Water Gurgling Sounds in Baseboard


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Old 12-30-05, 06:04 AM
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Water Gurgling Sounds in Baseboard

Hi,

Our 2nd home has developed some water gurgling sounds within the baseboard radiators. We've owned the home for 3 years and haven't noticed this until recently. The heat works fine, in general, just wondering if this is a warning sign. If the circulator is cycling often, this noise goes away, but if it hasn't run in a couple of hours or so, we hear the sounds. The forced hot water system is heated by an oil burner/boiler about 10 years old. Pressure guage on the boiler reads between 15-20 psi. Some corrosion noted on expansion tank pressure relief valve, but not actively releasing. The system is located in the basement of a 2-story house.

I would appreciate an expert opinion on whether this is something to be concerned about. Perhaps some maintenance is called for?

Thanks
 
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Old 12-30-05, 06:48 AM
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Sounds like you have "Unwanted air" in your system where there should be water. Residential systems such as yours usually operate at 12psi . Without knowing all the details of your system it's difficult to assess the problem.
Do you have a sight glass on your exp. tank and can you see any water in it?
Has the strainer in your pressure regulator ever been cleaned? (these strainers are very small and require periodic cleaning for proper operation).
 
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Old 12-30-05, 03:18 PM
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Kenbert

The pressure of 15-20 psig is nothing to be concerned about. Look on the ends of each run of baseboard for small bleeders. Some can be opened with a screwdriver & others require a special tool called a radiator key. These radiator keys are available at most plumbing supply houses. The gugling sound is caused by air in the system.
 
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Old 12-31-05, 05:13 AM
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Thanks for the answers. I don't think this system has a provision for manual venting. It uses the finned copper tube baseboards (Slant Fin or equiv.). It does have an expansion tank with an air purger mounted on top of it then a vent mounted on top of that. My understanding is that this arrangement is supposed to vent air automatcilly, eliminating the need for manual vents. However, as noted in my previous post, there is a lot of corrosion visible on this vent. Could this vent be clogged or otherwise inoperable? Should it be cleaned or replaced?

Thanks.
 
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Old 12-31-05, 05:21 AM
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Forgot to answer questions. The expansion tank is metal, with no sight glass. The top of the tank feels hot, the bottom just lukewarm. The screen in the pressure regulator would not have been cleaned. That cause is plausible because we have had grit enter the system in the last year due to municipal water supply work, which caused other plumbing problems in the house.

One more question to the experts - how urgent is it for this situation to be addressed? The problem so far is just mildly annoying. Heat is working fine.

Thanks
 
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Old 12-31-05, 11:47 AM
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kenbert

There is no real urgency to your situation. At your eariliest convenience, the air should be removed.
 
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Old 01-02-06, 01:20 AM
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Air in System

kenbert:

You should definitely have your expansion tank & its corroded valve checked out; from your post it sounds like the tank is mostly "waterlogged" (is completely filled with water); this type of expansion tank is designed to be 1/2 full of water & 1/2 full of air, so that when the boiler water heats up (water expands when heated) the extra volume created has somewhere to go, which is the air pocket in the upper portion of the expansion tank (the increased volume compresses the air cushion in the upper portion of the tank).

There may be a leak in one of the valves at the top of the expansion tank, which is letting needed air escape from the top portion of the expansion tank.

You will know when it is completely waterlogged, when the system water pressure starts to creep up to 30 psi & the pressure relief valve opens & dumps hot water onto the cellar floor.

The pipe leading up to the expansion tank either connects directly to the boiler, or is fed by an "air scoop" that directs air bubbles up to the expansion tank to keep it partially filled with air & thus eliminates air in the rest of the system piping, including the baseboards.

Some piping systems have "purge valves" on the return mains designed to manually purge air from the system.
 
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Old 01-03-06, 07:17 PM
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Chimney Cricket,

The bottom of the expansion tank (air supply side) is cool/warm, the top (water side) is very warm, as I understand should be the case. Pressure is consistently slightly below 20psi, but you make a good point, and it will be watched closely.
I don't think there are any manual purge valves, but I'll check on my next trip.

I agree with both you and Grady that I need to address the air problem, but it doesn't seem to be an emergency.

Thanks for the opinion.
 
 

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