Carrier 38TDB Guía para resolver problemas descargar pdf (Pagina 17)

Software Revs 3,5,6,8,10, 12 Infinity /Evolution Troubleshooting (Rev. 2)

10-12-2006

Options to control over zone conditioning:

• Set airflow limits in small zones to MAX if air noise is acceptable

• Set points should be set no more than 3 degrees different from zone to zone

• Evaluate duct system and upsize or add supplies and returns where required

• Evaluate structure design for zoning suitability

The system will allow some over conditioning to ensure minimum airflow through the equipment

and maintain selected airflow limits. The system may not be capable of wide set point

differences. For example, if a customer wants the upstairs bedroom at 62 degrees in heating

and the downstairs zone at 70, the upstairs zone may be allowed to over condition (up to 67

deg) in order to satisfy minimum airflow requirements through the equipment, and /or selected

airflow limits. Below is a description of this process.

Airflow limits and equipment protection

The maximum airflow allowed into a zone is based on the relative size of the zone determined

by the duct assessment, and the airflow limits selected for each zone. Airflow limits are set to

high as factory default. This means that 200% of the assessed air flow is allowed into the zone.

Example if a zone size is determined to be 25% of the entire system, and the maximum airflow

(heating or cooling) is 2000 cfm, the maximum airflow into this zone is 2000 x 25% x 200% =

1000cfm.

This airflow limit multiplier can be adjusted to reduce or increase allowable noise levels; Low =

100%, Med = 150%, Max = 210% (will not cause stage down when reached).

If the system determines that it cannot deliver the airflow into a zone that needs conditioning,

and that zone has an airflow limit selected, the system will take the following 4 steps:

1. Reduce airflow if possible

a. 275 CFM per ton minimum in high stage cooling (325 if Dehum airflow set to

High). 175 CFM per ton in low stage cooling for Bristol units. Minimum airflow for

Copeland 2-stage outdoor units will vary.

b. Comfort Heat airflow is minimum for heat pump heating (3.5 x outdoor temp +

137) cfm /ton

c. Use heat pump comfort airflow as minimum if AC Airflow is Efficiency or MAX

c. No adjustment for furnace heating

2. Dump air to zones set to Unoccupied

a. Unoccupied zones can be conditioned up to the most conditioned set point

3. Dump air to zones with lower set points

a. Zones with lower set points may be conditioned to within 3 deg of the most

conditioned set point.

b. Increase or decrease all zones an additional 0.75 deg

4. Stage down equipment

a. Equipment will stage down or shut off if necessary

b. Fault history will record an event of (AIRFLOW LIMITED SHUTDOWN

OCCURRED)

c. If shut down occurs, other zones need to call before equipment will resume

operation

Options if Airflow Limits are not satisfactory and AIRFLOW LIMITED events are

occurring:

• Increase airflow setting to MAX in suspect zones if air noise is acceptable. The system

will not stage down when the airflow limit is set to MAX. In extreme cases, even a zone

set to MAX may cause a shut down on static pressure if the minimum airflow through

the equipment cannot be maintained. “EXCESS STATIC PRESSURE” will be recorded

in these cases.

• Evaluate duct design and make improvements where necessary

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