Indoor Exhaust advice for natural gas burner

[gbrewing]

I am seeking some help in re configuring my indoor brewery exhaust system. I am seeking some input from folks who have experience with exhaust.

I currently have a commercial range hood installed over my boil kettle but it just isn't removing the heat that I want.

I will approach this issue with a simple question. If you were designing this exhaust system for your use, how would you do it.

System and building information is as follows
- 16' x 22' dedicated brewery. 8' ceiling
- natural gas - 23 tip jet burner (lets use 55,000 btu for any formula's)
- 55 gal kettle which will most likely be boiling 30 - 35 gallons batches

I am interested if there is a method of heating the BK without heating the entire room. Perhaps a make-up air intake?

 

[Stealthcruiser]

Post up a pic of the range hood, and the duct size exiting from it.
There are some stout fans out there made to fit in round ducting!

You may have answered it there, about the make -up air.........Do you have an additional air inlet for when your vent hood is running?
A screened door you might open, (weather permitting), to see if that's the problem?

 

[Hockeyman]

First off do you have any natural draft gas appliances in your brewery? ie: Furnace, Hot water tank, wood stove or anything that uses a chimney to remove products of combustion. If you do then its important to ensure that you're exhaust fan isn't causing a negative pressure. Negative pressure is when you're exhausting more air that what can be replaced by building leakage (air gaps in doors, windows, etc) and your chimney reverses becoming an intake. Now if a natural draft appliance on that chimney fires and cannot over come that negative the products of combustion spill into the room potentially causing CO poisoning.

If you don't have a chimney then negative pressure isn't a concern to you.

Now to determine what CFM is required 16 * 22 * 8 = 2816 cubic feet
Typical kitchen exhaust is 15 changes per hour so 15 * 2816 = 42,240 CFH / 60 (mins in an hr) = 740 CFM. So if your current fan isn't at least 740CFM then your problem is an undersized fan.

As for your room heating up, that comes down to burner efficiency and how much heat is actually being transferred to your BK and what gets lost to indirectly heating the space. The jet tip burners are typically found on restaurant woks which are round bottoms opposed to flat bottom kettles. Lots of heat lost up the sides...

 

[gbrewing]

Thank you for the responses.

I do have a natural gas water heater installed. I was somewhat aware of negative pressure so I have been opening the window or double doors when running the bk during testing. Is there an appropriate method to calculate the needed makeup air for a 720 - 1000 CFM fan based on the other measurements provided?

Based on your CFM calculations I am obviously undersized at this point. I am currently using a 7inch pipe as well. Is there a max CFM a pipe can carry for venting?

I have seen several inline fans which can accommodate the higher CFM ratings that will fit in my setup, but I how will they handle any heat?

It there any advantage to a centrifugal fan versus an inline fan. (Comparing CFM to CFM's)

 

[Bobby_M]

I'm not an HVAC expert so feel free to ignore me, but the best way to increase venting performance is to provide a fresh air intake that routes down to the floor area by the burner. This will not only help with the negative pressure issue you absolutely have with the water heater flu, but it will allow better flow out of your vent hood as well, while minimizing losing all your room heat in the winter. It wouldn't hurt to run a fresh air intake directly to the lower area of the water heater either. It's like creating an imaginary closed system.

 

[AlCophile]

All you folks using any carbon-based fuels indoors: Puh-leese remember that there is always the possibility of forming carbon monoxide, and if not, you are not out of the woods. Carbon Dioxide at a concentration of only 10% will render you unconscious. AND CO2 is 50% heavier than air.
If you SCUBA it is a good idea to keep your air system handy.
"There's no beer in Heaven".