Tuesday, November 22, 2016

Check Combustion Air

With the weather getting cooler, I thought that now would be a good time to talk about combustion air. Don’t forget to check for proper combustion air. Most codes provide detailed drawings illustrating where combustion air should come from and how much you need, but there are still many furnace installations that rely entirely on air from inside the building for combustion air. In days gone by this was often considered adequate so long as the furnace was located in a large enough space. In newer homes, combustion air should always be provided.

Most 90%  furnaces today can operate using sealed combustion. In the case of a sealed combustion furnace, the combustion air is being piped in from the outside. The combustion air is piped directly into the furnace. These are easy to spot, they have two pipes: one for combustion air and one for the vent. Also, their panels have no louvers for combustion air. 

Traditional furnaces get their combustion air from the space where they are installed. Combustion air enters through louvers in their panels.Since the furnace is drawing air from the space it is in, fresh combustion air must be supplied to the room to keep the process going. Failure to supply the correct amount of combustion air can lead to negative room pressure, vent spillage, poor combustion, and CO production. All these things together can be disastrous.

When a technician checks a furnace that does not have sealed combustion, one of the first things to look for is how the furnace receives combustion air. If the furnace is in a ventilated crawlspace or attic, the ventilation for those spaces provides the combustion air. However, even these can be a problem. A large furnace in a small crawl space may not have adequate combustion air if the crawl space vents are closed. I have also seen crawlspace vents clogged with debris, effectively reducing the combustion air.  

The most troublesome installations are furnaces located inside the house in a closet. They should have a combustion air vent near the floor and another near the ceiling. Someone asked me about a furnace installed in a closet off of a bathroom. When they turn on the bathroom vent fan, they can smell gas! Another story involved a fireplace and a furnace. When the furnace came on it sucked the smoke out of the fireplace into the room. These types of stories indicate that the furnace does not have adequate combustion air. 

What if there are no obvious combustion air vents? Sometimes the vents were never provided, other times they have been covered up. I have seen combustion air vents covered with tape or plastic. Undoubtedly, someone noticed cold air coming in the vent and “fixed” the problem – thereby creating a combustion air problem. Occasionally insulation covers the grille into the attic. Another problem is using the furnace closet for storage. This is dangerous in and of itself, but it can also cause combustion air problems if boxes are stacked in front of the combustion air grilles.  For details on combustion air requirements check your local code. Unit 53 Gas Furnace Installation in Fundamentals of HVACR, 3rd ed also has detailed drawings and specifications for the most common applications.  

Saturday, November 12, 2016

Veterans Have the Right Stuff

On this Veteran’s Day I would like to suggest a way that the HVACR Industry can help those who served their country: offer them jobs. Veterans have many characteristics that make them ideal employees.

Veterans are disciplined.
Veterans have developed both self discipline and group discipline – both crucial skills for employment.

Veterans know how to work hard.
Remember, they made it through boot camp and survived years of living conditions most of us would find intolerable, all the while performing their job.

Veterans know how to be a team player.
The armed forces cannot function if everyone is freelancing. Installation is so much easier if you have a good team. Far more efficient than working alone.

Veterans can master technically difficult machinery.
Take a look at the equipment today’s armed forces work with. Much of it is incredibly complex. A veteran is someone who has been in a position where their life depended upon knowing how to operate that machinery.

Today, finding people who are good candidates for employment in the trades can be tough. Veterans already have the traits employers look for in a good employee, and that is a good base to build on. If the industry will reach out to veterans we will also help ourselves.

Here are links for people considering hiring a veteran or for veterans looking for help getting started in HVACR.

Troops to Trades 
Nexstar Legacy

Sunday, November 6, 2016

Digital Data Recording and Reporting

A relatively new class of communicating digital tools makes it possible to share your readings electronically. They not only take accurate pressure and temperature readings, they can share those in an email with your supervisor, company, customer or energy utility. And many of these can take more than just refrigerant pressure and temperature readings. The Stride I-Manifold, Testo Smart Probes, Fieldpiece System Analyzer, Sporlan Smart Tools, Yellow Jacket Mantooth, and Appion ION gauges can all send data to your electronic devices, which then use free applications to create and send the reports. Some can collect information from a variety of instruments and report on them as well. For example, you can also get ambient temperature, indoor wet bulb, and indoor airflow. I am sure I probably missed a few.  The point is, tools are available now that can do more than collect data; they can help you organize it and report your results.

The reporting capability allows you to document what you have done. For example, you can produce before and after reports showing the system performance when you arrived and the system performance after you have made adjustments. You can also send reports to your supervisors if you need help. Some utilities have rebate programs which require that the contractor use a particular reporting setup. The idea is that the utility can verify that the system really is performing as designed by the manufacturer.

This is both exciting and a little bit intimidating. Until now, if you went on a call and checked the system performance, you were generally the only person that would see all the measurements and make the judgement. If you have checked more than a handful of systems, you know that checking system performance really is a judgement based on a lot of variables. And, you only have control of a few of those variables. It is not as simple as matching a couple of pressures and temperatures.

There is the outdoor temperature, the indoor temperature, the indoor wet bulb, the airflow across each coil; any one of which can make your system perform in a way you don’t expect. That is before issues such as plugged expansion valves, restricted filter driers, underperforming compressors, or installation errors. All of these things must be verified before adjusting the charge. It would be nice if we could just state a couple of pressures and/or temperatures and leave it at that, but that is not reality. Even manufacturer performance charts and tables assume a lot of this information. If just one value is off from the assumption, the manufacturer’s chart will not work.

So, if you ever needed any incentive to up your game when checking systems, having to send reports to supervisors, utilities, and customers should do the trick. Beer-can cold is just not good enough in an environment that expects documentation and verification. That is unless you plan to strap a can of Coors to the suction line and send in a photo of the color change. Here are a few links to check out these new-age tools.

Appion - http://www.appioninc.com/products/ptgauges.html
Fieldpiece - http://www.fieldpiece.com/products/detail/sman460-wireless-4-port-digital-manifold-with-micron-gauge/system-analyzers/
I-Manifold - http://imanifold.com/
Sporlan - https://sporlanonline.com/smart/
Testo - http://www.testo.us/smartprobes/index.jsp
Yellow Jacket - http://yellowjacket.com/product/mantooth-dual-pressure-wireless-digital-pt-gauge/