Refilling baseboard heater boiler and lines

Old 11-10-06, 10:09 PM
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Refilling baseboard heater boiler and lines

When I moved into my 50 year old house about 4 years ago, there were icemaker valves on the upper heating zone loop, presumably for purging air out of the system. A couple of years ago a heating tech replaced them with bleeder valves. (He also replaced the Fill-Trol unit and serviced the boiler) If I recall correctly, one of the bleeders leaked so he came back and removed it, leaving just one bleeder. Then, at the end of last winter I checked and noticed a very slow leak in the area in which the bleeder was removed. This is not my main heating system and it was almost spring so I decided to just drain some pressure from the boiler and leave it for a while. Now with 30 degree temperatures in NJ, I need to resolve this. I figured I would pressurize the system again and monitor closely for the same leak. I have never pressurized the system myself before.

Here is what I did....

-Lowered thermostats (disconnected for one of the zones that has been having the problem
-Turned off gas supply to boiler (probably should have done this a long time ago)
-Turned off electricity supply to boiler
-Ensured hose valves for both zones were closed
-Closed refill supply line valve
-Moved thermostat controlled electronic valves into manually open position for both zones. (Note: Forgot to do this the first time I went through this process)
-Attached hoses to each of the zones’ hose connections (one on each return leg) and hung them so they were submerged in water in a clean garbage pail
-Opened hose valves on both zones
-Opened refill supply line valve
-Allowed water to flow through the system (both hoses) and into the garbage pail.
-When garbage can was full, turned off refill supply valve, then turned off hose valves.
-Carefuly turned on refill supply valve (with hose connections still closed) to *TRY* to bring the pressure up into the 12-15 psi range.

When I turned on the refill supply valve in the last step, the pressure quickly increased to 10psi. However, I could not get the pressure to increase beyond 10psi.

Also, although air bubbles stopped coming out of the upstairs / attic zone, there were still air bubbles (some large) coming out of the downstairs / family room zone. These did reduce down to just a stream of very small bubbles, but did not seem to disappear 100%.

So, here are my questions...

1. Am I doing this right?
2. Is 10 psi acceptable and normal? Since the Fill-Trol is supposed to be charged to 12psi, maybe this is just a minor error in the boiler pressure gauge and means that the Fill-Trol is actually working correctly? I vaguely recall a couple of heating guys in the past complaining that they could not get the pressure up through the supply line so they "worked around it", I think by hooking up a garden hose somewhere to the system). However, with the replacement of the Fill-Trol, I don't understand why there would still be a problem.
3. How can I be sure the air is out of the system? There is some kind of bleeder valve in the upstairs baseboard loop. It looks like it has a flat head slot on it. With the system cold, I turned it counter clockwise and it seemed to loosen, but nothing happened. Am I doing this right? Does the system need to be hot for this to work?

Any help would be greatly appreciated.

Old 11-12-06, 12:49 PM
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Use a bicycle pump to add air to the fill-trol. The amount of water it will allow into a system is equal to the pressure in the tank. For two floors, you should be around 15#. At ten lbs., you probably don't have enough pressure to reach the second floor. If this is a zone valve system, you may have to manually open the valve for each floor to get water to flow thru it.
Old 11-12-06, 01:54 PM
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purging valves

Did you close the valve(s) on the return between each hose bib and the boiler so the water would go thru the whole zone and not just back out of the boiler to the hose connection?
Grady is right about the tank pressure but it's not as simple as just pumping it up again. If the tank lost it's air pressure there's probably a leak in the diaphragm. That's one reason those filtrol feeder's just plain suck. If you end up having someone out to do this right you should ask them to pipe in a by-pass around the feed valve so you can get out of jam in the middle of the night in a blizzard (which is when these things always fail!)!
If you have circulation now (and therefore heat) you can be sure most of the air is out.

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