old 04-03-12, 02:27 PM
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THANK YOU for that great reply! I do have an expansion tank like the one mentioned in that article. He is a pic of the boiler I had on my phone. I could upload some more later.

http://i255.photobucket.com/albums/h...-11-31_357.jpg

There is one circulator pump. There are 3 heat zones in the house that tree off a 2" (i think?) copper line on the right side of the boiler. The zone returns are on the left side of the boiler. The 2 - 1st floor "zone returns" combine into one return (right pipe with blue painters tape above ball valve) and the top floor zone has it's own return (left pipe)
 
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Old 04-03-12, 03:51 PM
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When you say "3 heat zones" do you mean that there are three thermostats each controlling a zone, or only 1 thermostat, and the three zones are individual 'loops' around the home?

I'd like to see where the expansion tank is connected to the piping, and also if there is something called an 'air scoop' on the system, so take pics of the piping and any gadgets on the piping.

If there is no air scoop, that might be the reason for the extensions on the air bleeds to make it easier to remove air.

Usually there is a central device (the air scoop) that removes the air from the system and vents it via an 'automatic float type' air vent. If you don't have one on your system, I can understand the need for easy access to the bleeders.

So yeah, load up some more pics and we'll see what we can see.

By the way, it appears that the bottom flange on the circ pump may have been weeping... I think I can see some rust there?
 
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Old 04-03-12, 07:04 PM
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I assume you would prefer not to have to remove/disconnect the covers to gain access to the vents, if possible. Have you test-fit the new baseboard covers with the new vents in mind?

Until you have the covers in place you won't really know the best way to install the vents...
 
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Old 04-04-12, 07:15 AM
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@ NJ Trooper

-Yes, we have 3 thermostats that operate 3 separate Taco zone valves with 3 loops.

I'll put up some pictures later today showing the expansion tank and all the goods in the same area.

There is some rust at the bottom of the circulator pump. There has been no evidence of any leaks since we bough the house (mid December). Maybe it was serviced recently? From what all our new neighbors say, the old owner was on top of maintenance....Up to now, things have looked that way.

@ Rockledge

We removed the old skins and replaced them with Slantfin 30 skins. Perfect fit. The bleeders are in the way of the front covers that snap on. Since they are all corroded, I'd rather replace them than cut the new heater skins. I wouldn't mind popping off the front cover to get access to the bleeders. I would think i would rarely have to bleed the system.

Thanks again for all this input guys.
 
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Old 04-04-12, 03:11 PM
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I would think i would rarely have to bleed the system.
One would think... but unless there's an air scoop on the system with an automatic vent, it could be more often than you would like. Thing is, once the air is out and the water in the system is O[SUP]2[/SUP] 'starved' you should be OK. It's those few weeks/months after fresh water is added that might be a PITA.

no evidence of any leaks since we bought the house
Since a heating system runs on relatively low pressure, unless it's a major leak you may never see it. The leak will be S L O W and when the system is hot will usually evaporate before you see any wetness. The water will leave behind greenish/whitish crusty mineral deposits as it evaporates... or rust...

But yer right, it may have been attended to. Something to keep an eye on though.
 
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Old 04-05-12, 07:18 AM
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Here is a link to some pics I took yesterday.

Boiler

Would the cylinder with the bicycle pump (schrader) valve on top be the air scoop? It's a little hard to see but it has a typical valve cap on it.

I will certainly keep an eye on the circ pump.

Sorry for delayed responses but if you guys knew the long story of what's going on in my house, you would be spinning.

Thanks!
 
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Old 04-05-12, 09:27 AM
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Would the cylinder with the bicycle pump (schrader) valve on top be the air scoop? It's a little hard to see but it has a typical valve cap on it.
That's an air vent, which is usually connected to the top of the air scoop. From what I can see, you system does not have an air scoop or any other kind of air elimination device.

Examples



 
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Old 04-05-12, 03:14 PM
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Some boilers are designed such that installing an air vent on the top like that can serve as an adequate air scoop... what's the make/model of yours?
 
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Old 04-05-12, 03:33 PM
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Don't even need the make and model; see where the discharge pipe comes out of the side? That boiler has a large area on top to allow air to dissociate from the water so no additional air eliminator is necessary.
 
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Old 04-25-12, 11:01 AM
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Wow, this thread describes the issues I am looking at with my boiler.
As previously mentioned in other threads, I also purchased my house this past december. I have a number of bleed screws that have had their heads broken off or are damaged, so I will also be replacing mine in a few weeks when I can shut it down.
One difference I have is my tank (looks the same as the one pictured below) is connected to the line out from the boiler on a tee.

The info provided in this thread will definately help me out greatly.

Any other tricks or tools suggested for the bleed screw removal?
I'm thinking an open end box wrench is probably the best option I can think of without having to remove the covers of all my rads.
 
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