air bubble in the system?


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Old 09-20-07, 09:28 AM
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air bubble in the system?

We've got a gas-fired boiler (single pipe system, I believe - it's a Utica Series Peg-B) in our house which we're in the process of selling. The buyer's inspector fired up the system yesterday and found that the temperature along the pipe dropped very close to the furnace -- the radiators (steam) did not heat -- and suggested that it might just be an air bubble and need to be bled. How do I bleed the system or what is involved in that?
The system worked perfectly through last season and had been serviced last year, so I just want to make sure that it's all good to go for the buyer of our home.

Thanks!
 
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Old 09-20-07, 12:34 PM
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If you have a steam system then of course you have air in the piping. The air is expelled ahead of the steam by means of air vents in the main piping runs and the air vents on the individual radiators. It does take a bit of time to expel the air so depending on just how long the boiler was being fired there may be nothing wrong with your system.

Of course nothing will happen until the boiler is actively producing steam. I have no idea of the amount of water contained in your boiler, the BTU input of the burner, the starting temperature of the boiler nor how long a time elapsed from the initiation of the burner until the "diagnosis" of air in the piping was made. I suggest that the heat be "turned up" and a period of time be allowed to heat up the boiler to the point that steam is being made and then allow some additional time for the steam to push the air from the radiators before worrying that there is "something wrong" with the system.

If after allowing the boiler to produce steam and there are specific problems, please post back and we can deal with those problems. I don't particularly like steam in residential installations but the systems rarely have any significant problems if the original installation and any subsequent revisions were done correctly.
 
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Old 09-20-07, 07:04 PM
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Furd,
Thanks for your reply. I should have included the information that the boiler turned itself off after the first 6 feet or so of piping reached it's target temp (145 degrees) and the remaining length of pipe was 70 degrees, and the radiators did not heat. The inspector had the unit on for about an hour (per my wife; I wasn't here to see).

Thanks
 
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Old 09-20-07, 10:25 PM
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Of course I have no way of knowing what kind of control system your boiler/heating system has but if it normally shuts down at 145 degrees then you will never get any heat in the radiators.

I'm more inclined to believe that the "home inspector" doesn't understand steam heating systems.

Now it is possible that the "inspector" only turned the room thermostat up a couple of degrees from the ambient room temperature and for one of several reasons the thermostat became satisfied and shutdown the system. It is also possible that you have a "summer / winter" changeover switch that prevents the boiler temperature from rising above that 145 degree point during the non-heating months. Such a control could even be automatic and controlled by outside air temperatures.

One thing I am certain of and that is that 145 degree boiler temperature will NEVER heat that house and never did.
 
 

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