Expansion Tank (Steel Drum) Question & More


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Old 12-16-04, 09:43 PM
J
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Expansion Tank (Steel Drum) Question & More

I have been trying unsucessfully to eliminate: low noise level banging, gurgling, and uneven heat temperature at the two pipes that Y into one before the circulator and a noisey expansion tank for many years. My system is in the neighborhood of 40-50 years old. Home is a one and a half story cap cod with the original hot water baseboard system expanded into the attic ( 2 bedrooms / hallway between) and basement (family room, bedroom,utility room, bathroom) some 20 years back as part of a dyi as the family grew. I keep purging system runs fine and quite then maybe hours later or the next day or so, the sounds return. I have a time & temperature set back thermistate and it is most common to hear this noise upon heat startup at 5:30am after sitting idle from 1:00am. I have to tune the cut offs before they join the single pipe to the circulator to get consistant heat temperature. If I have both valves full open then always one pipe will remain just warm only until the circulator is just about ending, while the other is HOT throughout the cycle. If I adjust the turn valve (on the one that gets hot) to say about 1/4 - 1/3 open then both pipes are equally HOT throughout all phases. AIR?
My other question and concern is the expansion tank. I replaced the original maybe 15 + plus years back (on original dain valve was leaking and could not remove) it was earier to just get another and sweat to the exisisting 1/2" copper line. When the system kicks on and the boiler starts to heat the line going to the tank becomes extremely hot (while the boiler is heating) only. The path from the top of the boiler is the copper line tees at a fitting to the pressure relief valve, travels up, right angles over, angles up again, have inline supply turn off valve 8" before tank entrance. Tank is round 12" dia. and 36"lg. and has a drain valve on one end. This tank can also be heard and felt popping and bang and as I said earlier the pipe leading to it are hotter then heck. Once the boiler kicks off everything is normal and the pipe quickly cools off. Ive always felt that if the system was getting to much pressure the relief valve would blow and I have check this function on more than one occasion. Is this style of tank suppose to have water in it. If so how much and how would you control the amount since you can't see inside. If it is not suppose to have water than should I close the valve that is 8" below the inlet and open drain valve on the 12" diameter end. This would remove most but not all of the water since the drain valve is about 1" up from the tank bottom side edge and the hose bib inlet is pointing towards the ceiling plus the supply valve would have the 8" of water. Any help to clarifiy issues would be really great.
 
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Old 12-16-04, 10:46 PM
A
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Hi Jay, and Welcome to the DIY Forum

I am really only going to comment on your expansion tank, 'cause other's (with more expertise) can assist you with the rest.

I'd turn the thermostat down all the way, close the valve between the expansion tank and the boiler, and use a bucket to drain all of the water out of the expansion tank. It will take a while, because there is no easy way for air to get back into the tank, except to gurgle as it drains.

You want the Expansion Tank full of air. The water in your heating system expands about 5% between cold and hot. This is the purpose of the expansion tank, to allow a "bulge in the pipeline" to prevent over-pressuring the system.

You need to look at your boiler pressure. It should be around 15 psig, +/- 2 psig. If it is higher than this, you have too much water in the boiler. If less, too little water.

Please post back if you need more help.
 
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Old 12-16-04, 11:23 PM
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Question back to Rick

Rick thanks for the quick reply and advise. Question: is it needed to drain all the water from the tank. Like I said in the original post with the way it's set up some water will remain. However, I am handy enough been sweating copper pipes since I was 12 yrs. old, too drain as much water as will come out and then cut the 1/2" copper line below the tank and above the cutoff valve and drain out everything remaining, then sweat in a 1/2" dia. copper coupler. Is this over kill?
 
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Old 12-17-04, 06:43 AM
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Yes, that is overkill. Drain what will come out through the valve.
 
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Old 12-17-04, 11:41 AM
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Question back to Rick

Hi, Rick you mentioned boiler pressure to check 15 PSI +/- 2.
is this a check at system idle or during boiler heating. When the system is fully to the heating point then no more than the 15 + or -. I'm working on the tank draining (system has been off for about 1 hour) and upon checking the pressure gauge, noticed these readings. Pressure has increments of 10 deg.
The needle is above the 10 deg mark but not half way. Looks to be about 12deg. It is also just a bit below the 30deg mark on the inside scale that shows altitude. After I drain the tank and fire up the system, Watch to see how high? and if goes past the recommended setting adjust the water feed setting to bring in line?
 
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Old 12-17-04, 03:43 PM
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Status and Question after tank drain

Rick, completed the tank drain removed (2) 2 1/2 gal pale fulls with no trouble it came flying out, then a slow drain of about 1 gal. I followed this up with sticking a small plastic tube into the open bib valve and using my little Mighty Mite hand pump I was able to extract another 5 quarts.
Closed off the bib valve and opened the shut off valve below the tank inlet. The system then proceded to fill. I good hear it as well as the feel on the cold water inlet tube. Is this right?, felt like I was returning all the water that had just drained! Fired up the system, the first pipe to get hot was the one leading to the expansion tank (too the point where you could not touch with out a major burn) the two line pipes eventually did get hot, but not as hot as that expansion tube. Towards the end of the boiler warming cycle, the expansion tank started it's bubbling for about 2 short bursts of 3-4 seconds. Again as soon as the boiler shuts off everything returned to peace. The initial tank pressure after turning the valve on to the expansion tank was below 10psi around 8 1/2 to 9 psi. After the first on heat cycle it read what I would estimate as 13 1/2 psi.
 
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Old 12-17-04, 03:54 PM
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Jay,

Everything sounds pretty good. The key is to make sure you have water (not air) at the highest radiator. If after bleeding, you still get more air, or you find the bleeder sucking rather than blowing, add some more water to the boiler. Creep, don't leap, when adding water (increasing boiler pressure).
 
 

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