hvac system survey ii - the hardy...

733 Ponte Vedra Blvd HVAC Survey II -- Advantek Consulting Engineering -- 2-5-2014

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HVAC SYSTEM SURVEY II Advantek Consulting EngineeringAdvantek Consulting EngineeringAdvantek Consulting EngineeringAdvantek Consulting Engineering | February 5, 2014 | February 5, 2014 | February 5, 2014 | February 5, 2014

Subject: Hoffecker House, 733 Ponte Vedra Blvd

Location: Ponte Vedra, St. John’s County Florida 32082

I. BACKGROUND

An initial site survey was conducted on October 30, 2013 and an Initial Report was

provided on November 8, 2013. The initial survey report describes several

recommendations for improving the cooling and dehumidification performance of the

five air-conditioning systems serving the 9,601 square foot home. Four of the

recommendations are addressed in this report based on work done at the home

November 21-23, 2013: performing a detailed cooling & heating load analysis,

diagnosing the under-performance of systems 1 and 2, checking airflow and fan control

programming on all AHUs, and performing envelope air-tightness testing.

II. FINDINGS

1. Cooling Load Analysis

An accurate zone-by-zone cooling load calculation was performed to positively identify

units that are significantly over- or under-sized and develop corrective actions.

Computed cooling loads were compared against the cooling load calculations submitted

with the 2006 permit application, and against the actual cooling capacity versus the

nominal nameplate rated capacity. Actual capacity is about 10% less than the rated

capacity for all systems, see Table 1. Computed cooling load is greater than both the

permitted cooling calculation and the actual cooling capacity for all systems except #1.

TABLE 1: HVAC CAPACITIES AND LOADS

STAGE 1 STAGE 2 Cool Tons Heat kW Cool Tons Heat kW

#1 Kitchen, South 1flr 5 3.4 4.6 3.3 4.4 13.9 4.4 13.9

1 Great Room 1flr 4.5 16.6

2 Loft 2flr 2.0 3.7

1 North bedrooms 1flr 1.6 10.3

2 North bedroom 2flr 1.4 2.9

#4 Master Suite 2lr 3 1.9 2.7 2.4 3.9 11.4 3.9 11.4

#5 Study, bedrooms 2flr 3 1.9 2.7 2.4 3.3 8.6 3.3 8.6

17 11.1 15.3 12.3 21.0 67.4 18.6 67.4

1 - NOM TONS is nameplate cooling capacity tonnage

2 - ACT TONS is actual cooling capacity at 74F / 63wb / 55%rh and 95F ambient.

3 - PERMIT references cooling load calculation submitted with permit application 8/3/2006

2.1

TOTAL

PERMIT3 COMPUTED LOADS PEAK LOADS

4.93.6

1.8

ACT TONS2

2.6

1.4#3 2

NOM

TONS1

4

SYSTEM ZONE SERVES

#2

13.2none

4.2 20.3

Pops

Typewritten Text

EXHIBIT "G1"


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Under-sizing is preferable to over-sizing since dehumidification performance improves

with longer compressor run time. With modified dehumidification controls, all systems

will be capable of providing ample dehumidification once the house is air-tightened and

slightly pressurized. Direct comparison of computed peak cooling load with the actual

available cooling capacity is shown in Table 2, and differences of more than ¾ -Ton

(9,000 Btuh) are highlighted in red. None of the systems are over-sized.

System #2 serving the Great Room and system #4 serving the Master Suite are

significantly undersized. When ready for replacement, outdoor compressor unit #2

should be increased from 4 to 5 tons. System #4 capacity shortfall can be mitigated with

air duct modifications and by directing more air to the occupied spaces and less to the

walk-in closets. Also, system #5 serving the study and bedrooms is undersized,

however, the next available equipment model would be too large. System #5 can be

mitigated with air duct modifications and air-tightening. Detailed results of the zone-by-

zone load analysis are provided at the end of this report. In summary:

• The permitted cooling load calculations submitted by the mechanical contractor in

2006 under-estimated the required equipment capacity, and missed two zones

entirely, resulting in systems having inadequate capacity.

• Actual cooling capacity is significantly less than the equipment nameplate rating for

all systems. This is good for dehumidification, but bad for temperature control.

• Even with modified fan programming and air duct mitigation measures, one of the

three under-sized systems should be increased in size when ready for replacement.

2. System #1 and #2 Under-Performance

Air handler AHU-1 condensate overflow switch was found to be bad (not making

contact) and incorrectly wired. The switch was found wired in series between

thermostat Y1 to the AHU only, so when the thermostat called for first-stage cooling the

TABLE 2: CAPACITY VS LOAD

PEAK

Cool Tons

#1 4.5 1750 4.4 0.1 3%

#4 2.7 1350 3.9 -1.2 -30%

#5 2.7 1350 3.3 -0.6 -17%

TOTAL 15.4 7150 18.6 -3.2 -17%

4.9

2.1

-1.3 -26%

-0.3 -14%

SHORT / OVER

3.6

1.8

ACT

TONS@CFM

1800

900

SYSTEM

#2

#3


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compressor energized but the fan speed stayed at the “circulate” speed setting. This is

likely the cause of poor cooling performance and ‘sweating’ diffusers noted by the

homeowners. The condensate switch should be replaced and wired in series with the R

terminal so the system (both the indoor air handler and the outdoor compressor) shuts

down if there is a condensate overflow event. The switch was temporarily

disconnected to restore operation, and the homeowner was advised. In any case,

condensate overflow on AHU-1 is unlikely because it is equipped with a condensate

pump.

System #2 was found low on refrigerant charge. Addition of 7/3-lbs/oz was needed; the

nominal system charge is 11/3-lbs/oz. The homeowner was advised that system #2 has

a considerable leak(s) that must be found and repaired before further refrigerant

additions can be made. This explains the poor performance found during testing.

3. Control Programming

The airflow and fan control programming was checked on all AHUs. Thermostat

program values were set to maximize dehumidification capability; however, thermostats

2-1, 2-2, and 3-1 are model versions that do not have a dehumidification feature, as

listed in Table 3. These three thermostats should be replaced with models to match the

other four TH8321U1006, see source below for ordering information1.

The dehumidification model of the Honeywell thermostat also does not have a “DH”

terminal for a true dehumidify signal. Instead, the thermostat simply energizes cooling

when there is a call for dehumidification, so the AHU controls should be modified to

create a dehumidification sequence. The existing controls will over-cool the space up to

3 degrees-F below setpoint in an attempt to satisfy the dehumidification call.

Alternatively, all thermostats could be replaced with a model having a true

dehumidification sequence, and the air handler connections modified accordingly, if the

homeowner prefers.

1 http://www.pexsupply.com/Honeywell-TH8321U1006-VisionPro-Thermostat-3H-2C-w-

Dehumidification-Control-3910000-p?gclid=CNGAxa6107wCFaxxOgodLiIAdw

TABLE 3: THERMOSTAT DEHUMIDIFICATION

#1 TH8321U1006 Yes

1 TH8320U1008 No

2 TH8320U1008 No

1 TH8320U1008 No

2 TH8321U1006 Yes

#4 TH8321U1006 Yes

#5 TH8321U1006 Yes

SYSTEM ZONETHERMOSTAT

Honeywell Model

#2

#3

DeH


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Existing AHU airflow and settings are listed in Table 4. These settings are not optimal

for the needed dehumidification and to satisfy the cooling demand. New settings

should be determined onsite after duct modifications are made, because external static

pressure (ESP) will need to be tested and airflow adjustments made iteratively to find

the best settings. Optimal settings along with modification of AHU controls will

significantly improve dehumidification performance and comfort.

4. Envelope Air-Tightness

Envelope infiltration testing using two instrumented blower doors and three static

pressure gauges was performed to (a) measure the home’s infiltration rate, (b) identify

locations needing sealing or other envelope remediation, and (c) determine the

required ventilation rate for pressurization. Observed leak locations are fireplace flues

(without dampers); the East wall notably around windows in the dining area, and

electrical boxes and baseboards in the bedroom; the North wall notably around

windows; and the recessed light fixtures and audio speakers in the outdoor ceilings

above the second floor Master Suite balcony, Study balcony, and the first floor terrace.

Overall, the envelope can be characterized as “moderately leaky”.

The chart below shows tested air leakage CFM (cubic feet per minute) versus the

pressure difference between indoors and outdoors. The various standard leakage

metrics shown on the chart were calculated from the power curve using generally

accepted formulae. ACH50 is air changes per hour at a 50 Pa (0.2 in-wc or about 40 mph

wind force) pressure differential. CFMnat is the estimated natural infiltration airflow rate

at 10 Pa (0.04 in-wc or about 9 mph wind force) pressure differential; 263 cfm is

somewhat high and indicates this space would benefit from positive ventilation and

pressurization. Minimum code-required ventilation for this house is 149 cfm. ELA is

the effective leakage area at 97 square inches.

TABLE 4: EXISTING AIRFLOW SETTINGS AND CFM

AHU 1 2 3 4 5 6 7 8 ESP in-wc Cool CFM Heat CFM

AIRFLOW

1280

0.59 1130

1500

1400

1125

600

600

4

5

0.58 1950

0.16 1595

0.17 840

0.51

SETTINGS AS FOUND

1

3

2


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The tested value of ACH50=4.9 is 26% leakier than the median of U.S. homes (3.9), and

nearly twice as leaky as a new energy efficient home. The applicable building code is

the 2012 IEEC Standard, which limits air leakage to a value of ACH50 less than 5 for most

of Florida and less than 3 for the northern areas. House pressurization to 5 Pa (0.02 in-

wc) would require 2100 cfm without air-tightening, which is an impractically large

airflow for a house of this size. Achieving ACH50 = 3 will require a 40% increase in air-

tightness to provide minimal 2.5 Pa (0.01 in-wc) pressurization with 850 cfm of

dehumidified fresh air. A blower door follow-up test will be needed after air-tightening.

END OF REPORT

Final review by:

2/14/2014 _________________________________________ Michael West, PhD, PE Date ADVANTEK CONSULTING ENGINEERING, INC. This is an initial report based on limited observations. The recommendations in this report are presented in good faith and believed to be correct, however, items needing further investigation and engineering are noted in the report.

Envelope Air Leakage Test Results[733 Ponte Vedra Blvd 32082]

CFM = 825.6 [Pa] 0.5767

R2 = 0.99

ACH50 = 4.9 Q50 = 7881

ACHnat = 0.16 Qnat = 263

ELA = 97 in2

0

2000

4000

6000

8000

10000

0 10 20 30 40 50 60 70

Negative Space Pressure [Pa]

Airflow

[C

FM

]

HOFFECKER HOUSE PHOTOS 11-21-2013

IR-1. Air leakage from outdoors around electrical box, moisture at window corners and

baseboard.

IR-2. Supply air leakage between register box and register, behind drywall.

IR-3. Supply air leakage at flex-duct collar joint at distribution box.

IR-4. Possible supply air leakage between register box and register.

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day (Solar Time)

January To June - Hoffecker Zone 1 - Kitchen

Total Cooling Load - Tons

Jan Feb Mar Apr May Jun

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


July To December - Hoffecker Zone 1 - Kitchen


Jul Aug Sep Oct Nov Dec

Peak Cooling Load Summary Report

Project Name : Hoffecker Zone 1 - KitchenProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013

Weather Station : Jacksonville, Mayport Naval, FloridaLatitude : 30.40 Deg NorthLongitude : 81.42 Deg WestElevation : 16.00 Feet

Outside Design DB Temp : 95.00 Deg FOutside Design WB Temp : 78.00 Deg FDaily Range : 15.30 Deg F

Inside Design DB Temp : 74.00 Deg FInside Design Rel Hum : 50.00 %RH

Peak Month : July Peak Hour : 11:00 AM, Solar Time

Summary of Heat Gains :Sensible Heat Latent Heat Total Heat

Item ( Ton ) ( Ton ) ( Ton )

Walls conduction 0.68 0.68Roof conduction 0.03 0.03Floor, ceiling, partitions 0.00 0.00Glass solar trans. 1.46 1.46Glass conduction 0.33 0.33Skylights 0.00 0.00Glass blocks 0.00 0.00Lights 0.00 0.00Electronic equipment 0.16 0.16Power equipment 0.18 0.18People 0.14 0.19 0.33Appliances 0.20 0.15 0.35Infiltration 0.20 0.47 0.67

Total Heat Gains 3.38 0.80 4.19

Sensible Heat Ratio : 0.81Ventilation Air : 40.00 CFM

Ventilation Load 0.06 0.13 0.18

Total Cooling Load on Coils and Refrig. Apparatus 4.37

Heating Load Report

Project Name : Hoffecker Zone 1 - KitchenProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013


Outside Design DB Temp : 34.00 Deg FInside Design DB Temp : 72.00 Deg F

Summary of Heat Losses :Sensible Heat

Item ( Btu/h )

Walls above grade 7750.70Walls below grade 0.00Roof 240.63Glass 11884.79Skylights 0.00Glass blocks 0.00Floor above unheated space 0.00Floors on or below grade 12124.85Ceiling 0.00Partitions 0.00Infiltration 13792.31Ventilation 1641.60

Total Heat Losses 47434.88

Ventilation Air : 40.00 CFM

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


January To June - Hoffecker Zone 2-1 Great Room



-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


July To December - Hoffecker Zone 2-1 Great Room




Project Name : Hoffecker Zone 2-1 Great RoomProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15,2013




Peak Month : June Peak Hour : 11:00 AM, Solar Time








Heating Load Report

Project Name : Hoffecker Zone 2-1 Great RoomProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15,2013




Item ( Btu/h )




-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


January To June - Hoffecker Zone 2-2 Loft



-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


July To December - Hoffecker Zone 2-2 Loft




Project Name : Hoffecker Zone 2-2 LoftProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013




Peak Month : July Peak Hour : 5:00 PM, Solar Time








Heating Load Report

Project Name : Hoffecker Zone 2-2 LoftProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013




Item ( Btu/h )




-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


January To June - Hoffecker Zone 3-1 Bedrooms Flr1



-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


July To December - Hoffecker Zone 3-1 Bedrooms Flr1




Project Name : Hoffecker Zone 3-1 Bedrooms Flr1Project Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013




Peak Month : June Peak Hour : 5:00 PM, Solar Time








Heating Load Report

Project Name : Hoffecker Zone 3-1 Bedrooms Flr1Project Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013




Item ( Btu/h )




-0.60

-0.40

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


January To June - Hoffecker Zone 3-2 Bed North Flr2



-0.60

-0.40

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


July To December - Hoffecker Zone 3-2 Bed North Flr2




Project Name : Hoffecker Zone 3-2 Bed North Flr2Project Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15,2013












Heating Load Report

Project Name : Hoffecker Zone 3-2 Bed North Flr2Project Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15,2013




Item ( Btu/h )




-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


January To June - Hoffecker Zone 4 Master Suite



-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


July To December - Hoffecker Zone 4 Master Suite




Project Name : Hoffecker Zone 4 Master SuiteProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013












Heating Load Report

Project Name : Hoffecker Zone 4 Master SuiteProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013




Item ( Btu/h )




-2.00

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


January To June - Hoffecker Zone 5 - Study & Bedrms



-2.00

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Cooling Load (T

ons)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24


July To December - Hoffecker Zone 5 - Study & Bedrms




Project Name : Hoffecker Zone 5 - Study & BedrmsProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013












Heating Load Report

Project Name : Hoffecker Zone 5 - Study & BedrmsProject Address : 733 Ponte Vedra Blvd, Ponte Vedra Beach, FLProject Designer : Devin PeckDate : Dec 15, 2013




Item ( Btu/h )




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