Air in system, do I have a serious problem?

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mpilihp

Feeling the Heat
Apr 22, 2008
438
Coastal ME
Hello I have been running an old conventional New Yorker wood boiler for 5-6 years now and other than generating a lot of creosote its worked well and done its job. This season when I started using it every day (I heat DHW with it in the summer still) I noticed quite a bit of air in the system. I bleed it out and Ive been still bleeding a little out every few days. Where can this air be coming from? I would think if air was getting into the system water will be leaking out somewhere as well??

Thanks

~ Phil
 
Phil, I'm just guessing but maybe the autofill valve just isn't filling - Happened to mine, 1962 era, I guess I got my moneys worth out of it. The old one had so much rust & crud in it it couldn't fill a water bottle, let alone the boiler.
 
If the system is tight & right, the auto fill is not even needed or doing anything. Has there been any pressure changes? Possible that the bladder in your expansion tank sprung a leak?
 
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I agree with mike van..had an air problem too quite a few years ago, sounded like a bubbling stream running through my house. I tinkered away at it for a while trying to get the air out, finally had the autofill valve replaced, end of problem.
 
I guess I'm not understanding how an auto fill valve can put air into a system.
Hi all thanks for the ideas, so Ill check the auto fill valve, but I just was looking at the system pressure and it appears fine. Also, the bladder pressure tank is only about 3 years old and I was just tapping on it and it doesn't appear full of water. The expansion tank hangs down and is below an air scoop where the air bleeder is so if it leaked It would fill and weigh a ton, I know as it happened about 3 years ago that's why I replaced it.

My fear is the boiler is weeping/leaking inside which right now is not a horrible problem but the day it lets go will be. Inside I wish it leaking as Id like a reason to upgrade, I just don't want it to be a painful process if I do!

Thanks

~ Phil
 
The boiler fill valve should be disassembled about once a year and the screen should be cleaned and the diaphragm checked for integrity. If the bladder was punctured and the expansion tank was waterlogged, then the PRV would be leaking when the boiler was heating up from cold.
 
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The boiler fill valve should be disassembled about once a year and the screen should be cleaned and the diaphragm checked for integrity. If the bladder was punctured and the expansion tank was waterlogged, then the PRV would be leaking when the boiler was heating up from cold.

Yes, but if its a tiny puncture it would take a while for it to get to that waterlogged point. Interested to hear the outcome, be sure to keep us posted.
 
The boiler fill valve should be disassembled about once a year and the screen should be cleaned and the diaphragm checked for integrity. If the bladder was punctured and the expansion tank was waterlogged, then the PRV would be leaking when the boiler was heating up from cold.
Really?? oil boilers have them as well and before I got the wood boiler I have watched my boiler person do the annual maint several times and he never touched it. Ive had more than one person/company and they never did anything with it....
 
Really?? oil boilers have them as well and before I got the wood boiler I have watched my boiler person do the annual maint several times and he never touched it. Ive had more than one person/company and they never did anything with it....


Here's an installation and maintenance PDF from a typical boiler fill valve by Watts: http://s3.pexsupply.com/product_files/0386422-install.pdf

It actually recommends that the strainer be serviced twice per year.
 
Hello I have been running an old conventional New Yorker wood boiler for 5-6 years now and other than generating a lot of creosote its worked well and done its job. This season when I started using it every day (I heat DHW with it in the summer still) I noticed quite a bit of air in the system. I bleed it out and Ive been still bleeding a little out every few days. Where can this air be coming from? I would think if air was getting into the system water will be leaking out somewhere as well??~ Phil

If the system pressure has dropped below that pressure required to prevent the pump from drawing the suction side (of the pump) to below atmospheric pressure, (causing cavitation) any auto-vents on the suction side can easily let air into the system. Check your pressures, and adjust so you have at least 5 psi at the highest point int he system. This applies to a closed loop system.
 
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I would definitely open up the autofill valve and take a look. The auto fill is NOT putting air in the system. The autofill allows water into the heating system until the pressure in the system reaches 14 lbs (I think 14). Once the heating system reaches 14 lbs the autofill closes. If your system is pressurized to 14+ lbs of pressure and maintained there by the autofill, air can not leak into the system unless the air pressure rose above 14 lbs. Not gonna happen.
The bladder tank keeps the system pressure from going too high. Once the boiler heats the system, the 14 lbs of pressure increases as the water expands. The expanded water is pushed into the bladder tank helping the pressure to remain the same. Once the water in the system cools, the bladder pushes the water back into the system.
So air in the system would be caused by autofill not doing its job. Check and be sure the system pressure on the boiler gauge is actually high enough.
 
Autofill can only be the cause if the system pressure is low (don't necessarily trust the gauge) in a perfect world the system is filled and the autofill can be shut off. I've had mine off for two years, there is a small amount of air which can get into the system throught the butyl diaphragm in the expansion tank, so they should be pressure checked every 5 years or so and the subsequent water added to the system...........

TS
 
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So both the wood boiler and the oil boilers pressure gauges are reading between 15-20 psi so I think that there is enough pressure in the system. Thecontrolguy, I do have a zone on the second floor of the house but I don't know how to test/tell if there is 5 psi of pressure up there?

As for the expansion tank it may have lost pressure over the years (3) but the bladder certainly isn't ruptured as the can is pretty light and has no liquid that I can detect in it. I can check the air pressure on it to verify I guess?
 
Air pressure in the tank will be the same as system pressure as long as its not valved off from it.

Edit: Psi decreases about .4/foot of rise. So if you have 15psi on your gauge, and system highpoint is 10' above that, it will be 11 psi up there.
 
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I stand corrected, looking at maple1's response as well as others, I recall that I had two problems several years ago...one was the autofill was not adding water, and replacing that took care of that, but the real problem was a small water leak in the oil furnace.
 
Air pressure in the tank will be the same as system pressure as long as its not valved off from it.

Edit: Psi decreases about .4/foot of rise. So if you have 15psi on your gauge, and system highpoint is 10' above that, it will be 11 psi up there.
Hi Maple1 ok thanks so even if its 20ft up I should still have over 5 psi up there....
 
I stand corrected, looking at maple1's response as well as others, I recall that I had two problems several years ago...one was the autofill was not adding water, and replacing that took care of that, but the real problem was a small water leak in the oil furnace.
Hmmm I don't want to replace my oil furnace..... hopefully that's not it.

If I cant figure it out then this coming summer I can valve off my heat zones and just run it with my DHW and see if I get air then, less area to be concerned with, I can also zone off each boiler and run just one at a time in the summer for DHW and see if the air stops when not using one of them??
 
it is possible that the "air" that you are experiencing could have its origin in the water supply. The cold water can dissolve more gases than the warm and when the make up water containing those gases is heated, the gases come out of solution. If there are leaks in your system and the boiler fill valves(s) are are adding make up water, that water may have considerable dissolved gases in it and show up as gaseous air when it is heated.
 
Good idea, thanks Ill try that tonight.

~ Phil
 
If your system pressure is good it should be pushing the air out through the bleeder valves as the water circulates. Are your bleeders working? Are they closed off?
 
I would valve the fresh feed line off all together and see how your system pressures react.
Hi I am, the fresh feed is off now, Ill monitor the pressure and keep releasing air to see if it stops and see if my pressure drops or not.

~ Phil
 
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