Brewhouse Comparison. Steam. gas, electric

[BSBC]

We are looking at expansion. We have been asked to design a brewpub in a building built in 1910.

There are a few decisions to make regarding the brewhouse. In our current brewpub we use a 3bbl electric stout system. It is very basic. Heat generated ,is extracted from the brewhouse by a centrifugal fan in line with the steam stack.

We are proposing a 10bbl system for this building

Any steam fired system we have seen has a jacket that is insulated and there is very little heat radiating from the system into the surrounding room and all boil off is extracted through the stack.

But a direct fired system is fired directly under the kettle with a skirt and heat exhaust stack vented out along with a steam stack from the kettle.

We have an abundant supply of natural gas in the area, but also have access to a brand new 480v service in the building so the electric system would be very easy to install and use.

There is room for a steam generator in the basement but obviously installing it would be more costly. Maintenace of the system would also be more costly to do rather than a direct fire or electric system.

So my question is this....Just how much heat could I expect to generate in a direct fired system and is such a system feasible in a brewpub that will be fully enclosed in a vintage 9 story building? How much more heat will a direct fired system release into the surrounding area?

I guess I really need help weighing the pros and cons of each system.

[Prospero_Equip]

Hello we offer a "oil heated" system that is self contained and runs off a closed loop system. No steam boiler required. Just 3PH Power. email me if interested: mdidonato@prosperoequipment.com

[MarksDMW]

BSBC Team,

You bring up a very interesting subject that we discuss every day. How do you choose between electric, direct fired, or steam systems. For the sake of today’s question I am going to limit it to the general thermal impact each will have on your conditioned space. Electric (assuming resistive heating elements) transfer more or less 100% of the heat generated directly into your wort. The concern then is limited to heat radiating off the vessels themselves, and the efficiency of the kettle’s ventilation. Most manufacturers will insulate the sidewalls of your MT, LT, BK, or WP, but leave the bottoms and tops single walled (BK fire box excluded). You will also want to ensure you have adequate ventilation which generally comes in three flavors. First you have a condensate stack which either has heat recovery features built in to capture and return to your HLT, or simply condenses the steam to a vapor where you run it down the floor drain. An inefficient condensate stack will heat your space more than just about anything else, and is the first item of concern. I see in your post that you are directly venting your Boil Kettle (BK), so that brings up the next two flavors of ventilation (powered and non-powered vents). A non-powered vent will be stainless steel single walled stove pipe exiting through the roof of your building. These are a popular option in the brewing space, and can work quite well. Another option is to put a powered vent fan on your roof to help facilitate ventilation. Depending on where you are located, a powered vent fan can be a significant load on your conditioned space. The question is where is your makeup air coming from? If you are in Phoenix and it is 116 outside, that makeup air is going to have a heavy impact on your room’s temp.

Now that the importance of ventilation is shown, on to steam vs direct fire. First, I’ll make the claim that a steam system will likely be a smaller thermal load on your brewery space. A steam system has features that in many ways makes it more inherently efficient than a direct fired brewhouse. As an example, a steam trap’s purpose is to vacate any condensate (water) from your steam jacket. Assuming you have a low pressure boiler, your steam will be at approximately 240F entering the jacket, and 180F or so leaving the steam trap. Because the steam and all it’s thermal energy is trapped in your jacket, it transfers this heat into your mash/wort before it is able to condense and exit. Even better, this condensate is pumped back to your boiler where it is recycled and turned into steam once again. A direct fired kettle on the other hand basically blows hot exhaust into an enclosed fire box, past the bottom of the kettle and a few inches of sidewall, then up and out the vent through the roof. Whereas the steam system traps that energy until it’s utilized, the direct fire system simply runs at one speed, hot.

A direct fired system is typically the most impactful on brewery temps. You have a power burner blowing hot exhaust (again consider makeup air) into an insulated fire box. That fire box radiates heat during the entire brew. It is also quite common to have a single walled vent box off the back of the kettle that you could cook an egg off.

To be entirely honest though, I wouldn’t weigh the thermal load on your space too heavily on your decision to choose steam or direct fire. Heat management in many ways just comes down to proper planning and process. As an example, draining a hot fermenter of caustic onto the floor 15’ from a trench drain adds a tremendous amount of heat to the general space. Making sure you have a drain closer, or running a hose from your tank to the drain will help mitigate this to a great degree. I could go on at great length about the pros and cons of each heating method. There are serious considerations to keep in mind, I just wouldn’t put thermal load too high on the list. Of course all of this assumes a decently engineered brewhouse. I’ve literally seen a 15bbl converted dairy tank with 3 industrial crab cookers underneath firing at full blast. For that one I was more worried about the carbon monoxide than I was the temperature in the room.

As a side note, there is still the issue of the boiler room itself. Boilers radiate a decent about of heat. If you build a dedicated boiler with dedicated ventilation, and makeup air you won’t have to worry about the boiler’s impact on your brewery space.


If you want to give me a call to discuss further feel free.
Joe Watzig – MARKS DMW
(360) 859-3535