Is this normal?

Was wondering what might be the cause of the markings at the interior of the hot air furnace. I did not operate the furnace because the AC was running when I arrived. Furnace is approximately 21 years old.


Why would the AC running stop you from testing the furnace?

Agree with Jim that you should have ran it.
Corrosion is usually from moisture but do you have a wider shot ? (How did the flue and hood area look?) and also I notice a paint bucket with water in it.
Is that where they are draining condensation?

The change in temperature between heat and cool mode can cause damage to the evaporator coil.

How do you account for the hot heat exchanger in the winter?

There is a condensation pump attached to the side of the furnace, the bucket may have been there to catch any leakage from the pump though I did not see any leaking when I was there. The slight corrosion on the furnace casing is likely a result of a past leak from the condensation pump or pvc drain pipe. There was no leaking or corrosion above the area in the picture. I was more concerned with the high temperature marks on the exterior casing of the heat exchanger.

Then thousands of Inspectors are wrong.
Please provide proof that we should not test furnaces in the summer.
Seriously there is no harm if you wait for a short time.
I assume you were there at least a few hours so the reasoning is not valid.

Got a wider shot?

I do not disagree with the idea that waiting a short time (perhaps inspecting the heat or cool at the beginning of the inspection, and testing the other mode closer to the end) would likely not harm the coil. I was told by my licensing course instructor 3 years ago that it was not required to test both aspects during a single inspection because of the potential damage. I believed it to be completely accurate as most inspectors around here test only one or the other.

Its slap worn out and not safe anymore since it was never intended to function for that long. Any HVAC tech will recommend replacing it on the next service call whether it runs or not.

That is insane.

If you are having people sign an inspection agreement and, on that agreement, if you are publishing that your inspections are being done in accordance with the NACHI SOP…you are violating that contract and can be subject to replacing a furnace that doesn’t work if ever called on it.

One of the interesting things about being in business for yourself is…when someone has you by the balls…you can’t get out of it by saying “My instructor told me…”

If you don’t have some hard, legitimate and credible material to base your deviation from this universally accepted industry standard…you are providing a disservice to your client and are creating the potential for some very bad relations between you, our industry, and your clients.

Please follow the SOP.

I believe your instructor was referring to heat pumps.

An inspector who doesn’t test a gas furnace during a home inspection is providing an incomplete inspection.

I turn off the AC at the end of the inspection. As soon as the blower comes to a stop, on comes the heat. As soon as I verify the heat functions (about 10 minutes), I turn it off. Once the blower comes to a stop, on comes the AC again.

By the way, do you know what the “AUTO” setting on a thermostat does?

Bruce what does “slap worn out” mean?
I am not familiar with the new rap lingo you kids have now in days.:cool:

Also age is not a reason to call it not safe as far as I know.
At what age does a furnace become not safe?
I want to know so I can stop testing all those over the safe age limit, and just insist it needs “automatic replacement”.

Joe, I’m not sure I understand what your “AUTO” comment is meant to be? Please explain the purpose of your question so I know where you are coming from.

Just for the record.

Every person who attends a NY Home Inspector Licensing Course is given an inspection book titled The Home Inspection Book, A Guide For Professionals by Marcia Darvin Spada. The NY licensing exam is based on the information in this book. Under the Section titled Inspecting the Furnace on page 193 it states Check the location of the thermostat and make sure that it is registering. Inspectors can use the thermostat to check the operation of the heating system. This operation should not be performed in warm weather, however, in a dual heating-air conditioning hot air system. It also should not be performed when a separate air-conditioning unit is on because the excess heat can damage the conditioner’s evaporator coils.

In that case, the instructor was not wrong in advising students not to test both systems and inspectors in NY are not wrong if they only test one or the other. To the contrary if damage is cause the inspector has made himself liable.

In my report I make it abundantly clear that I have not tested the Heat mode of the system and state the reason for it. I recommend that the system be tested prior to close of escrow and after the AC has been off for several hours.

Whenever possible, if none of the systems are running at the start of the inspection, I recommend testing the heat mode of the system over the AC, but I let my client make the call. In the report I make it clear that “at the client’s request” only one aspect of the heat/ac was tested.

Please don’t get me wrong that I am trying to short cut any inspection as my reputation locally is one of being extremely thorough - not a RE agent’s most welcomed face at an inspection. I am only following the State guidelines which supersede the NACHI SOP.

John I still think they are referring to a heat pump. Double check save yourself the grief. If a heat pump still check the emergency heat ( electric Coil) Just do not run the heat pump cycle. You will not hurt anything . I check all electric and and gas units. today it was 98 here . BTW check the heat at the last it gets everyone wanting to get out of the home lol.

Well Hell, I’ll have to come back to this one when I have a bunch of free time…

There is so much BS being slung around here, I need to go get my fishing waders on before I return!

Just keep on…

WTF?! What do you think is does very 45 min in the winter time?

What do you think they put an accumulator in there for?

Please, Ya’ll enlighten me on this! This thread is better than Jay Leno!
I’ll come back tonight, instead of watching Jay…

Got reports to do.

Just tested two gas furnaces today right after I turned the ac off… The only time i do not test gas furnaces is if the gas is off, or if the house has not cooled down below 90 degress to allow the thermostat to kick the furnace on… (and no i do not try and cool the thermostat down or put jumpers on it)

If this is the same Marci Darvin Spada who also writes the books for salesmen to pass the real estate exam…I would say that you are in very, very deep s h i t.

There is NO mechanically valid reason for the citizens of New York to have to guess if their furnace is going to work because they bought their home on a hot, August day. The whim of a an author who teaches real estate brokers how to “cram” for their tests is not a “state guide line”. There is nothing written in your state law or state SOP that allows you to exclude the heating system from an inspection if there is an air conditioner operating.


Meaning one unit–two functions. That refers to a heat pump, not a furnace and a slit-system A/C unit. The only “dual” in the latter is the blower.