Big Maxx heat exchanger glowing

[ride92]

Got my 80k btu heater installed and notice that when the garage lights are off at night and the heater is running there is a faint red glow on the 3 middle tube at the first bend. I bought a manometer and stepped the pressure down to about 3.8”w.c but it still glows. I checked the temps with my IR temp gun and got around 950F at the bends where it was glowing. Is this normal for the mr heaters? I find mixed answers when I search here or elsewhere on the web.

 

[Gizzi]

Is there good flow from the venting? What does the manufacturer state for manifold pressure?

 

[ride92]

Venting is all brand new b-vent with 2 45 elbows in the attic to get to where I needed it vent thru the roof so I can’t imagine there’d be an issue there. And when you say manifold pressure? You asking before or after the heaters regulator. Mr heater says 4”w.c pressure after regulator for elevations below 2000’, I’m at about 900’. I turned it down to about 3.8”w.c

 

[Gizzi]

Venting is all brand new b-vent with 2 45 elbows in the attic to get to where I needed it vent thru the roof so I can’t imagine there’d be an issue there. And when you say manifold pressure? You asking before or after the heaters regulator. Mr heater says 4”w.c pressure after regulator for elevations below 2000’, I’m at about 900’. I turned it down to about 3.8”w.c

Manifold pressure is after the gas valve, on the burner side. Do you have the proper vent cap? Some caps if they are set too low can block the flue. Combustion analysis would determine if it's normal or not.

 

[ride92]

This is the vent cap that I have:


Amerivent® 4" B-Vent Rain Cap at Menards
https://www.menards.com/main/p-1444432073849.htm

How much does a combustion analysis cost? I hate to call one of these hvac companies that gave me crazy high quotes for a garage heater (around $5000) after I’ve bought and installed a heater myself

 

[Gizzi]

This is the vent cap that I have:


Amerivent® 4" B-Vent Rain Cap at Menards
https://www.menards.com/main/p-1444432073849.htm

How much does a combustion analysis cost? I hate to call one of these hvac companies that gave me crazy high quotes for a garage heater (around $5000) after I’ve bought and installed a heater myself

That vent cap should be ok. You could try taking it off to see if it makes any difference. I would measure the flue temp to see how hot it is. If the flue temp is well above 450F, there could be an issue. 80K BTU may also be oversized for your application. Combustion analysis would be the standard cost of a service call, trip, labor, etc. Could also call their tech support to see if it's normal for those units.

 

[toyotadriver]

My Mr Heater Big Maxx 80k glows faintly at the first bend when running. It’s only visible when all the lights are off. I don’t recall my specific exhaust temps although years ago I measured them and they were within normal ranges. It’s been heating my shop for the past 7-8 years and been working fine.

It’s more visible when it’s just maintaining the temp vs heating up a cold shop but I’m sure that’s because 45* air causes more cooling effect on the tubes than 60* air.