confirming a good furnace installationseventhwave.org/sites/default/files/b1revised.pdf ·...

2/20/2019

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Confirming A Good Furnace Installation

Adrian Scott, SlipstreamNorman Bair

What is Covered

• Key components of quality heating system installation

• Complete WX Furnace and Boiler checklists

• What to test and how

• Review contractor test results and when callback needed

• Sizing

• Refined considerations of gas pressure and airflow

Quality Assurance Inspection

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Replacement Gas Furnace Checklist

Used with HE+ Emergency installations


Used with Weatherization installations


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Taken from Heat Loss Calculation

Depends on Location

Return and supply sealed to furnace PMI


Taken from information

plate

Used when clocking

natural gas meters

BTU InputFrom

metering chart

For Multi‐Stage Heating Systems

Used when clocking

natural gas meters

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Replacement Boiler Checklist

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Taken from Heat Loss Calculation

Depends on Location


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Total for whole house

Total for whole house

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Taken from heating curve calculation

Taken at time of SSE Test

Replacement Boiler Checklist Must Be within PMI Range


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SSE Test Procedures for 90+ Furnaces

• Commonly between 30˚F and 65 or 70˚F.

• Ideally, temperature rise near high end

Temperature Rise Test

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Temperature Rise Test

DEHCR Required Testing Method

and

26

Supply Test Locations

Return test location

Static Pressure Test Locations

Method used to calculate Airflow

BTU /K

Fan Flow

Chart

Measured

Flow Plate

Temperature

Rise

Calculation

40 750 680 625

60 940 785 1254

60 815 827 891

40 646 552 658

60 958 901 1175

40 627 693 639

Fan Flow Comparison

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• Test hole measures system operating pressure • Baseline with Filter• With Flow Plate

• Can test for• Heat• Air Conditioning• Constant Airflow

Flow Plate Method Test Procedure

• SSE Testing Same as Gas Furnaces

• O2% (or CO2 %) Within Manufacturer’s Range

• CO ppm Under Manufacturer’s Maximum

Testing High Efficiency Boilers

• Test High Fire and Low Fire Mode

• Selecting Mode Varies with Make and Model


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Testing High Efficiency Boilers • Test High Fire and Low Fire Mode

• Selecting Mode Varies with Make and Model

• System Water tested for PH And Total Dissolved Solids

• Need to check Manual


Design Heat Load Calculations

1. Client name:2. Client address:3. City:4. Job Number:3. Client telephone:4. General dwelling description:5. Stories 1 Story6. Shielding Normal7. Heated floor area: 15048. Outside design temp.(ODT), 97.5%: -259. Volume of building (cubic feet): 1203210. Estimated/Actual CFM50 1236 ACH 0.4011. Design temperature (DTD) = Dwelling temp. - ODT = 95

TransmissionSurface Area(sq.ft) / R-Value = Btu/FhrAttic 1504 25 60.2Attic 0 1 0.0Attic 0 1 0.0Attic 0 1 0.0Attic 0 1 0.0Sidewall 1284 19 67.6Sidewall 0 1 0.0Sillbox 0 1 0.0Slab-On Grade (Lineal Feet) 0 0.74 0.0Foundation 297 7 42.4Foundation 0 1 0.0Floor 0 1 0.0Floor 0 1 0.0Window 200 1.5 133.3Window 0 1 0.0Door 0 1 0.0Door 0 1 0.0

Total Calculated Heat Loss Factor 303.5

Ventilation (Total cfm capacity) 0.432 0.0Infiltration 0.018 12032 0.40 86.6

Infiltration & Ventilation Heat Loss Factor 86.6

Grand total=heat loss coefficient(HLC)

Furnace Output Capacity Needed

Maximum Furnace Output Capacity

Comparison of heated floor area x BTU's/sq ft

DESIGN HEAT LOAD WORKSHEET

37062

42622

30 35 40

390.1

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Eau Claire design temperature is ‐20


1. Client name:

2. Client address:

3. City: Eau Claire

4. Job Number:

3. Client telephone:

4. General dwelling description:

5. Stories 2 Story

6. Shielding Normal

7. Heated floor area: 1572

8. Outside design temp.(ODT), 97.5%: ‐20

9. Volume of building (cubic feet): 12576

10. Estimated/Actual CFM50 2400 ACH 0.77

11. Design temperature (DTD) = Dwelling temp. ‐ ODT = 90

Design Temperatures

‐25˚

‐20˚

‐15˚

‐10˚

SPS 320‐325 Appendix A, Page 231https://docs.legis.wisconsin.gov/code/admin_code/sps/safety_and_buildings_and_environment/320_325/325_a.pdf


Use house temperature at 65 (not 70) degrees plus 20 = 85


1. Client name:

2. Client address:

3. City: Eau Claire

4. Job Number:

3. Client telephone:

4. General dwelling description:

5. Stories 2 Story

6. Shielding Normal

7. Heated floor area: 1572

8. Outside design temp.(ODT), 97.5%: ‐20

9. Volume of building (cubic feet): 12576

10. Estimated/Actual CFM50 2400 ACH 0.77

11. Design temperature (DTD) = Dwelling temp. ‐ ODT = 90

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Look at higher percent areas

TransmissionSurface Area(sq.ft) / R‐Value = Btu/FhrAttic 670 38 17.6 4%Attic 328 22 14.9 3%Attic 480 11 43.6 9%Attic 0 1 0.0Attic 0 1 0.0Sidewall 1218 11 110.7 24%Sidewall 0 1 0.0Sillbox 134 11 12.2 3%Slab‐On Grade (Lineal Feet) 0 0.74 0.0Foundation 134 1 134.0 29%Foundation 0 1 0.0Floor 0 1 0.0Floor 0 1 0.0Window 185 1.5 123.3 27%Window 0 1 0.0Door 54 8 6.8Door 0 1 0.0

Total Calculated Heat Loss Factor 463.2 100%

Are they reasonable?


63,679 Btu/hr oversizes. Existing furnace was 70,000 Btu/hr and 89% efficient.670.3 x 90 = 63,679 Btu/hr

76 0.432 32.8 5%0.018 12576 0.77 174.3 26%

207.1 31%

100%

100%

115%

InfiltrationVentilation (Total cfm capacity)

Grand total=heat loss coefficient(HLC)

Furnace Output Capacity Needed

Maximum Furnace Output Capacity

63679

73231

670.3Infiltration & Ventilation Heat Loss Factor

Ignore MaximumOutput Capacity

REScheck™

927 x 0.026 = 2424 x 85 = 2,029Btu/hr

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REScheck™

Should be zero

REScheck™

Is it reasonable?

Input Review

• Review all area and R‐value inputs• Are R‐values/U‐values after weatherization?• Is infiltration reasonable knowing blower

door test and expected air sealing reduction?• Is 8,000 Btu/hr reasonable?• Is 16,000 Btu/hr reasonable?

• Is Oversizing Factor zero?• What percentage of the total heat load is the

basement?• Is 40% too high?

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Oversizing

• No penalty with gas efficiency• Penalty with higher electricity use• Pay contractor more for less benefit• Temperature rise exceeds maximum

Too High Temperature Rise

• Is furnace oversized?• Examine design heat load calculation

• Reduce gas pressure until temperature rise okay• Is CO ppm ≤100 ppm?

• If right size, increase fan speed• Don’t let contractor install more ductwork

• Unless comfort issue• Unless furnace is right‐sized and above steps

followed

Oversizing ‐ Summary

Before contractor buys furnace to install• Look at all design heat load calculations• Scrutinize every heat load over 40,000 Btu/hr• Look at biggest numbers in design heat load

calculation• Is percent of each building component to total

reasonable?• If foundation half the heat load, bad input• Are R‐values/U‐values after weatherization?• What is smallest furnace possible?

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Gas Manifold Pressure

• What is standard natural gas manifold pressure?



• 3.5 IWC (inches water column)



• 3.5 IWC (inches water column)• What is standard propane (LP) gas manifold pressure?

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• 3.5 IWC (inches water column)• What is standard propane (LP) gas manifold pressure?

• 10.0 IWC

Increasing or Lowering Gas Pressure

• Increasing gas pressure does what?


• Increasing gas pressure does what?• Increases input

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• Decreasing gas pressure does what?



• Decreasing gas pressure does what?• Decreases input




• What does decreasing gas pressure do to temperature rise?

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• Lowers it





• Lowers it• How many cubic feet of gas should the HVAC

contractor be clocking the gas meter?





• Lowers it

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Clocking Gas Meter

• How many cubic feet of gas should the HVAC contractor be clocking the gas meter?

• 2 Ft3

• One revolution in 10 seconds: 1 second is 1/10 of total• Two revolutions in 20 seconds: 1 second is 1/20 of total• Three revolutions in 30 seconds: 1 second is 1/30 of

total• Four revolutions in 40 seconds: 1 second is 1/40 of total

• Longer the read, the more accurate

Input With Different Natural Gas Pressures

Minutes Seconds

3.8 44,732 2 45 44,727

3.5 42,930 2 52 42,907

3.0 39,745 3 6 39,677

3.8 67,097 1 50 67,091

3.5 64,394 1 55 64,174

3.0 59,618 2 4 59,516

#

Orifice

#

Burners

Gas

Manifold

IWC

Btu/Hr

Input

Meter Time for

2 Ft3 Btu/Hr

Input

44 2

44 3

Gas Orifices

• What size orifice in furnace?• Is 44 or 45 orifice a bigger hole?

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Gas Orifices


• 44 – More input than 45

Gas Orifices


• 44 – More input than 45• Orifice numbers are drill sizes—

• Bigger number, smaller hole

Furnace Data Plates

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80,000 Btu/hr Furnace

Minutes Seconds

3.8 81,335 1 31 81,099

3.5 78,058 1 34 78,511

3.0 72,268 1 42 72,353

Natural Gas Input

#

Orifice

#

Burners

Gas

Manifold

IWC

Btu/Hr

Input

Meter Time for

2 Ft3 Btu/Hr

Input

45 4

70,000 Btu/hr Furnace

Minutes Seconds

3.8 67,875 1 49 67,706

3.5 65,140 1 53 65,310

3.0 60,308 2 2 60,492

Natural Gas Input

#

Orifice

#

Burners

Gas

Manifold

IWC

Btu/Hr

Input

Meter Time for

2 Ft3 Btu/Hr

Input

51 5

Furnace Bunsen Burner

Orifice

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Orifice


Orifice


Orifice

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Bernoulli’s Principle/Effect

• What is Bernoulli’s Effect?• A fluid flow in one direction causes a low pressure

perpendicular to the flow• The faster the flow, the higher the low pressure

• Which has a higher mass or weight, the combustion air or the gas?

Bernoulli’s Principle/Effect

• What is Bernoulli’s Effect?• A fluid flow in one direction causes a low pressure

perpendicular to the flow• The faster the flow, the higher the low pressure

• Which has a higher mass or weight, the combustion air or the gas?

• The air has a mass 20 to 40+ times the mass of the gas, depending on the O2%

• Higher O2%, higher excess air, more mass

Airflow

• What happens to the temperature rise when the fan speed is lowered?

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Airflow


• Goes up – Good, if below Maximum

Airflow


• Goes up – Good, if below Maximum• What happens to the efficiency?

Airflow



• Goes down – Bad – but less than 1%

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Airflow



• Goes down – Bad – but less than 1%• What happens to the electricity use?

Airflow



• Goes down – Bad – but less than 1%• What happens to the electricity use?

• Goes down – Good• Saves more than increased gas cost

Air Filter Gets Dirty

• What happens when air filter gets dirty?• With multi‐speed blower (constant torque)?

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• Go back to previous slide



• Go back to previous slide• With constant airflow ECM blower

• Discussion for the future

Lower Airflow – Higher Temp Rise

105 Btus

105 Btus

105 Btus

105 Btus

2020us

100 Btus

100 Btus

100 Btus

100 Btus

= 420 Btu’s

= 420 Btu’s

Lower Fan Speed

Higher Fan Speed

• Each CFM has more heat• Fewer CFM needed• Cost to move heat decreased

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Watts per 1,000 CFM – PSC Motor

0

50

100

150

200

250

300

350

400

450

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

High

MedHi

MedLow

Low

Watts Per1,000 CFM

1/3 HP Blower

External Static Pressure

Summary Limits—Gas Pressure & Airflow

• Temperature rise not above maximum• CO ppm ≤100• Temperature rise not below minimum

• Too high temperature rise• High limit shuts off furnace before thermostat satisfied – heat exchanger stressed more

• Too low temperature rise• Condensation occurs in primary heat exchanger –quickly destroys heat exchanger

Blower static pressure

• Little concern with multi‐speed, constant torque• PSC motors with current WX furnaces• Permanent split capacitor (PSC) = Multi‐speed

• Lower fan speed uses less electricity

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Return Drop

Which is better?

ACCA Residential Duct Systems Manual D

Return Drop

The Same

ACCA Residential Duct Systems Manual D

Thermostat

• Digital thermostat temperature differential• Set at 1 degree, not 2 or 3• Greater comfort• More efficient

• If mercury thermostat, follow instructions for setting heat anticipator

• Goal is 1 degree room temperature variance or customer preference

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Low LP Gas Pressure Switch

• Ensure propane furnace has safety pressure switch• If propane tank low on gas, will not let furnace start

Electrical Connections

• Install wire connections in junction box, unless:

Page 24 of Stylecrest Installation Manual: “Junction Box (may be int. or ext. to the furnace). These connections can be made in the field supplied disconnect at the furnace. NOTE: Connections made within the furnace burner compartment do not require a junction box.”

Questions

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