Anyone ever seen a duct system like this before?

Onepipe · January 21

Today I had a call to a house for poor heating in two rooms in the house. As I figured they were the two farthest duct runs that were suffering BUT to my surprise the whole house has 3” round duct feeding every register through the house! There is a main plenum off the furnace and then just like a unico system it has 3” take offs for each room. The duct is original to the house(1956) and I see the name “Coleman” stamped on some of the duct components. As you can emagine the static pressure is through the roof and to make matters work there is a terrible furnace install. Just looking to see if anyone has ever seen a system like this or knows what it was.

delcrossv · January 21

Oh man. What is that bottom picture?

mattmia2 · January 21

https://forum.heatinghelp.com/discussion/comment/1836667#Comment_1836667

baseboard register with a diffuser inside.

this obviously had some sort of original furnace that had a blower for the higher esp or a higher rise. coleman still makes furnaces today. same coleman as the lanterns and coolers and other camping gear but beyond that don't know anything about it.

Onepipe · January 21

yes. The last pic is a defuser that was behind the register. I see a lot of old stuff in my area but this one is new to me.

bburd · January 21

There was a small duct, high temperature, low airflow system briefly popular between the late 1950s and early 60s. I've seen that once before. The supply air temperature was about 250° F and the original supply diffusers induced room air into the flow so the outlet temperature was lower.

I believe this system is no longer code approved. The high temperature furnaces have not been made in a long time, and so far as I know the only solution is a new duct system built to conventional standards, or a completely new heating system of a different type.

pedmec · January 21

I had one of these systems too. Replaced a Coleman furnace. Mine had a high/low register duct within a duct set up. Could never find any info on it.

mattmia2 · January 21

You could probably make higher temp low velocity air with a hydroair coil and a boiler if you designed it for that, like maybe in the 180 range, but that isn't likely to be cost effective unless some of the ductwork is very hard to get to. the original system would have to have been oversized by a fair bit for that to work.

EBEBRATT-Ed · January 21

Had one like that in my brothers house probably from the 50s with small duct. The existing furnace was not the original and cracked from hitting HL constantly because it couldn't move enough air. Had all 3" round duct.

Re ducted, changed over to gas ditched the oil.

Onepipe · January 21

Got it. It also looks like there is a 3” run that is piped to the outside with a rain hood on it. Similar to a dryer hood. I can’t tell if it comes off a supply or return duct. I’m not sure the owner is going to be up for a re duct but likewise I’m sure they are not going to like the update.

retiredguy · January 21

I saw a couple of these systems in the late 1960's. They were called a "Coleman High Pressure System" designed by Coleman, that as others have said ran at a high static duct pressure and higher than normal air temp. They worked OK as long as they were mated with an original Coleman furnace. When that furnace was no longer available the duct system had to be replaced.

Larry Weingarten · January 21

Hi, If you really want to keep the system, an option is to make the shell of the house far more efficient. It's hard, but I've made homes use 80% less on heating. With such small loads, the 3" duct might work. Or maybe the ducting can provide a good chase for insulated pipe for some sort of hydronics 😊

Yours, Larry

bburd · January 21

https://forum.heatinghelp.com/discussion/comment/1836696#Comment_1836696

Another feature sometimes installed back in the day was a fresh air intake that brought outside air into the return duct. The major problem of course was that the colder it got, the more the furnace ran and the more ventilation you got. Also if it didn't have some kind of damper to shut off the air when the fan was off, cold air could drift in through the entire duct system during off cycles.

Onepipe · January 22

thanks for all the info…. Especially the fact that retiredguy actually saw them in action. That said it’s a bummer that a system was installed that became obsolete almost before it was broken in. I’m going to check about the potential fresh air inlet and if so I’ll block that off. Trying to just get them through winter.

Onepipe · January 22

on a different note I would predict that an A/C unit on one of these is next to impossible. Owner just purchased the home and there was a new A/C installed recently but they have never tried it yet…..

mattmia2 · January 22

Thar was a time when people thought they would buy an appliance and keep repairing it forever, not replace it every 20-30 years. That being said, with the higher temp hx, if the manufacturer wasn't careful with design and the installer wasn't careful, I can see where those furnaces could have had a short life. At the same time, I wonder if someone sold them a replacement for a working original furnace relatively recently just because it was old and they didn't understand it.

delcrossv · January 22

Reminds me of the old Sears tub faucets with the proprietary spacing. Also a lot of extra work replacing it with something standard.

ayetchvacker · January 22

Thanks for posting! Great thread! I have seen diffusers like that before and thought they were unusual. But I’ve never heard of a high temperature furnace before!

Anyone ever seen a duct system like this before?

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