[Equest-users] Secondary Loop Valve Type

Wed Aug 24 05:00:47 PDT 2016

If the primary loop is constant flow and the secondary loop is variable flow, I also suggest using a three-way valve. See DOE22Vol2-Dictionary_48r.pdf, page 241. DOE2 assumes a valve exists if the secondary loop has its own pump.

Christopher Jones, P. Eng.
Rowan Williams Davies & Irwin Inc.
Consulting Engineers & Scientists
901 King Street West, Suite 400, Toronto, Ontario, M5V 3H5
T: (519) 823-1311 ext 2052
M: (416) 697-0056

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Darryl Kasun via Equest-users
Sent: Tuesday, August 23, 2016 6:04 PM
To: David Berty
Cc: equest
Subject: Re: [Equest-users] Secondary Loop Valve Type

Great - that makes sense to me - thanks for you help David!

On Tue, Aug 23, 2016 at 2:54 PM, David Berty <dberty at baselineenergyconsulting.com<mailto:dberty at baselineenergyconsulting.com>> wrote:

Oh OK, I'm catching what you're pitching now.
I would enter that as a three way valve with no head loss as you suggested.

Anybody else done something different with this?

David Berty, P.E.
Baseline Energy Consulting
317.220.9272<tel:317.220.9272>

On Aug 23, 2016 5:46 PM, "Darryl Kasun" <darryl.kasun at gmail.com<mailto:darryl.kasun at gmail.com>> wrote:
Yup absolutely.  But there's no real valve at the primary/secondary connection - just a tee.

On Tue, Aug 23, 2016 at 2:44 PM, David Berty <dberty at baselineenergyconsulting.com<mailto:dberty at baselineenergyconsulting.com>> wrote:

Sounds to me like you have a three way valve at the primary-secondary interface. You said that the primary was constant, that most likely means a three way valve to ensure that primary pumps never vary in flow. What doesn't go to the secondary loop will return to the chiller. Does that make sense in your project design?

David Berty, P.E.
Baseline Energy Consulting
317.220.9272<tel:317.220.9272>

On Aug 23, 2016 5:35 PM, "Darryl Kasun" <darryl.kasun at gmail.com<mailto:darryl.kasun at gmail.com>> wrote:
Hi David,

The flow in the secondary loop definitely varies based on differential pressure setpoints.  There are two way valves at reheat coils, reflected ceiling plans, etc.  And I've entered this input (two-way valve) at the thermal zone level.

I guess I'm confused at the circulation loop level.  In this window, there is also an "valve type" input for the secondary loop.  I know the primary loop is constant and the secondary loop is variable so I'm thinking this input should be "two-way valve" again.  These two inputs seem redundant to me...

On Tue, Aug 23, 2016 at 2:12 PM, David Berty <dberty at baselineenergyconsulting.com<mailto:dberty at baselineenergyconsulting.com>> wrote:

Darryl,
A three-way valve will maintain constant total branch or loop flow by modulating the flow to either the coil or directly to the return line. A two-way valve will modulate open or closed to maintain a flow or temperature (usually leaving air temp), as it closes it will reduce the total loop or branch flow proportionally. 3 way valves are not generally an acceptable choice because they run counter to the desire to reduce flow to reduce energy consumption. These valves are usually at the coil but can be at the primary secondary interface they perform the same function in general at either location. Smaller systems that might lack sufficient diversity to ensure a minimum level of system flow sometimes use these valves to ensure that the pumps don't "dead-head".

David Berty, P.E.
Baseline Energy Consulting
317.220.9272<tel:317.220.9272>

On Aug 23, 2016 2:17 PM, "Darryl Kasun via Equest-users" <equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>> wrote:
Hi eQUESTers,

For a secondary loop, there is an input for valve type - either three way or two way.  Can anyone provide a schematic or quick explanation of the difference between how these two valves control the flow from the primary?  Is this input assuming there is a valve at the secondary loop connection?  If there is a simply a tee at the secondary connection, can the valve head input be zero?

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