FAQ for Construction Heaters

1. How do I calculate the heat requirements for my job site?
    
   Use this formula:

   Heat required = cubic feet of an area (x) temperature rise (x) .133
   
   Example:
   Area needling heat is 80' (length) (x) 80' (width) (x) 12' (height) = 76,800 cubic ft 

   Temperature rise = 60 degrees F
   
   76,800 cubic ft (x) 60 degrees F = 4,608,000
   4,608,000 (x) .133 = 612,864 BTU per hour
   

    

   Refer to the manufacturer to find a construction heater or heaters rated to handle that load.

    
2. What size propane gas supply cylinder is recommended for use on construction heaters?
   
   Most heaters can operate off of smaller cylinders such as 20#, 30# or 50# capacity.  The problem that arises is the heater can use the vapor at a faster rate than the cylinder will supply.  Which causes the heater to supply a lower blower outlet temperature and may eventually shut down.  To eliminate this problem I recommend using 100# cylinders wherever possible.  You may even need to have several 100# cylinders manifolded together or even use a larger tank depending on the heat load of the installation and temperature.  Consult your local propane gas supplier for recommendations.
3. How long will a 100# cylinder last?
   It depends on a couple factors:

   The amount of gas that the heater uses per hour.
   Air temperature surrounding the gas supply container

   Heaters with larger heat outputs consume more gas per hour than heaters with smaller outputs.  Also the gas supply container will supply less vapor as the temperature drops.  At some point the gas container will begin to develop a frost buildup at the lower portion of its shell which indicates that the container is getting near the low limits of its ability to supply proper gas supply pressure. 
4. How do I determine how much gas my construction heater will use over one hour if it continually runs?
   
   Natural Gas Heaters:
   Divide the output of the heater by the BTU's in one cubic foot of natural gas.
   Example: 365,000 BTUH / 1000 = 365 cubic feet of natural gas per hour
   
   LP Gas Heaters
   a) To determine gas consumption in pounds per hour:
   Divide the output of the heater by the BTU's in one pound of LP gas
   Example: 155,000 BTUH / 21,591 = 7.2 pounds per hour
   
   b) To determine gas consumption in gallons per hour of LP gas.
   Divide the gas consumption in pounds per hour of LP gas by the pounds of LP gas per gallon.
   Example: 7.2 pounds per hour gas consumption / 4.24 pounds per gallon = 1.7 gallons per hour
5. Can I use a construction heater to heat my shop of garage?
   
   Maybe - Depending on the type of heater you are using.  Most construction heaters are non-vented and are designed specifically for the heating of buildings under construction, alteration, or repair.  These are typically areas where air exchange is established to promote proper gas combustion within the heater.  If the heater is used in a tighter structure without proper air exchange, potentially dangerous gases such as carbon dioxide will accumulate.
   
   If you choose a Indirect heater with a heat exchanger that can be vented to the outside then using it in a shop or garage can work.  Always check with the manufacturer before using it in an enclosed area.
6. My eyes water and throat burns a short time after using the heater.  What is the problem?
   
   The problem could be attributable to any of the following conditions:
   a) Poor ventilation at the job site which contributes to poor gas combustion.  Introduction of more fresh air is needed.
   b) Poor gas pressure to the inlet of the heater.  Gas pressure will need to be checked by a qualified gas heater service person.  The heater's data plate refers to proper inlet and burner manifold pressures. 
   c) The heater is burning contaminants that are in the air which is used for combustion.  Examples would be parts cleaning solvents, paints, etc.
7. My heater's burner flame is yellow and gives off a strong gassy smell.  What's wrong?
   
   Check these things:
   a) Proper gas pressure to the heater (refer to the heater's data plate)
   b) Obstructions in the burner casting, gas manifold or plugged burner orifice.  Clean out the obstruction.
   c) Do you have the proper supply of fresh air?
8. My forced air heater sparks, but will not ignite.
   
   Check the following:
   a) Low fuel gas supply pressure
   b) Tank valve not completely open
   c) Tank valve opened too quickly, causing lock-up in excess flow valve in regulator, close tank valve and wait 5 minutes, then reopen the tank valve
   d) Defective gas control valve