Odor leaking from HPS hood ventilation system, not sure what to do!

Currently I have a wall of DIY cabinets in a temp stable downstairs bedroom. My ventilation systems goes like this:

A) 24/7 ventilation with scrubber: air from the bedroom is passively pulled into CFL cab, through to bigger HID side, then passes through a charcoal filter and pushed back out into the room by a 170 CFM inline fan. Works great for scrubbing and circulating air, and certainly keeps the CFL side within desired temperature range.

B) Originally, I had hoped to run this through my air cooled light hood, but the 600w HPS ran far too hot for that 4" system... So I installed a 6" system for the light, taking air from outside the room, running through the light, through another inline fan and back outside the room. Air never mixes with the air in the room, so I didn't think anything more of it... Here it is, coming and going:


The 6" system vents into my utility area, where my furnace and water heater live. There are two 6x12" screen vents to the outside that allow plenty of air circulation for any excess heat or humidity.


MY PROBLEM. The exhaust from the 6" can fan seems to be choosing to travel through the furnace and out the intake panels in my house instead of passing through the outside vents. I only know this because I can smell it coming from those damned intake panels.

I realize this means I've got a leak in my flex duct or on the light itself, which is pulling non-scrubbed grow air and pushing it into my living space (not good). But I have absolutely no idea how I can find the leak and/or otherwise solve this problem...

Can anyone help me figure out a solution here? kiss-ass

Smoke.
The hvac guys at Lowes can help with a safe smoker. My brother is in the heat/ac biz and that's what he uses to find leaks in intake ventilation.
Hope this helps, good luck.
Fred

This is exactly the direction I needed, thanks a bunch Fred!

If the HVAC smoke ends up being expensive, I'm wondering about making teeny tiny smoke bombs (sugar + salt peter) for my purposes... Of course I'd need to mock up some tin can shells to position them safely.

How did this turn into a fun project? I'll let you all know how it goes. GiGi

Here's a more visually accurate portrayal of my problem...

Intake comes from crawlspace beneath furnace room (pantyhose filter just to keep critters out), runs behind short cabinet and into tall flower chamber, directly through light hood and back out the cabinet pulled by inline fan, and out past a DIY muffler back into the furnace room.



To repeat, I suspect unscrubbed grow air is being pulled through leaks in the flex duct or light hood, and pushed into the furnace room (you can see the hole on the right wall beneath the light fixture, near what I thought was the furnace intake ducting.



I am not sure how it's backing up into the furnace intakes from my living space...



I would think the intake to the furnace comes from the main ducting above the furnace, seems to lead to the right place in my house. But I'm suspecting these holes around the water heater and furnace exhaust ducts are allowing some kind of additional intake into my house.

If that's the problem I'd love to patch those holes and not burn my house down; maybe there are some high temperature flanges for this? I'm off to go get some HVAC smoke to do a little testing. Wish me luck, folks!

Appears I've hit the end of the expert consultation line; indoor guru shrugged his shoulders, Lowe's HVAC guy said he only saw the pros ever use that orange smoke stuff.

Now that the heat of the summer is past, maybe I'll just reverse my fan and have the slight stank float into the crawlspace.

Whatever, dang it...

(Any good ideas still welcomed with open arms!) GiGi

I just had a "duh" moment... Turned the light on in my furnace room, went and peeked into the intake vent, I saw a bunch of light that confirmed it's those open gaps around the water heater and furnace exhaust pipes that are leaking the slight aroma. I'm headed to Lowe's right now to pick up some aluminum flashing.

Having a simular "sometimes" problem.
Just ordered a stand-alone fan / scrubber

I hope it works,,, and hope it'll utilize a speedcontroler.
Open windows make my closet breath.
I have the option of taking air in under the door or from the basement.
Basement good in summer but too cold in winter.
The breathing is from positive / negative presure depending on wind direction and gusting in the warmer months with windows opened.

Smoke bombs to figure out leaks in venting?...IF theres intake leaks, you can just light a stick of incense and put it near the vents to see if any air/smoke is being pulled in, our pushed out.

Silicone caulking, and aluminum tape are your best friends.

Whelp, apparently salt peter is used to make explosives for crimes against America so I never got to follow through with the smoke bomb idea... People at the farm and garden stores were all rude to me when I asked about it. Whatever... LOL

I tried incense but it was too faint to see where it went; I ended up just having to guess and try a solution (repeat). Kind of like finding the square root of a number...

I'm currently thinking flanges cut from sheet metal and some high temperature mortar. Will post when I've gotten somewhere with it.

Here's the latest. Cut some aluminum flashing to close the gap around the water heater tank and furnace exhaust vents. Foil tape and high temperature mortar to seal all of it except where the condensation drips down (due to non-insulated ductwork).



I have to wait until 8 pm to see if this has fixed my problem... Tick tock.

Aggg, nope. Stank still somehow creepin' in... WTF.

Did you ever get this figured out?

I'm trying to remember where I got my cans of 'smoke' that I used to use to test smoke detectors for fire inspections ot the end of my projects for work. I can't remember where I them though since it's been about 5 years since I had to do that.

They're little black spray cans that you just spray around smoke detectors and they're cheap. Hope you got this sorted out though.

Well, I ended up deciding that the hood I got for cheap (a second) must have had a seal issue... So I reversed the fan so it "pushed" air through the hood and out, avoiding sucking unscrubbed air and instead introducing external air to the space. Other than the risk of the external air being introduced to the grow space (cut a hepa filter to go over the intake) it worked just as I needed it to.

Since then, I've modified my space quite a bit and keep tinkering. I'll post more pics soon! GG