Purging a Hot Boiler


Old 03-16-15, 05:16 PM
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Purging a Hot Boiler

Is it necessary to let a boiler cool down before purging the air with cold water. I was told that a hot boiler may crack if it was not allowed to cool down for about 30 minutes. True/false? I have been doing it hot, so far no problems.
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Old 03-16-15, 05:29 PM
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It's the same as adding cold water to an overheated car radiator.
You can do it but start with adding water slowly until you temper the water down. It doesn't take that long just be patient. In a modern average boiler there is about 12 gals. of water so it doesn't take long to cool it down.
Old 03-16-15, 05:32 PM
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OK, got it thanks, let water in slowly at first.
Old 03-16-15, 05:36 PM
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The better question here is why are you constantly purging air? Once a system is filled, initially purged, it shouldn't need to be purged of air unless something is wrong...

Tell us the pressure of the system when it's cold to start.
Old 03-16-15, 06:21 PM
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Yes, I would also like to know why you seem to need to do this all the time...

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