Flue residue questions

[John W. Springstead]

Noted this residue on yesterdays inspection. Newer boiler ( 1990 ) venting into "Class A" type 8" chimney. Same age boiler mate water heater. Wondering if old unit ( water heater ) was gas and that's why the larger chimney. Would you write this up as "possible" orphaned type chimney? Or how? Thanks!

[Steve McIntire]

The Boiler/ water heater flue is corroded at ______ location. Recommend repairs by licensed HVAC contractor.

[Jason A. Sieg, CMI]

Originally Posted by smcintire

The Boiler/ water heater flue is corroded at ______ location. Recommend repairs by licensed HVAC contractor.

I agree

Was there any kind of a rain cover over the flue when it exited the roof of the house?

[rwand1]

Definetly water entry/condensation causing corrosion. Recommend further evaluation by licenced heating contractor.

The chimney elargement may be too large causing poor draft, resulting in condensation forming in upper area of chimney.

Raymond Wand
Alton, ON

[John W. Springstead]

Thanks guys, yes there was a S.S. cap which was stained quite dark at top. Makes me wonder if the orgional unit might have been fuel oil fired. No sign of underground tank was noted though. ( 1973 home )

[jrupert]

The damage you see was caused by the flue damper pictured. This damper has 4 bi-metal vans that close when they are cool and open when they become warm, this did create an energy saving of approx 8% in it’s day. However all most all of the manufactures years ago took a position that they were damaging to the flue and furnace and thus should be removed. I vaguely recall that they may even been a government recall on all of them due to failure and that they are not equipped with any safety device should they fail

The damage occurs when the damper closes (it only block 80%) trapping still hot flue gasses in the furnace, these gasses cool and condense, they are acidic and corrode the furnace, the 20% not trapped will condense in the flue, in your picture the condensed flue gas is leaking though the joint connections damaging the pipe

[rwand1]

If it is former oil fired unit and carbon deposits are still in flue the condensation from gas will mix with carbon and form carbonic acid which is corrrosive.

Raymond Wand
Alton, ON

[rwand1]

Also I don't like the junction box sitting where it is.

Raymond Wand
Alton, ON