Should heat exchanger glow dull orange?

[rponfick]

I just installed the new Big Maxx 80K NG unit in my garage, and have only operated it spordically. It got pretty cold last night, so I decided to give it a little test run. After about 10 min. running, I noticed the first bend in the heat exchanger tubes were glowing a dull orange. It was nighttime so I could notice it more.

Is this normal, and what have you other owner's noticed? I live above 5000ft and have not had it adjusted for altitude, which would cut down the gas pressure somewhat. I am afraid that it might be operating too hot.

Any comments? Ralph

 

[philjafo]

No it shouldn't get that hot, I'm not very familiar with high altitude settings for that kind of stuff but I have seen furnaces that were run too hot at 600 ft and in a short time it will burn a hole in the back of that first bend.

Definatly want to have an HVAC tech come out there and set that thing with a combustion analyzer, it will run more efficiently and last longer.

 

[rponfick]

Just talked to my local utility that supplies natural gas in my area. Technician said I should have the operating pressure at the gas valve in the heater reduced to manufacturer specs. I was under the mistaken impression that the BTU value of the gas may already be reduced at altitude because it could burn too hot otherwise. He indicated that in my local area the BTU content was actually richer (higher) than some other areas in the metropolitan Denver, and he would recommend reducing pressure.

Heat exchangers could burn out earlier than normal, and I guess that could be a safety hazard.

Looks like I will be looking for someone with a Manometer.

Keep warm. Ralph

 

[philjafo]

A manometer will get you close, but it should be set with a combustion analyzer to get the best efficiency out of it.

 

[rponfick]

Phil, not sure what an combustion analyzer entails. Also, not sure if the usual plumbing tech would have access to what is required to conduct such a test.

Any help? Ralph.

 

[philjafo]

A combustion analyzer is a tool that measures what comes out of the exhaust on a fuel burning appliance. Think like the oxygen sensor in a car, it tells the computer what's coming out so it can adjust for optimum mileage and performance, except on a furnace the computer is the HVAC technician and the furnace only runs at 1 or 2 speeds. So it only needs to be set once and just verified every year.

A plumber might have a manometer because they work on water heaters but I doubt they would have an analyzer. You wouldn't call a mechanic to reshingle your roof would you? A professional HVAC tech should have the analyzer and the ability to read what its saying, not all of them out there do. Get references and check on licenses and insurance, it is gas and a heat source after all google gas leak explosions.

 

[rponfick]

I got my manometer from Amazon and adjusted my operating pressure down to 3.3"WC. End of first bend in heat exchanger still glows dull orange in low light conditions.

Emailed tech line at Mr. Heater and they said this is normal. He indicated that the gas pressure sounds good and the heat exchanger has a 10 year warranty. So, I guess I am good to go.

Just wanted to update post.

Ralph.

 

[DPelletier]

Good deal.

I'm too late on this one, but you always want to ensure that you have the right gas pressure going into any gas fired appliance. Too high gas input pressure can cause all kinds of problems.

My company once installed two furnaces into a residence (one in the main house and one in the guest "casita"). The secondary furnace had all kinds of problems, complaints of "banging" and "popping" on start up, gas smells, etc. After I had two different techs look at it and replaced the control board (twice) and the gas valve, I finally sent someone else who correctly diagnosed the incoming gas pressure was too high. Turns out the gas fitter (done by another company) used a step down reg on the line upstream of the main house furnace but took the run for the casita off on the high pressure side of the gas line.

Lots of money and time wasted.


Dave

 

[CADPoint]

Negating bad settings, I just finished wiring twenty walk in boxes.

My contact was illustrated that my wiring be away from the coils because they did get to glow...

These were precise machines that could control the temperature to with a fraction of a degree, that were installed in a lab setting.

 

[Steevo]

I got my manometer from Amazon and adjusted my operating pressure down to 3.3"WC. End of first bend in heat exchanger still glows dull orange in low light conditions.

Emailed tech line at Mr. Heater and they said this is normal. He indicated that the gas pressure sounds good and the heat exchanger has a 10 year warranty. So, I guess I am good to go.

Just wanted to update post.

Ralph.

I checked mine last week, and even in a darkened room, under full heating power, I can see no perceptible glow at all from the heat exchanger on mine.

 

[Mike007]

I checked mine last week, and even in a darkened room, under full heating power, I can see no perceptible glow at all from the heat exchanger on mine.

Ive never seen a heat exchanger on a unit heater glow either.

 

[rponfick]

Must be my high altitude and high BTU gas. You guys don't make me feel any more comfortable.

Ralph

 

[Steevo]

Mine is at 4700' elevation, running NG.
Not high altitude, but not coastal either.

 

[dave67fd]

I'm using propane at 1500' and mine glows.

 

[nwav8tor]

NG @ 1950' MSL and mine also glow orange on the first bend (some more than others).

Paul

 

[CADPoint]

This is where you need to get an inexpensive thermal gun and take some readings.

You also have to remember all the forces at work, if this is the first coil were else
is the first work going to show up. You also have to remember exactly what the coil is
doing at any one time. Some times its forcing air across the heated coil, sometimes
it's a cooled coils.

I think it's fine.

Get it serviced and ask 10 questions if your not comfortable.

 

[z28dad]

Mine glows on the first three rows, top to bottom. I purchased a manometer and made all the checks. Everything was ok. I have noticed a discoloration in the heat exchanger on the first bends.