Lost Art Of Steam Page 237

Tim_16

Does the air check on the Air Eliminator Trap just let air out or will it break a vacuum. If it fails can you just use a regular Hoffman #75 vent?

Thanks

Patrick Linhardt, \"Linhardt's Field Guide to Ste

be careful

Hi Tim,

The air check was normally fitted with a disc or ball to prevent the air from getting back into the system, putting the system into a vacuum. These were the coal-fired days when vacuum was your friend. With automatic fire, the recommendation is to remove the disc or ball.

The size of the hole was also very large compared to what we have available in a vent today. That's where you have to be careful. Depending on the size of the system (quantity of air in pipes) you may need more than one #75. See chart on page 85, LFGTSH.

But the real point is, make sure all your traps are working. There wasn't a thermostatic element in that original vent to prevent the escape of steam if the radiator traps fail open. The #75 does have a thermostatic element and will hide the fact of a trap blowing steam into the dry return.

Best regards, Pat

Steamhead (in transit)

If you remove the check

and put a vent on, use a Gorton #2. Its throughput is probably more than that of the opening in the cast housing.

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