[Equest-users] Secondary Loop Valve Type

[David Berty via Equest-users]

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

On Aug 23, 2016 5:35 PM, "Darryl Kasun" <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@
> 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
>>
>> On Aug 23, 2016 2:17 PM, "Darryl Kasun via Equest-users" <
>> 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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