Garage Heater - Natural Gas - Just installed and flames are tiny

[jonathan4465]

Hey all! I'm really struggling with this and any advice would be great.

I had a friend who has a pipe cutting and threading machine help me extend my natural gas line to the other side of my basement and into my attached 2-stall garage\workshop. I bought a used Dayton natural gas heater to put in the garage. It's a Dayton 3E402.

We got the gas line in place (1/2" the heater is 40k BTU) and the total length we ran from where it comes into the house is about 50 feet total. We have good pressure in the garage. We hooked the heater up, lit the pilot light and set the thermostat. As expected, you hear the valve open (Robertshaw 7200ER), gas runs for a bit, then the burners light. After the burners are lit for abut 2 minutes, the fan kicks on.

The issue is, it blows air that is barely warm. When I look at the flames coming out of the burners, they are only a couple inches high. I'm no HVAC guru at all, but they should extend a good 6 inches up into the heating element tubes right? I ran the heater for 2 hours and it barely increased the garage temperature by 5 degrees. (And it was rather warm today at high 30's)

What I've tried:

- Pull burners and make sure there were no clogs or other blockages
- Checked both orifices - no obstructions
- Pulled gas line off valve and checked screen, nothing restricting gas flow
- Tried adjusting pressure on valve, was already maxed out from previous owner
- Tried reducing pressure, flames even smaller
- Tried adjusting air allowed in burners - no adjustment gets the flames more than 2 inches high.

I'm thinking of replacing the valve with a new one, because this is an older heater and very simplistic and I'm not sure what else it could be.

Any ideas are welcome!

See pic...I have gotten a slid flame all the way across after adjusting the air intake on the burners, but the size of the flame stays the same!

[Failure2Comply]

The flame is composed of two sections, the outer section and the inner section called the mantle. The mantle should be very well defined and approx. one inch tall. From your pictures it appears that the burners themselves are stopped up hence not all openings along the burner are burning as noted by the open areas between the flames. If on natural gas you need to verify that the manifold gas pressure is set to 3.5" WC, but check the nameplate for proper setting, it could require 4"WC. Your unit heater is capable at full burn of approx 32K BTU/Hr output. Also if that is your drip/sediment trap right before the gas cock it is installed against code. The trap must be on the "Run" of the TEE, not the "Branch". More pictures of your setup would be helpful.

[jacobsond]

Just a silly question. Is the heater setup for natural gas or propane? Propane pressure is higher so the orface is smaller. On nat gas then the flame would be lower

[jadnashua]

Just a silly question. Is the heater setup for natural gas or propane? Propane pressure is higher so the orface is smaller. On nat gas then the flame would be lower

Good point...make sure both the regulator and the orifice are the proper ones for NG.