Run more than one gas appliance off a single LPG cylinder — a BBQ and a patio heater, a caravan's cooktop and hot water service, a shed heater alongside a forge or burner — and the regulator sizing question becomes real rather than academic. Undersize it and appliances starve for gas under simultaneous load: burners drop flame, ignition gets harder, and a heater that ran fine on its own splutters the moment the BBQ is lit next to it. The fix isn't a bigger cylinder — it's a regulator rated for the combined load.
Single stage vs dual stage: what the extra step buys you
A single-stage regulator drops cylinder pressure to appliance pressure in one step. It works, but the output pressure it holds drifts more as cylinder pressure falls (as the bottle empties) and as ambient temperature changes — LPG cylinder pressure is temperature-dependent, so a single-stage setup can deliver a noticeably different pressure on a cold morning than a hot afternoon. A dual stage regulator, like the Bromic range stocked here, splits the drop into two stages — a first stage that brings cylinder pressure down to an intermediate pressure regardless of how full the cylinder is, then a second stage that regulates that intermediate pressure down to final appliance pressure. The result is a steadier, more consistent output across the cylinder's full run and across temperature swings — the difference that matters once you're feeding more than one appliance off the one regulator, since an appliance that's marginal on gas supply is far more likely to show it when something else on the same line is also drawing.
Sizing by MJ load, not by guesswork
Every gas appliance is rated in megajoules per hour (MJ/hr) — check the appliance data plate or spec sheet. To size a regulator, add up the MJ/hr rating of every appliance that will run off it at once (not just what's installed — what could realistically be running simultaneously), then choose a regulator rated above that total, with headroom for anything you might add later. Our Dual Stage Gas Regulators range runs from 160MJ through to 790MJ, in both bare and bracket-and-pigtail-adaptor configurations, so there's a genuine range of headroom to size into rather than one-size-fits-most.
Manual vs automatic changeover
Where two cylinders feed the one regulator — the standard setup for anything that can't risk running dry mid-use, like a caravan or a continuously-fired commercial appliance — the changeover method matters as much as the MJ rating. A manual changeover regulator needs someone to physically switch to the second cylinder once the first runs empty; fine for a set-and-forget domestic BBQ line, less fine for anything unattended. An automatic changeover regulator switches to the standby cylinder itself the moment the duty cylinder empties, so supply doesn't drop out mid-use — worth the extra spend anywhere a gas interruption is actually a problem rather than an inconvenience.
Regulator only, or a complete dual-cylinder kit
If you're replacing a regulator on an existing dual-cylinder bracket, the standalone Dual Stage Gas Regulators range covers that — most models ship complete with bracket and pigtail hose, a couple bare or with an adaptor only, so check what's included before ordering. Setting up a dual-cylinder installation from scratch is usually cheaper and simpler as a complete kit: our LPG Dual Cylinder Installation Kits range bundles a matched regulator, mounting bracket and pigtail hoses in one SKU, from 160MJ to 500MJ, in both manual and automatic changeover.
Compliance note
LPG cylinder and regulator installations in Australia fall under AS/NZS 1596 (The storage and handling of LP Gas), which covers cylinder positioning, ventilation and regulator/pigtail specification for both domestic and commercial installs. It's worth checking your installation against AS/NZS 1596 — or having a licensed gasfitter sign off on it — particularly for commercial or multi-cylinder setups, since the standard's requirements go beyond just picking a correctly-sized regulator.
Frequently Asked Questions
How do I calculate the MJ load for a regulator?
Add the MJ/hr rating (from the data plate or spec sheet) of every appliance that could run at the same time off that regulator, then choose a regulator rated above that total, with some headroom for future additions.
Do I need automatic changeover, or is manual enough?
Manual changeover suits a domestic setup where running out mid-use is an inconvenience, not a real problem — you switch cylinders by hand when one empties. Automatic changeover switches to the standby cylinder itself the moment the duty cylinder runs dry, and is the safer choice for caravans, commercial kitchens or any appliance that can't tolerate a gas interruption.
What's the difference between a dual stage regulator and a dual cylinder kit?
A dual stage regulator is the regulator only — it drops pressure in two steps for more consistent output, and can be fitted to a single or dual cylinder setup depending on the model. A dual cylinder installation kit bundles that regulator with the bracket and pigtail hoses needed to mount it across two cylinders, as one complete SKU.
Does a bigger LPG cylinder solve a low-pressure problem?
No — cylinder size affects how long the gas lasts, not the pressure or flow rate delivered. A low-pressure or starving-appliance problem is a regulator sizing issue (the regulator's MJ rating is below the combined appliance load), not a cylinder capacity issue.