Went to NAPA and got 5 gal of the "Orange" GM OAT coolant (all they had) as I didn't know how low the boiler was on fluid.
Surprise! must have been very close to bone dry, took 4 1/4 gallons to fill to the tippy top.
Got the old fill neck off and another Surprise.... there was only a 1/4 inch spot of solder holding the neck on..... looked to be a factory solder job.
Cleaned up the tank neck with emery cloth and followed directions that came with the No solder filler neck replacement from Roger.. (Thank You Rudy for suggesting this work around!)
pic showing the old filler neck with just a 1/4 inch of solder that was holding it onto the tank.
Looks to be an mfg error.
Looks good now!
I had Rudy install one of these a couple of years ago. Great fix. Works like a champ.
I urge anyone with an Aqua Hot to check the fluid level in the "puke tank" to see if the level is fluctuating from not running ( boiler off) to when it is running (boiler running/hot). When running the puke tank should be warm to the touch.
If it doesn't, it indicates that either the radiator(fill neck) cap is bad or that the the system has a leak and not holding pressure.
In my case it was both, and the fluid was just boiling away loosing pressure thru the bad solder gap on the fill neck.
You're lucky you had the hear room. I shudder to think what I would do if that neck came loose.