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| Overview

Trim & Respond is a proprietary algorithm of Guideline 36. It resets a setpoint for pressure, temperature, or other variables at an air handler or plant. It reduces the setpoint at a fixed rate until a zone is no longer satisfied and generates a request. When a sufficient number of requests are present, the setpoint is increased in response.

The importance of each zone’s requests can be adjusted to ensure that critical zones are always satisfied. When a sufficient number of requests no longer exist, the setpoint resumes decreasing at its fixed rate. A running total of the requests generated by each zone is kept identifying zones that are driving the reset logic. 

| Guideline 36 to ClimaVision System

At ClimaVision, we are keen and cautious about the adherence to Guideline 36. As a part of this, all our terminal profile-related algorithms follow them in every sequence of its operation. For more information on the same refer to VAV Terminal Profile- Damper Position Calculation & Operation.

For the Trim and response sequences, we have implemented the corresponding influencing parameters as tuners, and they play a vital role in energy savings. For more information on the same refer Trim & Respond Logic.

| Guideline 36 Requests Generation for Trim Respond

The requests for the trim & respond logic algorithm are usually driven by the temperatures of the terminal side zone. Requests are generated based on the following conditions.

  • If the zone temperature exceeds the zone’s cooling setpoint by 3°C (5°F) for 2 minutes.
  • Else, if the zone temperature exceeds the zone’s cooling setpoint by 2°C (3°F) for 2 minutes.
  • Else, if the Cooling Loop is greater than 95%, send 1 request until the Cooling Loop is less than 85%.
  • Else, if the Cooling Loop is less than 95%, send 0 requests.

| ClimaVision Requests Generation for Trim & Respond

At ClimaVision, we have brought all of the aspects of guideline 36 together and the request generation is driven by the Damper position (%), with which we have the following conditional for the rest generation in the system.

DamperOpen.PNG

  • If the damper position is greater than 95%, the zone sends 3 requests.
  • If the damper position is greater than 85%, the zone sends 3 requests.
  • If the damper position is greater than 75%, the zone sends 3 requests.
  • Otherwise, the zone sends no requests

| Importance Multiplier as Zone Priority

The Importance multiplier is the concept of Guideline 36 that scales the number of requests the zone/system is generating. A value of zero causes the requests from that zone or system to be ignored.

A value greater than one can be used to effectively increase the number of requests from the zone/system based on the critical nature of the spaces served.

The Importance Multiplier is the Zone Priority in the ClimaVision system, the priority plays its role on scaling requests generated through the damper position (%)

Zone Priority.PNG

The system uses the following zone priority in place of the numerics in Guideline 36

  • No Priority
  • Low
  • Normal
  • High

The zone priorities are mapped to numeric values that, as follows

  • No Priority-0
  • Low-1
  • Normal- 2
  • High- 3
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