Ah, we didn't have one, all circulation was done by pump. There was a steam eductor to pull water from the double bottom using steam . It would only work if we dumped the domestics down to give a head. I expect it was worn out by then.
Flashing was done with the smallest burner tip and 3 minutes every 30 minutes firing rotating the furnace. The second had been there a long time, he was absolutely wild at the fireman when a boiler came up suspiciously quick. When the steam blew from the air vent it was closed.
We were on the railway dock with 2 boilers banked and the third online. I was duty engineer over the weekend, after I was down a couple of times, I noticed the fire was in the same furnace. I asked if the fires were being rotated thru the furnaces. After a No answer, it was my turn to get perturbed. Good boilers, but you had to respect them and be very cautious. The next ship I was on the crew was careless about firing. I was glad to get off there. They collapsed the furnaces in both boilers, it was a miracle no one was killed.