Natural gas furnace not working properly

warno

> @SuperTech said:
> Please do. I can't stress the importance enough. A properly trained technician with a digital combustion analyzer is the only way to ensure that your equipment is operating safely and efficiently. The technician can also test for CO Inside your home, down to one part per million.
> Make sure the tech leaves a printout from his analyzer

I just called the local 24/7 service company that's in my town. They've been in service 24 years and the guy i talked to seemed as though he'd never heard of a combustion analysis. He said they do the typical checks of gas pressure, air flow, heat exchanger integrity, and tune up. But no combustion analysis. I'll call another company tomorrow and ask them.

Is there something technical I should ask other then "do you guys do combustion analysis on natural gas furnaces"?

SuperTech

I would leave it at that. I have seen the good, bad and ugly sides of HVAC service. And a technician or company that doesn't care enough to have the tools required to do the job isn't one that is welcome in my house.

Maybe try a company that services oil and gas fired equipment. But don't waste your money in a company that isn't equipped for the job.

Maybe try the find a contractor tool on this site.

warno

I tried the contractor tool. Closest one is 100 miles away.

I emailed another company about the test and the response I got was "we don't normally do that on residential units. That's something more for 1 million btu or greater furnaces. Ushally we set the gas pressure and insure flame remains blue and that is it." This was a company from the nearest large city to me.

I'll call another company tomorrow.

SuperTech

Yikes. Any fuel burning equipment requires combustion analysis to ensure safe, efficient and reliable operation. It doesn't matter what size the equipment is.
No amount of staring at a flame will provide the information that is learned from combustion testing.
I've been doing HVAC service for a long time and there have been plenty of situations where a technician feels like the flame looks good but then the analyzer provides evidence to the contrary.
Code should require any technician working on a fuel burning appliance to be trained, certified and equipped with combustion testing equipment. In many other countries that's the way it is.

I'm guessing that you might be located down south? It seems like standards are more relaxed in warmer climates. I really hope you can find a contractor who knows how to properly analyze combustion. It's the most important aspect of my job as a service technician. Please keep me updated, I hope you find someone soon

warno

I live in central Illinois.

The guy I called first spouted about his certifications being good for nation wide service. And still didn't seem to think it was necessary.

I'll call a few more places tomorrow. There's one on my list to call that has been in service for over 60 years in this area. If they don't understand or recommend what I'm asking I don't know who will.

NY_Rob

Call Lochinvar, Triangle Tube, HTP, Buderus, Burnham, etc... ask for sales... tell them you're interested in one of their mod-con boilers and they'll gladly supply you with the name of their sellers/installers in your area. They in turn would have to have a combustion analyzer (and someone trained to use it) in order to sell/install/service mod-cons.

warno

Finally found a company that will do the test. I'm waiting to here back on what they actually test for to be sure it's the right test I'm looking for. When I called, the lady that takes the calls had to ask the technician if that's a test they can do. She called me back and said it was and when I asked what exactly they test for she had to call the technician again. I'm waiting for that phone call now probably going to be tomorrow because it's after hours now.

I'm honestly thinking a combustion analysis is just something that isn't done in this area. Or is uncommon anyway. My friend that looked at it Sunday is an ex HVAC company owner and I trust his judgement but that might have been why he just looked at the burn and said it's good. Just like another company I called that said if the pressure was good and the flame was blue, it's good.

SuperTech

I've seen perfect gas pressure and blue flames on a system with a bad heat exchanger before. That's why combustion testing is so critical.

I'll explain how a proper test is performed on a gas furnace so you know what to expect from the technician. The analyzer should be started up outside in the fresh air to avoid it zeroing in potentially contaminated indoor air. Then the technician should perform a test for ambient carbon monoxide when he gets inside. A digital combustion analyzer is much more sensitive than any CO detector..

A small hole will be drilled into the flue pipe right after the connection to the furnace and before the draft hood or barometric damper. The technician should insert the probe of the analyzer into the hole and start the pump in the analyzer before turning on the furnace. This way the test will begin as soon as ignition occurs. The tech should pay attention to several points of information that the analyzer provides, percentage of oxygen (O2) percentage of carbon dioxide (CO2), excess air and of course carbon monoxide measured in parts per million. O2 and CO2 should reach a steady state where the percentages remain steady. If these percentages change when the furnace blower motor is Energized this is very bad and could be an indication of a failed heat exchanger. Carbon monoxide (CO) should never at any point exceed 100 PPM. If it does the equipment is considered unsafe and replaced asap. The lower the level of CO the better. Also, if you have an older furnace that doesn't have a draft fan blowing the exhaust through the flue pipe, the test should include checking the draft in the flue pipe and adjusting the barometric damper if necessary.

If you have any questions please feel free to contact me. I'm so glad you found a technician to perform the test. It should be something every HVAC technician is required to do. I tried to explain in detail how I was taught to perform combustion analysis. Remember, at no point did anything I mentioned include looking at the flame.

That's like saying a doctor gave you a physical exam by just looking at how you appear. It's ridiculous that so many find this practice acceptable.

warno

The company that said they would do it is the one I mentioned that's been in business over 60 years. So hopefully they know what they're doing.

Thank you. As soon as I get it figured out that this is the test they'll do then I'll post the results.

SuperTech

That's combustion testing I don't expect every technician to do it exactly the same way, but all the same things are checked each time. Now a true test of a technicians skill is based on how a technician proceeds after the analysis. I forgot to mention that all digital analyzers also show stack temperature (temperature of the flue gas being tested) and efficiency. The efficiency percentage is the least important bit of information provided by the testing. It's determined by the stack temperature, fuel type and CO2 percentage measured. I prefer to judge system efficiency by the amount of fuel consumption seasonally. But anyway I can usually find room for improvement on most tests and make recommendations for system improvement. A good technician will usually want to see your system be at it's best, bad techs are usually the type that use any excuse to condemn equipment and sell new systems more often than performing repairs.

warno

I just got off the phone with the tech from the company that said they could do it. He basically told that the test wouldn't tell me much I don't already know. He said they do have the analyzer and they do do that test but it's not a typical thing on natural gas. He said it's a must on oil furnaces but not typical on natural gas.

He said the biggest thing to watch for is a bad heat exchanger. Given the Year of my furnace he said the heat exchanger is at the point it should be checked more often.

So once again I'm thinking the combustion test is something that is just not done in this area.

I know it is probably illadvised but I think I'm at the point of just having someone come out and do an annual check on this furnace. If nothing else to keep an eye on the heat exchanger. I mean with it's age it might not be long for the world much longer anyway so I think I'll start saving for a replacement. Plus once I get my boiler plumbed in the natural gas will never get used or at least very seldom anyway.

SuperTech

That's terrible. Maybe this is a tactic used to sell more new equipment? By giving the customer every reason to question the integrity of the system I can understand how some people would replace equipment based on age alone. Why perform the proper tests to ensure safe operation when you can just sell a new one.
I suppose the only other advice I can offer is to keep up on maintenance and replace carbon monoxide detector batteries often.

warno

I do have one question though. If the heat exchanger is good and the draft fan is good what would be left to have a carbon monoxide getting in the house?

icy78

Silver tape between you and death. Really?

Being blunt now...shut it down, find a qualified tech.

Look for an NCI certified tech. Google National Comfort Institute to see if there's someone in your area.

Standard CO detectors are worse than useless, they are dumbed-down to avoid nuisance alarms, such as the one that would save your life.
As far as flame color. Just worked on a boiler with beautiful flame. 4000 ppm. 4 thousand.

300 ppm in the basement of another backdrafting home. Nice CO detector in the same room. Won't alarm until over 70 ppm for 4 hours. Hmmm. Never alarmed because the CO would drop to below 70 at times, thus avoiding a nuisance alarm, but which probably was the cause of the previous owners mysterious deaths.

BTW you can see higher than 100 on light-off. Up to 1000 on a 90%er but rapid drop to below 100. Above 100 often can be fixed. Simple flame impingement, or alignment,or burners, that type of thing.

Often on lightoff a mechanical/fixable problem will show up. Most important is 02 and CO are steady. 02 around 6-9 ideally and CO below 100. Better below 30. STEADY STATE. (02 is often a bit higher. One sample reading is not good enough.)

Like @SuperTech said also.

About your filter. Filters are for the equipment, not the house. Use a very unrestrictive one. Pleated is restrictive. Washable are terrible. Alergy filters are furnace killers. (Because of airflow restriction)

warno

> @icy78 said:
> Silver tape between you and death. Really?
>
> Being blunt now...shut it down, find a qualified tech.
>
> Look for an NCI certified tech. Google National Comfort Institute to see if there's someone in your area.
>
> Standard CO detectors are worse than useless, they are dumbed-down to avoid nuisance alarms, such as the one that would save your life.
> As far as flame color. Just worked on a boiler with beautiful flame. 4000 ppm. 4 thousand.
>
> 300 ppm in the basement of another backdrafting home. Nice CO detector in the same room. Won't alarm until over 70 ppm for 4 hours. Hmmm. Never alarmed because the CO would drop to below 70 at times, thus avoiding a nuisance alarm, but which probably was the cause of the previous owners mysterious deaths.
>
> BTW you can see higher than 100 on light-off. Up to 1000 on a 90%er but rapid drop to below 100. Above 100 often can be fixed. Simple flame impingement, or alignment,or burners, that type of thing.
>
> Often on lightoff a mechanical/fixable problem will show up. Most important is 02 and CO are steady. 02 around 6-9 ideally and CO below 100. Better below 30. STEADY STATE. (02 is often a bit higher. One sample reading is not good enough.)
>
> Like @SuperTech said also.
>
> About your filter. Filters are for the equipment, not the house. Use a very unrestrictive one. Pleated is restrictive. Washable are terrible. Alergy filters are furnace killers. (Because of airflow restriction)
>

My tape "bush fix" is only until it warms up enough I can shut it down for long enough to get the RTV seal on it and cured. I adjusted the flue duct so it is actually on the draft fan as it should be. I couldn't feel any leakage around the duct, I just threw the tape on there as precaution until I can get enough time to do the rtv seal.

Funny you mention allergy filters being furnace killers because that's what I had in it to start this mess. I'm going with just regular filters changed every month from now on.

I'm still curious though, if the flue is clear, draft fan is working properly, and the heat exchanger is good where else could CO gas come from?

icy78

Well good I'm glad that you did that and I'm glad you're responding this morning :-) I was worried last night! Okay so CO that you're seeing in the house. Most often that is from a backdrafting water heater. If you have a gas water heater vented into the same chimney as your 80%er it probably backdrafts.

They are notorious for this. Or too much draft causing too much dilution air up the draft hood. This "blocks" the flue so the combustion products now roll out on to the top of the water heater. Often one can see this by heat evidence or white buildup. Extreme cases will have some flue gases coming out the air intake to the burner. All the appliances affect each other, running or not. As do your exhaust fans and whole house fans , supply fans, and building effect and wind effect. An electruc stove with a hood exhaust fan....affects the water heater.

Garage attached to home?
Chimney good?
Trees close to flue?
Flue height?
Appliance burning properly?

The chances of a small heatex crack giving a CO reading in the home are slim.

I just saw your pics. Best get the whole setup analysed by an NCI tech.

warno

@icy78 I just got off the phone with NCI and there closest tech is 70 miles north of me. I called that company and was told I'm out of their service area. So now I'm lost.

Is the CO monitoring the most important thing at this point? Because I'm wondering about calling the local company that said they'd do it and ask them how low their CO detector reads. Other then that I don't know what to do.

icy78

Well that is a real bummer! I'm pleased that you tried though. All I can suggest is that the locals come out and check, however be aware that CO from any particular source may or may not spill when the tech is there, and it requires a bit more skill to determine "that this is probably what happens at times."
What I do suggest is that you purchase a low-level CO detector. I personally have the NSI 3000 which I believe is the best one on the market. There are others, I think there is one that is called the Defender. I believe that is a low-level alarm also. I don't want to state any specs because my memory will fail me so just look it up online. But I think that every home should have a low level CO detector.

If you have sealed your flue leaks, that is a good start. Post a pic of the water heater setup and the top of that heater, close up, and the burner area.

If you're nervous about it, a good thing to do would be to shut down the h20 heater at night.

I wish @captainco would chime in. He may since I just typed his username!

Whatever he says is the right thing to do.

icy78

As a general statement here. If you think about it , the separated flue, like in your picture, is really not much different than a draft Hood. A draft hood is simply a separation in the flu from the appliance, and allows the appliance to vent into the room if there's a blockage of any kind north of the draft Hood. So with that flu apart you may very well have been down drafting from the chimney into the house because that's the way the house wants to draft.
And no way am I saying that that was safe or that was right. I'm just throwing it out there as food for thought and to think about draft hoods in a new light.

warno

We've lived in this house since late 09 and I'll be perfectly honest, I wouldn't doubt if that flue had been disconnected this whole time. But like I said I had enough play in the elbows to close the gap at the draft fan and added the tape for time being. I'm actually not worried about it. But I would like to know if there's an issue. Which is why I'm still posting.

I grabbed some pictures for you. I think I got what you asked for.

The whole setup in the closet

Close up on water heater flue

Water heater burn area

I also took a close up of the tee fitting where the furnace and water heater come together. I'm wondering if this white stuff is what you're talking about.

SuperTech

I have to agree with icy78. You definitely need a low level CO detector. I also wish your water heater had what's called spill switches on it. They are a relatively cheap safety device that is supposed to shut down the water heater in event of a blocked flue or back draft. The flue pipe corrosion is an indication something is wrong with the venting. But without any further proper combustion testing we can only speculate.

warno

I'm going to have the local company come to do their test and while he's here I'll pick his brain about the corrosion around the flue duct.

I'm looking into the "defender" which is found here. http://www.inspectortools.com/Defender-Low-Level-CO-Carbon-Monoxide-Monitor-p/dsll6070.htm?gclid=EAIaIQobChMI8drKpdmm2QIV1bbACh0P7AMlEAQYAiABEgJDS_D_BwE

For the money it seems like a good investment.

We have had this detector for a few years now. It's not great but better then nothing, sort of.

icy78

Ok. He will be doing draft tests as part of the procedure. Not with the analyser prope but a separate instrument. Draft with each appliance separately and together. Draft should not increase when one appliance is removed. Should not decrease when appliance is added.

Most likely you are underfired. Most likely you need barometric dampers and spill switches in both flues.
The water heater also gets a device that interrupts the thermocouple circuit.

There's a lot of dust. They may not be breathing properly.
You said a 270 stack temp on the 80%er. Too low. You'll be condensating in the flue which is evidenced by the aldehydes.

Most people in my area will get this wrong. The company I work for will get this wrong. I really have to push to get in on these "simple" jobs so they get setup properly and safely.
to correctly analyze the water heater he will need to drill a hole on each side of the draft hood and go down into each side of the turbulator that is inside the water heater. Looking for a -0.015 draft approximately for both appliances. If he comes in and drills a hole for draft and inserts a separate draft gauge that would be a good sign. A floating ball type draft gauge is excellent because you can view the draft in real time. A digital type draft gauge such as would be incorporated into an analyzer will lag and not be accurate enough. there is a lot more to it but that gives you something to observe while the process is happening . Again I will stress that the carbon monoxide and the oxygen must remain steady over a period of minutes.
The door to the furnace room must be closed while this is happening.
Lot more to it but it'll give you something to watch for.
(If you opt for a new 90% furnace, don't fall for the orphaned water heater pitch.)

warno

> @icy78 said:
> Ok. He will be doing draft tests as part of the procedure. Not with the analyser prope but a separate instrument. Draft with each appliance separately and together. Draft should not increase when one appliance is removed. Should not decrease when appliance is added.
>
> Most likely you are underfired. Most likely you need barometric dampers and spill switches in both flues.
> The water heater also gets a device that interrupts the thermocouple circuit.
>
> There's a lot of dust. They may not be breathing properly.
> You said a 270 stack temp on the 80%er. Too low. You'll be condensating in the flue which is evidenced by the aldehydes.
>
> Most people in my area will get this wrong. The company I work for will get this wrong. I really have to push to get in on these "simple" jobs so they get setup properly and safely.
> to correctly analyze the water heater he will need to drill a hole on each side of the draft hood and go down into each side of the turbulator that is inside the water heater. Looking for a -0.015 draft approximately for both appliances. If he comes in and drills a hole for draft and inserts a separate draft gauge that would be a good sign. A floating ball type draft gauge is excellent because you can view the draft in real time. A digital type draft gauge such as would be incorporated into an analyzer will lag and not be accurate enough. there is a lot more to it but that gives you something to observe while the process is happening . Again I will stress that the carbon monoxide and the oxygen must remain steady over a period of minutes.
> The door to the furnace room must be closed while this is happening.
> Lot more to it but it'll give you something to watch for.
> (If you opt for a new 90% furnace, don't fall for the orphaned water heater pitch.)



So when he comes out what if he doesn't check the draft of the water heater at all? I'm getting ready to purchase a "Dwyer Mark II Model 25 Inclined Manometer" for my OWB, could I use this to test my draft in both places if the tech doesn't?

My furnace is in a closet space in our kitchen. The door is a slatted bi fold door. So the surrounding air flow would still be there just less with the doors closed. But I'll take note on how the tech does his thing.

What exactly do you mean by the orphaned water heater pitch? You mean because it would be alone in the flue if I went 90%?

icy78

I use the Dwyer 460 manometer. It's pretty inexpensive around $40. The 25 would not be good for that. Has to be leveled, is setup for positive pressure. It will show negative, but hard to read that accuratly.
By the orphaned water heater I mean that often when a natural draft or 80% furnace is taken out of the chimney that you will be told, well now we have to install a liner or resize the chimney because the water heater will be too small, or the chimney will be too big for the water heater . The question you should ask then is, well why was it okay before when the furnace was connected to it , I'm sure they didn't always run at the same time .? A campfire smoke rises, yes? Big chimney on a campfire!☺

As far as using a draft gauge goes, it is a necessary part of the measurement. If you don't know the the draft then you can't set up the equipment. The first step of combustion setup is to control the draft, can't do that without knowing what it is. Too much draft is just as bad as too little draft , maybe worse.