Furnace

I stated that earlier in this thread. . .

We’ve been discussing heat-pumps for some time now. . .

My post wasn’t directed at your heat pump comments Jeff…it was in regards to David Andersons post about furnaces and short cycling if they are tested longer than just letting the blower start-up. I was making sure other inspectors knew this infomation was incorrect. (see top of post #19) and post #10.

It is not about “testing damage”.
Yes, you can run the hell out of it if it will stay running.

But, if you call it because it shuts down when you live in a hotter than hell part of the country, you may be WRONG!

It does not always mean there is something wrong. It means the heat exchanger is possibly getting hotter than the set point of the high limit control. That may be all. If the return air temperature is starting out at 85-90 degrees, what temp rise would you expect from the furnace? Isn’t that above the high limit range?

I have spent many an hour on new equipment installs where a particular TVA Program Inspector wanted the furnace to run for 15 min. when it was 98 degrees F with 89% rh. Trane told me to just change the limit control till the inspector went away!

As I posted, it “could” be an indication of a problem but is is not a “definitive” defect.

I would have to agree with David the longer you operate a furnace in the summer months the more likely you are to exceed the high limit switch setting. As it was stated you are going to have a very high return temp quickly especially when the outside ambient is in the 90’s and 100’s. You will also notice a longer run time after the burner shuts down unless the fan cycles on time v/s temp.

I always operate a furnace in the summer months no matter what, just don’t do it quite so long as in the winter. I don’t care for a hot house any more than any one else. I just try to precondition the thought pattern before any one else can complain about the heat. I tell anyone present what is about to happen before it does and then its over with.

David Anderson…
“I never “evaluate” a furnace in the “off-season” because the ambient conditions are not conducive for equipment evaluation. There is no heating/cooling load proportionate to the design conditions. Simply operating the unit to see if it runs is sufficient. Any attempts to further evaluate is futile. An engineer cannot make these determinations and therefore a home inspector should not be held liable either.”

Good point. A furnace may well appear to “heat” in the warmer weather of summer, but fail to produce enough to satisfy the required temperature ranges in winter.

We shouldn’t “evaluate” a furnace operation, anyway. That’s why the other HVAC guys were invented. Of course, at my age, I don’t want to do any more work than I have to.

Now, like anything else I do, I will be more than obliged to be paid for this evaluation! :slight_smile:

Still, I am not going to say that the unit will work to capacity in the oposing season. Just that the components came on like they should.