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Home Energy Magazine Online March/April 2000

Home Performance Contracting

Tools to Know for Home Diagnostics

by Stewart Selman

Tools can be a home performance contractor's best friends. Here are the tools you must get to know intimately for high-quality diagnostic work and solving home performance problems.

Investing in compact, lightweight tools can be helpful for quick loading and unloading, and will allow you to fit everything in a small car.

Out of the long list of tools that a home performance contractor needs for optimal work, each of us must choose the specific types and brands that work best for us individually. Some tools, such as blower doors, are made by a small number of manufacturers, so the range of choices is small. Others, such as data loggers, are available from many different companies. In this article I discuss the makes and models that I and some of my colleagues have found to work the best for us over the years, and in some cases I give the reasons that I think a certain tool is the best choice. The ultimate judge, however, is you. Table 1 (on p. 36) lists the models that I use on a regular basis, and provides prices and manufacturer contact information. It also includes information on other manufacturers, for those who want to investigate other options.

Are Tools Worth the Price?

Many of the tools listed here do not come cheap. Some of them also require the added investment of training. When deciding whether or not to invest in a new diagnostic tool, I ask myself the following questions:

Will it let me work more efficiently?
Will it improve my measurement capability? and
Will it satisfy my curiosity?

I can't put a dollar figure on the value of my equipment purchases--they are far more valuable than the money they cost. For example, I know that some of the work I get comes to me because I have the right tools for the job. I also know that by having greater confidence in my measurements, I can give better recommendations to my clients.

You must also consider the wear and tear on your body. Testing houses is physical work; if your body wears out, you can't work. Investing in proper tools--especially those that ensure your safety--will always pay off in terms of increased productivity and a better quality of life.

If an instrument fits your budget but does not take reliable measurements, is it worth the initial savings? Obviously not. On the other hand, it is not easy to make some of these purchases when times are lean. When you have a good year financially, that's the time to invest in tools.

Basic Tools

Before giving you the details of high-tech diagnostic gadgets, I want to go over some simple basics.

To see in dark attics and crawlspaces, I use a standard Mag flashlight. What I find really helpful, though especially when crawling around attics, is a head-mounted spelunker flashlight (also called a head lamp), which leaves my hands free. Inspection mirrors are also very helpful, especially for inspecting combustion appliance venting and for peering into out-of-the-way places. If what you want to examine is well out of reach--for example, a section of flashing 20 feet up--a pair of binoculars may do the trick and save the effort of hauling out the ladders. To protect my knees, I wear pants, called Skillers, with built-in kneepads. Another important form of protection, of course, is the hard hat; although it isn't always called for, it is essential to use it in certain situations.

The smoke bottle or smoke pencil is another important basic tool. Designed to react with the moisture in the air, the "smoke" has no natural buoyancy of its own, so it is good for checking for spillage on natural vented heating appliances, whether rooms have air flowing in or out of them, and relative flow rates at supply and return registers. The smoke is a nasty substance to breathe, so be careful. A heavy-duty version of this substance is stage fog, which is used, often in conjunction with a duct tester (see below), to check for leakage and air flow patterns in ductwork or long passageways.

I use an aluminum combination step and extension ladder, but there are many others out there; the model I use is the right size to fit easily in my car. The main consideration is that the ladder be sturdy and safe. Fiberglass ladders are good for getting on roofs, and I like the protection they offer against electrocution.

When crawling through attics or other areas where I could expose my lungs to hazardous substances, I sometimes use an asbestos respirator, although that level of protection is rarely needed. A local insulator recently introduced me to a heavy-duty, disposable respirator that appears to be sturdy enough for many uses and is very comfortable. Comfort is the key: You must have protection that is both very comfortable--so you will actually use it every time--and is effective in filtering out the pollutants that concern you. Always check the manufacturer's documentation.

Other items that are important are connectors, colored tubing, and static pressure probes. I have flexible plastic tubes of many different colors that help me to remember what is connected to what. For most jobs, I combine two tubes and telephone wire coiled in one of those round devices that are used to coil long extension cords: This makes it easy to quickly set up and break down the tubing connected to my blower door and the outside, and run it down to the basement, where I will have my computer and data logger set up (the phone wire is for the data logger).

Contractors who do weatherization, remodeling, repairs, and improvements as well as diagnostics will of course need a variety of carpentry tools ranging from hammers to caulk guns. Duct tape is always useful, but never use it for sealing ducts--mastic is the right tool for duct sealing. Those who test for indoor air problems will need a microscope and sampling equipment (for more about these, see "Sampling Stains for Fun and Profit," HE Sept/Oct '98, p. 12).

If you work with a partner, a walkie-talkie will help you communicate when you find yourselves, for example, on opposite ends of a duct or want your partner to turn a fan on or off. It's worth spending a little more for a better model--they won't be helpful to you if there is a lot of static in your ear. Furthermore, every house doctor needs a stethescope (the mechanics version) so you can listen to air flowing through all the leaks you're going to patch up.

Finally, music can help you relax and will break the monotony of long, involved work, so a portable radio/CD/cassette player can be a good piece of equipment to have.

Blower Door

The blower door makes an appearance in almost every issue of Home Energy, and rightly so--it is one of the most important home performance diagnostic tools. The blower door that I use is manufactured by The Energy Conservatory in Minneapolis, Minnesota. I use it at many levels of sophistication. The most basic level is to suck air out of the house and then use my chemical smoke to identify bypasses, sometimes in conjunction with infrared equipment. I also use the blower door to determine house tightness, either with a digital manometer (see below) or by hooking up the blower door to my laptop computer via the Energy Conservatory APT data logger and software (see below). Different circumstances will warrant different levels of testing. Testing at higher-tech levels does require some additional setup, but it gives more accurate information.

Duct Tester

The duct tester is like a blower door for ducts. It is an invaluable tool for both testing and repair of forced-air duct systems as it can both tell you how much leakage there is and show you where the leaks are. The duct tester measures the air flow that occurs when the duct system is sealed at all the registers and pressurized to operating pressure (typically 25 Pa). Many energy codes and utility incentive programs use the air leakage measured by a duct tester to verify duct performance.

The duct tester most commonly used for diagnostic and verification work is the Duct Blaster, manufactured by The Energy Conservatory, but there are a couple of other companies that make duct testers. When you prepare to use a duct tester, make sure to bring your digital manometer and lots of masking tape. Although there are some special tapes available, 3-in-wide masking tape works well and is inexpensive. First lay up rows of tape on the wall next to the register to be covered, and seal all the seams; then peel the entire sheet off the wall and place it over the register.

The duct tester can also be used in other ways. In conjunction with a blower door, it can determine the amount of leakage to outdoors. By turning the system fan on and matching the duct pressures, it can provide highly accurate register air flow measurements.

Flow Hood

Flow hoods are used extensively in the commercial test and balance industry to determine air flows at each register. You can also use them to check system fan performance, to determine total system flow, and to check for adequate distribution, but don't expect perfect accuracy in these situations. Recent side-by-side testing of flow hoods against tracer gas and fan-assisted techniques, performed by Lawrence Berkeley Laboratory and others, has raised questions about their accuracy when used on residential systems. While return air flows were accurate, individual supply flows were not, due to the low flow rates found in typical residential systems.

Even given its shortcomings, the flow hood is a very useful tool for verifying hunches and checking for flow problems.

Pressure Pan

I use the pressure pan manufactured by The Energy Conservatory. It is a gasketed pan that comes in two sizes that are designed to fit over a variety of supply and return registers or grilles. You also get a 6-ft extension poll that comes in handy for ceiling registers and grilles. I use it to perform a quick test of the tightness of ducts that travel outside of the building envelope. I connect the pressure pan to my digital gauge and depressurize the house to minus 50 Pa. I then take a measurement with the pressure pan fitted tightly over the supply or return register. This has been a good tool in identifying duct runs that needed further investigation. It is a good idea to have some duct mask on hand when using a pressure pan, as molding and other obstructions can sometimes make it difficult to get a good seal.

Digital Manometer

One of my most useful tools is the digital manometer. It can be used to get pressure and flow readings from the blower door, to take vent pressures, to measure pressure differences between rooms, to take pressures in supply and return plenums, to measure pressure pan readings, and to do other miscellaneous tasks. It comes with two channels, and can do one-, five-, and ten-second averaging. It can also take long-term continuous average pressure.

Pay careful attention when averaging. Wind spikes can distort your average. Imagine that you have one-second readings (in Pa) of -1, -1.3, -1.1, -1.5, and -10 (the wind spike). The average = -2.98, yet the readings before the wind spike were between 1 and 1.5. The more accurate pressure is more likely to be somewhere between -1 and -1.5, so it is best to omit the -10. If you don't have a flow hood, you can use the digital manometer along with a handmade orifice box (instructions for making this are available through The Energy Conservatory) to measure exhaust fan flows. This is particularly useful for determining whether a fan is properly sized and/or has ducting problems.

APT Data Logger

The automated performance testing system (APT) data logger is at the core of much of the testing that I perform. Using it with my laptop computer, I am able to measure and document invisible air flows through the generation of graphs. I use the APT in conjunction with my blower door to conduct multipoint blower door testing and zonal pressure diagnostics. For example, I used it to conduct a series of 20- to 30-minute combustion safety and simultaneous zonal pressure measurement tests as part of the Twin Cities Metropolitan Airport Commission's Sound Insulation Project (SIP). I tested approximately 800 houses with that program and found the APT to be the key piece of equipment that I used. The APT is available through The Energy Conservatory.

APT Software

The Energy Conservatory's software that I use for the APT are TECTITE and TECLOG.

TECTITE version 2 is a building airtightness test analysis program that allows you to conduct an automated blower door test. It is capable of simultaneously measuring up to six building-to-zone and zone-to-outside pressures. TECTITE also has a "cruise control" feature that maintains a constant building pressure while the user conducts additional testing. There are other features as well; for example, TECTITE also generates a homeowner-friendly report as well as a detailed technical report.

In addition to providing accurate information, TECTITE saves a great deal of time. While it runs the blower door, I typically walk through a house and check for bypasses, conduct infrared scanning, plan the next series of tests, consult with the homeowner, or do paperwork. I use the digital manometer and APT together for certain types of zonal pressure diagnostics.

TECLOG is a DOS-based data logging program used in conjunction with the APT system. I use it primarily to conduct 30-minute combustion safety tests. During this type of test, I check to be sure that no conditions in the house create enough depressurization to cause the combustion appliances to start backdrafting. At a minimum, I graph the draft pressure of the combustion venting with respect to the combustion zone, and the pressure of the combustion zone with respect to the outside. Then I log the base- and worst-case depressurization conditions. For this test, I am primarily concerned with the effects of depressurization on the combustion venting draft pressures.

One great benefit of monitoring pressures during this test is that it lets me customize the testing protocol on the spot. Usually I follow a set series of steps during the testing protocol. However, the graph on the computer records how air flows are affected as I go through the process. In the middle of the testing protocol, I may observe on the graph, for example, that the pressure in the combustion zone dropped by 2 Pa when the door to the second floor was shut (and the furnace air handler was on). Often, a fully backdrafting water heater or furnace will begin to draft when a particular door is opened, even without any other changes in the worst-case setup. On TECLOG's graphs, I can see the problem and guage when it occurred during my tests. This allows me to offer more precise recommendations to the home owner. I might suggest installing transfer grills or additional return capacity, for example. In addition, having a graphic record of the tests allow me to show the homeowner exactly what changes in pressure occurred in a given situation.

Other Data Loggers

About two years, ago I bought some HOBO 8 data loggers from Onset Computing. I use these very compact data loggers to collect data on house conditions over longer periods of time than for the standard test--usually about a week. The HOBOs need to be connected to a computer for uploading and downloading information and for setting the time when they are to begin logging. The ones I use take temperature and relative humidity.

They also have an external port, to which I connect a CO₂ monitor to record CO₂ levels in the home's combustion zone. When I use the HOBOs, I also ask the homeowner to keep a diary of activities such as when they are at home or out, and when they cook and take showers. Correlating occupant behavior to the data can be quite helpful--you may find that just having them use the existing exhaust fans can eliminate moisture problems.

Laptop Computer

One of my primary tools is a laptop computer. There are many brands out there. You need to evaluate your present and future computing needs, take a look at your budget, and then go from there. Two very important factors to consider are the quality of the screen and the mouse control. It is worth paying more for a high-quality screen, because the graphs can get complicated and the lines in the graphs can be difficult to read on a mediocre screen. I have a touchpad mouse control with my Compaq laptop that I really like. Most models can also be used with a traditional mouse, although that is not very practical in most in-field testing situations.

Infrared Scanner

For several years I used an Agema 750 IR scanner, the type you add liquid nitrogen to and mount on a harness to carry. I leased that from a company in New Jersey. Although I was very happy with its performance, it was my heaviest piece of equipment, and having to keep a constant supply of liquid nitrogen on hand was a real hassle. I wanted something with good image quality that was easy to set up and maintain. One of my colleagues here in St. Paul learned of such a unit about a year and half ago--the Raytheon Palm IR 250. This scanner is about the size of a video camera and produces a very high-quality black-and-white image. It does not require nitrogen, and it is very reliable. Color imaging, while pretty to look at, would cost several thousand dollars more and would not substantially improve the quality of the data. Note that, if you purchase an infrared scanner, you must specify how you will use the device, so that you get the right type of lens for the camera.

Occasionally I get a request for photo or video documentation of thermal flows. There is a very slick Sony product, which sells for more than $1,000, that makes this easy to do. But given how rarely I get a call for that level of documentation, I instead purchased a 9-inch screen TV/VCR for around $250. The Palm IR 250 has an output jack for video. Using RCA-type cables, I have successfully videotaped IR images to the TV/VCR. This system also allows the client to observe the IR images on the TV screen while you are scanning. The TV/VCR can be powered by a 12V battery system.

Infrared Thermometer

An infrared thermometer can also be used to check the temperatures of surfaces in a building. Instead of a picture, it simply tells you the temperature of whatever your pointing at. Getting surface temperatures allows you to assess the potential of condensation formation, detect thermally powered airflow, discover defects in the insulation, find spots where outside air leaks in, and determine thermal comfort by radiation.

I recently bought a Raynger MX4 infrared thermometer. This is a good unit with a nice laser feature that will project a circle around the area you are measuring. The Raynger MX4 also comes with a several other useful features that include a built in emissivity table, the ability to save maximum and minimum figures, and features that allow for data logging. On a recent cold, snowy January night, I got inspired to go out and experiment with my IR thermometer and camera. I scanned my neighbors' two-story house with the camera and could clearly see the heat at the soffits. The thermometer showed that the surface temperature at the soffit was nearly 10°F warmer than the surface temperature of the outside walls. My neighbors have ongoing ice dam problems, and now they know why!

Dual Temperature Gauge

The dual temperature gauge is a readily available measuring device that, with the increased popularity of off-the-shelf air-cleaning furnace filters that can severely restrict return air flow, has become a wonderful asset. I tend to use mine in conjunction with a digital manometer: First, I measure pressures on both sides of the furnace filter and in the supply plenum. Then I take temperature readings in the same locations. It is then easy to compare these measurements with the manufacturer's operating parameters, which are usually listed on the nameplate. I can quickly determine if the furnace is operating within manufacturer's specifications (the Btu input is also easily determined by clocking the meter). This is an important consideration for issues such as depressurization, short cycling, and premature furnace failure. If I wanted to graph these measurements, I would do so with the APT.

Moisture Meter

A moisture meter is used to determine the dampness of porous materials. It helps you to trace water migration paths and tells you whether or not a surface is wet enough to grow mold. Although most of the moisture meters available are primarily geared towards measuring wood moisture content, many are advertised for use with other materials such as concrete, composite materials, or gypsum.

Moisture meters can be divided into two general categories, those with a pin, and those without. The pin type requires you to make a penetration into the material that you are testing. There is no penetration of the material with the pinless type. Some models on the market have both options (pin and pinless). Make sure the one you buy can adjust for the density of different types of materials. Moisture meters range in price from around $80 to well over $1,000, based upon quality and features.

Relative Humidity Meter

I recently purchased a relative humidity meter, the MC-PDP from Panametrics. This hand-held device allows me to take relative humidity and temperature readings accurately and easily. It also calculates dew points. You can even choose between temperature results in Fahrenheit or Celsius. What is really nice about this device is that it comes with its own calibration kit.

Carbon Monoxide Monitor

I use a Bascom-Turner carbon monoxide monitor. It has a very good reaction time, and I consider that to be an important safety consideration in situations where there is downdrafting or combustion spillage. The model I use also comes with an oxygen sensor. When I purchased this unit, I thought that it would be interesting to make oxygen-free CO calculations of gas ovens, because the CO operating parameters of many combustion appliances have been tested in protocols that use the oxygen-free method. My first, now spare, instrument was a Bacharach Monoxer II. While this was a good instrument, it took a lot longer to get readings (1.5 minutes as opposed to 30-45 seconds). Other manufacturers offer a variety of other models, such as Kane-May SGA-91, which also seems to be a reliable instrument.

Watt Meter

When doing building audits or checking electrical equipment, there is no replacement for a good watt meter. The name plate ratings on most equipment is there just for electrical safety and should never be used for estimating energy use. Amp meters are cheaper and simpler to use, but in order to calculate power use, you will have to estimate the power factor, which can be very difficult for low loads and inductive equipment such as motors.

Watt meters come in many types, and costs range from a couple of hundred dollars to over $3,000. For most residential work, there are two types that are appropriate. The appliance measuring type has a plug and a socket so that any plug-in device can be measured. These can sometimes also record total energy use and show power factor. A clamp-on type is similar to a clamp-on amp meter but also has voltage measuring leads. This type is most useful for measuring the power use of permanent equipment such as air-conditioners and pool pumps. If you get one of these, make sure it can measure both 120V and 240V power. Also make sure that the resolution is low enough for your expected use: A meter that has a resolution of 100 watts will not be very useful for measuring small appliances.

Digital Camera

A digital cameras is a great documentation tool to help you keep track of particular problems, situations, and configurations in a house and to keep a record of your work. The model that I recommend is the SONY Mavica. Its best feature is that is stores the images on floppy disks, which helps you keep your photos organized and allows you to store other data and/or reports on the same disk. These cameras come with their own imaging software.

The Most Important Tool

Clearly, a home performance contractor needs many important tools to do the job right. The most important tool, however, is not one that you can buy, it's something that you carry around on your shoulders.

Paying attention is the best thing that you can do when conducting any home evaluation. When in doubt, take the more conservative course of action--one that will ensure both your own safety and that of the occupants. Be aware of your surroundings, and know how to remove yourself quickly from a dangerous situation.

When I conduct space heater and water heater combustion safety and venting tests, for example, I always use a CO monitor. That lets me know if I am being exposed to dangerous levels of this odorless gas. Many other tools listed here will help to protect you in similar situations, but always remember to keep your most important tool--your brain--fully charged.

Stewart Selman of Selman & Associates does house diagnostics in the Twin Cities area of Minnesota.

Leo Rainer of Davis Energy Group in Davis, California, and Terry Brennan of Camroden Associates in Rome, New York, contributed to this article.

Table 1. Equipment Details

Favorite Models

Item Model Price Available From Phone Website Other Manufacturers or Distributors

Blower door Minneapolis Blower Door $2,250 w/ digital gauge; $1,850 w/ magnehelic The Energy Conservatory (612)827-1117 www.energyconservatory.com/index.html Infiltec (793)820-7696; Retrotec (360) 738-9835

CO₂ monitor 701 $500 Tellaire (805)964-1699 www.sensors.engelhard.com The Energy Conservatory

CO monitor Gas Sentry $1,500 Bascom-Turner (800)225-3298 www.bascom-turner.com Kane-May

Monoxer II $500 Bacharach, Inc. (714)895-0050 www.bacharach-inc.com Fluke (425)347-6100; ControlCo Automation (510)636-7900

Data logger APT 2-channel, $1,700; 3-channel, $2,000 plus $200 for each additional channel The Energy Conservatory (612)827-1117 www.energyconservatory.com/index.html Davis Instrument catalog (800) 368-2516

HOBO 8 $75-$100 Onset Computing (800)564-4377 www.onsetcomp.com

Data logger software TECTITE $150 The Energy Conservatory (612)827-1117 www.energyconservatory.com/index.html

TECLOG comes w/APT The Energy Conservatory (612)827-1117 www.energyconservatory.com/index.html many

Digital camera Mavica Sony Sony (800)686-7669 www.ita.sel.sony.com/products/imaging Infiltec (703)827-1117; Retrotec (360)738-9835; Shortridge; Alnor (800)424-7427

Digital manometer DG-3 $650 The Energy Conservatory (612)827-1117 www.energyconservatory.com/index.html Davis Instrument catalog (800)368-2516

Dual temperature gauge Fluke Model 52 $219 Davis Instruments (800)368-2516 www.davisontheweb.com Infiltec (793)820-7696; Retrotec (360) 738-9835

Duct tester Minneapolis Duct Blaster $1,725 The Energy Conservatory (612)827-1117 www.energyconservatory.com/index.html Professional Equipment catalog (800) 334-9291

Combination step and extension ladder various $300-$500, depending on size Little Giant (800)785-3557 www.ladders.com Alnor Instrument Co.

Flow hood FlowHood 8405 $1,635 Shortridge Instruments (480)991-6744 www.shortridge.com/index.html Agema

Infrared scanner Palm IR 250 $1,300-$1,500 Raytheon TI Systems (800)990-3275 www.raytheon.com Fluke (425)347-6100

Infrared themometer Raynger MX4 $1,000 Raytek (800)458-1110 www.raytek.com Tramex; California Instrument Co. (800)870-9494

Moisture meter MMS 35 series $80-$100 Panametrics (800)325-8330 www.panametrics.com

Pressure pan small and large $60 and $75 The Energy Conservatory (612)827-1117 www.energyconservatory.com/index.html Panametrics (800)325-8330, www.panametrics.com; California Instrument Co. (800)870-9494

Relative humidity meter ME-1 $85 Tylor Industries (510)594-8872 Binks, www.binks.com

Respirator various models $20-$30 3M (800)243-4630 www.3m.com Infiltec (793)820-7696

Smoke bottle Smoke Puffer $45 TEC (612)827-1117 www.energyconservatory.com/index.html Edwin L. Thompson and Son

Walkie talkie various models varies Lacom Communications PTE LTD www.lacom-pl.com Applied Industrial Technology (510) 568-6690; Graybar Connunications (510)873-8895

Watt meter Fluke 39 $995 Fluke (425)347-6100 www.fluke.com

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