Mr. Heater Buddy Troubleshooting

Which Buddy do you have?

The model number is printed in each manual, and the four models differ in ways that change the answer: the fresh-air opening the troubleshooting chart asks for, the rooms they may be used in, and whether a hose and filter are allowed at all. The rows below come from each manual's specifications table and troubleshooting chart.

These are the US editions. Mr. Heater publishes separate Massachusetts and Canada editions of the same heaters, and the Canadian Big Buddy manual (78433) carries "WARNING: For Outdoor Use Only." on its cover, so check which edition came with yours.

Troubleshooting charts by model

Each manual has a one-page troubleshooting chart with the same five symptoms, but the causes and remedies are not identical: the Little Buddy has fewer rows, the Big Buddy omits the regulator and contamination rows, and the FLEX adds "See Service Dealer." to every parts remedy. Each table is copied row by row from the manual, spelling included.

The Little Buddy's "No gas to heater" remedy is the one row that does not fit its own manual: it says to connect a hose to a remote cylinder, while the same manual's lighting instructions cover only "16.4 oz. (1 lb.) disposable cylinders" and name no hose. On a Little Buddy, no gas means the 1 lb. cylinder.

Every chart ends the same way: "For additional assistance or information, please call Technical services."

Why won't my Buddy heater pilot light?

Look at the spark first. If the electrode does not spark, the charts point at the electrode, the igniter wire or the piezo igniter, and every remedy there is a replacement part. If it sparks but the pilot will not catch, the charts list no gas, a knob not aligned at "PILOT" and a pilot blocked with debris.

The gas-supply row is the one an owner can settle: a fresh 1 lb. cylinder, or the valve open at the remote cylinder with the hose and filter the manual names. Mr. Heater's 2013 Little Buddy sheet puts the first check plainly: "Check propane tank for fuel by shaking or replace with a new full tank." Holding the knob matters as well; the Portable Buddy manual (p. 5) says: "If heater does not light, hold down for approximately 30 seconds; release and depress again. Repeat until pilot lights."

Why won't the pilot stay lit when I release the knob?

The charts list four causes: improper lighting, a pilot flame that does not surround the thermocouple, a defective pilot assembly and disconnected tip switch wires. The first is usually the answer. The knob has to be fully pressed in "PILOT" and held long enough, and after the pilot lights the Portable Buddy manual says to "hold down for 30 -60 seconds and then release knob."

The Little Buddy chart gives the reason for the wait: long enough "to purge air from lines and to heat up thermocouple once the pilot flame appears." On a hose-fed Big Buddy, the manual adds that lighting "may take longer to purge air from the supply hose depending on the length of the hose being used."

Mr. Heater's 2013 troubleshooting sheets split this symptom by how the flame dies, which none of the 2020 manuals do. When it goes out immediately on release, the first cause listed is "Control knob not depressed long enough", fixed by "After pilot is lit, keep control knob depressed for 30-60 seconds". When it goes out gradually, the sheets add "Inlet gas pressure too low" ("Check/replace gas cylinder supply" on the Big Buddy sheet) and "Defective regulator". Both sheets also list a loose thermocouple, a defective thermocouple, tip switch and control valve. Those are parts jobs, which the 2020 manuals reserve for a qualified service agency.

Why does my Buddy shut off after a few minutes?

Usually because it is short of fresh air, which is what the shut-off is for. Every manual's warning page says: "This heater is equipped with a SAFETY SYSTEM designed to turn off the heater if not enough fresh air is available." The charts' fresh-air remedy is a minimum opening of 4, 9, 18 or 11 square inches, depending on the model.

The same warning tells you what not to do: "WARNING: DO NOT TAMPER WITH THE SAFETY SYSTEM! If heater shuts off, do not relight until you provide fresh air. If heater keeps shutting off, have the heater serviced. Keep burner and control compartment clean." (MH9BX p. 2; the same box is on p. 2 of the MH4B, MH18B and MH11BFLEX manuals.)

The manuals name four other reasons for a shut-off in use, and only two of them are owner steps:

• A blocked pilot: "Clean pilot. See MAINTENANCE section."
• The tip-over switch after a bump: "Re-light."
• A defective regulator, or internal contamination (MH9BX and MH11BFLEX charts): a regulator, or a control valve and regulator, which are replacement parts.
• Wind outdoors: the MH9BX and MH11BFLEX manuals (p. 4) say "The heater is to be used outdoors, but may experience nuisance shutoffs due to certain wind conditions."; the MH4B (p. 3) says it "can be used outdoors" with the same caution.

The 2013 sheets add one more cause under "Heater shuts off during operation": "Inlet gas pressure is too low". On the Big Buddy they also add "Oil contamination due to improper shutdown", whose remedy includes "Replace control valve & regulator." and "See owner's manual for proper shutdown when using remote tank."

Tip-over switch

Every Buddy here has one, and it shuts the heater off by design. The general safety section of each manual says: "THIS HEATER IS EQUIPPED WITH A TIP OVER SWITCH THAT WILL SHUT THE HEATER OFF IF THE HEATER TIPS OVER HOWEVER, DO NOT LEAVE HEATER UNATTENDED OR WHERE CHILDREN MAY CAUSE THE HEATER TO TIP OVER. NEVER OPERATE THE HEATER WHILE SLEEPING!"

A bump is enough to trip it. The MH9BX, MH18B and MH11BFLEX manuals put it this way: "When moving heater when lit or bumping heater setting it down, the tip over switch may shut off heater. If this happens, re-light." The Little Buddy manual (p. 3): "Nuisance shut-downs may be experienced if the unit is bumped or moved. if this occurs simply relight the heater." Set it on level ground first; each manual asks you to "make sure the ground is level and keep any objects at least 24 inches from the front of the heater."

High altitude

Above 7,000 feet a Buddy may burn dimmer and shut itself off, and the Little Buddy, Portable Buddy and Big Buddy manuals all say so in the same bold paragraph: "When operating the heater at altitudes over 7,000 FT. above sea level, the unit may not burn as bright as in lower altitudes. This is normal. At higher altitudes, the heater may shut-off. If this happens, provide fresh air, wait 5 minutes and re-light. Due to local atmospheric conditions heater may not relight." (MH9BX p. 5; MH4B p. 3; MH18B p. 4.)

The warning pages carry the short form as a caution: "When operating the heater at altitudes over 7,000 FT above sea level the heater may shut off." The Buddy FLEX manual (78541) has no altitude statement in its English section, so this page does not state one for the FLEX.

Cold weather and propane cylinders

The manuals do not give a cut-off temperature for every model, but they do warn that cold shortens run time. The Portable Buddy manual (p. 5): "Due to the properties of LP gas, runtimes can be significantly reduced when operating continuously at temperatures below 20ºF. Use of a 20 lb. tank is recommended in these conditions." The Big Buddy (p. 4) and FLEX (p. 5) manuals say the same; the Little Buddy (p. 3) has the first sentence only. The MH9BX and MH11BFLEX specification tables list a "Minimum Ambient Temperature" of "-18˚C/ 0˚F".

Frost on a small cylinder is expected. The Little Buddy manual: "Due to natural operation of small tanks, condensation may build up on tank and drip on surface under heater. Sometimes this condensation may freeze due to the extreme cold caused when propane vaporizes. This is normal and no reason for alarm."

A larger tank brings a hose, and the hose brings the filter. The MH9BX, MH18B and MH11BFLEX manuals allow a remote cylinder of up to 20 lbs only "when the cylinder is located outdoors and the Heater is used with Mr. Heater Hose No. F273701, F273702 or F272702 and fuel filter F273699. Fuel filter must be replaced annually. (NOTE: Do not operate without the fuel filter as fuel contamination may damage the heater.) Or use F273704 Buddy series hose. Fuel filter not required." And: "Mr. Heater strongly recommends using disposable fuel filter F273699 to trap any oil substances when connected to a remote cylinder that can make heater inoperable."

Shutting down on a hose has its own order (MH9BX p. 6): "To shut off heater, shut off propane at supply tank, allow heater to use-up propane in supply line until heater shuts off, then slightly push down and turn Control Knob clockwise to "OFF" position."

Where Mr. Heater says a Buddy can be used

All four manuals give the approved use in one paragraph, quoted here from the MH9BX (p. 4; the MH18B and MH11BFLEX p. 4 and the MH4B p. 3 carry the same paragraph): "This heater is safe for indoor use in small recreational enclosures having means for providing combustion air and ventilation, such as enclosed porches, cabins, fishing huts, trailers, tent trailers, tents, truck caps and vans. It may be used for emergency indoor heating when connected to a disposable 1 lb. propane cylinder."

The limits that go with it, each verbatim:

The Big Buddy manual (p. 5) defines emergency use when running on two 1 lb. cylinders: "a. The permanent heating system is temporarily out of service. b. Heat is necessary to prevent damage to the buildings or contents. c. The temporary heating equipment is not left unattended. d. This heater requires a vent area of 18 square inches (example 4.25" x 4.25" opening) minimum for adequate ventilation during operation. Do not use other fuel burning appliances inside. e. The portable heater used shall be discontinued and removed from the building at the time the permanently installed appliances are placed back in operation."

Mr. Heater's carbon monoxide and fire warnings

These warnings come first in each manual, on the page before any instructions, and they apply before you relight a heater that shut itself off. A Buddy is an unvented heater that takes its combustion air from the room, so a heater shutting off for lack of air is also a carbon monoxide question.

Cleaning the pilot, as the manuals describe it

Several chart remedies say "Clean pilot. See MAINTENANCE section." The manuals describe what a healthy pilot looks like: "The pilot flame should be blue in color (not yellow) and will extend to the thermocouple. The flame will surround the thermocouple just below the tip." (MH9BX p. 7.) "If the pilot is yellow or the burner has a noticeable flame, cleaning may be required."

The Big Buddy procedure (p. 8) starts with the heater cool and the gas off, then removes the wire guard, rear cover and lower baffle before you "Inspect and clean pilot (mounted to bracket) by using a vacuum or apply air pressure through the holes in the pilot". The Little Buddy (p. 5) uses "a doubled over pipe cleaner" in the pilot tube instead. Every manual carries the same warning: "Never use needles, wires or similar cylindrical objects to clean the pilot to avoid damaging the calibrated ruby that controls the gas flow through the pilot orifice." If you would rather not open the case, that is a service-agency job.

Parts and consumables

The parts warning on the last page of the MH9BX, MH18B and MH11BFLEX manuals reads in full: "USE ONLY MANUFACTURER'S REPLACEMENT PARTS. USE OF ANY OTHER PARTS COULD CAUSE INJURY OR DEATH. REPLACEMENT PARTS ARE ONLY AVAILABLE DIRECT FROM THE FACTORY AND MUST BE INSTALLED BY A QUALIFIED SERVICE AGENCY. MR. HEATER HOSES F273701, F273702 AND F272702 ARE SPECIFICALLY DESIGNED FOR USE WITH THIS HEATER ALONG WITH F273699 DISPOSABLE FUEL FILTER (REPLACE ANNUALLY). USE OF OTHER HOSES MAY CAUSE THE HEATER TO BECOME INOPERABLE." The Little Buddy's version (p. 8) stops after "QUALIFIED SERVICE AGENCY." and names no hose. The parts-list pages of the 2020 manuals are missing from the files Mr. Heater published, so this page lists no internal part numbers.

The links below are only for the hoses and filter the manuals tell owners to use, so check your model's row above before buying.

When to stop and contact Mr. Heater

Related pages

An electric space heater that keeps shutting itself off is a different problem with different protections: see space heater keeps shutting off. For a Lasko heater that will not power on, see Lasko heater won't turn on.