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Question DetailsAsked on 4/19/2016

Yesterday my furnace way red tagged .supposed to have had furnace inspected 6 months ago before closing.

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2 Answers


Things could easily change in 6 months. Red Tag indicates gas leak, or CO poisoning , both very dangerous.

Why did they Red Tag?


Answered 4 years ago by BayAreaAC


As BayAreaAC said - could be a problem was not noticed in the inspection, especially if done by a normal home inspector rather than a specific furnace inspection by a HVAC contractor, as home inspectors do not inspect the heat exchanger.

Or as BayAreaAC says, could be a new problem in the last 6 months.

There is also a possibility there is nothing wrong with it - a small percentage of HVAC contractors have taken to unjustifiably red-tagging heating devices as a nasty way to get more work for themselves, because most people can not tell whether it is legit or not, and that puts a "rush" or "emergency" frame of mind on the homeowner, pressuring them (especially in peak heating/cooling season for furnaces/AC's respectively) to tell the contractor to go ahead and do the repair without the benefit of competitive bids, and commonly without even a firm bid from that contractor which also then opens up an opportunity for an unscrupulous contractors to gouge the customer.

Heat exchangers are a prime example of where this happens - when I went to the Carrier factory training school decades ago they had about a hundred heat exchangers that had been sent back under warranty to show the class as examples of types of failures. Fully 80% of them were not actually leaking when heater and pressure tested but had scratches, surface scale cracking, burned-on cobwebs, rust streaks, etc that caused them to be red-tagged as cracked when they were actually fine, at least when they were taken out. And because a heat exchanger cannot be seen by the homeowner in place, it is an easy thing to red-tag and say it needs replacing, for typically $1000-2000 total cost.

Commonly a red-tagging, especially on a heat exchangaer, is done because the tech legitimately believes it MIGHT be leaking - and many do not realize that a bit of rust or condensation streaking, a bit of corrosion where the exchanger plugs into the furnace, or scratches with a bit of electrolytic bloom is NOT generally a sign of leakage. Unfortunately, the manufacturers have resisted making heat exchangers readily removeable and air-pressure testable, so they remain a major cost to homeowners, in many cases unnecessarily. But if you look at it from the contractor's point of view, he needs to be conservative because having a family gassed with carbon monoxide shortly after he inspected and approved a furnace is a risk he cannot accept.

If in doubt if the red-tagging is legit (meaning you do not know and trust the tech), especially if he is telling you that you need a brand new unit because it is unfixable, if under 20-25 years old (or more like 25-35 years old for gas fired boilers) you might consider getting another technician from another company to come and look at it, as well as to give a repair/replace bid. If a heat exchanger cracking is the diagnosis, commonly they lasst about 7-10 years with modern aluminum units or about 20 years with older or high-end cast iron or stainless ones.

Answered 4 years ago by LCD

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