On a big commercial attic, the bottleneck usually isn't the machine. It's that one hose can only be in one place at a time, and every bag change stops the whole crew. Running two insulation vacuums into one bag fixes both problems: two hoses clearing two zones, feeding a single large bag that doesn't need changing until the job is nearly done.
It only works with the right bag. You need a large-format bag with more than one inlet, which in our range means the four-inlet PRO-20 YARD trailer bag (540 cubic feet) or the 30 Yard dumpster bag (840 cubic feet). Both are designed to take two machines at once.
When a second machine pays for itself
Two machines double your fuel, your hose and your setup time, so they need a job big enough to justify it. The setups where we see crews get the most out of them:
- Large or split attics. Commercial buildings, long ranch houses, and attics divided by firewalls or with two separate hatches let each operator own a zone without tripping over the other hose.
- Multi-unit work. Townhomes and small apartment buildings where each unit has its own access.
- Tight deadlines. Restoration work after a water or fire loss, where the attic has to be clear before the drying or rebuild trades can start.
- Heavy, slow material. Wet cellulose and packed or fire-damaged insulation move more slowly through a hose. A second hose keeps overall progress up.
It's rarely worth it for a typical single-family attic with one hatch. Two hoses through one small opening means two operators crawling over each other, and you'll lose more time to tangles than you gain in suction.
Pairing the machines
The two vacuums don't have to match. Each one runs into its own inlet, so a crew can pair a big diesel with a smaller gas machine and give each the work that suits it.
A common split is to put the larger machine on the longest, deepest part of the attic and the smaller one on the awkward sections near the eaves or a second access. Our RAMVAC-40D diesel has a 12 gallon tank that runs for about half a day, and we recommend 8 inch hose on it for top production, which makes it the natural anchor machine. The RAMVAC-23 is a 23 HP gas machine on run-flat wheels at 295 pounds, so it's easy to move to a second side of the building. Both machines are quoted by phone.
Whatever the pairing, both machines stay outside, and each one reaches its inlet through a length of hose rather than a bag fastened directly to the outlet. With two exhausts throwing nails into the same bag, that buffer matters twice as much.
Setting up the bag for two hoses
Set the bag up in its final position before anything else. In a dump trailer or roll-off, that means spreading it flat and square to the walls with the inlets on the side facing the house.
- Pick two inlets that split the bag. With four inlets to choose from, connect the two hoses at opposite ends of the bag so each machine fills its own half. Two hoses side by side pack one end while the other stays empty.
- Tie off the unused inlets. An open inlet is a dust vent. Close the two you aren't using before either machine starts.
- Mark the hoses. A strip of colored tape at both ends of each hose lets the ground person see at a glance which machine feeds which inlet. On a 150 foot run, that saves a lot of shouting.
- Route the hoses apart. Keep each hose on its own path from the machine to the house so they don't cross, kink or rub against each other where they come together near the trailer.
- Start one machine at a time. Bring the first machine up and check its hose is pulling and its inlet is seated, then start the second and repeat.
The full specifications for each bag are on our trailer and dumpster bag page. The 12 Yard bag in the same range has a single inlet, so it isn't the one for this setup.
Two hose operators and one ground person
A two-machine job runs best with a clear split of responsibilities. We usually see a crew of at least three set up like this:
Two hose operators in the attic. Each owns a zone and works from the far end back toward their access point, so they're never crawling over freshly cleared joists. They watch their own hose for loss of suction and call out when they need a break or a move.
One ground person. This is the most important role on a dual-machine job, and the one most crews undersell. The ground person watches the bag, both machines, both fuel levels and both hose runs. They're the only one who can see whether one end of the bag is packing faster than the other, and the only one who knows when a machine has started to struggle.
Communication between the attic and the ground needs to be fast. Radios or a phone on speaker work far better than yelling through a gable vent. Agree on simple calls in advance: stop one, stop both, bag check, moving.
If your crew already runs one machine well, our post on crew productivity on insulation removal jobs covers the scheduling side of adding people and equipment.
Keeping the fill even
A single large bag fed by two hoses doesn't always fill evenly. One machine may be pulling deep, dense material while the other works a thin section near the eaves, so the ground person should check the bag regularly rather than once at the end.
Signs of trouble are a bulge building at one inlet while the far side stays flat, the bag pulling tight against the trailer wall, or suction fading on one hose when the hose itself is clear. When that happens, stop the machine feeding the full end and let the other catch up, or move that hose to a less loaded inlet once the machine is off.
Plan to stop around 85 percent full, as you would with a standard bag, so there's room to close it cleanly. For rock wool or wet loads, stop sooner. Before anyone touches an inlet or the bag closure, both machines go off. A bag is never disconnected while either hose is still moving material.
A few safety habits for a two-machine site
Two engines running means twice the exhaust and twice the noise. Park the machines so their exhaust points away from doors, windows, the attic access and any air intake, and keep crew breaks away from them too. Ear protection is a must for the ground person, who spends the whole shift beside both machines.
Attics on big commercial jobs get hot, and with two operators up there for long stretches the heat adds up. Breathable Cool-Suits coveralls keep fiberglass off skin without trapping as much heat as a heavier suit, and planned breaks matter more than any clothing.
Big jobs in older commercial buildings are exactly where asbestos turns up, so identify the material before either machine starts. Two vacuums double the dust you'd spread, and none of these bags (or anyone else's) is HEPA rated. Vermiculite should be treated as asbestos-containing, other suspect material gets tested before work starts, and either way the removal belongs to a licensed abatement contractor.
Set up the two-machine job with one call
If you're planning your first dual-machine job, call us at 404-354-6268. We can help you choose between the 540 and 840 cubic foot bags for your trailer or dumpster and quote a RAMVAC to pair with the machine you already run. The line is staffed 24/7, and bag orders leave the same day with free shipping.
Frequently Asked Questions
Can I run two machines into a standard 75 cubic foot bag?
No. Standard bags have a single spout and nowhere near enough capacity for two machines. Two hoses into one small bag will overpressure and fill it in minutes, so use a four-inlet large-format bag.
Does running two vacuums double the speed of the job?
Rarely in practice. Hose management, attic layout and how fast operators can move all limit the gain. Where it helps most is on large or divided attics, where each operator has a separate zone and the single bag removes most bag-change stops.
Can I run three or four machines into one four-inlet bag?
The four-inlet bags are designed for two machines running together. The spare inlets give you choices about where to connect so the fill stays even; they aren't extra machine capacity.
Can I mix fiberglass and cellulose in the same bag?
Yes, as long as both are ordinary, uncontaminated insulation and your disposal facility accepts it mixed. Keep anything contaminated by rodents, mold or fire separate if the facility asks for it.
What happens if one machine stalls mid-job?
Shut the other machine down before anyone touches the bag, then tie off the stalled machine's inlet so it can't vent dust. The healthy machine can carry on alone into the same bag while the other is sorted out.