[equest-users]

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Greetings-
I have set up PVAV systems with hot water coils. I am getting error messages (See Below) for each of my systems. On the LS-S reports, heating capacity for unit and zones is zero, but I do have hot water coils and a boiler loop, etc.

See below,
Thansk,
W. Peter Anderson, P.E

**WARNING**********************************************************************
ZONE EL1 NE Perim Zn (G.NE2)

might have insufficient heating capability.

Check that the SYSTEM or ZONE HEATING-CAPACITY plus this

ZONEs BASEBOARD-RATING is adequate to maintain the ZONE

specified DESIGN-HEAT-T for the calculated peak ZONE load

(see LS-A or LS-B for the ZONE peak load.)

SYSTEM HVAC-1

which supplies the above listed ZONE, has a design heating

coil exit temperature, HEAT-SET-T,(plus any zone reheat)

below its MAX-SUPPLY-T or the ZONE DESIGN-HEAT-T, which

might account for the insufficient heating capability.

**WARNING**********************************************************************

ZONE EL4 East Perim Zn (G.E2)

might have insufficient heating capability.

Check that the SYSTEM or ZONE HEATING-CAPACITY plus this

ZONEs BASEBOARD-RATING is adequate to maintain the ZONE

specified DESIGN-HEAT-T for the calculated peak ZONE load

(see LS-A or LS-B for the ZONE peak load.)

SYSTEM HVAC-1

which supplies the above listed ZONE, has a design heating

coil exit temperature, HEAT-SET-T,(plus any zone reheat)

below its MAX-SUPPLY-T or the ZONE DESIGN-HEAT-T, which

might account for the insufficient heating capability.

**WARNING**********************************************************************

PREHEAT/HEATING-CAPACITY in SYSTEM HVAC-1

is too low to provide the requested supply temperature for

the calculated mixed air temperature using total ZONE loads

(on LS-A/B) and SYSTEM design parameters, plus outside air

conditions (on LS-C), and specified capacities & air flows.

Requested temperature is 55.00 calculated is -3.14

Check HEATING-CAPACITY, HEAT-SET-T, PRE-HEAT-T, MAX-SUPPLY-T,

DESIGN-HEAT-T, and ZONE loads for consistency.

W. Peter Anderson's picture
Joined: 2011-09-30
Reputation: 0

One item that can cause this error notice on VAV systems is if you have not selected zone coils. Also, you need to watch your values for Zone Entering Max Supply Temp, Reheat Delta T, and Hot Deck Max Leaving Temp to ensure they are reasonable.

Tim Dion's picture
Offline
Joined: 2011-09-30
Reputation: 0

W. Peter,

Check your zone airflows - if too low, it will take quite a bit of heat from the coil to change the space temperature. 1 cfm/SF of supply air is typical for many building types and spaces with standard ventilation requirements.

Check your reheat deltaT - this delta plus your preheat coil in your air handler need to be higher than your space setpoint

Check your zone supply air temperature - I think eQuest defaults to 95; I would bump this up to 105.

If you have simplified the zoning of the building you may want to break these problem spaces up into smaller zones.

You can also override your zone coil capacities, but should coordinate this with the mechanical designer to ensure that your modeling is realistic (for example you have simplified and combined several zones; make sure that the coil capacity is at least the summation of all these zones).

Good luck.

Jon Evans, PE, LEED AP

Jon Evans's picture
Offline
Joined: 2011-09-30
Reputation: 0

Thanks, I will give this a try

W. Peter Anderson's picture
Joined: 2011-09-30
Reputation: 0

I left to defualt values, but will check.

Thanks,
Peter

W. Peter Anderson's picture
Joined: 2011-09-30
Reputation: 0