Diagnostic Services

CALCS PLUS provides professional diagnostic services on Commercial and Residential Systems. Diagnostic Services are necessary when other programs (State & Utility, Federal, and Private) have failed.

Brief Overview of our Procedures, Explanation and Our Diagnostic Services:

Diagnosing Procedures

SECTION 1. A short description of mold and how to control it.

Molds are complex forms of fungi that can develop into large colonies indoors under appropriate conditions. The four conditions that must be met to support the growth of mold are:

the presence of a mold spore.
The right temperature.
Food
Water.

Spores are ubiquitous in the air and will be present indoors even if conditions do not support growth. A temperature range of 40 to 100° F is fairly wide and with in the typical human’s “comfort” zone. Oxygen is needed to support all life including our own. Food consists of almost anything that is biodegradable (starches, sugars, cellulous, etc.) which covers most building materials used in construction. Water in the form of vapor of 70% relative humidity is ideal for mold growth and it is the only thing we can successfully control to prevent the growth of mold. The most common factor for heavy mold growth indoors is excess moisture in the substrate (mold food) the mold spores are growing on. Sources of high substrate humidity are infiltration through foundations, vapor diffusion through the building envelope, leaks in roofs, walls, or windows, improperly designed or maintained HVAC systems, condensation, and poor circulation. Needless to say, if major water damage has occurred due to a plumbing leak, roof leak, etc. it should be dried within 24 to 48 hours to prevent germination and subsequent mold growth.

As mentioned above food and water are the two biggies to support the growth of mold. Most of our building materials are comprised of mold food. Mold foods are the starches and sugars in organic materials such as wood. So if we build our homes using organic materials that can become mold food the only thing we can control is the moisture. Since mold likes temperatures anywhere from 40° to 100°F and a relative humidity around 70%. Their ideal environment falls right inside our own comfort levels. But if we can control humidity and keep it below 55% there should be no mold growth in the structure. Average design humidity in Florida is 50%. One could say that mold is just a symptom on too much humidity. Our investigation will be limited to identifying the sources of moisture intrusion.

SECTION 2. A description of what takes place during a diagnostic investigation.

The diagnostic investigation is a four part process that looks at the building envelope as a dynamic system breaking down all the forces that contribute to moisture intrusion. The procedure listed below is a road map to problem solving.

Site-Visit 1, is a data gathering process that includes:

Observing problems and listening to what involved persons have to say about the problems.
Understanding normal operating procedures for the building; occupants general living habits.
Obtain a blueprint or draw a floor plan, note the wall materials, roof materials, floor materials, and glass type.

Take pictures to verify conditions.
Record size of each AC system and the area it serves.
Launch 7 Day Data Logger. Record temperature & Humidity.
Schedule Site Visit 2.

Office 1, initial data organization and beginning calculations.

Perform HVAC load calculations.
Record all data from Site Visit 1.
Enter data into rating and diagnostic software.
Review the acquired data and try to reach a hypothesis of what is taking place.

Site Visit 2, diagnostic testing.

Download the Data Loggers
Verify Plans and HVAC Load Calculations to existing conditions. Update as needed
Take pictures to verify conditions before any testing is performed.
Record weather conditions i.e. out door temperature dry bulb and wet bulb, indoor temperature dry bulb and wet bulb, wind speed, etc.
Measure air duct leakages at CFM25 and convert to leakage rate % of rated AHU airflow. (5% or less is considered tight)
Identify the location of duct leaks.
Building pressurization test, measure and record CFM50 and convert to ACH.
Identify air pathways (leaks) through the building envelope.
Measure and record CFM25 per SQ FT. (Code is .5 CFM25/SQ FT.
Pressure map the building with AC system operating in the cool position with thermostat set low enough to insure equipment operation. Record on blueprint.
Measure airflow across the evaporator (indoor) coil.
Measure and record the supply and return CFM at each diffuser and grill. Record locations on plans.

Office 2, assessing the data and report.

Record all data from Site Visit 2.
Obtain daily weather report for the # of days the data loggers were recording.
Analyze all data, and compare with the hypothesis.
Prepare the report.

If the problem of moisture intrusion has been readily and confidently identified some time during the above process than the rest of the diagnostic investigation may be suspended and a report will be written and submitted.

We start out by looking at the infested area and the air conditioning system that serves the area. If blueprints are not available we will measure the house and develop a cad drawing of the floor plan to be used later. We conduct a house pressure/infiltration test, a duct test, and an airflow test on all air conditioning systems.

Data loggers are set in key positions to measure the temperature, humidity, and dew point of the envelope. The data loggers collect this information every 2.5 minutes for 6 days. The collected data is compared to other conditions that have a dynamic effect on the envelope such as wind conditions during the data logging period, HVAC operations during the same period, life styles during the same period, etc.

The floor plan is used to do a room-by-room HVAC load calculation to determine the required size of the air conditioning system. The calculation takes into consideration the floor type & area, wall type & area, ceiling type & area, glass type, area and orientation. We calculate the total required tons of air conditioning for the whole building along with breaking the total down in systems or zones and also the required BTUH for each room. We also use the drawing to record the airflow and approximant location of the air distribution system, building leaks, etc.

A duct test is conducted to find out how much air leakage the duct system has. Considering that the air conditioning duct system is actually part of the air-conditioned space, duct leaks can affect health, comfort, and energy cost. To conduct the test all of the supply diffusers and the return grills are blocked off. This would completely seal off the inside of the duct system including the air handler from all of the spaces around it. A calibrated fan is connected to the largest return or the air handler itself and it is depressurized to -25 Pascal. The fan flow in CFM is calculated. The calculated leakage is divided by the rated air handler airflow in CFM and a percent of leakage is obtained. Today’s standards calls for air duct systems to have a leakage factor of less than 5% of the air handler’s rated flow.

The building air tightness test is done to calculate the amount of building leakage using a Minneapolis Blower Door. A blower door consists of an adjustable 2½”x¾” aluminum frame that mounts to the doorframe of an exterior door. The blower doorframe is covered with a nylon panel. A calibrated fan is secured to the blower doorframe and is fitted through the elastic collar in the panel connecting the conditioned space to the outside through the calibrated fan when it is not covered. All other doors, windows, and fireplace dampers are closed. The conditioned space is depressurized to –50 pascals in relation to the outside and the fan flow is read in CFM of airflow. The amount of air being pushed out of the conditioned space is the same that is coming in the condition space via the leaks in the building envelope area. The building envelope is the inner seal or air barrier that separates the conditioned space from unconditioned space. In most homes it consists of drywall, taped and sealed. Normally we conduct a multi point test consisting of six test points between –60 Pascal and –25 Pascal and using a computer program the test points are averaged and calculated to an accurate air leakage rate at –50 pascals then converted to the natural infiltration rate, ACH (air changes/hour).

The infiltration rate is a measurement of the amount of uncontrolled airflow from inside the building envelope (conditioned space) to unconditioned spaces and the out door world, then back again carrying with it moisture, dirt, hot air, and what ever. But in order to move the air a driver or force is needed.

There are three types of drivers that will cause uncontrolled air flow and pull unwanted out door air into the conditioned space, they are mechanical, stack effect, and wind.

1. A mechanical means of making a house go negative is a range hood exhaust fan, bathroom exhaust fans, a clothes dryer operating in the conditioned space, duct leakage, and unbalanced pressure across closed doors. If a supply duct is leaking and the return is not it will cause the house to go negative. If the return air duct is leaking in the attic the house will tend to go positive but unconditioned moist air may enter the house through the AC system.

2. Stack effect works like a natural flue for a fireplace. As the fire burns the very light hot gasses from combustion go up the flue dragging conditioned air with it. This usually applies to cold climates in the winter and a fire is not needed just the fact that the air in the house is warmer than the air outside the house will create stack effect.

3. The wind is a very common cause for a house to go negative. The wind blows over and around the house causing pressure differences both positive and negative in various parts of the house. When the wind blows across the chimney of a fireplace it tends to draw the air out of the house if the damper is open. It works much the same way a garden hose fertilizer applicator works.

Pressure Mapping is a procedure that measures the pressure difference across closed doors when the air conditioning system is in operation. The Florida Building Code Says: “Pressure differentials across closed doors where returns are centrally located shall be limited to 0.01 inch WC (2.5 pascals) or less” (part of M601.4). A digital manometer that reads in pascals is connected to a tube placed under the closed door. The manometer senses the room pressure relative to the pressure in the main living area. Typically all readings will reference the rooms with closed doors with respect to the main open area of the conditioned space.

Unbalanced pressures across closed doors will increase unwanted air infiltration of hot moisture laden air through building materials.

The last test we perform is an airflow test. The airflow across the evaporator (indoor) coil is measured; it should be around 400 CFM per ton (no less than 350 CFM per ton if the ductwork is located in a vented attic). We measure the amount of air coming out of each supply diffuser and return grill + out door air intakes. The supply airflow should be the same as the return + out door air back to the air handler. The difference in airflow between supply, return, and the measured airflow over the evaporator coil is duct leakage. This procedure is also used as a cross check to the duct test described above.

The information gathered will then assist us to determine where and how moisture intrusion is creating problems.

Calcs-Plus uses a wide range of the latest diagnostic equipment and software packages to perform their services. Their diagnostic arsenal includes Minneapolis Blower Doors, Minneapolis Duct Blasters, TSI Accubalance Air Capture Hood, TSI Velocicalc Velocity Meter, Oncet Hobo H-8 Data Loggers (temperature & humidity), TruFlow Air Handler Flow Meter by the Energy Conservatory along with a DG 700 pressure and flow gauge, DG 3 pressure and flow gauges, the APT (Automated Performance Testing System), and the Surveymaster BLD5360 moisture meter just to mention a few. These state-of-the-art precision instruments aid Calcs-Plus in their mission to provide the best possible service.

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