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What is the Difference Between Blow Through and Draw Through?


This blog was guest written by Chris Leach, Applications Engineer. There are two main non-recirculating direct gas-fired heater designs for commercial and industrial applications and those are blow-through and draw-through. The main difference in these two systems is the location of the blower relative to the burner. While a simple difference, blow-through units provide multiple benefits for large industrial space heating driven applications. Blow-through, as defined by the DOE (Department of Energy) as HTHV (High Temperature Heating & Ventilation) and employed in our S-Series heaters, places the blower before the burner and benefits from a higher LAT (Leaving Air Temperature) and temperature rise (∆T). HTHV units are not limited by the fan components in the hot airstream and can safely discharge at the maximum allowable limit for CSA certified direct fired applications. Draw-through units place the blower after the burner and have a lower LAT and ∆T due to limitations of the fan components in the hot air stream. Each of these systems has a specific purpose for large industrial spaces. For heating driven applications, maximizing the BTU to CFM ratio maximizes efficiency ...

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The Right Solution For Industrial Cooling Lies Somewhere Between DX Cooling And HVLS Fans


Evaporative cooling can provide significant temperature relief at a fraction of the cost of mechanical cooling. Industrial settings - with much exhaust airflow for contaminants and a substantial footprint - can struggle to achieve clean and temperate indoor air conditions without expensive mechanical cooling systems. However, the sheer size of many of these facilities prices that technology out of the possible solution set. On the other end of the cooling option spectrum, HVLS fans tend to move the hot air around, dependent on contact cooling for temperature relief. The moving air from HVLS fans can help employees feel more comfortable but cannot address internal heat gains within a facility nor provide temperature relief. Somewhere between those two options stands evaporative cooling technology, which provides tempered make-up air while also improving indoor air quality with the usage of 100% outdoor air.    Two-Stage Evaporative Cooling Technology Shines in Industrial Facilities The Cambridge ESC-Series evaporative cooling unit is a semi-custom fabricated air handler that can utilize direct (DEC), indirect (IEC) evaporative cooling, or a combination of both indirect/direct (two-stage) evaporative cooling to meet specific usage ...

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Customizing the standard S-Series for better performance in humid environments


In warehouse and distribution center spaces where our standard S-Series HTHV (high-temperature heaving & ventilation) heaters are commonly installed, the units see 20-30+ year lifespans under routine maintenance and within the range of normal environmental conditions.

However, not all applications are “standard” and need specific conditions to be considered in the system design. A prime example of a situation where a facility needs the heat throw and efficiency that our S-Series provides, but with an overly humid environment, is that of heating a carwash tunnel. 

First, the facts: the car wash industry is one of the fastest-growing industries in the U.S., valued at a record $14.21 billion in 2020 and expected to expand 4.8% annually from 2021 to 2028. Based on conversations with industry leaders, a significant portion of their profit comes in the winter months; however, outside winter weather conditions paired with open bay doors present a challenge to keeping the tunnel warm enough for the car wash equipment to stay optimally functional. Closing the bay doors to retain heat is not an option because people may assume it is not open for business if the tunnel doors are closed. 

Chains Mike’s Carwash and Crew Carwash partnered with the Cambridge applications engineering team to develop solutions to the heating and equipment longevity challenges they faced in their tunnels.

A simple, yet effective solution: a Cambridge S-Series HTHV unit that keeps the bay from freezing and can often double as a method of drying a vehicle once the cleansing process has been completed. The S-Series meets the heating and airflow needs well and can be adapted to provide optimal performance and unit longevity amidst high humidity levels and corrosive environments that exist in car wash tunnels. 

The standard unit for Mike’s and Crew’s car washes was an S1200 unit with a stainless base, downturn housing, burner, discharge duct, and 12” roof curb and rail. However, these units historically lasted only two years before needing extensive maintenance due to the high humidity levels put out by the continual wash process.

In addition to the impact humidity had on the units, the tunnels also experienced high acidity levels from the strong mineral acids - hydrochloric, nitric, and sulfuric acids - used in their car wash process. The corrosion rate of galvanized steel is increased at low and high pH levels, explaining the discrepancy in unit life expectancies between S-Series in these environments versus those in standard conditions.

Our applications engineering team developed stainless steel selections to increase unit longevity – a stainless fan, fan shaft, unit housing, supply duct, damper and downturn.

These improvements were implemented two years ago. The stainless steel changes to the S-Series units in Mike’s and Crew’s car washes required far less maintenance. They were able to keep their tunnel doors open with less downtime replacing, adjusting, or fixing worn out components. Units remain structurally sound with the stainless improvements. 

While it is not yet known exactly how much the stainless additions have increased life expectancy, it is undoubtedly true that they have added time and reduced maintenance and part cost along the way. 

By virtue of a continuous improvement culture – we are continually making improvements to our products and process. If you want to discuss how our product lines and technology could help you bring healthy working environments to your people, our manufacturing rep network is local to you and can tour your buildings and discuss solutions specific to your space and climate. You can find your local rep here.