Heating problems....

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This is still my first time creating my simulation and I thought I was on the right track...
I have a 100% OA unit with a preheat coil and chilled water cooling coils to maintain a 52 deg off the coil. The zones are
handled by singe duct, straight VAV terminal units with hot water reheat coils. I have set all
the zone set points to 72 degrees and I am getting a message that reads as shown below. I have
inputted the heating capacity for the preheat coil and the capacity for heating in the zonal VAV terminal unit.
Just to see what would happen I grossly oversized the VAV heating capacity to see if the error would be fixed,
it did not. I checked the LS-B space peak loads and it shows that the zone heating capacity required is only 25% of what I am inputting. Please help, I have no clue what I am doing wrong.


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.)


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.



Jeff Schorsch's picture
Joined: 2011-09-30
Reputation: 0

Thank you for responding. When I do a simulation it aborts the run, then I cant see the SS-F / SS-R reports.

Jeff Schorsch's picture
Joined: 2011-09-30
Reputation: 0


I would check the value of "Reheat Delta T" under Heating > Coil Cap/Control
on your system. This value sets a limit on the change in supply air
temperature as it passes through the terminal unit reheat coils. The default
of 30 F often causes this warning for me. For example if your air handler
discharge temperature is 55 F and your desired zone supply temperature is 100
F, your "Reheat Delta T" would need to be 45 to allow this to happen in the
simulation. The default of 30 would only allow 85 F zone supply air

Jay Keazer, EI

Jay Keazer's picture
Joined: 2011-09-30
Reputation: 0