UNWANTED FLOW

smklin

I have a system where I get unwanted flow through my zones. The system is a 399 tt piped with seperator the near boiler piping is 2'' the zone piping is 2'' the seperator is a 4'' . the boiler pump is a 26-150.I have a 30 or 40 gal indirect on there it is piped with close spaced tees on the boiler side . When i get a call for heat on the indirect it pushes water through my Zones the zone pumps. I have s 26-150 at about 20gal a piece for each zone. The indirect has a 26-99 on their. I unpluged my zone pumps. To check the unwanted flow. THANKS FOR YOUR VALUABLE TIME MERRY CHRISTMAS

furnacefigher15

You most likely need flow control valves on the zones to stop the gravity heating - or internal check valves on the pumps.

Pictures of the piping would also help determine what else might be hapening

smklin

how do i put a pic on here

smklin

the pumps have internal checks

lchmb

sounds like an internal flow check has failed. Is this a new problem or new system and have trouble from the start? click on the attach image/picture to put a photo on here..

Paul48

Hmmm........That should not be possible, with everything on the boiler side of a hydraulic separator.

smklin

The zones are not on the boiler side of the seperator the indirect is. How can a internal check cause it? Water is going the correct way it should flow . Is the 2'' piping to small?

Paul48

I know........Here's my thinking. Any, and all the flow is occurring on the primary(boiler) side of the separator. How can you be getting ghost flow on the secondary (system) side?

furnacefigher15

If the primary pump has more capacity then required, the pressure can lift the internal check of the other zones, and once lifted, gravity flow will start.

Theory and reality don't always align. Most of the time it does, but you have a situation where it does not. I have had this hapen to me before.

The solution is more resistance on the zoned secondary. Either another anti flow device, such as a flow control valve, or a physical zone valve that opens first, then an end switch to start the pump.

hot rod

sounds like an awful lot of zone pump also?

If you have a properly sized and installed separator, it is almost unheard of to get secondary side ghost flow? I have seen it on primary secondary piping however. I'd always check both S&R on P/S takeoff tees.

furnacefigher15

One more thing to look into is pump control scheem. If the indirect pump has enough flow capacity for the boiler, then you need to make sure the boilers pump is off during indirect only operation.

Its worth a try anyway, before making any major piping alterations.