How to Calculate the Cost of Electric & Gas Conveyor Dryers
When looking at conveyor dryers for screen printing and direct-to-garment (DTG) drying, the first question is deciding whether you want an electric or a gas dryer. Most commercial and residential locations have both utility services available, so deciding between curing shirts with electric or gas often comes down to which dryer is cheaper to operate.To figure out the cost it takes to operate a gas conveyor dryer versus an electric tunnel dryer, you need to understand the difference in how the utility companies charge you for the amount of electricity and gas you use.
To Calculate the Cost of Operating a Gas Conveyor Dryer:When the utility company provides gas to your location, it often measures your consumption in British Thermal Units (BTUs). The term BTU originated around the 1800s during the rise in steam power and is why BTU is a measure of the calculated amount of energy that's required to increase the temperature of a pound of water by 1° F.
Some utility companies charge you by how many Therms you consume. One Therm equals 100,000 BTUs (1 T = 100,000 BTUs). Knowing how to calculate Therms to BTUs lets you use them interchangeably.
To give a real life example for screen printers, if you wanted to calculate the amount of BTUs based on your Therms, you would divide BTUs by 100,000 (Amount of BTUs Used / 100,000 = Therms used). For example, if you use 180,000 BTUs, that is 1.8 Therms (180,000 / 100,000 = 1.8).
Taking an average cost of natural gas at $0.95 per Therm shows up how to calculate the cost of running a screen printing or DTG gas dryer. Using the cost of natural gas, calculating the hourly cost is simple: Therms Used Per Hour x 0.95 = Hourly Cost of Operation.
To make this calculation specific to you, replace the average gas price with what you pay. For example, if you only pay $0.87 per Therm, your hourly cost calculation becomes: Therms Used Per Hour x 0.87.Once you have your hourly cost, you can multiply that by the number of hours in a month you are running your gas dryer. A standard work month has about 160 hours (20 working days per month x 8 hours per day = 160 hours). Mathematically, the expression looks like this:
BTUs / 100,000 x (hours per month) x (gas rate) = Cost per Month.
Continuing our example: if you use 180,000 BTUs, that is 1.8 Therms; multiple by 160 hours equals 288 Therms per month. Multiply 288 by the hourly rate of $0.95 to get $273.60 for your monthly gas cost. Your math equation would look like this:
(180,000 / 100,000) x 160 x 0.95 = 273.60.
Remember that your gas dryer needs some electricity, primarily to run the controls, belt motor and blower. Add these electricity costs and you will have the actual cost of running your gas dryer.
To Calculate the Cost of Operating an Electric Conveyor Dryer:Comparing the cost of an all electric dryer to a gas dryer, requires using the same unit of measurement so they can be compared. Therefore, we must convert the energy used for an electric dryer into BTUs, or vice-versa.
There are 3,412 BTUs in 1 Kilowatt (kW) of electricity (3,412 BTUs = 1 kW). To convert the BTUs of a gas dryer into its equivalent electrical consumption, divide the BTUs of the dryer by 3,412 (BTUs of Dryer / 3,412 = Equivalent kW electric consumption).
Taking an average cost of Kilowatt hour (kWh) in the U.S. at $0.105 per hour we can compare gas versus electric conveyor dryers. Using the same formula for calculating monthly cost as before, take your total kWs x 160 average hours per month; x the cost of a kW hour to equal the cost per month. Written as an equation, it looks like this: (kW x 160) x 0.105 = cost per month.
Conclusion
Being able to compare energy costs of gas versus electric screen printing and DTG dryers provides a great way to compare which one will save you the most money on utilities. Typically, printers see the best long term savings on gas dryers, which off-set the larger upfront capital expense.
A quick note on that the above comparison is done on average and nominal gas, electrical and fuel costs. It is intended for relative comparison only as your actual rate may vary.
