Basement Electric Brewing, Ventilation and Negative Pressure Downsides

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geoffm33

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I am about to begin brewing in my basement with a 3500W induction burner doing 5.5 gallon batches. After reading about ventilation suggestions throughout HBT I've decided on simply brewing in front of the open basement window which will have a standard window fan blowing out.

As this is the only window in the basement, I will have a box fan at the bottom of the stairs (that lead to the kitchen) blowing towards the kettle/window for make up air. So it will be a straight path from the box fan (make up air) towards the kettle and to the window fan exhausting out the window.

Feel free to comment on the above thought process in addition to my my main question:

With an off the shelf window fan, do I need to be concerned about creating negative pressure in my basement? We have natural gas hot water heater and heating system. They vent into the old chimney (no longer have any fireplaces) but not sure if it simply vents into the flue or if the vent runs the whole length to the rooftop (it's a 3 story old townhouse, never been on the roof).

I was reading the following on another post and it got me thinking:

I'd be very leery running a high powered exhaust in your home if any of your natural gas appliances are vented into a chimney. Turning on the exhaust will cause a negative pressure in your home and flue products will enter your living space, especially in the winter when your furnace is running.

I've responded to many of CO emergency calls from customers installing high powered kitchen range hoods and unknowingly causing a negative pressure in their home...

So even if you brew in a different area from where your chimney is situated, air takes the path of least resistance and will back draft down your chimney.

I understand that you're going to have intake air blown into your brew space from outside, but remember that your make up air to be as close to 100% or better yet 90% to ensure complete removal of products of combustion. If you don't have a way to ensure this proper air balance you'll be needing to hire a professional air balance company.

So if you have natural draft gas appliances in your home DO NOT BREW INSIDE! You may be putting yourself and your family at risk.

Thanks!
 
There is a CO detector down there. I may pick up another one that has the CO level readout.

LAHammer, good call. It is fairly new (7 years old).
 
I am about to begin brewing in my basement with a 3500W induction burner doing 5.5 gallon batches. After reading about ventilation suggestions throughout HBT I've decided on simply brewing in front of the open basement window which will have a standard window fan blowing out.

As this is the only window in the basement, I will have a box fan at the bottom of the stairs (that lead to the kitchen) blowing towards the kettle/window for make up air. So it will be a straight path from the box fan (make up air) towards the kettle and to the window fan exhausting out the window.

Feel free to comment on the above thought process in addition to my my main question:

With an off the shelf window fan, do I need to be concerned about creating negative pressure in my basement? We have natural gas hot water heater and heating system. They vent into the old chimney (no longer have any fireplaces) but not sure if it simply vents into the flue or if the vent runs the whole length to the rooftop (it's a 3 story old townhouse, never been on the roof).

I was reading the following on another post and it got me thinking:



Thanks!

I basically have the same setup as you describe. Never had an issue. Additionally if the exhaust pipe that goes into the chimney has a back draft damper on it, a negative pressure issue would cause it to close and force the fumes up the chimney. Normally this is attached perpendicular on a inline tee and with positive pressure pulls air from the living space in to create a current up the chimney carrying the fumes with it. If negative pressure occurs, the damper closes, creating a closed system between the water heater and the chimney so the fumes are pulled out by the vacuum created by air moving over the top of the chimney.

rsk4-4.jpg
 
I am about to begin brewing in my basement with a 3500W induction burner doing 5.5 gallon batches. After reading about ventilation suggestions throughout HBT I've decided on simply brewing in front of the open basement window which will have a standard window fan


Thanks!

Why don't you make a board, with flexible duct attached to it, that you can put in the window opening when brewing. Will fit better and won't let cold air in winter time. The other end of the flex duct can have a hood and in line vent attached to it. Look into a motor controller to slow the vent down so your not dumping too much air outside.

Hope this makes sense:)
 
A box fan is not going to create that much of a pressure gradient, it just isn't powerful enough. I also don' t think you need two of them. I think one by the basement window would be fine. It's an electric rig, you're just using it to pull out water vapor right?. Either way, you're not going to suck exhaust air from your natural gas appliances into the basement with a set up like that. Now if you had an 800 cfm inline duct fan or something, you might want to worry a little, but you're not going to get anywhere close to the danger zone.
 
I just did a high gravity beer this morning. Started with 18.5 lbs of grain and 9.75 gallons of water at 6am. Used 5.75 gal for strike and fly spared with the remaining 4 gallons. Lost about 2.25 gal in the grain and it took about 2 hrs to boil down the 7.5 to 5.5 gallons. I started the boil on the 3500 setting as soon as I had about in inch in the brew kettle from the start of the sparge. I over shot my efficiently, was looking for about 70% with the low sparge volume for a gravity of 1.086 but hit 78.5% for a gravity of 1.097. I pitched around 11am for a total brew time of about five hours.

I don’t have any exhaust fan or open any windows. I have a CO detector and my gas water heater is in the same room but has forced ventilation. The only problem I have had with brewing indoors is that my kettle sits right under a cold water pipe that would condense like crazy and drip back into my kettle. I fixed it by stapling up some Reflectix rap on the ceiling over kettle. It’s an unfinished basement with about 1,500 sq feet. It gets a little humid for a few hours but it’s not too bad.

Here is my setup:

Burner: 1 Avantco ic3500 Induction cook top

BK: Bayou Classic 10-gal with two ball valves for whirlpooling, thermometer and Reflectix rap.

HLT: Rubbermaid 10-gal with two ball valves for whirlpooling while chilling, thermometer and sight glass.

MT: Rubbermaid 10-gal with 12” false bottom, thermometer and Blichmann Auto Sparge

Immersion Chiller: 25’ of ½” copper

Pumps: 2 Chugger Pump SS-Inline

Mill: Cereal Killer

img_5009-62296.jpg


MT with auto sparge
img_4978-62270.jpg


Sparge & start boil
5-sparge--boil-start-62343.jpg


Keg
img_4998-62299.jpg


Drink
img_5002-62297.jpg
 
I also have natural gas water and furnace. They also both duct into the old chimney. I was also concerned about negative pressure and sucking furnace exhaust because I brew in my basement.

I have a normal flexible duct makeup air intake for the furnace. I have *two* inline duct fans on my vent hood, one 400 6" CFM and one 180 4" CFM fan (the 400 is constricted to 4" through a glass block window and wasn't exhausting enough moisture so I added the 180 one). I also have a CO detector and never once have I triggered it despite brewing in the same room as the furnace and water heater.

I cannot say absolutely that you'll have no problem. I would absolutely get a CO detector for your brewing area. But my point is that if you have a regular makeup air duct, or basement windows you can open, I believe you will be just fine even with 400 CFM fans.

If you're still concerned you can get a spillover detector and put it on your water heater. It measures temperature and alarms when it gets too high. If you are sucking water heater exhaust into your basement it spills over onto the top of the heater and would trigger the detector. But when I had my house insulated and sealed, I specifically asked about this issue and the contractor did not think it would be a problem.
 
Rdavid,

Dumping that much moisture into your basement isn't a good idea. Could lead to mold. The fact that it dissipates quickly helps. If you stick with this method at the very least I would get a dehumidifier.
 
If you're worried about pulling your home in a vacuum, open 2 or 3 window's an inch or two. That's it, all ya gotta do. When I was starting out in HVAC 20 years ago whole house fans were popular (very big fans) and some customers would have the pilot light sucked off the thermocouple. Just cracking a window would fix the problem. If you want to check draft, light a match and watch the direction the flame points. You can do this at the incoming fresh air /make up air points, like the cracked window.
 
Rdavid,

Dumping that much moisture into your basement isn't a good idea. Could lead to mold. The fact that it dissipates quickly helps. If you stick with this method at the very least I would get a dehumidifier at the least.

Very good suggestion. I was not thinking about mold. I just got a big dehumidifier that will pump into my utility sink. Thanks for the heads up.
 
A box fan is not going to create that much of a pressure gradient, it just isn't powerful enough.
+1

You'll really only get negative pressure if you have a duct fan that is directly connected to the outside.

A freestanding/standalone fan in the room blowing in the general direction of the window won't cause negative pressure.

If you put this fan in the window and have it such that it seals the inside from outside then yes, you could get a negative pressure.

I also don' t think you need two of them. I think one by the basement window would be fine.
+1 again.

I would simply put the fan in the window but make sure it's not really sealing inside from outside. You'll get air coming in on the sides to make up what you're blowing out. A bit of circulation will occur (maybe) but you should be ok.

Best would be to have another window in the basement open if you have one (I don't think you do). Another window open upstairs would work too but then you're evacuating your house air which is going to cost you in either heating (furnace) or cooling (AC) depending on the time of year.

Dumping that much moisture into your basement isn't a good idea.
+1 to this as well. (I'm full of +1's today!)

Kal
 
Very good suggestion. I was not thinking about mold. I just got a big dehumidifier that will pump into my utility sink. Thanks for the heads up.

You know, for about $100 and the price of ducting, you could do what I just did. Get an inline fan (@$75 on Amazon), and fan speed controller (@$25). Use 4" duct to go outside between your joist bays. Use a dryer vent with self closing doors/flaps. Buy or rent a ~4" hole saw to drill the hole for the vent to the outside. Fabricate a makeshift hood out of anything like plywood or foamcore, at least initially. Good little saturday project.
 
Dude, you really need to learn how to scale pictures for viewing on the internet.

GIANTEST PICTURES EVAR
 
You know, for about $100 and the price of ducting, you could do what I just did. Get an inline fan (@$75 on Amazon), and fan speed controller (@$25). Use 4" duct to go outside between your joist bays. Use a dryer vent with self closing doors/flaps. Buy or rent a ~4" hole saw to drill the hole for the vent to the outside. Fabricate a makeshift hood out of anything like plywood or foamcore, at least initially. Good little saturday project.

Which fan and speed controller from Amazon did you get?
 
You know, for about $100 and the price of ducting, you could do what I just did. Get an inline fan (@$75 on Amazon), and fan speed controller (@$25). Use 4" duct to go outside between your joist bays. Use a dryer vent with self closing doors/flaps. Buy or rent a ~4" hole saw to drill the hole for the vent to the outside. Fabricate a makeshift hood out of anything like plywood or foamcore, at least initially. Good little saturday project.

Good idea - I may do that. Just to test I took a humidity reading in my basement at 32% and then boiled off 2.5 gallons and the reading was 64%! I kept all the windows and doors shut overnight and then took a reading in the morning at 32%. I think its not too much of a problem when its cold out and the heat is on. The summer will be much worse. I got a good sized dehumidifier that has a built in pump and ran the drain line up to a pipe that dumps into my utility sink that I have for my reef fish tank on the above floor. I boiled off about a gallon with it running and it came back to 32% in about two hours. Mold is no joke - thanks again for the heads up.
 
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