some problems after piping in buffer tank

Rodney Summers

If you have continuous circ in the circuit with the headers and buffer tank and the flowchecks are swingvalves, odds are you are getting some flow in your zones. Spring loaded valves are better, say with a 1.5 lb opening pressure. The easy way ti check is to disable the continuous circ pump ad see if the zones cool off.

Dave F_2

some problems after piping in buffer tank

We just finished piping a buffer tank to ourlow mass coipper tube boiler this past weekend. It originally had a deadended supply header with 5 individual zone pumps coming off a boiler loop and a deadended return header returning to the boiler loop.
We put a buffer tank in and piped it to the boiler via 2" copper pipe. A Taco 0010 pump pumps water into the boiler and through the heat exchanger. The water comes out of the boiler and passes through a swingcheck valve. The 2" pipe then tees to the 1.5" supply header before entering the top of the tank. At the bottom of the tank , the 1.5" return header is teed to the pipe that returns water through the boiler.
Do you have any ideas why all zones remain hot even when pumps are not running?
I will post some pics once I get the camera batteries replaced.
Thanks.
Dave

Ed_26

hot zones

constant circ. on buffer tank?

Guy_6

ghost

Do the zones have check valves? If not, ghost flow (gravity)is the culprit.

Dave_61

Here is a schematic of the system...

Dave_61

schematic

Here is the schematic of what we have...

Dave_82

tank

The zones all have flowchecks just beyond the pumps. Could our expansion tank be too small? It is an Extrol model 60. But now we have about 90 gallons of water/glycol in a 50/50 mixture in the system. What would be the correct size extrol?