zone valves on return

Unknown

heat can migrate up through a single pipe with the other end closed(via ZV), you don`t need an open loop,, how do you think joist mounted expansion tanks waterlog? Why would Siggy suggest thermal traps even though <I>flow checks</i> may be used?<BR><BR>Dave

chuck172

Boiler Return header getting busy


My zone valves are piped to a return header with the circulator flowing into the boiler and now I'm adding a large basement zone with it's own circulater, also a Tarm boiler that will pump to the oil boiler's return. Are there any problems with piping two additional lines with circulater pumps into the existing return? I'm thinking check valves on the pump discharges.

Unknown

Return ZVs

With ZVs on the return the heated water will migrate faster by gravity to the zones not calling for heat.

Dave

tomd7735

ZVs on return

With the zones that aren't calling, the only heat 'migration' would be through conduction of the copper pipe. To get a gravity feed going, you need an open loop, not so when the ZV's shut.
I've heard that one should pump away the exp. tank, specially if that's where your water feed comes in.
check valves would only be necessary if you have a single zone with DHW. Otherwise the ZVs will check flow.

ALH_4

ZV on Return

I have always felt that putting the zone valves on the return was better because the temperature is lower. Lower temps generally extend component life. if the zone valve is shutting off completely, there should be no heat migration. Be careful of the pump head and use a differential pressure bypass to avoid pumping past closed zone valves.