HRV and ERV Best Practices - Northwest ENERGY STAR Homes

HRV and ERV Best Practices
December 18, 2012
Portland Metro Home Builders Association
The Basics: The “X” Flow
Ports Connected to Inside
72F
61F
42F
32F
Ports Connected to Outside
The Single Most Important
Installation Detail
Make sure exhausts exhaust and intakes intake
PORT
Stale Air
From
Inside
Fresh Air
From
Outside
Fresh Air
To Inside
Stale Air
To Outside
Location
Inside
Outside
Inside
Outside
Negative
House
Pressure
Positive
House
Pressure
PORT
Stale Air
From
Inside
Fresh Air
From
Outside
Fresh Air
To Inside
Stale Air
To Outside
Location
Outside
Outside
Inside
Inside
Negative
House
Pressure
Positive
House
Pressure
PORT
Stale Air
From
Inside
Fresh Air
From
Outside
Fresh Air
To Inside
Stale Air
To Outside
Location
Inside
Inside
Outside
Outside
Negative
House
Pressure
Positive
House
Pressure
Where Data Lives
IS A HRV OR ERV
Latent Recovery/Moisture Transfer (LRMT): Moisture recovered divided
by moisture exhausted and corrected for the effects of cross-leakage. LRMT =
0 indicates that moisture was not transferred (net of cross-leakage) from the
exhaust airstream to the supply airstream. LRMT = 1 would indicate complete
transfer of moisture. LRMT is provided for the Heating Season Performance
and the Very Low Temperature Test as an indication of moisture handling
characteristics, and may be used to evaluate the moisture transfer ability of the
equipment in order to assess the humidification or dehumidification
performance of the product at the specified test condition.
Some Definitions
Net Supply Airflow
The gross supply airflow reduced by measured cross-leakage (EATR). This is
the actual amount of outside air supplied by the unit and is used only for sizing
the equipment for the required ventilation rate.
USE THIS RATING FOR VENTILATION SIZING
9
Airflow Is Not a Given
FAN curves
Flex Like You Have Never Seen
INSTALLATION GUIDELINES – ELBOWS
Long-Radius Elbows
VS
Image Source: http://isystemsweb.thomasnet.com/item/duct-and-components/machine-made-elbows/elmm11-45?&seo=110&bc=100%7C1015
Account for bends and offsets in the flexible duct. A 90-degree bend has a pressure drop equal to
approximately twenty (20) lineal feet of flexible duct. So each 90-degree bend will add twenty (20)
equivalent feet to the length used for sizing calculations. A gradual 45-degree bend has a pressure
drop equal to about ten (10) lineal feet of flexible duct. A 180-degree offset has a pressure drop
equal to about forty (40) lineal feet of flexible duct.
Equivalent Length Multipliers1 for Wire Helix Duct with Compression and Sag
Compression
0% to 4%
15%
30%
45%
Bagged
Coiled
Negligible
Superimposed Sag
1-inch/Ft
2-inch/Ft
1.0
1.1
2.0
2.2
3.4
3.7
5.2
5.7
Excess length should not be stored in a bag
Excess length should not be coiled
1)
The recommended standard of care is 4% or less coil compression and negligible sag (2.5 inches sag per 5 feet of
span).
2) These multipliers apply to airway sizing tools (friction chart or slide rule) that model the performance of duct that has
less than 4% excess length and negligible sag (test stand condition).
3) Compression occurs when excess length is squeezed into a shorter straight line span (see Table A17-3, next page).
It is possible to have excess length with negligible compression.
4) The measured span length of flexible duct is the straight line length from entrance to exit (no Group 11 turns), from
entrance from a Group 11 turn to the exit.
5) The equivalent length of compressed duct equals the product of the measured span length and a compression-sag
multiplier.
6) These equivalent length values do not apply any to other type of duct material.
7) Airway sizes for wire helix duct are read from the Manual D wire helix friction chart, or equivalent; or use the wire
helix scale on the ACCA Duct Sizing Slide Rule, or equivalent.
8) Duct fiction charts vary from product to product (depending on construction details). The friction chart or duct slide
rule provided by the manufacturer of a particular flexible duct product supersedes the Manual D friction chart and the
ACCA Slide Rule.
Table A17-2
Other Ducting Options
Some More Definitions
Apparent Sensible Effectiveness (ASE)
The measured temperature rise of the supply air stream divided by the
difference between the supply temperature ( and exhaust temperature and
multiplied by the ratio of mass flow rate of the supply divided by the minimum
of the mass flow rate of the supply or exhaust streams. This value is useful
principally to predict final delivered air temperature at a given flow rate.
The efficiency not including the electrical energy used by the system.
Some More Definitions
Sensible Recovery Efficiency (SRE)
The sensible energy recovered minus the supply fan energy and preheat coil
energy, divided by the sensible energy exhausted plus the exhaust fan energy.
This calculation corrects for the effects of cross-leakage, purchased energy for
fan and controls, as well as defrost systems. This value is used principally to
predict and compare energy performance.
The efficiency including the energy use of the system
20
Why Efficiency Matters
Yes, it lowers energy use
But it also increases the delivered air temperature
This means less air conditioning and higher air delivered air
temperatures
Check Wattage of HRV/ERV
Efficiency
Watts
Annual Fan
Energy Use
101
84%
69
604
HRV
63
70%
87
762
Guardian HRV 200H
HRV
109
69%
92
806
Bryant
HRVBBLVU1200-A
HRV
111
84%
158
1384
Bryant
ERVBBLHU1200-A
ERV
110
69%
93
815
Lennox
HRV2-195DDP
HRV
114
77%
116
1016
Lifebreath
200 MAX
HRV
63
70%
87
762
Lifebreath
300DCS
HRV
119
77%
150
1314
Renewaire
EV200
ERV
181
78%
157
1375
Rheem/Ruud
84-HRV-200
HRV
109
70%
92
806
Ultimate Air
RecoupAerator 200DX
ERV
101
83%
73
639
Trent Metals Ltd.
Summeraire SHRV185ST
HRV
117
68%
114
999
Venmar
HRV5585 Compact
HRV
119
77%
110
964
Venmar
AVS HRV EKO 1.5
HRV
81
73%
32
280
Lifebreath
155 ECM
HRV
98
63%
74
648
Manufacturer/Brand
Model
Type
cfm
JE Stork Air
WHR 950 / CA 350
HRV
Am Aldes
200 SRD
Broan/Nutone
(Low Speed) (Low Speed)
Higher Efficiency = Higher Delivered Temperatures
Delivered Air Temp at Various OATs and ASEs
75
D
e
l
i
v
e
r
e
d
70
65
60
55
50
A
i
45
r
40
T
e
m 35
p
30
65
70
75
60F
80
85
Apparent Sensible Efficiency
40F
Outdoor Air Temp
20F
0F
90
95
Options for Installation
Stand Alone Systems
Stale Air from House, Fresh Air to Return
Stale Air from Return, Supply Air to Return
Stale Air from Return, Fresh Air to Supply
Detail for Introducing Fresh Air into a Supply
Duct
Potential Problems For Air Handler Connected
Systems
Increased energy use
To avoid cross commination of air streams, the furnace fan should run
whenever the DHP is in exchanging air:
400 watts X 24hr/day X365 days/year =3504 KWh/year
Could be up to 3000 kWh a year in energy use; that’s $300 @ .10cents/kWh
That’s ignoring any extra duct losses if the duct are outside
Potential Problems For Air Handler Connected
Systems
Overcoming large negative and positive pressures in the return and
supply
Do the pressures generated by big furnace fan ever overpower the
pressure generated by the small ERV/HRV fan?
Potential Problems For Air Handler Connected
Systems
Balancing
With an increase of multi-staged or modulating equipment that have
ECMs, what fan speed do you balance at?
How do you know what fan speed you’re at?
As filters and coils get dirty, the pressures in the duct change
Noise: Keep it Quiet Stupid
Separate Exhaust from Intake
ASHRAE 62.2-2010
www.ashrae.org
Basic Formula for Continuous Ventilation Rate
Required CFM for continuous ventilation
CFM = .01 X Floor area =7.5 X (#bedrooms +1)
Example:
2500 square foot house with 2 bedrooms
.01 X 2500 +7.5X(2+1)= 25+22.5= 47.5 cfm
Ventilation Air Requirements, CFM
Based on: ASHRAE 62.2, Table 4.1a (I-P)
Non-Continuous Ventilation
Non-Continuous Run Time Multipliers
Based on ASHRAE 62.2, Table 4.2
This chart estimates the required cfm need for non-continuous ventilation systems
Room Airflows
Supply to bedrooms and main body
10 cfm per person
 10 cfm small bedroom
 20 cfm master bedroom
 20 cfm main body
Exhaust from bathrooms, kitchen (not near the stove)
 ASHRAE 62.2 allows 20 cfm continuous instead of 50 cfm bath fan (saves
some money)
Don’t Use Wall Hoods with Gravity Dampers
as Fresh Air Intakes
Setting the Controls
Controls
need to be
up to meet
ASHRAE
62.2
Defrost Options
Recirculation of indoor-air: No ventilation when this occurs!
Exhaust only, no heat recovery
Electric heating element
Geo-thermal or pumped glycol loop
Defrost
Defrost Logic:
Logic changes between
systems
 Temp only
 Change in efficiency
 How long does it last?
Geo Thermal Booster
Can help heat the air in winter and cool air in summer; also works as
defrost
Other Types of HRVS
Lunas reversing heat recovery Hrvs
Panasonic Spot ERN
Balancing
Aldes
Iaq source
supply
Balancing: Why it’s Important
Efficiency: The rated efficiency is given at
specific set of conditions. If unbalanced, the
rated efficiency is unknown.
Building pressure
Exhaust > than supply = negative building
pressures
Supply > than exhaust = positive building
pressures
Best Practices: System Selection
 High apparent sensible efficiency will produce higher delivered air
temperatures
 High sensible recovery efficiency will produce the lowest energy use
Best Practices: Location Of Unit
1. Easily accessible
2. Inside the conditioned space
venmar
Best Practices: Distribution
1.
Stand alone is the best
2.
Stale from house, fresh air to return side of air handler
o
AH static pressures work with HRV/ERN not against
o
AH and HRV/ERV do not have to be tied together
o
When AH is off fresh air will into the duct work, some might exit the
return, but who cares?
Best Practices: Duct Work
1.
Size using a low friction rate
(.06) or manufactures
recommendation
2.
Keep inside the condition space
3.
Don’t do stupid stuff with flex
duct
4.
Minimize duct length through
central location
5.
Use mastic, seal them airtight
Best Practices: Wall Hoods
1.
Maintain separation of exhaust
and intake units hoods
2.
Don’t use gravity dampers on
intakes
3.
Place where the homeowner can
clean them
4.
Caulk insect screen in place if it
has gaps
Venmar
Best Practice: Commissioning
 Balance as per manufacturer’s
recommendation
 Measure airflow per room
 Double-check that intakes intake and
exhausts exhaust
 Set controller to meet ASHRAE 62.2
 Record all readings and post on unit
Best Practice: Commissioning
Compare temperatures between incoming and outgoing air.
Does it match efficiency rating?
aldes
Best Practices: Homeowner Education
 Leave all manuals, especially ones concerning setting the controller
 Emphasize filter and screen cleaning
 Document all testing and commissioning
 Sell a maintenance contract
 Emphasize the importance of ventilation
THANK YOU
QUESTIONS?
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NorthwestENERGYSTAR.com
P: 1.800.539.9362
E: info@northwestenergystar.com