Best Of

It was a good day, thanks for putting it together Matt

Yikes Again!

I believe that all three of the installation images provided by Alan Forbes are 3/4 filled with air and 1/4 filled with water. I can't imagine any other scenario. I also believe this tank installation scenario defeats the holy grail sought by those who believe the correct way to handle air in a closed loop system is to expel it from the system by mechanical means.

Speaking to Ground Up, I acknowledge being annoyed that my original statement about the tank being completely empty of water was not taken at face value and apologize for not giving your question more attention. To answer your question though, it was determined that the tank had no water in it when the union just upstream of the tank was broken and no water came out. That having been determined, the operator decided that tank filling protocol was irrelevant until the cause of the empty tank and the pegging pressure gauge was determined. That's when he called me. Prompted by your message here, however, I have advised the operator to disconnect the union again, crack the valve next to it to see if boiler fluid is available there, and to run a rod or something into the tank to rule out the tank inlet being filled with crud (and perhaps discover that there is in fact water in the tank). The manner in which it is piped would promote rust, crud, and corruption at that location. This scenario would explain all the symptoms described by the operator because the air cushion would in fact be isolated from the system in general due to a blockage at the inlet to the tank.

When I was in the business I never used bladder tanks because they did not fit into my Air Control piping technique. I used plain steel tanks, placing them directly above the boiler and piped from a tap on the top of the boiler. I viewed the boiler as a "wide spot in the road" where air WANTED to come out of solution. I modified the supply nipple (also on top of the boiler) with a "dip tube" so that the supply fluid was drawn from just below the top of the boiler casting. This left a small cavity at the top of the casting where air would collect and eventually find the inlet to the air tank. I always put a drip leg at the inlet to the tank to catch the crud that invariably collects in that kind of a tank. My thinking was that oxygen, not air, was bad and that once the oxygen-containing air (21%) was captured in the plain steel tank it, the oxygen, reacted with the steel, and was converted into iron oxide, (a solid) leaving only inert, harmless nitrogen (79%) in the system.

I owe this technique to Dan Holohan who, at one of his seminars when I was comin' up, told us to "think like an air bubble".

Ground Up, I just cannot tell you how satisfying it is to stand next to a newly-fired-up boiler and listen to all that air in the system going Bloop - Bloop - Bloop into the tank. 🙂 Yes!

Is there a drip that is connected to the wet return not far enough below the water line such that it can push a slug of water with air or steam behind it up the return to the vent?