Patio Heater Covers Wholesale Supplier China — What Your First Factory Order Gets Wrong

Three winters ago, a customer in Hamburg called me about a container of 600 patio heater covers he couldn't sell. The fabric was fine. The PU coating held. But every single zipper on every single cover had seized up, frozen solid, and when his warehouse crew tried to force one open, the zipper teeth stripped straight off the tape.

The spec sheet said "zipper closure." The factory delivered zipper closures. What it didn't say was "#5 nylon coil zipper, cold-rated to -20°C." The factory had used a standard #3 polyester zipper that gets brittle below about -5°C. On a cover designed for a product that sits outside through a German winter. The entire container had to be reworked at the importer's cost. New zippers sewn in at a local alteration shop, before a single unit could ship to a retailer.

This is the patio heater cover procurement trap. Buyers think about denier, waterproofing, and whether the cover fits a standard mushroom heater. They stop there. The things that kill a heater cover order aren't the big specs everyone remembers to negotiate. They're the details nobody writes down until they've been burned once: zipper grade, ventilation design, heat resistance near the exhaust dome, and the flame retardancy spec that most factories won't mention unless you ask.

I've watched this from the factory side for over a dozen years. Here's what your spec sheet is missing.

The Heater Shape Problem No Import Guide Mentions

Gas patio heaters come in three basic shapes: mushroom (the classic round-top standing heater), pyramid (tapered square body, glass tube), and standing cylinder. A cover that fits a mushroom heater will drown a pyramid heater in excess fabric that flaps in the wind. A cover designed for a pyramid will never zip over a mushroom's dome.

Most Alibaba listings say "fits most standard patio heaters." That sentence alone should raise a flag. There is no standard patio heater shape. East Oak, Hampton Bay, Fire Sense, and Outsunny all use slightly different dome diameters and body profiles. A universal-fit cover that claims to fit all of them is a cover that fits none of them well. Too loose here, too tight there, and the excess fabric billows in wind until it tears at the seam.

If you're importing for a specific market, you need to decide early whether you're going with a generic universal-cut cover (which will have returns from customers whose heater doesn't match the cut) or a brand-specific fitted cover (which limits your addressable market but eliminates fit-related returns). The former costs less per unit. The latter costs less in returns. There's no free lunch, just a tradeoff you should make deliberately, not accidentally.

For the UK and Northern European market, where the mushroom-style standing heater dominates hospitality (pub gardens, restaurant terraces), the most common heater footprint is roughly 89cm dome diameter × 48-53cm base × 220-227cm height. If you're importing for that market, start with that footprint. For the North American market, pyramid heaters with glass tubes are more common in residential settings, with bases around 53×53cm and heights of 220-230cm.

What to write in your spec sheet: "Cover cut to fit [mushroom/pyramid/standing cylinder] heater with dome diameter [X]cm, base [X]×[X]cm, total heater height [X]cm. Hem tolerance ±2cm at all measurement points. If universal-fit: state target heater models tested."

Why 600D Oxford Alone Won't Save a Heater Cover

Every factory quote says "600D Oxford with PU coating." It's the default answer. The problem is that a patio heater cover faces something most outdoor covers don't: heat.

When you put a cover on a gas patio heater, especially within an hour or two of use, the residual heat from the burner head and the reflector dome can push the temperature inside the cover to 40-60°C. A standard PU coating formulated for rain and UV exposure starts to soften at around 60°C, and if it softens while pressed against the hot reflector dome, it can bond to the metal surface on contact. The next time someone pulls the cover off, it tears.

This isn't theoretical. I've seen it happen on a batch of 800 covers shipped to a distributor in southern Spain, where summer ambient temperatures already push 40°C before the heater even runs. The covers were technically fine. Correct denier, correct coating weight, passed the water spray test. They just weren't spec'd for the thermal load of sitting against a warm heater dome.

The fix is a heat-reflective inner lining at the dome contact area. Not the whole cover, just the top panel that sits against the burner head. A simple aluminum-coated polyester fabric (like the material used in ironing board covers) sewn as an inner patch at the dome area reflects radiant heat and keeps the PU outer shell 15-20°C cooler at the contact point. It adds about $0.40-0.60 per cover in material cost. On a 500-unit order, that's $200-300.

The alternative is your customers peeling melted fabric off their $300 patio heaters and sending both back.

What to write in your spec sheet: "Dome contact area: heat-reflective inner lining, aluminum-coated polyester, minimum 150×150mm patch sewn to inside of top panel. PU coating minimum softening point 80°C per ASTM D1525 (Vicat)."

The Zipper That Survives Winter and Summer

Back to those Hamburg zippers. A patio heater cover zipper has a harder life than almost any other cover zipper. It's exposed to freeze-thaw cycles in northern markets and heat-soak in southern ones. It gets yanked by customers who don't unzip carefully. And it sits on a vertical seam that bears the full weight of the cover when it's being pulled on and off.

Here's what actually holds up, ranked by how many seasons you get before failure:

Most factories default to #3 polyester because it's what they have on the shelf for general outdoor covers. You have to specify #5 nylon coil, and you have to specify the slider finish. A nylon coil zipper with a zinc-plated steel slider will function fine — but the slider will rust in about one season of rain, and a rusted slider binds just as badly as a frozen one.

The slider upgrade to nickel-plated or powder-coated steel costs about $0.10 per cover. On the Hamburg order of 600 units, that's $60 to prevent a repeat of the frozen-zipper container disaster. Sixty dollars.

What to write in your spec sheet: "Zipper: #5 nylon coil, full-length vertical closure. Slider: nickel-plated steel or 304 stainless. Zipper tape: polyester, UV-stabilized, minimum 25mm width. Cold-flex tested to -20°C minimum."

Ventilation: The Moisture Trap Nobody Designs For

Here's a physics problem most heater cover designs ignore: condensation.

A gas patio heater's burner assembly is mostly metal. After use, the metal is warm. You pull the cover over it. The residual heat warms the air trapped inside the cover. Warm air holds moisture. Then the temperature drops overnight. The moisture condenses on the inside of the cover and drips onto the heater. Over weeks, that trapped moisture cycle rusts the burner assembly, corrodes the gas fittings, and generates mildew inside the cover itself.

The fix is ventilation ports. Not big flapping holes, two or three mesh-covered vents positioned at the upper third of the cover, roughly where the dome meets the body tube. These allow moist air to escape without letting rain in. The vents should be covered with a fine polyester mesh (not metal screen, which rusts) and positioned under a small fabric hood that sheds water.

A well-designed ventilation system adds roughly $0.30-0.50 per cover in production cost and eliminates the most common cause of long-term heater damage reported by end users. It's the kind of feature that doesn't look impressive in a product photo but prevents warranty claims.

If your market is anywhere with humidity above 60% (which is most of Europe outside the Mediterranean summer, all of the UK, and the entire US East Coast), put ventilation in your spec.

What to write in your spec sheet: "Two mesh-covered ventilation ports, positioned at upper-third of cover body, minimum 50mm diameter each. Mesh: polyester, UV-stabilized, ≤1mm aperture. Rain hood: fabric overhang extending 30mm minimum below port opening."

The Flame Retardancy Spec Most Factories Won't Bring Up

This one matters more than most buyers realize. In the EU and UK, textile products sold as covers for gas appliances fall under general product safety regulations. There's no universal legal requirement for flame retardancy on heater covers. But there's a liability reality.

If a customer puts a cover on a heater that isn't fully cooled, and the cover catches fire near the burner head, your importer is holding the liability. Most factory-grade 600D Oxford with standard PU coating will burn. It's polyester. It melts and drips burning droplets. A flame-retardant treatment adds about $0.50-0.80 per cover and changes the burn behavior from "melts and drips" to "chars and self-extinguishes."

Ask your factory: "Does this fabric meet BS 5852 Crib 5 or California TB 117-2013 for flame retardancy?" If they don't know what those standards are, they haven't tested for flame retardancy. If they have, they'll send you the test report.

The treatment isn't permanent. FR-treated polyester typically holds its rating through about 20-30 wash cycles or roughly 3 years of rain exposure before the treatment leaches out. For a heater cover that sits in rain all winter, the effective FR window is about 2-3 seasons. After that, it's no more flame-resistant than untreated fabric. But those first 2-3 seasons are when the cover is newest, the customer is least experienced, and the "put the cover on while it's still warm" mistake is most likely to happen.

What to write in your spec sheet: "Fabric: FR-treated to BS 5852 Crib 5 or equivalent. Treatment penetration: through-thickness, not surface spray. FR test report required with pre-production sample."

What the Regional Spec Matrix Looks Like for Heater Covers

Same product category, different failure modes depending on where you ship:

This isn't a theoretical exercise. A cover spec'd for the UK will fail in Dubai within one summer. A cover built for the Gulf will be over-engineered and overpriced for the Irish market. The factory can build to any of these specs. They just need you to tell them which market you're selling into.

Why MOQ Sits Where It Sits for Heater Covers

I get this question routinely: "Why is MOQ 200-300 pieces for patio heater covers? Can we start with 50?"

The answer is cutting dies. Unlike furniture covers or grill covers that can be cut from rectangular panels on a straight-line cutter, a mushroom-style patio heater cover has a domed top panel that requires a shaped cutting die. That die costs about $150-300 to fabricate, depending on complexity, and it has to be amortized across the production run. At 50 units, the die cost alone adds $3-6 per cover. At 300 units, it's $0.50-1.00.

The pyramid-style cover has simpler geometry, mostly rectangular panels, so the MOQ can be lower. But most factories won't split a fabric coating run below about 150-200 covers' worth of material. Below that threshold, the per-unit cost climbs fast.

What you can negotiate: a 50-piece sample order at a 20-30% price premium, with the premium credited against your first full production PO. Most established factories will accept this structure. It lets you test fit, zipper quality, and heat-reflective panel performance before committing to volume. For more on factory negotiations, see our OEM vs ODM guide.

Sourcing patio heater covers from a Chinese factory isn't complicated. It's detail-oriented. The factories that build good covers aren't hiding anything. They're waiting for you to tell them: what heater shape, what zipper grade, whether you need a heat-reflective dome patch, whether the cover needs ventilation ports, and what flame retardancy standard your market expects.

Write those five things into your spec sheet. Get photos from the production line mid-run: zipper installation, dome panel stitching, ventilation port placement. The factory that sends them without hesitation is the one you want.

And if they tell you "our standard cover works for all heaters," find another factory.