A precision steam pasteurizer for bulk mushroom substrate, built entirely from rust-proof stainless steel — no coating, ever. Set your target temperature and run time on the PID controller, load up to ~200 lb of substrate, and walk away. Built to order with a 2–4 week lead time and delivered by freight.
Most substrate steamers ask you to babysit a boiling drum. This one runs itself — the PID controller and automatic water valve handle the entire pasteurization cycle without you standing over it.
Switch it on and it heats until the barrel reaches your set point (we recommend 200°F for the best cost efficiency). Once the barrel stabilizes, the controller runs a countdown to let the load core reach pasteurization temperature, then shuts the heating loop off automatically. Repeatable results, no babysitting.
A stainless float valve maintains the water level in the base automatically, so the barrel can't boil dry during a long unattended run. Connect a hose and the steamer manages its own water.
A 12-gauge perforated steel false bottom plus a spacer grid keeps your substrate bags up out of the water and in the steam, so heat penetrates evenly to the core of every block in the load.
A quick look at our latest, improved PID controller — setting your target temperature, starting a run, and letting it manage the pasteurization cycle for you.
Both versions pasteurize a full insulated load in a single session. The difference is the heating element: the 220V runs a much larger 5,500-watt element, which reaches pasteurization temperature about an hour faster, tolerates running uninsulated, and recovers quicker between batches.
*Insulated, the 1,500W element brings a full load's core to pasteurization temperature in about 4.5 hours from a cold start. Insulation matters at 110V — bare, it fights heat loss and struggles to hold higher temperatures, so plan to wrap the barrel.
*The 5,500W element reaches pasteurization temperature about an hour faster than the 110V, runs well even without insulation, and recovers quickly between loads. The pick for production volume. Add $300 over the 110V price.
Times are from our calibrated thermal model of a full ~200 lb load, measured as the block core reaching pasteurization temperature (~160°F) from a cold start. Actual times vary with ambient temperature and how well the barrel is insulated.
This barrel is built entirely from stainless steel, so it never rusts and never needs a coating — no painting, no epoxy, no re-lining, ever. Set it up once and run it for years.
Stainless steel shrugs off the hot, humid steam environment that would rust bare carbon steel — with no coating to apply or maintain, ever.
With nothing to re-coat or re-line, a stainless barrel just keeps working. It's the set-it-once, never-think-about-longevity choice.
The smooth stainless interior wipes down easily between batches and won't flake or leach, so your substrate stays clean.
Our carbon steel PID barrel runs the same PID controller, heating element, and hardware for less — starting at $2,000. The trade-off: carbon steel needs a food-safe coating (either your own, or our factory epoxy lining) to prevent rust. If you'd rather save now and handle the coating, view the carbon steel PID barrel.
| Barrel | 55-gallon stainless steel, modified lid with tri-clamp ports |
|---|---|
| Substrate capacity | Up to ~200 lb (approx. 40 blocks per load) — plan your throughput → |
| Inner diameter | 22.5" |
| Barrel height | 34" |
| Heating element | 1,500 W on 110V / 5,500 W on 220V |
| Control | PID temperature controller with countdown timer |
| Water management | Stainless float valve for automatic fill |
| False bottom | 12-gauge perforated steel + spacer grid |
| Time to pasteurize (insulated) | Core to ~160°F in ~3.5 hr (220V) / ~4.5 hr (110V), from a cold start* |
| Method | Atmospheric steam — super-pasteurization (not pressurized sterilization) |
| Material | Stainless steel — never rusts, no coating ever required |
| Power options | 110V or 220V (+$300) |
| Lead time | Made to order — typically 2–4 weeks before it ships |
| Shipping | Freight only; arranged at time of shipping (see estimates below) |
| Build | Made to order in the USA |
*Modeled estimates for a full load; actual times vary with ambient conditions and insulation.
Estimate how much substrate this barrel can pasteurize — bags per load, per day, per week, and per month. Adjust the heater, ambient temperature, pasteurization level, bag size, and how many loads you run per day.
Every barrel steamer is built to order in the USA, with a typical lead time of 2 to 4 weeks before it ships. This is a large, heavy unit that ships by freight truck — freight is arranged at the time of shipping and billed separately, so the price you see here is for the steamer itself.
These are ballpark figures to help you plan — actual freight depends on your exact destination, address type, and current carrier rates. We'll arrange the freight and confirm the real cost with you before it ships. Want a quote before ordering? Call us at (530) 300-9292 with your ZIP code and address type.
This is an atmospheric steam pasteurizer — sometimes called a substrate sterilizer or barrel steamer. It heats your load with steam at ambient pressure, which is exactly what you want for bulk substrate: straw, masters mix, supplemented sawdust, and CVG. It super-pasteurizes those materials so beneficial competition is knocked back and your spawn can take over.
It is not a pressure sterilizer. Grain spawn and agar need true sterilization at 15 PSI / 250°F in an autoclave or pressure canner — a barrel steamer isn't intended for those. Use this for bulk substrate, and use a pressure sterilizer for grain and agar.
Choose your power (110V or 220V) at the top of the page, then order. Built to order in the USA.
