Furnace Vent Pipe Clearance

Anyone know if this is acceptable for a high efficiency furnace vent pipe clearance? (It is the lower house colored vent pipe)

What does the manufactures installation manual recommend?

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That is the only way to know the clearance needed.

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And if I cannot locate the manual online as its a 1999 American Standard, would writing it up as a potential safety hazard and referring to a qualified HVAC tech be appropriate?

Post the model number please. Sometimes we can dig up a manual.

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Some info at link below:


Looks like a Diversitech Hvent2. Here is a link to the installation manual.

If it is, seems that it should have a horizontal installation… :thinking:


It is a horizontal installation.

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In general, clearances for flue terminations from condensing furnaces can be small, like 12", so that one looks too close to the soffitt. Flue gas temperatures are not a concern, but there could be excessive condensation on the soffit. So, without the manufacturer’s installation instructions, I would probably just comment that the termination appears closer than best practice to the soffit.

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After Guinness and laying on your side looking at it.

Appears it could be installed either way, but I didn’t bother to check clearance. Something the OP needs to read and digest.

I would worry about moisture damage to the soffit also.

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Because you don’t know? I don’t think so.

What is the safety hazard your thinking about?

The soffit is located outdoors. All the water from the roof cascades just over it.
Moisture damage? How’s that?
Do you see moisture damage in the pic?

Is that not a condensing furnace? What does it condense?

Could the hazardous carbon monoxide gases vented by the furnace not potentially draft into the window or door next to it? Seems like a safety hazard to me.

I know the soffit is on the exterior!

Hot and cold create condensation which will cause moisture on the soffit. (Think winter). This also happens with a radon mitigation exhaust located under a soffit.

Have you ever measured CO from a high efficiency furnace?
Did you look up the distances required anywhere as suggested by others?
If air is Drafting into the house in the winter with windows and doors closed, you have another real serious problem aside from this.

Cool thanks



Yes, that is correct.
So based on the OP’s picture, what material is subject to damage?

I’m not saying condensation doesn’t happen, I want to know why it is a significant issue that home inspectors report on. We don’t just make stuff up to report. There has to be something actually there.

Again, is this not a condensing furnace? Just how much moisture is left in the combustion gas discharge vs. how much went down the drain.

Speaking of drains, will that drain discharging on the concrete cause an issue?

(6) General Exclusions
(b) Home inspectors are not required to
8. Predict future condition, including but not limited to failure of components

I looked again, and I still don’t see moisture damage in that pic.

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If the manufacturer specs are not followed, then it should be called out.
Whether there is or is not any currently visible deficiencies is irrelevant.