Commercial Dryers for Laundromats: Models, Error Codes and Maintenance by Brand

Dryers are half of your floor, most of your gas bill, and the machines customers judge hardest: the load either came out dry or it didn't. This guide covers Speed Queen, Huebsch, Dexter, ADC and Electrolux dryers at the level you need to buy them, size the bank, read the display and keep them heating. Each section points to a deeper post on that one question.

Who Makes What

Speed Queen and Huebsch are both Alliance Laundry Systems brands, and their tumble dryers are the same hardware with a different badge. A Huebsch HTT30 and a Speed Queen STT30 both list a 22.6-inch door opening and 73,000 Btu/hr per pocket on their spec sheets. If you run the Huebsch side of the family, the Huebsch washer and dryer guide covers the Galaxy controls and warranty terms that differ.

ADC (American Dryer Corp) is the third name you'll see on older dryer rows, and its installation and service manuals now live on Alliance's parts site. Dexter sells its T-series dryers only through distributors and publishes no prices; the Dexter T-series guide covers the washers that usually sit across from them. Electrolux Professional and Wascomat dryers come through Laundrylux in North America. Maytag Commercial is a Whirlpool brand, not an Alliance one, and Continental Girbau sells its ED-series dryers into the same stores.

Reading the Model Number

Every brand encodes pocket count and capacity in the model number, but each uses its own pattern. Once you can read it, a used listing or a parts diagram tells you what you're looking at.

Brand	Single pocket	Stack	What the number means
Speed Queen	ST030, ST055, ST075, STS30	STT30, STT45, STT55	Digits are pounds per pocket; the second T means stacked
Huebsch	HT030, HT035, HT050, HT055, HT075	HTT30, HTT45	Same pattern as Speed Queen with an H prefix
Dexter	T-30, T-50, T-80	T-30X2, T-50X2	Pounds per pocket; X2 means two pockets
ADC	AD-30V, AD-50V, AD-78	AD-30x2, AD-236, AD-330	Pounds per pocket on V and x2 models; the 75 lb single is the AD-78, not "AD-75"
Electrolux	T5290, T5550, T5675	T5300S, T5425S	Digits are drum litres (T5290 = 290 L), not pounds; S marks the stack

The Speed Queen 2025 sheet adds a wrinkle: the STS30 is a 30 lb single with a 30-inch cylinder, while the older ST030 used a 26.5-inch cylinder. The full breakdown of prefixes, suffixes and what changed between sheet years is in the dryer model-number decoder.

Capacity and Door Opening by Model

Capacity is what you sell. Door opening decides whether a customer can pull a comforter out without a fight, and it's the dimension that sizes any label on the door. Both numbers come straight from the manufacturer spec sheets.

Model	Capacity	Door opening	Heat input (gas)	Airflow
Speed Queen STT30	30 lb × 2	22.6 in	73,000 × 2 Btu/hr	2 × 400 cfm
Speed Queen STT45	45 lb × 2	26.9 in	95,000 × 2 Btu/hr	2 × 600 cfm
Speed Queen STT55	55 lb × 2	26.9 in	105,000 × 2 Btu/hr	2 × 600 cfm
Speed Queen ST075	75 lb	26.9 in	150,000 Btu/hr	800 cfm
Speed Queen ST055	55 lb	26.9 in	112,000 Btu/hr	700 cfm
Huebsch HTT30	30 lb × 2	22.6 in	73,000 × 2 Btu/hr	—
Huebsch HTT45	45 lb × 2	26.9 in	95,000 × 2 Btu/hr	—
Dexter T-30X2	30 lb × 2	22 5/8 in	90,000 Btu/hr per tumbler	600 cfm
Dexter T-50X2	50 lb × 2	25 5/8 in	108,000 Btu/hr per tumbler	650 cfm
Dexter T-50	50 lb	25 5/8 in	145,000 Btu/hr	910 cfm
Dexter T-80	80 lb	25 5/8 in	—	—
ADC AD-30x2	30 lb × 2	21 1/2 in	—	—
ADC AD-50V	50 lb	—	150,000 Btu/hr	750 cfm
Electrolux T5300S	35 lb × 2	22 13/16 in	—	—
Electrolux T5425S	50 lb × 2	27 1/16 in	—	—

Two things stand out. A 30 lb pocket has a 22 to 23-inch door across every brand, and a 45 to 55 lb pocket has a 26 to 27-inch door. Door size tracks capacity more than badge. And Dexter puts the same 25 5/8-inch door on its 50 lb stack and its 80 lb single.

Whether a stack or two singles earns more per square foot is the question the Speed Queen ST030 vs ST055 vs STT30 vs STT45 comparison works through with the Alliance sheets. The Dexter T-30 vs T-50 vs T-80 comparison does the same for the T-series, including when a T-50X2 beats two singles.

How Many Dryers You Need

Distributor guidance from Unity and Coin-O-Matic puts the ratio at 1.1 to 1.5 dryer pockets per washer pocket, or roughly 1.25 pockets per washer as a planning figure. A 20-washer store lands at 22 to 30 dryer pockets, which is 11 to 15 stacks. The ratio drops as extraction speed rises: National Laundry Equipment notes that high-extraction washers can carry a store at four washers to three dryers, because the load arrives with less water in it.

Match pocket size to washer size, not just pocket count. A 60 lb washer load split across two 30 lb pockets ties up two machines and two customers' patience. Sizing a laundromat dryer bank runs the math with the capacities above and shows where the ratio moves when you add 200 G washers.

Error Codes by Brand

Most dryer faults on the display come down to three parts: the temperature sensor, the airflow switch and the ignition chain. The codes below are printed exactly as the manuals show them. The Speed Queen and Huebsch pair comes from Alliance troubleshooting manual 70398301; Dexter from the C-series and T-50X2 fault-code sheets; ADC from the AD-50V Phase 7 installation manual.

Brand and control	Display	Meaning	First check
Speed Queen / Huebsch electronic control	OP	Open temperature sensor; shows if the sensor reads under 24 °F or the circuit is open	Replace sensor if the tumbler is above 24 °F
Speed Queen / Huebsch electronic control	SH	Shorted temperature sensor, or sensor over 191 °F	Let the tumbler cool, press ON/SELECT; replace sensor if SH returns
Speed Queen / Huebsch (Quantum)	door	Door open	Close door; check door switch wiring
Speed Queen / Huebsch (Quantum)	Alrm / OFF	Break-in alarm	Service door and coin vault switches
Speed Queen / Huebsch (Quantum)	EC:19, EC:20, EC:31	Card reader: no communication, unreadable card, hotlisted card	Power cycle, clean contacts; EC:31 destroys the card by design
Dexter C-series	TEMP SENSOR SHORT (F1)	Shorted sensor or wire	Won't start until the short is cleared
Dexter C-series	TEMP SENSOR OPEN (F2)	Open sensor or wire	Same
Dexter C-series	PCB ERROR1 (F3)	Memory corrupted	Power down and reset; replace control if it stays
Dexter C-series	COMM ERROR2	No dryer model selected	Check the Jumpers connector on the control board
Dexter C-series	COMM ERROR7	DexterLive bus error	Disconnect the DexterLive cable, soft restart
Dexter T-50X2 (4-digit display)	F1 / F2	Shorted / open sensor or harness	Sensor and harness
Dexter T-50X2 (4-digit display)	F3	Possible grounding problem	Power down, repower, press program button
Dexter T-50X2 (4-digit display)	F4 / F5	Controller chip problem	F5: remove power one minute; F4: replace controller
ADC Phase 7 coin	SAIL SWITCH CLOSED	Sail switch closed before starting	Switch stuck or misadjusted
ADC Phase 7 coin	SAIL SWITCH OPEN	Sail switch failed to close after starting	Airflow: lint screen, duct, make-up air
ADC Phase 7 coin	BURNER HI-LIMIT / EXHAUST HI-LIMIT	Oven or tumbler thermostat has opened	Overheat; check airflow before resetting
ADC Phase 7 coin	IGNITION FAULT / FLAME FAULT	No flame through all retries / flame lit then failed	Gas supply, electrode, valve, DSI module
ADC Phase 7 coin	CLEAN LINT	Lint not cleaned out	Clean the lint drawer

On an ADC Phase 7 the display just says "Out of Order"; you press LO to see which cause tripped it. Dexter's older stack dryers use F-numbers and the C-series shows text, so identify the control before you read a chart. ADC's full Phase 7 fault list, including the sail-switch faults that shut down most older stores, gets its own walkthrough in the ADC dryer error code explainer.

OP and SH mean the same thing on Speed Queen washers, and the washer side of the store has its own list in the commercial washer troubleshooting guide. Electrolux and Wascomat dryers on Compass Pro show plain-text alarms rather than short codes. The dryer-side list isn't in a manual I could verify, and the numbered codes quoted on Q&A sites for Wascomat dryers are unconfirmed, so pull the Laundrylux manual for your model.

When a Dryer Runs but Won't Heat

A gas dryer that tumbles with no heat is the most common ticket on a dryer row, and every brand's manual walks the same ladder. Dexter's T-50X2 sheet spells it out. If the tumbler turns but there's no spark, check the glass control fuse, then the temperature sensor, which should read 30,000 to 60,000 ohms at room temperature. Then check for 24 VAC from the transformer, the red-button over-temperature thermostat, the ignition control, the airflow switch, and the hi-limit, which should read 0 ohms cold.

If it sparks but no flame lights, the list shortens: gas supply, gas pressure at a manometer, the spark electrode, gas valve coil continuity, and 24 VAC from the ignition control to the coils. Alliance's manual adds the detail that explains most "runs cold" calls: if the airflow switch opens during the cycle, the heating system shuts off but the cylinder and fan keep running. The customer sees a working dryer; the machine sees no airflow.

Gas and electrical work beyond checking a fuse or a reset button belongs to a technician. The igniter vs gas valve vs airflow switch vs hi-limit guide gives you the resistance and voltage checks in order so you can tell the tech which part to bring. Stacks add one more variable: each pocket has its own sensor, gas valve and heat circuit, and Dexter's control has a heat light per pocket. When the top pocket stops heating while the bottom works, that per-pocket circuit is where to look first.

Slow Drying, Back Pressure and Make-Up Air

When customers say the dryers take too long, the manuals give you one number to measure first. Dexter and ADC both set the maximum exhaust static back pressure at 0.3 in WC, read with a manometer at the dryer exhaust; Alliance's tumble dryer installation manual (70457901) allows 0.5 in WC on its 050, 075 and F75 series, measured 12 inches from the outlet with the machine running. Above that, the burner cycles off on the airflow switch or a hi-limit and drying time climbs. Dexter's T-50 sheet recommends 14 ft of exhaust with two elbows as the design case. ADC says to avoid 90-degree turns and use 30 or 45-degree angles instead.

Make-up air is the other half. ADC's AD-50V manual calls for 750 cfm to each dryer and a minimum unrestricted opening of 1-1/2 square feet per dryer, larger if you put a louver over it. For a bank of eight dryers the manual's own example is two openings of 2 ft by 3 ft. Dexter's T-50 sheet asks for 1.25 sq ft and its stack sheets ask for 1.5 sq ft per stack. If your make-up air comes through the front door, the dryers slow down every time it closes.

Dexter's slow-drying order is worth memorizing: temperature setting, lint screen, exhaust length and cleanliness, exhaust damper, make-up air, then back pressure. The 0.3 in back-pressure rule and lint checklist by brand turns that into a walk you can do in twenty minutes. For a new build or a retool, the commercial dryer venting requirements post covers duct sizing, elbows and make-up air openings by brand.

The Maintenance Schedule

Speed Queen publishes a maintenance page for its tumble dryers that is short enough to put on the wall. Dexter and ADC add checks tied to their own hardware.

Interval	Task	Source
Daily	Clean the lint compartment and screen; check the cylinder for foreign objects	Speed Queen maintenance tips
Daily	Empty the lint drawer; on ADC, the control shows CLEAN LINT if it's skipped	ADC AD-50V manual
Monthly	Remove lint from inside the exhaust duct	Speed Queen maintenance tips
At install and after any duct change	Check the sail switch: start a cycle with the lint drawer switch pushed in; heat should not activate within 30 seconds	ADC AD-50V manual
When the over-temp thermostat trips repeatedly	Clear lint from the recirculating chamber, exhaust duct and heat chamber above the tumbler	Dexter common dryer troubleshooting
Annually	Authorized service rep cleans the tumbler and inspects ductwork through the inspection doors	Speed Queen maintenance tips; ADC AD-50V manual

Alliance ships its current tumble dryers with ProCapture, which it markets as reducing lint buildup; the 2025 sheet rates a ProCapture STT30 at 68,000 Btu/hr per pocket against 73,000 standard. It doesn't replace the daily screen. The fire-prevention side of this list is in dryer maintenance tips for laundromat owners.

What Dryers Cost

No dryer manufacturer publishes a list price. Secondary-market listings collected by Unity show a Speed Queen STT30 stack at about $7,875, and stack dryers generally in the $8,000 to $8,600 range. Dealer quotes vary by region and volume. Unity's own UDG75 75 lb single is listed at about $5,795, which gives a floor for a large single pocket. Dexter T-50 and T-50X2 dryers have no published price anywhere; every distributor quotes on request.

Warranty is part of the price. Speed Queen sells its stack tumble dryers with Quantum Touch on a 5-year limited warranty and Quantum Gold on a 3-year limited warranty. Dexter's stack sheets carry 5 years on trunnion, bearings and bearing housing plus 3 years on parts. Unity's repair-versus-replace rule is to replace when a repair exceeds 50% of the new price; it estimates a dryer motor replacement at $150 to $500. The 2026 commercial dryer price guide lays out brand-by-brand ranges with dates so you can read a quote against the market.

Building the Right Dryer Bank

Start with the washers. Count washer pockets, multiply by 1.25, and round to whole stacks; then move pocket sizes up until your largest washer load fits in one dryer pocket. Pick the brand your washer distributor already services, because dryer parts and dryer techs come from the same truck, and Speed Queen and Huebsch dryers are the same Alliance hardware.

Before you sign, have the duct run and make-up air opening measured against the 0.3 in WC limit and the square-footage figure in that brand's install manual. A bank that's under-vented on day one reads slow forever. Then number every pocket and write the model designation on your maintenance sheet so the next OP, F2 or SAIL SWITCH OPEN gets matched to the right chart.

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