Three Stooges HVAC

**wayne soper** · 06-20-2007, 05:04 AM

Yes they are alive and well, Flipping houses in CT. What do you think?

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**neal lewis** · 06-20-2007, 05:31 AM

Nyuk, nyuk...

**Michael Thomas** · 06-20-2007, 06:42 AM

It's not pretty, and it's probably not an optimal design, but it would be neither difficult or expensive to clean up the problems I see.

Was the previous unit a gravity furnace? (Looks from the location of the return like that might have been the case.) If so, the installers may have elected to take round duct off the plenum to easily mate with existing ductwork, and the installation may not be as irrational as it looks at first glance.

**DavidR** · 06-20-2007, 02:25 PM

They just signed the death sentence on that chimney.

**Michael Thomas** · 06-20-2007, 05:58 PM

OK David, I'll bite. Cat I furnace (I think) and GFWH going into the chimney, no way of knowing if or how it's lined from the pics. How do we know for sure they will eat it?

Kevin VanderWarf · 06-20-2007, 07:16 PM

Not a bad looking job. Except maybe the flu pipes. At least they used metal ducts.
The return shows what this company is capable of. You just don't see metal like that any more. Now, they probably could have made some nice fabricated pieces for the supply but maybe the price wasn't there.
It does look they could have combined a couple of trunk lines with a larger one and I wonder why the took that 4" straight out of the plenum. They were probably follow the exsisting layout.

Ed Janowiak · 06-20-2007, 08:35 PM

Originally Posted by Michael Thomas

OK David, I'll bite. Cat I furnace (I think) and GFWH going into the chimney, no way of knowing if or how it's lined from the pics. How do we know for sure they will eat it?

He doesn't know, David is just a fear monger

**wayne soper** · 06-21-2007, 04:39 AM

This guy watched too many Flip that House shows. He started by sheetrocking the whole basement. No drainage, barrier or insulation behind the walls. Then he decided to do the electric,plumbing and ductwork. Everything a mess. Everything on the wall surface.
I think he might have been at too many Grateful Dead concerts,what do you think Barry?
Put in a pump up waste system with the vent sticking out the wall under the kitchen window.
Stood there an looked me in the eye and lied to my face about everything, as I was waving my recorder under his nose to let him know I was recording every word he said.

**DavidR** · 06-21-2007, 07:02 PM

Originally Posted by Michael Thomas

OK David, I'll bite. Cat I furnace (I think) and GFWH going into the chimney, no way of knowing if or how it's lined from the pics. How do we know for sure they will eat it?

Anytime you tap an induced draft furnace into a masonry chimney & many times a liner the possibility for condensation is huge.

IMHO liners have their place but many times are used as a band-aid for more underlying problems.
If furnace manufacturers actually fitted post purge circuits into the induced draft furnaces many of the condensation related issues would go away.

The only way to find out if the potential is there for that flue to be eaten up is through combustion testing.
The furnace already has the fact that once the heating cycle is over the inducer shuts off almost immediately.
This creates a huge potential for any airflow up the flue effectively trapping the flue gases in the flue allowing them to condense.

If the room pressure that the appliances are located in is positive & the flue stays in a positive pressure after the heating cycle there is a good bet that all will be okay.

**DavidR** · 06-21-2007, 07:03 PM

Originally Posted by Ed Janowiak

He doesn't know, David is just a fear monger

Lol...Referred to by some as "chicken little".

**Bob Harper** · 06-21-2007, 08:17 PM

David, I think that danged "Ductopus" not only followed you over from the other site but the damn thing is mating!

Yeah, that vent job makes me real proud.

I have been following Davidr's postings on another site for some time and we see eye to eye on almost everything. I think we both are concerned here that the Category I for negative flue gasv pressure coupled with a stack loss of not less than 17% has created a gap that a monster slid in. The old soldiers that came up with these venting tables and categories (which date back to 1927, btw) have relied on limited data to develop their venting tables. (GAMA/ GRI). What we're seeing in practice is rampant rotting of masonry chimneys, weaker natural drafting, shunting of flue gases from fan assised furnaces out water heater draft hoods, and so on. The marriage just doesn't seem to be working out that well. Cat. I includes 78-83% AFUE appliances. While less efficient heaters have higher stack temps. with more dilution air and, like water heaters, stack temps well above the 140F above dewpoint. This translates into higher draft, drier flues, less condensation but lower efficiency. The current Cat I fan assisted furnaces behave much more like a Cat II, which is really a theoretical category because you can't practically use natural draft to vent something with a stack temp less than 140F above dewpoint and still expect the chimney, heat exchanger and occupants to survive. Cats. III & IV are positive vent pressure meaning a fan must blow the exhaust out because there ain't enough stack losses to generate any draft. These vents are sopping wet. The Cat IIIs use the AL29-4C stainless such as on tankless heaters for example. Still too much heat for PVC yet must be air and liquid tight. Cat IV is your PVC vented condensing furnaces. Here, you're more worried about icing up the termination or snow blockage as in Mass.

Aw, we're bitching too much. Of course, this is probably located in a confined space without MUA but does have a clothes dryer!