House Air Ducts Question for Building Code Type

[stoveliker]

I have the plastic insulated duct rather than flexible metal. It transfers less noise/vibration because it's less stiff.
And the motor is mounted to the floor slab. But a concrete wall may work as well.

I also added a speed controller but in the end always run it at full speed.

 

[Ssyko]

In order to use the room blower you would need an OAK for fresh air to the fire. Then you would need to encase th. Back of the stove so the room blower would create the suction through the pipes to cycle the air.

 

[stoveliker]

I'm not sure what you mean by room blower, but as long as you blow colder air into the stove room (so that warmer air is pushed up stairs), it should be okay.

 

[Ssyko]

The next step is to try and use the distribution blower on the stove? I wonder if anyone ever did that? Why run two blowers when I'm already running the one on the stove.

 

[stoveliker]

Yeah, saw that. Just don't know what that is.

If it cycles air from the room to the room, it won't change the pressure.
If it cycles air from one place (past the stove) to another place, it's best to push air to the stove (room).

 

[Whitenuckler]

I have the plastic insulated duct rather than flexible metal. It transfers less noise/vibration because it's less stiff.
And the motor is mounted to the floor slab. But a concrete wall may work as well.

I also added a speed controller but in the end always run it at full speed.

Yes, that would have been a better choice. I should have designed it that way. Also, my vent size of 4x10 is probably too small but I already had the floor register and 4" in line fan. Right now I shut the fan off for night, and cranked up the dist fan on full. Maybe I will get some air circulation through the vent pipe. My blower is probably to fast, and will try to reduce the voltage to it with a SCR/TRIAC module use for my electric egg smoker.

 

[stoveliker]

Mine is also 4x10. My fan is a 188 cfm Terrabloom (Amazon) with a simple plug in variable resistor.
I don't hear much in my living room other than the air flow itself. And that will be less than 188 cfm given the 11 ft of 6" or so, half of which is not smooth (plastic flex), and the elbow, fire damper and registers .

6" is 28.5 sq inch.
4x10 is 40 sq inch. With the impedance of the register that should still be enough imo.

Regardless it's 26 W well spent.

 

[Ssyko]

Amazon.com

 

[Whitenuckler]

Mine is also 4x10. My fan is a 188 cfm Terrabloom (Amazon) with a simple plug in variable resistor.
I don't hear much in my living room other than the air flow itself. And that will be less than 188 cfm given the 11 ft of 6" or so, half of which is not smooth (plastic flex), and the elbow, fire damper and registers .

6" is 28.5 sq inch.
4x10 is 40 sq inch. With the impedance of the register that should still be enough imo.

Regardless it's 26 W well spent.

To be honest I don't know what is causing all the noise from the intake. The discharge side at the stove is fine. Is this some HVAC rule that I don't know about? How much bigger should the intake side of a fan be then the discharge?

 

[Ssyko]

Depends on the cfm of the fan, dont want to choke the fan. It will change sound as you restrict air flow

 

[Whitenuckler]

Depends on the cfm of the fan, dont want to choke the fan. It will change sound as you restrict air flow

• Effective Ventilation: Powerful blower with a fanspeed of2500RPM for an air flow of 195 CFM. Moves air through your target location efficiently for optimal ventilation
• Efficient Design: Lightweight, compact fan takes up minimal space
• ideal for applications where larger fans just won't fit. Efficient flow deflector feature increases air flow while cutting noise output
• Low Noise Level: Fitted with a flow deflector that concentrates the fan stream and cuts turbulent kinetic energy to reduce sound output to just 30 dB
• Easy Installation: Flanges on both the intake and exhaust ends for simple and easy hookup and a cord length of 5.9 feet for hassle free setup
• Versatile Applications: Use anywhere that would benefit from improved air flow to reduce humidity, clear the air and lower temperatures in grow rooms, basements or kitchens
• Can be used with a variable speed controller (bought separately).

Looks like tomorrow I will try to reduce the voltage which will reduce the speed and I believe the CFM goes down by the square? Power goes down by the cube? Been too long
› See more product details

 

[Ssyko]

Just watch out for voltage, you go to low and it will put the motor in hysterics and will barely run and get real hot/maybe melt the case. Some dont like speed controls at all

 

[Whitenuckler]

Just watch out for voltage, you go to low and it will put the motor in hysterics and will barely run and get real hot/maybe melt the case. Some dont like speed controls at all

OK.I will measure it and only drop it say 20%. It must be a basic induction motor so voltage reduction is not the proper way to get another speed. However, it says I can use a speed controller in the spec, so maybe the motor can handle it. I wonder if I will get any natural draft at all? The dist blower should be making a bit of a "vacuum" right where I have my outlet

 

[Whitenuckler]

Update. I have been running without the inline duct fan for awhile. I tried a little "Tarzan" small 120V square fan mounted on the face of the duct cover
next to the stove. It did work, but noisy in the basement room and not that much air. Finally got the hammer drill out and tapcons. Now the inline duct fan is mounted on some 1/2" MDF with some foam spacers. Then the MDF is screwed into the concrete wall with 2 inch tapcons and washers. The difference in sound is like night and day. I am not using insulated duct, so that was not helping. I can run it at full voltage no problem now, but I have a voltage controller in line to lower the speed also. It is making less noise than when I had it suspended on a bungee cord. I guess the fan can't vibrate as much when mounted on a 10000 lb piece of concrete.

 

[stoveliker]

Exactly.