Gal Power 2017-08-19 00:25:07
EIGHT HOT STEPS Follow these steps to recommend the right heat solution. With winter around the corner, thoughts are turning to preparations for the upcoming winter season. For many people, this also means looking at sourcing temporary heat for a variety of situations. Whether it be a construction site, warehouse, hotel, health care facility, office building, film set or special event, if you need to provide temporary heat this winter planning ahead is critical to make sure you have the heat you need when you need it. Getting the right equipment for the job is key, no matter where you are located. In order to help determine the size and type of heater your customer needs, there are some basic steps that are key. 1. KNOW THE ZONE Get an understanding of the area where your customer wants to control the temperature through heating. You will need to determine the surface area of the exterior walls and roof as well as total volume of the space. Take into consideration other equipment or machinery that may have an impact on the heat load. For example, machinery or ovens will give off an additional heat load when running. 2. VENTILATE OR RECIRCULATE? Ventilating a space will bring fresh air into the space while recirculating the air will reuse the existing air in the space. There are advantages to both, however, it is also important to consider whether the space is occupied by people as this will determine what type of heater you are able to use. [For a full discussion of using make-up air versus recirculating, see page 30.] 3. CALCULATE THE HEATING OR COOLING LOAD There is a formula to calculate heat loads with many variables to input. For example, you need to consider the type of building being heated and what type of insulation is in place, if any. Heating calculations do take into consideration insulation R-values, and having an idea of how tight the building envelope is also helps. Buildings retain more heat, for example, than tents, so this makes a difference when determining what equipment you need. Other considerations are the lighting load and the equipment load in the building or space and any additional heat loads. Another important factor is the number of people in the zone, as people are also a heat source that can affect heat load. (Interesting fact: did you know that 200 people sitting give off less heat than 200 people dancing?) Over and above these considerations, the outside temperature and the desired inside temperature must also be factored in. What is important to note is that the heat calculations be done with as much information as possible to ensure an accurate translation into BTUs and CFMs needed for the purpose of selecting a heater. 4. HEATING SMALLER AREAS In smaller areas and open areas with good air circulation you can reduce the volume of air pushed and increase the heat. The crucial factor in heating this way is to start early and ensure that heat is not escaping through open doors or windows. 5. SAFETY FIRST It is always important to ensure that the setup of the equipment does not interfere with the normal operation of the building and that its placement should always follow safety guidelines. It is important to ensure regular maintenance and testing of all equipment and functions and that installation is completed by a licensed and qualified person. Heaters are usually self-contained, however, they can get hot, depending on the type of unit, so it is important that steps are taken to ensure that the unit is placed in a safe location and distanced from any combustible materials. As air is often ducted in (sometimes ceiling-mounted or wall-mounted), it is important to ensure that all duct work is properly installed and secured. 6. YOU GOT THE POWER? Determine the available power at the location. If additional power is required, arrange for a generator or look at using a self-contained unit. Depending on the size of the heater, heaters can use from one to 400 kilowatts. Also, voltage needs to be considered depending on what type of equipment is supplied. Many units also incorporate fuel tanks for ease of use with longer-term jobs. If using natural gas or propane, ensure that you understand the minimum pressures required to run the equipment and ensure that you are able to meet them. For example, if gas pressures are too low, heating equipment will become finicky and not run properly. Common issues with propane and natural gas pressures stem from improper installation by unlicensed people or lack of consistent supply. This can be addressed by the service provider, however, it is important to note that it is critical that the piping system design must be done properly to ensure not only proper pressures, but also the flow of gas. In other words, the correct volume of gas is just as important as the correct pressure of delivery. If either of these are not at the level the heater requires, there will be issues with performance of the heater. 7. PLAN AHEAD You might want to consider offering discounts to customers who book heating equipment for a full season. Being able to plan ahead will allow you an opportunity to budget better. It’s also a good idea to make fuel consumption estimates for any type of heater (propane, diesel or oil) with your supplier. All heaters are tested for fuel consumption at different percentages of usage by manufacturers and this information can be accessed by your supplier to help determine fuel consumption estimates based on the usage of the heater. Your customers will appreciate the assistance in determining their costs. 8. GET HELP Select equipment with the assistance of your specialist and consider the typSelect equipment with the assistance of your specialist and consider the typical space layout and restrictions your customers face. When trying to maintain a building or area temperature, it’s all about having the right BTUs and also the right CFMs to ensure that the building is under adequate pressure and receiving adequate air changes. These are important factors when selecting the right equipment. Designing and installing temporary heat for very large or complex projects obviously requires much more expertise than can be communicated here. But these eight simple steps may get you on the right track for your everyday heater rentals. FRESH AIR To use make-up air or recirculate – that is the question. When building your heat fleet it is a good idea to have a mix of different heater styles to meet any application your customers may encounter. One consideration is whether your heaters use a “make-up” air or a recirculating air supply. There are some significant differences between the two and where each is best used. WHAT IS MAKE-UP AIR? Make-up air is air from the outdoors that is heated and then evenly distributed indoors in a controlled manner. This drier, tempered, fresh air has the ability to absorb moisture and diffuse the fumes from the construction process by replacing the contaminated air in the building with fresh air. It provides lower relative humidity levels and dew point temperatures inside the building to prevent condensation and minimize the potential for mould. WHAT ARE RECIRCULATING HEATERS? Recirculated air heaters are indirect-fired units that come in a variety of types and sizes. They can use diesel fuel, natural gas or propane. Recirculating units use their fuel to power a heat exchanger, rather than directly heating the air, and the combustion process is fully contained and the exhaust is vented back outside. WHAT ARE THE ADVANTAGES OF USING MAKE-UP AIR UNITS? Make-up air heat is better for curing and drying wet building materials such as drywall, concrete, paint and adhesives. Ordinary recirculation does not remove moisture from the building. As existing moisture evaporates from construction materials, it stays in the air and is simply recirculated through the heating process. Buildings that are heated via recirculation typically have a higher relative humidity, which can extend drying times. Because makeup air units are constantly introducing fresh outside air, the evaporated moisture is forced out of the building by the new dry air coming in. Outside air in the winter typically has a very low relative humidity, however, this is always dependent on location. WHEN TO USE RECIRCULATING HEATERS Perhaps the biggest advantage of recirculating heaters is that they can be used to heat occupied buildings. It is important to note that make-up air units cannot be used in an occupied building and are for use during construction only. Diesel fuel is not available in make-up air applications, so if that is the only fuel available on site, recirculating or indirect-fired heaters need to be used. A recirculating heater attempts to control the temperature issue only. It does add moisture from the combustion process and relies on uncontrolled infiltration to ventilate. Recirculating heaters can potentially save on fuel consumption. Depending on the unit, they can also be used to duct the heated air to remote locations to heat colder spots. WHAT ABOUT SET UP? As make-up air units typically offer more BTUs and CFMs per unit, you usually need fewer units on a site. As a result, the installation costs are often lower. There may also be savings because your staff is maintaining less units over the long term. All buildings infiltrate, or “breathe.” This naturally occurring air movement happens when there is a temperature difference between the inside and the outside air. Because buildings breathe, and because there are air contaminants (paint, adhesives, exhaust gases, etc.) and moisture during construction that needs to be diffused or exhausted, it is desirable to mechanically control the process through the heater. Make-up air heaters allow the introduction of controlled amounts of fresh, tempered air from the outside. When using a make-up air unit, it is desirable to seal up the building as much as possible to avoid normal infiltration through doors and windows. The more a building is sealed, the better the heat retention, and this applies for all types of heat. However, some of the largest benefits of using make-up air will occur in a loosely sealed building as the building’s pressurization, via the make-up air unit, essentially moves interior air outwards continually and exhausts it while keeping the outside elements out. This is where make-up air units excel at keeping even heat distribution even in the largest and densest of buildings. As you can see, the choice between make-up air heat and recirculating heat can be complex. Is drying the goal, or simply heating the work space? What is the outdoor humidity? Is the building occupied? What fuel sources are available? How much ducting is required? The answers to all these questions will determine the right choice for your customer. GO NATURAL Natural gas can be an attractive heat option. There are a wide range of natural gas heaters on the market today. They can be open flame, make-up air or indirect-fired units that can range from 100,000 BTUs to 4.5 million BTUs and CFMs are variable depending on the type of unit. The main differences between models are typically the complexity of control systems and the construction materials used in these units. The more features and options, such as units with remote thermostats that can be monitored remotely, the higher also the price. Things to also consider when purchasing natural gas units are warranty, availability of replacement parts and manufacturer support. The most common natural gas heaters are open flame “salamander” heaters along with 750,000-BTU indirect-fired heaters, however, there are enough styles of natural gas heaters that there is a size for almost any application. Salamander heaters are most often found at construction sites and date as far back as 1915 when they were created to provide warmth to construction workers in inclement weather. WHY USE NATURAL GAS? The most common attraction for using natural gas is usually price and the constant availability of a fuel source. According to Union Gas, a natural gas supplier in Ontario, natural gas can cost up to 60 per cent less than propane or electricity. Union Gas also says natural gas produces a drier heat than other fuels, making it more attractive for drying and curing construction materials. There is no worrying about calling for and organizing fuel refills or the tank emptying out, so there is one less thing to manage. Sometimes the customer can pay for their own gas consumption and the contractor heating the building just supplies the equipment, so the customer takes care of the gas. These arrangements often make natural gas an attractive option for the customer. INSTALLATION OF NATURAL GAS HEATERS To hook up a natural gas heater, a qualified gas fitter (G1 licence) and an electrician to make the connections must be used. Fuel pressure needs to be confirmed, as well as voltage and a combustion analysis to determine proper fuel/air ratios. This being said, rental store staff can be trained in certain areas. ROT training can offer your staff the ability to work on heaters up to certain BTUs and also to be trained on start-up and maintenance of the units. However, it is important to note that for a full install, a licensed gas fitter and electrician are required. For questions related to install, contact your local regulatory body for clarification on what the regulations are as they can vary by province throughout Canada. One limitation of natural gas is that the site must be ready to receive the line before service can be put in. For instance, in Ontario, Union Gas requires the building foundation to be poured and backfilled, with the soil compacted to within six inches of final grade. The gas meter location must be marked on the foundation with the correct clearances from building openings. There has to be a clear route, free of debris, machinery and construction materials, from the meter to the property line in order to install the line. SAFETY CONSIDERATIONS As with all types of heating equipment, it is imperative that the manufacturer’s instructions be followed closely and that no modifications be made to the equipment without checking with the manufacturer first. Ensure that all local and national codes and regulations are followed (for example, from the Technical Standards and Safety Authority, which is the regulatory body in Ontario) and ensure you are in compliance with the most recent code updates. Using natural gas does eliminate the need to handle and replace fuel and fuel tanks, reducing the chances of an accident while refuelling. The lack of spare and empty containers on the job site reduces clutter and fire hazards. MAINTAINING NATURAL GAS HEATERS Natural gas heaters need to be kept clean from debris and need to be well maintained for optimum performance. Bearings need to be greased on a regular basis, belts adjusted and hardware (screws, nuts, bolts) tightened. It is also important to carry out electrical system inspections and clean and test the burners on a regular basis. HEATERS THAT ARE SWITCHABLE BETWEEN PROPANE AND NG Today, there are heaters that have flexible fuel capacities between both propane and natural gas. Changing fuels in these units is fairly simple. As there are very few drawbacks, these units are good options that give rental stores the flexibility to adhere to their customer’s needs. Obviously, natural gas is not in common use everywhere in the country and therefore many construction sites will not have service. But where there is service, it can be a less expensive and convenient way to heat a construction site.
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