gravity conversion puzzle

Stew_5

Just went to  check out a house built in 1895 that must have had one of the first hydronic heating systems in Juneau. Around 5 years ago a new boiler was installed. The cast iron radiators are producing heat; the house seemed a comfortable temperature. All the old piping is still in use. There's more piping than seems necessary in the eves and in the 2 foot -high attic. It's a two story house, boiler in the basement.  No sign of an expansion tank up there. All pipes are hot. Here's what I'm trying to figure out:



The Taco circ pump is mounted on the top of the Weil-Mclain boiler, goes thru a new cast iron 'flow control' then thru some other cast iron fitting, then to the new expansion tank then on to a myraid of old piping (I didn't have long to study this, wish I'd taken pictures).   That top side of the boiler is luke warm and the bottom return side is very hot. This condition does not change when the boiler and pump kick on.



Is it possible that the system is gravity circulating Backwards, against the pump?

Or is the Taco pump mounted in backwards? I looked for flow arrows on the pump but couldn't find any. How can I tell input side from output side of the pump.

Mark Eatherton

The Helen Keller method of pump direction...

THe water comes into the center of the impeller and discharges through the outer edges. So, if you feel the back side of the pump, you will feel the suction channel coming from one end of the pump and going to the center. The flattest part is the pump outlet. Some of the older gravity systems use to use the radiators as the expansion tank. You would bottom fill the system, but not vent any radiators, and the large bubble that was in each radiator would accept the expanding water. I know this because I ran into one once, and in my rookie wannabe ways, bled all the air out of the radiators, only to get called back due to a lifting relief valve. I added an expansion tank to the mix, and read about it in one of Dan's book some time later. It is entirely possible that they system is being pumped backwards, and the radiators really don't care. One way to find out for sure would be to shut of the pumps and fire the boiler. Gravity will tell you the correct direction the water is SUPPOSED to be flowing. If the circulator is pumping towards the expansion tank, that is a no no. If it is being pumped through the boiler backwards, all of your safety limit controls are in the wrong spot, ,and the system will run much hotter that is necessary to deliver comfort. It would be expensive to operate.Is the boiler a condensing boiler? ME PS, Sorry for the run on response. For some reason, I can't hit the return and get another paragraph. Not sure if it is the web site or my Mac. ME