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Another Main vent question

Can an improperly sized or a malfunctioning main vent be the cause of water not returning to the system? ( one pipe - oil fired - steam system ). I'm having to add water

approx. 2x a day ! ...No visible leaks ..........

Any ideas? Thanks to all the pros on this site!

(p.s. still looking for a steam pro in The Bronx )


  • Adding water too frequently

    If the main vents are not adequate, then the water may be slow in returning, but in your case, it seems as if the water never comes back. Look over the system, and see if you can find a leak especially in the returns. Fresh water Is very damaging to cast iron boilers because of the excess oxygen.

    Check your chimney when the boiler is firing to see if steam is coming out there.

    If you want to check for a leaking section in the boiler, then it should be cooled, and then overfilled to the top. After a few hours, then look inside the firebox for any dripping.--NBC
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