Open fireplaces. Not for NG.
If you had to reline a chimney with terra cotta it would be twice the expense, and that’s if a company had the equipment and know how to do it. Now chimney repairs companies mold with poured grout. Stainless is ><$1,500.00. The crown does not have to be modified.
Right, of course, absolutely, 100%. Thank you for making my point.
Your point is moot.
Thirty years ago, it was common practice to vent gas furnaces and water heaters into tile-lined masonry chimneys. These appliances used draft hoods, also known as draft diverters, in their venting systems. Appliances manufactured around this time were about sixty percent efficient (fuel used versus heat generated for the structure). The draft diverter introduced dilution air to the furnace vent gases, and with the escaping heat, prevented moisture issues in the chimney. Exterior chimneys and interior chimneys were commonly used for venting. Today’s mid-efficiency furnaces can destroy tile lined chimneys. Here are some technological differences with modern appliances that make using chimneys more difficult.
https://www.jadelearning.com/blog/venting-gas-furnaces-into-masonry-chimneys/
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So, a clay lined chimney with a natural draft NG water heater is unacceptable in all circumstances?
The natural gas hot water heater venting into the chimney was a 2014 model. I called out several issues with it. PEX directly connected to the top of the heater, TPR Valve missing discharge pipe, and the vent pipe was rusting. They had some sort of plastic tray for an overflow pan. Looked like a pan for mixing cement. If the tank did leak, it would flood the combustion chamber. Maybe, if the basement gets water, they figured this would protect the tank? The basement did have a working sump pump.
Good job. That Pex next to the single wall flue pipe is a real gem. 
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Yep probably what someone was thinking but wrong, IMHO.
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I think a heat saver would be referred to as a heat pump, Marcel.
In the situation you are referring to, I would narrate it as, a small site manufactured Heat Exchanger.
Morning, Brian.
Sorry for the delay.
To answer your question, No. In this case though, “one piece CMU block chimneys” have been banned for almost 50 years in my neck of the woods. Only your jurisdiction would know.
As for the condition. Poor drafting, and a combination of failures, lead to the overall condition you see today. Furthermore, I would not be surprised if occupants felt unwell on many occasions during the year. It is only by the grace of God no one perished due to asphyxiation or to suffocate.
Have a great day.
Robert
Not quite.
Not quite again.
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I’ve never seen a flue run through the middle of a heat saver or recovery or heat pump.
Possible exhaust assist fan? Or something else?
No sir, I have not seen one of those. What is the operating principle? Or, what is it, I’ll Google.
Does the same thing as Ryan just posted above.
Both of them through convection heat the surrounding.
I had one of those Magic Heat units on a Franklin Stove when I lived up North. They work pretty good.
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Ok, I got it. Seems to me, on the configuration above water heater (especially if that clay liner is not lined with a metal flue) the last thing you would want to do is slow down or risk cooling the exhaust.
Do you think this box is a potential problem on a modern NG natural draft appliance?
I sure see a lot of possible moisture staining and rust, exterior condition not excluded.
In my opinion yes. They assembly looks too mickey mouse to me. And with natural gas not sure what it would cause other than the visible rust we are seein on that elbow.
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