What Size Gas Bottle for Patio Heater: Tank Size Guide

For most full-size freestanding patio heaters running at 40,000 to 50,000 BTU/hr, a 20 lb (roughly 9 kg) propane cylinder is the standard go-to. For example, a 40,000 BTU/hr patio heater is estimated to use about 0.44 gallons of propane per hour, and a 20-lb tank typically provides roughly 8 to 10 hours at max output 40,000 BTU/hr patio heater consumes propane at about 0.44 gallons per hour. It gives you around 8 to 10 hours of runtime at max output, which covers a long evening with room to spare. On a 48,000 BTU/hr patio heater, runtime depends on your propane cylinder size, typically giving around 8 to 10 hours at maximum output for a 20 lb cylinder 48,000 BTU patio heater how long does it last. If you want a direct answer for your situation, the key factor is how many hours your propane (or LPG) cylinder will last at your heater's BTU rating how long do patio heaters burn. If you want to run the heater across a full weekend without swapping bottles, step up to a 33 lb (15 kg) or 47 lb (20 kg) cylinder. Smaller tabletop or infrared heaters rated at 10,000 to 15,000 BTU/hr can get by with a 1 lb disposable canister for casual use, but a refillable 11 lb (5 kg) bottle is a much better deal for regular use.

Find your patio heater's fuel and BTU requirements

Before buying any cylinder, find out exactly what your heater needs. Flip the heater over or look for a metal rating plate near the base or burner head. It will list the BTU/hr output, the fuel type (propane/LPG or natural gas), and usually the required gas pressure in inches of water column (WC) or millibar. This is not optional reading. Using the wrong fuel type or pressure will either damage the heater or simply mean it won't light at all.

If you can't find the plate, pull up the owner's manual. Most manuals are available as PDFs from the manufacturer's website. Search for your model number plus 'owner's manual PDF' and you'll usually find it within a minute. The manual will also tell you the regulator pressure the heater is designed for, which matters when you're checking compatibility later.

One important note: propane and natural gas are not interchangeable. Propane heaters use a cylinder with a regulator. Natural gas heaters connect to a fixed gas line. If your heater is rated for natural gas, a propane bottle is not a solution. This guide focuses on propane/LPG cylinder-fed heaters.

Choose cylinder size by expected runtime

Here's the simple math behind runtime: take the energy content of propane (roughly 91,452 BTU per gallon, or about 21,548 BTU per pound) and divide by your heater's BTU/hr rating. That tells you how many hours the fuel will last at full blast. Knowing the runtime for your specific model also tells you how long does patio heater propane tank last between refills. A 20 lb cylinder holds roughly 4.7 gallons of propane, which works out to about 430,000 BTU total. Run a 40,000 BTU/hr heater off that and you get around 10 to 11 hours of runtime. Real-world conditions like cold weather, wind, and partial throttle settings will shift that number, but it's a solid planning figure.

For a typical 3 to 4 hour evening on the patio, even an 11 lb cylinder is technically enough for most heaters. But the 20 lb cylinder is the sweet spot for homeowners because the price-per-BTU is better when you refill rather than exchange, and you won't be caught short if guests stay late. If you're hosting an all-night event or want to run the heater across multiple days without thinking about it, go straight to the 33 lb or 47 lb option. Just make sure your heater's base can accommodate the larger cylinder safely without tipping.

Worth knowing: propane efficiency drops noticeably below 40°F (5°C). If you're heating a patio in cold weather, budget for shorter runtimes than the table suggests, or start with a fuller cylinder than you think you need.

Check compatibility: regulator, hose/connection, and pressure

Tank size is only half the equation. The cylinder, regulator, and hose all have to be matched correctly or the heater won't work and could be dangerous. Most standard propane patio heaters in North America use a Type 1 (QCC1/Acme) valve connection, which is the same thread you find on a standard 20 lb barbecue cylinder. If your heater shipped with a regulator and hose, it almost certainly fits that standard cylinder.

In the UK and Europe, the connection standard is different. Most LPG patio heaters there use a clip-on or screw-in regulator that matches butane or propane cylinders from suppliers like Calor or Flogas. A 13 kg propane cylinder is the common choice for outdoor heaters in that market. If you’re using a 13 kg propane cylinder on a typical patio heater, the runtime will depend on the heater’s BTU output and whether you run it at full blast. Do not assume a regulator from one region will fit a cylinder from another. Forcing mismatched fittings is how leaks happen.

The regulator itself controls output pressure, typically stepping the high-pressure cylinder gas down to around 11 inches WC (roughly 27 mbar) for most propane patio heaters. Your manual's spec sheet will confirm the required pressure. If you're using a replacement or third-party regulator, verify the output pressure matches what the heater requires. Using the wrong regulator is explicitly warned against in most manufacturer manuals, and for good reason. A low-flow regulator will starve the burner; an over-pressure setup can damage valves.

• Check the cylinder valve type: Type 1 (QCC1/Acme) for most North American setups, POL for older tanks
• Verify the regulator output pressure matches your heater's rated inlet pressure (check the spec label)
• Inspect the hose for cracks, abrasion, kinking, or stiffness before every season
• Replace any hose that shows visible wear before connecting a new cylinder
• Never use adapters to force a mismatched fitting — get the correct regulator for your cylinder type

Safe hookup and leak-check steps outdoors

Every time you connect a new cylinder, you need to run a leak check. No exceptions. This takes about two minutes and it's the single most important safety step you'll do. If you see bubbles on any connection while doing a leak check, that can indicate a leak, so straighten the hose and repeat the test Home Depot operator manual. Do it outdoors, away from anything ignition-related.

1. Set the heater and cylinder outdoors on a stable, level surface before connecting anything
2. Thread the regulator onto the cylinder valve hand-tight, then snug it with a wrench if required by your regulator type (Type 1 connections tighten clockwise)
3. Make sure the heater's control knob is in the OFF position
4. Mix a leak-check solution: 1 part dish soap to 3 parts water
5. Slowly open the cylinder valve one full turn
6. Apply the soapy solution generously to every connection: regulator-to-cylinder, hose-to-regulator, and hose-to-heater valve
7. Watch for growing bubbles for at least 30 seconds at each joint
8. If you see bubbles, close the cylinder valve immediately, tighten the connection, and retest
9. If bubbles persist after retightening, disconnect the regulator and do not use the heater until the connection or hose is replaced
10. If no bubbles appear at any connection, the connections are secure and you're safe to light

A few non-negotiables: never use a flame to check for leaks. Never operate the heater indoors, in a garage, or under a canopy without proper open-air clearance. Most manufacturer manuals specify a minimum clearance of 24 inches (61 cm) above the heater to combustibles. Keep the cylinder upright at all times during use and storage. When the heater is not in use, close the cylinder valve first, let the heater burn off the residual gas in the line, then turn the control knob to off.

What to do if the heater won't ignite or won't stay lit after changing the bottle

Swapping to a fresh cylinder and still getting nothing is frustrating, but it's almost always one of a handful of fixable issues. Work through these in order before assuming the heater is done.

If it won't ignite at all

• Confirm the cylinder valve is open and the regulator is fully seated — a partially connected regulator may not flow gas
• Check whether the igniter is sparking: hold the control knob in, press the igniter, and listen/look for a click and spark near the pilot. If there's no spark, try lighting the pilot manually with a long match or lighter while holding the knob in, then replace the igniter electrode
• Low gas pressure from a nearly empty or very cold cylinder can prevent ignition — try a different cylinder to rule this out
• Check the orifice and pilot tube for blockage; spider webs and debris are common after the heater has sat unused. A can of compressed air often clears it
• Make sure the tilt switch (usually located in the base) hasn't tripped. Some heaters have a safety cutoff that activates if the unit isn't perfectly level. Slightly adjusting the heater position can reset it

If it lights but won't stay lit

• The most common cause is a thermocouple that isn't sensing the flame correctly. Hold the control knob in for a full 30 to 45 seconds after lighting to give the thermocouple time to heat up. If the flame dies the moment you release the knob, the thermocouple is likely faulty and needs replacing
• Check the thermocouple tip position — it should be sitting directly in the pilot flame. If it's bent away from the flame, carefully reposition it
• A dirty pilot area can produce a weak flame that doesn't heat the thermocouple enough to hold the valve open. Clean around the pilot with compressed air
• Loose connection between the gas valve and pilot assembly: tighten and re-do the leak check
• If the heater went out mid-session: wait at least 5 minutes before relighting to clear any gas buildup, then retry from the beginning of the lighting sequence

If you've worked through all of the above and the heater still won't stay lit, and you're not comfortable replacing the thermocouple or gas valve yourself, that's the point to stop DIY and contact the manufacturer or a certified gas appliance technician. A heater that repeatedly fails to hold a flame despite a working thermocouple may have an internal valve problem that isn't safe to DIY.

Maintenance tips to keep propane heaters running reliably

A little attention before and after the season pays off. Most call-outs for 'heater not working' are caused by issues that five minutes of seasonal maintenance would have prevented.

• At the start of each season, inspect the hose and regulator for cracking, stiffness, UV damage, or corrosion. Replace the hose assembly if there's any visible wear — they're inexpensive and the risk of a gas leak is not worth saving a few dollars
• Clean the burner head and pilot area with compressed air before first use each year. Insects and debris love to nest in burner tubes over winter
• Run a full leak test every time you connect a new or refilled cylinder, not just the first time
• After the heater is lit and running, do a visual flame check: a healthy propane flame should be mostly blue with small orange tips. A large, wavering orange flame often indicates a blocked orifice or incorrect air-to-gas mixture
• Store the cylinder upright in a ventilated outdoor space, away from heat sources and direct sunlight. Never store a connected cylinder indoors
• Check the electrode gap on the igniter once a year. A wide or carbon-fouled gap won't spark reliably. Clean with fine sandpaper and check the gap matches your manual's spec
• If your heater has a tilt switch, test it by gently rocking the base and confirming the flame extinguishes. If it doesn't cut out, the tilt switch needs attention before you use the heater again

Propane patio heaters are genuinely repairable appliances. The igniter, thermocouple, hose, and regulator are all parts you can source and swap yourself with basic tools. If you keep on top of the connection checks and seasonal cleaning, a well-made heater should give you many years of reliable service.