Output from the calculations

Output from the calculations The model calculates the energy use and losses based upon constant fractions. The fraction of the energy use and the different losses is displayed by the model. A diagram shows the energy supply per temperature bin and how it is covered from different energy sources.  The seasonal energy efficiency, etas, is calculated.  
Etas = Lh/Qtot+cctrl where Qtot=Lh + Lsys + Qgen + Qel
etas is the net space heating demand of the house over the sum of the generated heat of the system. Qtot is the sum of the space heating demand (Lh), the losses from the heating system (Lsys), the primary energy losses of the energy input to the system (Qgen) and the energy needed by the auxiliary equipment such as control and heat sink pumps (Qel).  
All electricity used by the heat pump and the backup heater is multiplied by a primary energy factor of 2.5. The model is not transparent. It is tricky to follow the outputs of the model since it consists from several excel-sheets and the information turns up all over. It is also difficult to understand all steps of the calculations. To be able to compare the results with field measurements and prEN14825 a value of SPF, the so called “average COP” (see the system boundaries) is calculated without the system losses. Average COP corresponds to SCOPnet in prEN14825.

is a calculation program

SP-method A3 528 SPA3 528 is a calculation program that is used to calculate the seasonal performance factor and energy saving over the year for houses having a defined heating requirement. It can be used for air/air heat pumps, air source heat pumps and ground source heat pumps. The heat loss from the house is defined in the program and given as the total loss factor, k-value, of the house [W/K]. The method can be used to calculate the energy requirement of a building with a k-value of either 109 W/K or 199W/K. A duration diagram of the outdoor temperature can be calculated from the mean annual temperature and together with the loss factor, the area under the duration curve gives the actual power requirement.
The heat pump is tested in accordance to EN 14511 at outdoor temperatures of -15°C, - 7°C, +2°C and +7°C with an indoor temperature of +20°C. The heat pump is also tested in part load conditions according to CEN/TS 14825 at +7°C (75% and 50%) and at +2°C (50%). The lowest ambient temperature is assumed to be -15 °C and no heating is assumed to be required for ambient temperatures above +17 °C. The output data from the tests, thermal heat capacity and electrical input power, is used as input to the calculation

The model is not completely clear

Strenghts A strength of standard prEN14825 is that it includes all kinds of heat pumps (except exhaust air heat pumps). The model treats heat pumps both in heating and cooling operation. The fact that the heat pump is tested in exactly part load should result in more sufficient results compared to degradation coefficient etc. The model is foreseeable and quite easy to follow.  
Weakness The model is not completely clear with its definitions of part loads. The part load ratio for which the heat pump is to be tested is the part load energy demand of the building at the corresponding temperature bin. To perform the SPF calculations according to prEN14825 the heat pump is tested at a certain climate (A,W or C) and a certain heat load profile for the building. This means that the test data might not be suitable for another climate or another heat load

HVAC Contamination Type

HVAC Contamination Type
Cleaning methods, project specifications, environmental
engineering controls, and cleanliness verification
methods may vary depending on the type of
contaminants found within a building and its HVAC
system. Recognizing the type of contaminants present
and the type of HVAC system(s) within the building are
important parts of the overall project evaluation.
The HVAC systems, including air-handling units and
representative areas of the HVAC system components
and ductwork, must be evaluated for contamination type
and levels.
An HVAC system component is considered
contaminated when evidence of significant particulate
debris and/or visual microbial growth exists. A system is
considered to have microbial contamination when the
HVAC cleanliness evaluation identifies microbial growth
through visual inspection and/or analytical verification.
An HVAC system that is part of a building that has been
classified as having Condition 3 mold contamination
does not require further evaluation of the contaminants
by an IEP for restoration to commence.
It is highly recommended that any individual taking and
interpreting samples from the interior of HVAC systems
be an IEP with specific training in taking samples from
within such systems.

The HVAC contamination type and the environmental

The HVAC contamination type and the environmental
impact survey must include a visual evaluation of
representative sections of the HVAC components and
the occupied spaces served by the HVAC system. This
evaluation serves to visually inspect conditions within the
HVAC system and verify the overall physical integrity of
system components and surfaces.
Information collected from the project evaluation should
be used to define the scope of the cleaning and
restoration project, cleaning techniques to be employed,
the environmental engineering controls required for the
workspace, and any unique project requirements.

4.1 Building Use Classification
Classifying the type of building and its uses is an
important part of project evaluation. Cleaning methods,
project specifications, environmental engineering
controls, and cleanliness verification methods may vary
among different buildings. Building classifications are
listed in Sections 4.1.1 to 4.1.8 of this standard. If the
HVAC system restoration project is being conducted as
part of a larger mold remediation project, it is
recommended the building’s usage classification be
determined by an IEP to assess the overall impact of the
contamination present and the corrective cleaning
actions specified to remediate the contamination.

design inadequate for the current needs of the

design inadequate for the current needs of the
building and its occupants;
• The system may not have been installed as
designed, or commissioned so as to assure that its
operation met the design objectives; and
• Mechanical deterioration and/or physical damage to
system components may have degraded their
performance to the point where they cannot provide
the necessary level of air flow or capacity.
The description of what constitutes an adequate
engineering evaluation of HVAC system condition and
capacity is beyond the scope of this standard. It is
recommended that qualified engineering professionals or
HVAC contractors be consulted for such an evaluation.
4 Project Evaluation and Recommendation
When contamination is identified or other criteria
triggering cleaning in Section 3 are met, it is highly
recommended a project evaluation take place prior to
initiating cleaning work. The project evaluation includes
three steps: 1) determining the building usage by
classification; 2) identifying the type of contamination
present in the HVAC system; and 3) conducting an
indoor environmental impact survey.

HVAC System Engineering Assessment

HVAC System Engineering Assessment
It is highly recommended that in addition to an HVAC
cleanliness inspection, a complete engineering
assessment of the design and condition of the entire
HVAC system be considered depending on the
conditions that exist in the project. This is especially
important if temperature and/or relative humidity
conditions cannot be maintained within the spaces in
compliance with the requirements of ASHRAE
Standards 62.1 or 62.2; if temperatures, relative humidity
or airflow varies between different areas of the building;
or, if the mechanical components are not in good
condition and/or repair. There are four primary reasons
this HVAC System Engineering Assessment is important
to the success of a remediation project:
• The original system design may not have been
adequate to maintain optimal indoor environmental
(or psychrometric) conditions in the building;
• Expansions, renovations or changes of use of the
original space may have rendered the HVAC system

If the HVAC system

If the HVAC system discharges visible particulate into
the occupied space, or a contribution of airborne
particles from the HVAC system into the indoor ambient
air is confirmed, then cleaning is highly recommended.
See the guideline to this standard for discussion of the
Particle Profiling (PP) procedure, which may be used to
confirm if non-visible contaminants are being introduced
into the indoor environment via the HVAC system.
3.5.2 Compromised Performance
Cleaning is highly recommended for heat exchange
coils, cooling coils, air flow control devices, filtration
devices, and air-handling equipment determined to have
restrictions, blockages, or contamination deposits that
may cause system performance inefficiencies, air flow
degradation, or that may significantly affect the design
intent of the HVAC system.
3.5.3 Indoor Air Quality Management
Indoor air quality management plans that include
periodic cleaning and maintenance are highly
recommended to minimize recurring contamination
within HVAC systems. It is highly recommended that
special consideration be given to buildings or residences
with sensitive populations such as individuals with
compromised immune systems, and specialized
environments or buildings with sensitive building
contents or critical processes.

HVAC Inspector Qualifications

HVAC Inspector Qualifications
It is highly recommended that a qualified HVAC
inspector be used to determine the preliminary state of
HVAC system cleanliness. At minimum, such personnel
should have a verifiable working knowledge of basic
HVAC system design, fundamental HVAC engineering
practices, current industry HVAC cleaning and
restoration techniques, and applicable industry
standards. Individuals who are inspecting for microbial
contamination should be qualified to determine
Conditions 1, 2 and 3.
3.5 Conditions Requiring Cleaning
It is highly recommended HVAC system cleaning be
performed when any of the following conditions are
found during the HVAC Cleanliness Inspection.
3.5.1 HVAC System Contamination
If significant accumulations of contaminants or debris are
visually observed within the HVAC system, then cleaning
is necessary. Likewise, if evidence of active fungal
colonization is visually observed or confirmed by
analytical methods, then cleaning is required. If the
system has been confirmed by an IEP to be at Condition

Preliminary Determination for Mold

Preliminary Determination for Mold
After the initial HVAC system component inspection, a
preliminary determination must be made by the person
performing the inspection regarding potential mold
contamination. Making a determination involves the
collection, analysis and summary of information to
identify areas of moisture accumulation and potential
mold growth. A preliminary determination may indicate
the need for further assessment by an IEP and/or other
appropriate professionals (See IICRC S520).
3.3.2 Surface Mold Growth
If the preliminary determination indicates a small,
isolated area of mold growth on a surface layer of
condensation on painted walls or non-porous surfaces,
and mold growth has not occurred in concealed areas,
the use of an IEP generally is not necessary and the
mold usually can be removed as part of a regular HVAC
maintenance program (See IICRC S520).
3.3.3 Limited Mold Growth
If the preliminary determination indicates a limited
amount of visible mold confined to a specific area, (e.g.
a small area of a mechanical system that is not in the
path of the major air circulation system of the structure),
the use of an IEP may or may not be necessary and the
restorer or remediator’s professional judgment is needed

Indoor climate

Indoor climate
The indoor climate is expected to reach 20°C for all models. In the calculation models the heat pump is used to reach a temperature of 16°C. Internal gains are expected to contribute to the last temperature increase.
The actual indoor temperature has not been measured in the Fraunhofer field measurements. Thereby it is not possible to compare the real indoor temperatures with the temperatures estimated in the calculation models.

heat requirement

Weakness The model takes only air to air heat pumps into account. In accordance to prEN14825 the test points for the heat pump has to be chosen specifically to fit the chosen climate and heat profile of the house.  In accordance to LOT 1 the model does not include an effect balance at each temperature bin. This results in that the heat demand of a house at a specific temperature bin is different at different climates and that the heat requirement of a backup heater is misleading.  The model does not seem to be entirely consistent, partly it is contradicting itself.

Possibility

Possibility To make the model usable at other spots it would be better to make it possible to use other climates. Now the model only provides a number of specified heat loads of the house. It would be useful to be able to freely choose the heat demand of the house. There is a risk though, that since the heat pump has to be tested in part load, it has to be tested at each specific heat requirement.  
Other types of heat pumps could be included in the model. The model only provides the SPF (SCOP) with the backup heater included. For comparable reasons, it would be useful to include a SPF with backup heater excluded

Even though

Even though the program is transparent  in the sense that all equations are  reported in the model, it is very hard to understand and follow the calculations, and the program cannot be said to be transparent in the general sense. The interface of the program is not very friendly and can easily confuse the user. The model does not include tap water.
Possibility Making the ground water and borehole temperature climate dependent might lead to results more sufficient to its actual installation spot.  
Risk The model is not adjusted to fit heat pumps and is disadvantaging heat pumps. Despite this the COP and capacity of water to water heat pumps can be overestimated since they are tested at +10°C at the cold side (this can also happen to ground source heat pumps, but probably not to the same extent

The night set

The night set back function uses the same night temperature all year around, which is not the case in reality.
It is not possible to choose the energy requirement of the house; instead the energy demand is an outcome of the capacity of the heat pump. If the heat pump is not monovalent also the fraction of backup heat is needed to decide the energy demand of the house.  
GSHP’s are treated unfairly when recalculating the operation data to part load operation. The ground source heat pumps are degraded by a factor 0.89 at 50 % of the delivered capacity. (The Cd factor, i.e. the on/off control, is overestimated for water borne systems

Weakness Unfortunately

Weakness Unfortunately the model still contains bugs and technical mistakes in the equations and the way of thinking. It seems to be adjusted to boilers and bio boilers instead of heat pumps.  
The model does not include a power balance, but is doing a temperature balance instead. This makes the distribution of the energy need and the required amounts of backup heat differ from the theoretical needed.  
The model includes a decided fraction of heat loss that cannot be escaped from. For example if the heat pump does not use night set back a default penalty loss of 12% from the total delivered energy is subtracted. The losses from the apparatus and system operation are also decided in percentages.  
At part load operation there is no change in the system flows. This does not seem right with controlled radiators. (Should the radiators be controlled or is it enough with a displacement/adjustment of the radiator curve?)

FIGURE 4

FIGURE 4
In addition to a reversing valve, a heat pump is equipped
with an expansion device and check valve for the inside coil,
and similar equipment for the outside coil. It is also provided
with a defrost control system.
The expansion device performs the same function on the
heating cycle as on the cooling cycle. The check valves are
required due to the reverse flow of refrigerant when changing
from cooling to heating or vice versa.
When the heat pump is on the heating cycle, at which time
the outdoor coil is functioning as an evaporator, the
temperature of the refrigerant in the outdoor coil must be
below the temperature of the outdoor air in order for the
refrigerant in the outdoor coil to extract heat from the air.
Thus, the greater the difference in outdoor temperature and
outdoor coil temperature, the greater the heating capacity of
the heat pump. Since this is characteristic of heat pumps, it

This study

This study is focused on heat pumps for indoor heating. The study is made in houses with different heat demand. The ground source heat pumps in this study are considered monovalent, but it is difficult to determine the actual energy demand of the house. When using the calculation models the required heat load of the house is decided by the capacity of the heat pump.
The studied air to air heat pump is not monovalent. The energy demand of the house with the heat pump installation was estimated in the field study. When using the calculation models the energy demand of the house were tried to be the same as in the field study.

is good practice

is good practice to provide supplementary heat for all heat
pump installations in areas where the temperature drops
below 45°F. It is also good practice to provide sufficient
supplementary heat to handle the entire heating requirements
if there should be a failure of heat pump, such as a
compressor failure, or refrigerant leak, etc.
Since the temperature of the liquid refrigerant in the outdoor
coil on the heating cycle is generally below the freezing point,
frost forms on the surfaces of the outdoor coil under certain
weather conditions of temperature and relative humidity,
Therefore, it is necessary to reverse the flow of the refrigerant
to provide hot gas in the outdoor coil to melt the frost
accumulation. This is accomplished by reversing the heat
pump to the cooling cycle. At the same time, the outdoor fan
stops to hasten the temperature rise of the outdoor coil and
lessen the time required for defrosting. The indoor blower
continues to run and the supplementary heaters are
energized

MAINTENANCE

MAINTENANCE
General
Outdoor units do not require a planned prevenative
maintenance program under normal operating conditions, but
not less than once each cooling season, it is recommended
that the unit be inspected and, if necessary, cleaned.
Particular attention should be given to the air inlet side of the
outdoor coil to insure that leaves, grass, etc., are not being
drawn into the unit. Restriction to air flow across the coil will
result in loss of system capacity, high operating pressures
and excessive operating costs. If the outdoor unit is installed
adjacent to a grassy area, it is suggested that lawn mowers
be routed in such a manner that the discharge of the mower
will be directed away from the unit. There must be air filters
installed in the system at some point upstream to the indoor
coil. Air filters should be inspected and, if necessary, replaced
and/or cleaned AT LEAST once a month

Disconnect outdoor

Disconnect outdoor fan by removing the purple lead from
"DF2" on defrost control.
E. Restart unit and allow frost to accumulate.
F. After a few minutes of operation, the defrost thermostat
should close. To verify this, check for 24 volts between
"DFT" and "C" on board. If the temperature at the
thermostat is less than 28°F and the thermostat is open,
replace the thermostat as it is defective.
G. When the defrost thermostat has closed, short the "test"
pins on the board until the reversing valve shifts,
indicating defrost. This could take up to 21 seconds
depending on what timing period the board is set on.
After defrost initiation, the short must instantly be removed
or the defrost period will only last 2.3 seconds.
H. After the defrost has terminated, check the defrost
thermostat for 24 volts between "DFT" and "C". The
reading should indicate 0 volts (open sensor).
I. Shut off power to unit.
J. Replace outdoor fan motor lead and turn on power

General Explanation and Guidance

General Explanation and Guidance
The heat pump is a relatively simple device. It operates exactly
as a Summer Air Conditioning unit when it is on the cooling
cycle. Therefore, all the charts and data for service that apply
to summer air conditioning apply to the heat pump when it is
on the cooling cycle, and most apply on the heating cycle
except that "condenser" becomes "evaporator", "evaporator"
becomes "condenser" and "cooling" becomes "heating".
When the heat pump is on the heating cycle, it is necessary
to redirect the refrigerant flow through the refrigerant circuit
external to the compressor. This is accomplished with a
reversing valve. Thus, the hot discharge vapor from the
compressor is directed to the inside coil (evaporator on the
cooling cycle) where the heat is removed, and the vapor
condenses into liquid. It then goes through a capillary tube,
or expansion valve, to the outside coil (condenser on the
cooling cycle) where the liquid is evaporated, and vapor goes
to the compressor.

OPERATION - DEFROST CONTROL

OPERATION - DEFROST CONTROL
Timing
When operating, the power to the circuit board is controlled
by a temperature sensor which is clamped to a return bend
on the outdoor coil. Timing periods of 30, 60, or 90 minutes
may be selected by connecting the circuit board jumper wire
to 30, 60, 90 respectively. Accumulation of time for the timing
period selected starts when the sensor closes (approximately
28°F) and when the wall thermostat is calling for heat. At the
end of the timing period, a defrost cycle will be initiated,
provided the sensor remains closed. When the sensor opens
(approximately 65°F), the defrost cycle is terminated. If the
defrost cycle is not terminated due to the sensor temperature,
a 10 minute override interrupts the defrost period.
Field Testing / Trouble Shooting
A. Run unit in heat mode.
B. Check unit for proper charge. Note: Bands of frost indicate
low refrigerant charge
C. Shut off power to unit

If unit operates

 If unit operates properly on the heating cycle, raise the
heating temperature setting high enough until the heating
second-stage mercury bulb (lower) makes contact.
13. Supplementary resistance heat, if installed, should now
come on. Make sure it is operating correctly. If outdoor
thermostats are installed, the outdoor ambient must be
below the set point of these thermostats for heaters to
operate. It may be necessary to jumper these thermostats
to check heater operation if outdoor ambient is mild.
14. For thermostats with emergency heat switch, return to
startup (Step #9). The emergency heat switch is located
at the bottom of the thermostat. Move this switch to
emergency heat. The heat pump will stop, the indoor
blower will continue to run, all heaters will come on and
the thermostat emergency heat light will come on.
15. If checking the unit on the heating cycle in the wintertime,
when the outdoor coil is cold enough to actuate the defrost
control, observe at least one defrost cycle to make sure
the unit defrosts properly.

Problem

The UCIAQ Committee discourages the use of chemical sanitizers or biocides to treat building supply and return duct work. Although many antimicrobial products are EPA approved for use on hard, non-porous surfaces, these products were not specifically designed for use in HVAC systems and have not been evaluated for potential occupant health exposure issues. Any use of chemical sanitizers or biocides in duct work should be carefully reviewed by a health and safety professional prior to treatment. Problems involving visible fungal growth inside duct work must be addressed by first determining the source of moisture and correcting this problem. Following correction of the moisture problem, the system can be cleaned using mechanical techniques and detergents. Porous HVAC system materials such as insulation or fabric filters contaminated with visible fungal growth should be discarded and replaced.

Chemical

Chemical Sanitizers and Biocides  The use of chemical sanitizers or biocides may be necessary to clean certain HVAC system components such as heating or cooling coils. Following the use of chemical cleaners, all residues should be completely rinsed from the coil surfaces and removed from the HVAC system. Chapter 3, HVAC Operation and Maintenance, discusses the importance of routine sanitizing and use of biocides in cooling towers to reduce the number of microorganisms including Legionella spp.

When using

When using mechanical cleaning techniques, care must be taken to avoid damaging insulated or lined duct work. Fiber glass insulated components should be cleaned using HEPA filtered exhaust equipment while the system is maintained under negative pressure. Fibrous glass insulated materials identified as damaged prior to or following system cleaning should be identified and replaced. Potential damage to fibrous glass insulation materials includes delaminating, friable material, fungal growth, or damp, wet material. If fiber glass insulation material must be replaced, all replacement materials and repair work must conform to applicable industry standards and codes.

Mechanical

Mechanical Cleaning Techniques  Mechanical techniques are useful to clean certain HVAC components including duct work, fan components, diffusers, dampers, and internal surfaces of the air handling unit. When using mechanical cleaning methods, strict controls such as physical barriers, devices equipped with HEPA filtered exhaust, and system negative pressure must be used to contain and collect debris. Mechanical cleaning methods incorporate techniques to agitate and dislodge material as well as contain and remove it. Agitation devices may include power brushes, pressurized air and water systems, as well as hand tools such as brushes. Collection of dislodged particulate debris is achieved by vacuums. A vacuum collection device with an appropriate capture velocity should be connected to a service opening and operated continuously to collect material as it is dislodged. In certain areas of the HVAC system, direct contact vacuuming with a brush may be used to remove material from contaminated surfaces

HVAC

HVAC System Cleaning  For cleaning purposes, the HVAC system includes any interior surface of the air distribution system. This includes all components from where the air enters the system to all points of discharge in the facility. Methods to clean HVAC systems involve both mechanical techniques and chemical sanitizers or biocides. The preferred method of cleaning depends on the system component, type of debris or contamination, and access to the area. In no case should encapsulants or coatings be used prior to or instead of appropriate cleaning

Determining

Determining the Need for Cleaning  HVAC systems should be cleaned when a visual inspection indicates excessive particulate debris or microbiological growth on any interior surfaces. A fiber optic system or video inspection system is recommended to document the condition of the system both before and after any cleaning. A limited amount of adhered dust is expected on the inside surfaces of HVAC systems and may not indicate a problem. Obvious problems that require cleaning and restoration would include visible microbiological contamination, significant amounts of particulate debris coming out of supply ducts, or deteriorated fiberglass insulation that was contaminating the supply air. In all cases, the source or cause of particulate contamination or microbiological proliferation must be determined and corrected prior to system cleaning