BOC TECHNICAL WEBINAR SERIES

THE ESSENTIAL CREDENTIALN O R T H W E S TENERGY EFFICIENCY COUNCIL

SPEAKERS:Kevin Fish, Sr. Associate, Strategic Energy Group

Scott Lindquist, Operations Manager,University of New Hampshire

www.TheBOC.info

Troubleshooting Common Air Handler Problems

May 17, 2017 11:00am Pacific Time

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This presentation is intended for use by the Building Operator Certification program. No copy or use of this presentation should occur without the permission of NEEC and speakers.

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Learning Objectives

▪ Understand the configuration of an air handling unit

▪ Understand common problems and how to address them

▪ Learn different tools and devices to measure air flow

▪ Understand and learn to establish and document procedures for troubleshooting & response

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Today’s Speakers

Kevin Fish Scott Lindquist

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▪ Understand the configuration (hardware and software)!

▪ Get eyes on control system (if BAS)

▪ Get eyes on the unit

▪ Understand the root cause

▪ Consider possible undesired consequences

▪ Make changes as small and as temporary…

In general, when problem arises…

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Hardware configuration

▪ Type of unit, return/relief, control, volume control

▪ Outside air capacity & damper config.

▪ Type of terminal units, TU control, TU reheat

▪ Type of heating / cooling in AHU

▪ Location of controlling duct static pressure (DSP) sensor

Understand the configuration /

intent of the AHU!

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Understand the configuration /

intent of the AHU (cont’d)

Software configuration

▪ What is the official setting for the following? How was it determined?

▪ Optimal start; Night Low Limit setpoint

▪ Damper control: Min OA & Economizer

▪ CO2 sensor setpoints

▪ DAT & DSP setpoint / reset

▪ Night setback of TU airflow

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▪ Electrical / VFD / Control problem

▪ Broken belts

▪ Failed motor

▪ Fan bearing failure

▪ Freeze stat trip…

AHU won’t run / no airflow

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(Trouble achieving DSP setpoint or VFD at higher than normal speed)

▪ Obstructed coils, OA intakes, filters, turning vanes

▪ Fan turning backwards

▪ Fan bearing issues

▪ VFD issue

▪ DSP setpoint too low / high

▪ Damper issues

▪ AHU door left open, duct separation

Lack of sufficient airflow

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▪ Insufficient water temp or pressure

▪ Leaky valves

▪ Faulty control signal to valves

▪ Valve won’t open completely

▪ DX cooling or gas pack issues

Lack of sufficient heating / cooling

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▪ Improper settings on MinOA and OA dampers

▪ Linkage issues

▪ Actuator issues

▪ Bound/frozen dampers

▪ Blade “flops”

Damper / Economizer issues

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▪ Document hardware and software configurations

▪ Look for control points that are overridden / manual

▪ Focus on root causes

▪ Address issues at the most local level

▪ What is the least energy intensive response

Establish and document procedures for troubleshooting & response

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Periodic scheduled review is highly recommended

▪ Physical checks of AHU

▪ Review of BAS graphic screens

▪ Trend review of AHU function

3 types of verifications

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Physical checks of AHU

▪ Function of dampers (OAD, RAD & EAD)

▪ CHW and HW valves close completely

▪ Check / replace filters

▪ Clean OA intakes, reclaim coils, airflow sensors

▪ Confirm sensor calibration (OA, airflow, others)

3 types of verifications (cont’d)

Sensor Error Causes

• Never Calibrated

• Only a simple comparison check

• Calibrated with inaccurate reference tool

• Incorrect placement (esp. OSA, mixed air and pressure)

• Incorrect type sensor (i.e. bulb type vs averaging)

• Failed, cut wires or offline sensors (can paralyze control algorithms)

• Deteriorated connections (Water intrusion/condensation causes corrosion

Outside Air Temperature Sensors

▪ Starting/stopping equipment

▪ Used for locking out heating and cooling

modes

▪ Resetting of setpoints

▪ Also for freeze protection

Why would Outside air temperature be a critical sensor?

Location, location, location

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Review of BAS graphic screens

▪ Set-points and resets are reasonable / official

▪ No overridden values

▪ Point values are reasonable (especially in relation to each other)

▪ Summary screen of terminal unit damper positions

3 types of verifications (cont’d)

What’s wrong with this picture?

Simultaneous Heating & CoolingHeating valve open 26% while Cooling valve open 23%

What’s wrong with this picture?

Over-Economizing! OSA damper 100% open

AND Heating Valve open 20% !

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Trend review of AHU function

▪ Scheduling and Optimal Start

▪ Values change, and change reasonably

▪ Economizer function

▪ Setpoints are reset and satisfied / maintained

▪ Fan speeds modulate

▪ Simultaneous heating & cooling?

3 types of verifications (cont’d)

time for … Q&A

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Air apparatus Test Report

time for … Q&A

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Washington & Oregon• Smart Buildings Center - http://www.smartbuildingscenter.org/tool-library/

Idaho

• University of Idaho – Integrated Design Lab - http://www.idlboise.com/tool-loan-library

California• Pacific Gas & Electric - http://www.pge.com/pec/tll/

• Sonoma County - http://sonomacountyenergy.org/resources/contractor-resource-center/tool-lending-library/

• Southern California Edison - https://www.sce.com/wps/portal/home/business/consulting-services/energy-educationcenters/tulare/!ut/p/b1/hdBNb4MwDAbgX8OVmCRldDdDGSRizRjVSnOZ6MQoEyUVZeXvL6u6w759s_W8lmyiSUl0X53aphpb01fde6_9RykW6CWcikDiDMRSFWmMdzSaexZsLIBfCuG__JroM_GCBFNRgFB8wUGEqyy8CW4Z9-EbCIVvQYSRUhIg97-C5P6KgpAPcaZCjwKnFzBPIE6lsmCVMxAsh2WByAA-NvxxhSS66cz2_JEN9lsWNEQP9XM91IP7OtjxbhwPx2sHHJimyW2MabrafTJ7B36K7MxxJOVnSQ77ElrxMutOGb4BKlagaA!!/dl4/d5/L2dBISEvZ0FBIS9nQSEh/?from=agtac

• San Diego Gas & Electric - https://c95021.eos-intl.net/C95021/OPAC/Index.aspx

New York• CUNY Building Performance Lab - http://www.cunybpl.org

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➢September TBD - Addressing Hot and Cold Calls –What’s your Procedure?

➢ October 18 - Building Re-tuning without a Building Automation Systems

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