Venting/Exhaust

[MrNate]

Well, I finally moved into the new house and am now planning out the basement brewery. The HLT and MT will be electric, but for the boil kettle I was planning on using one of those 200k BTU NG burners.

I'm looking into exhaust hoods and they seem to be fairly expensive. Does anyone have any suggestions as to what I should use? I would imagine a shroud could be easily fabricated from sheet, so would I be able to just buy a blower, some ducting and a dryer vent to pipe it out?

Any suggestions would be appreciated. I've never done any HVAC work before, but I would like a cheap and effective system.

[Mad Scientist]

You have the idea, I would also make it close-able so that rain/snow is blocked. You'll also need an intake, inparticular if you have to move a large volume of air. I don't recall, but there should ber some guildence somewhere (why does 200 CFM sound right?)

[MrNate]

An intake for makeup air, you mean? Does that have to be powered (i.e. blower) as well, or does it just vacuum draw?

I haven't been able to find any good guidelines for NG, only propane. I think NG actually requires a lot less in terms of venting, but hell... I under-engineer and overbuild everything else, why not this? :D

Oh, I'm also planning on getting one of those nifty new CO detectors with the digital readout instead of just the limit alarm.

[Mad Scientist]

I would figure a vacuum draw is enough. There are figures somewhere for required air volume movement, I just do not remeber where I saw them....something tells me that this may have been a BYO (http://www.byo.com) Mr. Wizard question from a year or more back. If not, it might be a good question for him.

I like the CO detector idea....at least you would be albe to adjust your blower rate to achieve the right exhaust. In this case, trial and error are okay as long as you do not pass out. May I suggest a scuba tank......

[wortchillergoal]

I believe that the fan size formula is the following. The square feet of the hood x 100= cfm of fan. Well, that was for retaurant quality hood and fan systems. The hood does nothing more than define capture area. the fan is the important part.

The make up air can be vacum drawn as this is how many commercial kitchens operate. I do think you want good make air for this situation. Some commercial kitchens need them more for air pressure than fresh air. I have seen fans so big in bulidings that the doors were hard to open when the fan was running.

[MrNate]

Thanks a lot guys, this has been a big help!

[takhsh]

I have mine in the basement next to a basement window. I do absolutely nothing else. No exhaust, no air intake.

I worried very much about all these at the beginning. Nothing proved to be a problem (so far!). I am brewing in this basement for 8 years now. I have installed two shut-off valves in the gas line (in the case that one of them opens, and is left open by mistake). I do have a carbon monoxide censor but it has never triggered on. Even in winter I leave the window crack opend though. I am very pleased with the set up.
For the first year two years I used propane gas, but later I converted to natural gas, so I do not have to make refil trips.
In winter time, the furnace burner which is in the same room uses ten times more gas! so ten times more oxygen. Yet the basement does not starve from oxygen. Why? Diffusion forces is the answer. This is why I do not worry about bring new air into the area (by means of a blower etc)
I am not saying that there is no potential problem with this set up. I am saying that we probably excagerate the problem. Be careful is very imporant, expect the un-expected. One thing that bothered me was what happens if a case of boil over. Would the fire set off? There is no mechanism to stop the gas flow (like in the furnace burner and the water heater). Of course, I will be there, to restart the fire, but if I am not there for 5 minutes? what it would happen? What I said. Expect the un-expected. In this case in my set up, the boil over does not put the fire off, since my boiling pot is a converted keg and the bottom lips, do not allow the boil over water to run over the fire.
In any case every set up is different, and as I said, be careful, and be prepared for the un-expected.

[takhsh]

Ops,
One thing that I forgot to mention. in my earlier reply.
If you are using a propane gas burner with NG then you will find out that the flame is very-very small. What yo uneed to do? Either replace the burner with a NG burner, or do what I did. I drilled out the orofice of the burner to make it bigger. NG has much much less pressure and it would not go through small holes very much. Enlarge that hole and here you go. You need to adjust the air intake (mine has a diafragm I do not know what yours may have) to make the flame blue. This is all I did.

[Chubber]

Remember that your fan needs to serve two purposes:
1) Remove the combustion byproducts so you don't give yourself carbon monoxide poisoning.
2) Remove vapors from the boil.

A hood above the pot will do both functions, but may have a hard time capturing both well if it is not located well. Big boilers at breweries tend to have two different exhausts so they can shut off one or the other.

If your basement is dank and damp to start with you may not need to vent it much. But if it is 55 or 60 degrees down there and you boil a couple of gallons of water off of your wort, it's the same as just pouring that water on the floor if you don't vent it.

[takhsh]

As I said, these are potential problems, but in my case proved not to be.
My basement (in the Boston area), is more or less at 70 degrees, year around (+/- 5 degrees). I boil off about 1.5 gallon of wort. I donot see any condensation. As I said, the boiling pot is under a window that is cracked open winter time, and wide open summer time.
The flame does not produce CO. It is blue. CO is in the NG, and this is why I am worrying what it would happen if the flame turns off (it is iginited by me with a spark). If the flame turns off (by any reason), the gas will continue to run, and this can blow out the house in no time! This is the real danger, and at this point I do not have a solution. It seams to me, if I replace the burner with something similar to the water heater (with a pilot and a turn off device) I am under that danger.

[MrNate]

Ok, since it's under discussion and I've been researching/thinking about this for a while let me just clarify a couple of points.

1. The brewery room is likely going to be a small, closed off area in the basement, and it may not be near a window at all. Even if I wasn't worried about venting gases, I would be worried about adequate ventilation for the brewer.

2. Do you have a NG hot water heater in your basement? I do. Have you ever noticed that it has a vent pipe? There's a reason it's required by code. Combustion doesn't always go the way we want it to, and that unit uses a high BTU burner just like the kettle does.

3. That being said, there is one major difference. The kettle is an open tank, and as mentioned before will generate much more moisture than you want trapped in a room. Exhausting moist air, unlike the dry gases the HWH generates, requires powered ventilation instead of just a vent pipe.

4. Now we come to the critical bit. If you have to exhaust the air from a small room because you don't want the room to be hot and sticky, then you have to add makeup air so that you don't pull all the O2 out of the room and make the flame produce CO.

5. It ain't that big a deal to run 2 ducts into a room, especially a room in the basement that hasn't been constructed yet. I've found 200 CFM inline fans on ebay for $40, and like I said earlier I can just make a hood out of sheet.

6. CO Detectors. Unless it has a digital readout of PPM CO, it's just an idiot light. I do not trust limit alarms alone to critical systems. A gauge + limit alarm is always better. Even then I remain skeptical.

Anyway, that's my opinion and reasoning. It is based on what I could fact check and logically reason, but also tempered with a fair bit of natural paranoia. I don't plan on giving up my paranoia anytime soon - it's kept me safe so far.

I don't claim that this is 100% accurate information, just accurate to the best of my knowledge. If you know better, I'm happy to hear it.

[takhsh]

Originally posted by MrNate

2. Do you have a NG hot water heater in your basement? I do. Have you ever noticed that it has a vent pipe? There's a reason it's required by code. Combustion doesn't always go the way we want it to, and that unit uses a high BTU burner just like the kettle does.


In fact I do. In the same basement that I have my brewing going on there are:
1. Heating furnace for heating the house.
2. Hot water heater.
3. Laundry dryer.
4. My brewing set up.

Yes, all have exhaust ducks (except my brewry). The water heater exhaust is tied to the furnace which goes into the chimney. The dryer has a separate exhaust and this drives the results of the gas buring and the steam of the clothes out of hte house.

If I judge from the gas pipe supply size, my brewery uses the less. The furnace may go for hours, full speed to keep my house warm in the winter. The dryer usually runs for one hour to dry the cloths, and this is I think a little more powerful than my brewery.

As I said, I do not supply any extra air. There are basement windows. None of them is hermetic, or of the latest technology of air tight/energy saving windows. Probalby this is where the oxygen is coming form to keep all this going, and not have me suffocate. My homebrew burner consumes a little more that a top stove burner. If you have two burners going on a top stove we are equal. For one hour cooking you do not need in your kitchen air intake. Do you? In restaurants when they cook all day long, it is a different story.

Of course, in your case where the brewry is going to be in a small room with no window, things my be different. To be honest, I do not expect that the fire would starve of oxygen. Do not underestimate the diffusion forces that want to have oxygen everywhere. But I do expect to be discomfort from the heat and the steam towards the end of a brewing session, especially if you are doing 10 gallons batches. For htis reason an exhaust will be very useful. But a device to supply extra air I think it is un-necessary. If you are handy and do this, definately is not going to hurt.