Ashley Hearth 11,000 BTU Direct-Vent Propane Heater Review

The only propane arrangement that belongs in a sealed structure, and the install is most of the job.

Best Off-Grid Heat

Ashley Hearth Direct Vent Liquid Propane Wall Heater, 11,000 BTU

~$450

A sealed-combustion wall heater that draws combustion air from outside and exhausts outside, with a safety pilot, a built-in pressure regulator and piezo ignition.

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Specifications

Output	11,000 BTU
Fuel	Liquid propane only
Combustion	Direct vent, sealed burn system
Coverage	Manufacturer states up to 375 sq ft
Safety	Safety pilot with built-in pressure regulator, stops gas flow if the pilot goes out
Burner	Stainless steel ported burner, silent operation
Ignition	Matchless piezo
Kit contents	Heat shield, air intake pipe, connecting rod
Dimensions	17.36 x 6.61 x 20.00 in

Specifications above come from Ashley Hearth's published feature list for this model. Treat pricing as approximate, since Amazon pricing moves.

What it does well

Sealed combustion is the whole point. A direct-vent unit takes its air from outside and puts its exhaust outside, so nothing from the burner enters the space the plants and you are in.
A safety pilot with an integral pressure regulator shuts the gas off if the pilot is extinguished, which is the failure mode that makes unvented propane a bad idea in a closed structure.
No electricity required for the heat itself, which is the single reason to consider propane at all when the greenhouse has no mains supply.
A stainless ported burner running silently matters more in a greenhouse than in a living room, because there is nothing to absorb noise and you will be working next to it.
11,000 BTU is a sensible size for a domestic greenhouse. Oversizing a heater makes temperature control worse, not better, because it short-cycles.

Where it falls short

The manufacturer sells this as a room heater for homes and mobile homes, not as a greenhouse heater. Nothing in its documentation addresses the humidity, splash and corrosion of a growing space, and that gap is yours to close.
It must be installed through an exterior wall with correct clearances and vent termination, and gas work is not a DIY job. Have it installed and commissioned by a qualified gas fitter and confirm your local code permits it in an accessory structure.
It has no built-in thermostat suited to greenhouse setpoints, so you are adding an external controller if you want it holding a minimum overnight temperature rather than running on a dial.
Propane costs money per hour in a way that a thermostatically cycled electric unit does not, and there is no easy way to meter it. Budget by tank rather than by kilowatt hour.
A wall-mounted unit sized 17 by 20 in takes real estate off a 6 by 8 wall, and the clearances around it take more. On a small house that is bench space you are giving up.

What owners report

Owner reports on direct-vent propane wall heaters are broadly positive about the appliance and consistently unhappy about the install, and that is the right way round to read them. The heater is a straightforward, quiet, reliable sealed-combustion unit. The install involves cutting an exterior wall, setting a vent terminal with correct clearances, running gas line and commissioning it. Every one of those is a step where amateur work goes wrong, and gas is the one category on this site where we will not encourage a self-build. Use a qualified gas fitter and check local code, particularly if your greenhouse is a permitted accessory structure.

The second theme is the choice of fuel itself, and it is worth revisiting before you spend. Propane wins on exactly one axis: no mains power at the greenhouse. If a 120 V circuit exists or can be run safely, a thermostatically controlled electric unit is cheaper to buy, needs no flue and cannot produce combustion products at all. Our electric versus propane greenhouse heater comparison works through the running cost arithmetic, and the greenhouse electrical and safety guide covers what a supply to an outbuilding involves.

Third, sizing. 11,000 BTU sounds small next to household heaters and is a reasonable figure for a domestic greenhouse, but it is a figure you should check rather than assume. Put your own glazing type, footprint, target minimum and local design temperature through the greenhouse heater BTU calculator. If the answer comes back well under 11,000, an electric unit like the one in our Bio Green Palma review is the simpler purchase.

Who it suits

Growers whose greenhouse has no mains power and no safe route to get any.
Anyone heating a larger or leakier structure than a 1500 W electric unit can hold.
People who will pay a qualified gas fitter to install and commission it properly.

Who should skip it

Anyone with a 120 V circuit at the greenhouse. Electric is cheaper, simpler and thermostatically controlled out of the box.
Anyone considering an unvented propane heater instead. Do not: unvented combustion in a sealed structure puts water and combustion products into the air you and the crop share.
Growers who want to install it themselves. Gas work belongs to a qualified fitter.

Alternatives worth considering

Electric Step-Up

Bio Green Phoenix 2.8 kW 240 V Greenhouse Heater, 9,553 BTU

~$290

9,553 BTU on a 240 V circuit with a stepless thermostat and a stainless body built for a damp greenhouse. Similar output for less money, with no flue and no gas fitter, if you have or can get the circuit.

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Simplest Alternative

Bio Green Palma 1500 W Greenhouse Heater with Digital Thermostat

~$161

5,100 BTU on a standard 120 V outlet with IPX4 splash protection and a digital thermostat. For houses to roughly 120 sq ft it is usually enough, and it plugs in.

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Bench-Warming Alternative

Dr. Infrared Heater DR218 1500 W Infrared Heater with BioGreen Thermo 2 Thermostat

~$178

Infrared warms surfaces and soil rather than air, which suits a bench of seedlings, and the bundled external thermostat controls it properly. A different heating strategy rather than a smaller version of the same one.

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Keep reading

This review draws on published specifications, manufacturer figures and the consensus of verified owner reviews. We have not tested this product ourselves, and we say so rather than implying otherwise. As an Amazon Associate we earn from qualifying purchases.

Common questions

5 answers

+ Can you use a propane heater in a greenhouse?

Only a direct-vent or otherwise sealed-combustion unit, installed and commissioned by a qualified gas fitter to local code. Unvented propane burners put water vapour and combustion products directly into the air, which in a closed humid structure is bad for you and encourages fungal disease on the crop. If in any doubt, use electric.

+ Electric or propane for a greenhouse heater?

Electric whenever a safe mains circuit is available: cheaper to buy, thermostatically controlled out of the box, no flue, no combustion. Propane when there is no power at the greenhouse and no safe way to run any. Our electric versus propane comparison covers the running costs, which vary far too much by region for a single answer.

+ Is 11,000 BTU enough for my greenhouse?

It depends on glazing, footprint, how leaky the structure is, your target minimum temperature and your local design low. For many domestic greenhouses it is generous. Put your own numbers into the greenhouse heater BTU calculator before buying, because oversizing makes control worse through short cycling rather than better.

+ Does it need a thermostat?

For greenhouse use, effectively yes. The unit is designed for room heating rather than for holding a minimum crop temperature overnight, so plan on an external greenhouse thermostat that switches it at a setpoint. Our heater thermostat versus external controller comparison covers what to look for.

+ Will it make the greenhouse humid?

Not directly, because sealed combustion sends its water vapour outside with the exhaust. That is the main horticultural argument for direct vent over unvented propane. Any heater will still change relative humidity by changing air temperature, so pair heating with air movement to keep condensation off the leaves.

Working out the figures for your own house and season? The Greenhouse Build & Growing Planner is the paid version of these pages: 8 printable worksheets you fill in with your own numbers, plus the full PDF, $29.

How this page was researched

Everything here is researched general information for growing vegetables, herbs, fruit and flowers, not professional horticultural, structural or electrical advice. Figures come from published manufacturer specifications, published horticultural references and verified owner reviews. We do not claim hands-on testing of the equipment described. Temperature, light and heating requirements vary by climate, crop and structure, so treat every number here as a starting point to check against your own conditions. Follow the label on any product you apply to an edible crop, follow local code for electrical and gas work, and consult a qualified professional for anything structural.