Upgrading existing heat transfer system

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smac

267 posts

Ultimate Geek

Topic # 146744 28-May-2014 08:38

I have just moved into a house that already had a 3 room Weiss heat transfer system installed (pulling from room with wood burner). After about 5 minutes searching online I see I'm not alone in thinking this system is....not great.

The fan set up is 3 small impeller fans in the 3 way plastic splitter housing, one fan at the beginning of each room duct.

The runs are kinda long, particularly the intake duct, but the end result is minimal air flow at the outlets.

Now the ducting and controller etc are all good, so I'm wondering if I can simply bung a 150mm or 200mm centrifugal fan into the intake duct....that sound like it would work/help? Anyone know the volume rating of these small fans? Not sure if I should disconnect the 3 small fans (worried about backpressure, turbulance etc) or just leave them all going?

Actually the more I think about this I realise the 3 way splitter housing will be a completely different design for a single fan unit. If I put an inline single fan it will blow straight down the central path, and the 2 side branches won't get anything. I assume the purpose built 3-way single fan systems have some sort of baffles or ducting to distribute the air as it passes through the splitter?

Thanks heaps

andrewNZ

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Reply # 1054750 28-May-2014 08:51

You'll want to find a fan that can handle the heat.

If the rooms have adjustable vents, then the splitter arrangement doesn't matter. Just adjust the vents for equal flow.

I'd be trying to remove the existing fans, they'll significantly restrict the airflow. If they can't be removed, stop them spinning freely.
Not quite the same, but any pilot will tell you, a spinning unpowered propellor creates as much drag as a solid disk the same size.

Location: Dunedin

Fred99

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Reply # 1055323 28-May-2014 18:10

I know I mentioned this in another thread on heat transfer systems, but the "Weiss" brand was named by NZ Fire Service as a brand implicated in several house fires in NZ cause by motor overheating and flammable ducting liners.
Hopefully the media will be following up with reports when inquiries are completed. Until then, I'd be holding off on making any changes to a Weiss system, as if it is established that there is a real issue, then it's the kind of thing where a recall would be warranted.

smac

267 posts

Ultimate Geek

Reply # 1055367 28-May-2014 19:27

Fred99: I know I mentioned this in another thread on heat transfer systems, but the "Weiss" brand was named by NZ Fire Service as a brand implicated in several house fires in NZ cause by motor overheating and flammable ducting liners.
Hopefully the media will be following up with reports when inquiries are completed. Until then, I'd be holding off on making any changes to a Weiss system, as if it is established that there is a real issue, then it's the kind of thing where a recall would be warranted.

Hmm...found this:

http://www.stuff.co.nz/national/10066036/Heating-system-investigated-after-home-fire

All the more reason to do something about it in my mind. I'm not having my boy sleeping in a cold room waiting for a recall, so I've ordered an inline 150mm centrifugal fan, and will insert it inline in the inlet duct, and remove the 3 small fans.

oxnsox

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Reply # 1055425 28-May-2014 20:06

A lot depends on the installation as there's a couple of elements at play here. First is the volume of air being transferred, second is getting the right (location) source for the transfer. Often the source point is put too close (above) to the fire heat source, at a point where the air flow in the room is downward as it's drawn into the firebox.

nzcloud9

47 posts

Geek
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Reply # 1055447 28-May-2014 20:47

I have a yunca old model woodburner, which puts out very good heat.
About 4 years ago i wanted to transfer some heat up to the bedrooms, but being in
a two story house, it was going to be hard. Luckily i am a sheet metal fabricator, so i could
make most of the ducting.
I installed a vent next to the flue, wall corner traps heat. Also i have high ceilings
about 3.3m. After the vent it goes to a 200mm motor, on variable fan switch, so i
can put on low at night, daytime on high, which moves lots of air.
After the motor goes to two way splitter (one for upstairs shut off), other goes to the bedrooms down stairs,
which splits again to the two rooms.

Before i put this in, the bedrooms would get down to 8 or 10 degrees, now never below 15 or 16 degrees.
Also no wet windows.

With the fire i also dry washing on daughters old playpen fence turned into airing rack up at 3.2m.
It can get up to 35 to 40 degrees up there. At about 1.8m would be 10 degrees lower.

Hope this helps.

smac

267 posts

Ultimate Geek

Reply # 1055503 28-May-2014 21:53

Ya good points, once the new fan is in if I am still not happy I am open to the idea of moving the vent. I have an infrared temp gizmo, so I'll check around the ceiling for the best spot. Thanks all, will report back in case anyone is interested in how it goes.

BTR

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Reply # 1055811 29-May-2014 11:54

I have recently installed one, can't remember what brand it was but bought extra grilles, splitters and ducting from Manrose.

DarthKermit

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Trusted

Reply # 1065798 14-Jun-2014 22:53

Unsafe Weiss heat units banned:

http://www.stuff.co.nz/business/10158619/Unsafe-Weiss-heat-units-banned

Whatifthespacekeyhadneverbeeninvented?