Clogged furnace

Timco

My opinion is that if it can be fixed, it is the HO's call to fix or replace. I explain the options, and give a reason why this happened, and recommend fixes to ensure it does not happen again. I also give a life expectancy to the best of my ability. A combustion analyzer is the only way to know if it is firing correct and safe, and to know why it happened in the first place...ALL good techs should have one...or you are just guessing that all is well with people's safty at risk.

Tim

Barrington White

Clogged furnace

Barrington White

Clogged gas fired furnace need professional opinion

I was working on a Rheem gas fired furnace. The unit was not working. The pressure switch connected to the inducer draft motor was not closing. When I removed the smoke pipe, the flue outlet was clogged with some type of material. Then the smoke pipe just fell apart. It was corroded. The system was only six years old. The chimney base was filled with some white stuff that was moist. It was one of most disguisting things I have ever seen. In the bottom of the unit where the controls and blower was you can see some of that stuff in a dried up form. I figured that came from the heat exchanger. I told the home owner that he had to get his chimney cleaned and inspected. I told him the unit would run if I cleaned out the flue exhaust and replaced the pressure switch. But I told him the unit was unsafe to run because of the corrosion and the sediment reaching the blower area. There is possible damage to the heat exchanger.

The chimney was cleaned out and lined. Another technician went then replaced the smoke stack, replaced the pressure switch and then literally had to hammer and chisel that sediment out of the flue exhaust. Then operated the unit.

Then my boss had conversation with me about condemning things that can be fixed. He also said that it was calicum deposits in the bottom of the chimney base

I just want to know, did I do the right thing by condemning this furnace. Could there be possible corrosive effects in the heat exchanger. Since that sediment reached the blower area. Is this unit safe to run in current condition

My professor at school said I did the right thing by condemning the unit.

Mark Hunt

I'd bet a lot of money


that the furnace is underfired. Only way to be sure, Timco nailed it, is with a digital combustion analyzer.

Here are a few pics of a fan assisted furnace that vented into a masonry chimney. Only 4 years old. The unit was so underfired the stack temp was only about 150 degrees. The gas condensed and destroyed the chimney and the attached flue pipe.

It must have been like this for a couple years at least before we found it.

The night before we audited this home, the woman of the house had to go to the hospital because she was suffering from dizziness, nausea and headaches. Hospital said it was , "the flu". Only off by one letter. It was the "flue", not the "flu".

Mark H

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Mark Hunt

I'd bet a lot of money


that the furnace is underfired. Only way to be sure, Timco nailed it, is with a digital combustion analyzer.

Here are a few pics of a fan assisted furnace that vented into a masonry chimney. Only 4 years old. The unit was so underfired the stack temp was only about 150 degrees. The gas condensed and destroyed the chimney and the attached flue pipe.

It must have been like this for a couple years at least before we found it.

The night before we audited this home, the woman of the house had to go to the hospital because she was suffering from dizziness, nausea and headaches. Hospital said it was , "the flu". Only off by one letter. It was the "flue", not the "flu".

Mark H

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Mark Hunt

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Mark Hunt

Timco is right


Without a combustion test, you will never know why the unit did this in the first place and it will probably happen again.

I saw this on a fan assisted furnace a few years back. Furnace was 4 years old. The masonry in the chimney collapsed after being eaten by the flue gas condensate caused by an extremely low stack temp. The chimney was completely plugged and the flue pipe was rotted through. The furnace had been venting into the house through the holes in the flue pipe. The night before we did an energy audit on this house, the woman of the house had to be taken to the hospital suffering from dizziness, nausea and a severe headache. The hospital said she had "the flu".

They were only off by one letter. Her health problems were caused by the "flue" not the "flu".

A combustion analyzer confirmed that the unit had not been firing correctly from the day it was installed. Of course no one ever checked it before we did. These things are set up at the factory....right?

Mark H

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Steamhead (in transit)

If it was that badly corroded

I would advise replacement also. Even if the heat exchanger had not been breached at that point, it was obviously weakened by the corrosion and could be expected to fail in the near future. Hang onto your documentation; if that thing fails and causes another CO event, your company could be liable.

This would have been a great time to sell an upgrade to hydronics.

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Jim Davis_7

It is absolutely the requirement of the service tech to determine the condition of the heat exchanger. The problem that you encountered was caused by poor venting and possible underfiring. The same thing will happen again but this time the people might be poisoned or killed. They were lucky once, will they be lucky again?
Anyone whose does not use an analyzer on combustion equipment should not be touching it at all, for they are not qualified or knowledgeable enough to do so!!