Air handling in Mushroom Lab 1

[hongoman]

I am designing a small laboratory for producing mushroom spawn in Costa Rica. The laboratory is in the higher mountains at 8000 feet and has fairly constant temperature year around of between 55 degrees at night and up to 70 degrees in the day. Humidity outside is between 50% and 90%. The lab size will be 15’x 10’ with 11’ceilings. There are also two spawn storage closets of 5’x4’. The laboratory is being built with 6” Styrofoam walls with a plaster coating and should have an insulation value of R30 in the walls and floor and R40 in the ceiling. It should be very well sealed from the outside and has triple door entry. The lab will have one or two persons working in it a few hours a day. There is a refrigerator, incubator, autoclave and other equipment that will product heat. The goal is to keep the laboratory at a temperature of between 70 and 80 degrees and an RH of between 35%-50%. It should be positive pressurized through HEPA filters. Both the workers and the mushroom spawn produce some CO2 that may need to be exchanged.

My guess is that a heating or cooling system will not be needed but an Economizer can be used to control the temperature and that a small dehumidifier in the laboratory can control the humidity.

The laboratory is being built on a very tight budget.

I have considered several systems that may work. One is the Honeywell Jade Economizer Controller, with two Jade temperature sensors and the M7215 Damper Motor that can be purchased for around $400. Also Jackson Systems offers an Economizer system with the controller and motorized dampers, but I haven’t been able to find their price. I also thought that I could just assume that the temperature outside will be cooler then the temperature inside and instead of using an Economizer, I could just start taking in outside air anytime the temperature inside reaches the limits, then all I would need is a temperature controller that would open the air intake and exhaust damper and close the connecting damper (see diagram).

Your comments on whether this will work and the best items to purchase for the system will be greatly appreciated. All the items will be purchased in the US and then shipped to Costa Rica.

The other items that I need to figure is how to keep a positive pressure in the laboratory. Can that be done with just a pressure damper in the return air line?

And how do I figure the correct size fan and type for the system as it will be pushing air through a course air filter, an electrostatic filter and finally a 24” x 24” x 12” ASTROCEL I MODEL HT500 HEPA filter tested at 1000 CFM with PENETRATION 006% DOP @ 20% 009%.

Any suggestions, comments, ideas, etc will be greatly appreciated.

 

[willard3]

Find a person who does these systems professionally. You're doing this by the seat of your pants, not a good idea.

The psychrometrics and systems for this are more complicated than you think.

 

[MechEngNCPE]

assume 2" external static for the hepa alone. I think you're out of your league.

 

[hongoman]

I am certain that I am "out of my league". But don't have an idea of where to find a "person who does these systems professionally" here in Costa Rica. So again any help will be appreciated.

 

[chicopee]

I remember a place called "Lundy Mushrooms" in MA back in the early 80's. It grew Oak mushrooms. The room in which the mushroom grew was water resistant with little or no ventilation, and a constant temperature and a high relatively humidity were
maintained. Heat and humidity was provided by a steam boiler operating on an open loop. All of this was designed by the owner who unfortunately died later in his own airplane.

 

[hongoman]

Each type of mushroom has it's own "best environment" for growing, I am working now with the most common commercial mushroom, the button or portebello mushroom. They like to grow in a high humidity (90%+), high CO2 (5000 ppm+) and cool environment (75 degrees). After they have grown through the compost then the temperature needs to be lowered a bit (65 degrees)for them to start fruiting (producing mushrooms). My environment here in Costa Rica is great for mushrooms as it is high humidity and cool all year around.

Right now I'm working on the laboratory to produce the spawn (seed). As you start with just a few small pieces of mushroom and within weeks have enough to produce thousands of lbs, it is very important that no contamination gets in at the beginning or it to will grow exponentially.

This will save me from having to purchase my spawn (seed) from other sources and give me better control.

 

[willard3]

I'm sure you can find a professional who can help you, even in Costa Rica....you're not on Mars.

You already have the web and a phone.

 

[MechEngNCPE]

Good luck with the magical mushrooms, you know they are illegal in the US, right?

 

[cry22]

Although this sound like marijuana growing to me than mushrooms, I offer a comment on your diagram regarding the economizer, It will not work without a Return fan, because your supply fan will suck air from the exhaust damper and the Outside air dampers. I.e air will come from the path of least resitance which will be the Exhaust and OA dampers close to the fan and not from the space.

Without a return fan - you can provide RA/OA damper control and install a space Relief damper connected directly to outside and wired to the RA damper.

 

[hongoman]

Cry22 - Thanks for the comments. It's a mushroom farm, if I was in the marijuana type thing, then I would grow those kind of mushrooms, but not my thing and even if it was, prisons here in Costa Rica arent the kinda place I would want to be in. But if your ever in Costa Rica come check it out and if it's in the next few months I would be glad to exchange some tour guiding for some advice. Take care and thanks again.

 

[cry22]

Hummm, you seem highly knowledgable of Costa Rica prisons ))

 

[hongoman]

We've had two recent Presidents end up in prison for taking bribes, so I have seen the pictures on the news and visited an employee one time that was in one, (it was because he didn't go to court on a bad debt charge). But fortunately I haven't been in one myself yet, hopefully I will keep my nose clean and stay away from any trouble, thats the plan anyway. I actually live in a very small, very catholic, very conservitive, very agrigultural community in the higher mountains of CR. Many of my neighbors still plow their fields with oxen and most make a living taking food down to the farmers markets in the city. It's a great place to live and to visit, we are in our winter now (rainy season) best time to come is from December to May.