Bitcoin Space Heater Specs — ASIC Heat-Reuse & Suitability

Quick answer

A Bitcoin ASIC miner is a resistive heater that pays you back: ~100% of its wall power becomes heat, so BTU/h = watts x 3.412. This table profiles 8 home-relevant miners — an Antminer S9 (1,400 W -> ~4,777 BTU/h) up to an S21 (3,500 W -> ~11,942 BTU/h), with a near-silent Bitaxe Gamma (~18 W) for contrast. The net-new layer here is the heat-REUSE decision: which miner suits a forced-air garage, a ducted whole-room setup, an immersion-to-hydronic loop, or no living space at all.

Stock Antminers run 75-76 dBA and need a 240V circuit, so they are garage / ducted / immersion appliances, not bedroom heaters. Heated-area numbers are a sizing heuristic (~10 W/ft2), not a manufacturer rating. Airflow CFM is an estimate flagged unverified — Bitmain does not publish stock-fan CFM. Free CSV/JSON under CC BY 4.0.

Download CSV Download JSON REST API →

Model	Wall W	Heat BTU/h	kW th	Heated area ft²*	Noise dBA†	Airflow CFM‡	Best heat-reuse
Antminer S9 / S9i	1,400	4,777	1.40	~140	76	~600 (unverified)	forced-air garage / workshop (or immersion->hydronic)
Antminer L3+	800	2,730	0.80	~80	75	~600 (unverified)	forced-air garage / workshop (or ducted whole-room)
Antminer S17 / T17 (underclocked)	1,800	6,142	1.80	~180	75	~750 (unverified)	ducted whole-room (or forced-air garage)
Antminer S19 Pro	3,250	11,090	3.25	~325	75	~750 (unverified)	ducted whole-room (or immersion->hydronic)
Antminer S19j Pro	3,050	10,407	3.05	~305	75	~750 (unverified)	ducted whole-room (or immersion->hydronic)
Antminer T19	3,150	10,748	3.15	~315	75	~750 (unverified)	ducted whole-room (or forced-air garage)
Antminer S21	3,500	11,943	3.50	~350	75	~750 (unverified)	immersion->hydronic (or ducted whole-room)
Bitaxe Gamma (contrast row)	18	61	0.02	~2	38	~20 (unverified)	not-for-living-space (negligible heat — silent desk miner)

* Heated-area figures are a ROUGH heuristic at ~10 W/ft2 (~34 BTU/h.ft2): a moderately insulated modern space holding ~21C indoor against ~0C outdoor (roughly climate zone 5-6). HALVE the area for a poorly insulated room or a sub-zero climate; DOUBLE it for a mild climate or a tight, well-sealed envelope. Use it for sizing intuition, not as a manufacturer rating. † Stock fans at full load, pulled from our dc_miner noise database (not recomputed). ‡ Airflow is an engineering estimate flagged unverified — Bitmain does not publish stock-fan CFM and the Mining Bible lists fan airflow as an open research gap.

Home-fit verdict, model by model

Antminer S9 / S9i forced-air garage / workshop (or immersion->hydronic)

1,400 W · 4,777 BTU/h · 1.40 kW thermal · 76 dBA stock

The classic DIY heater base: lowest BTU here (~4,777 BTU/h) suits a small room, but 76 dBA stock fans are too loud for a living space. Duct it, swap to quiet fans, or keep it in the garage/shop. SHA-256 is obsolete for profit — run it for the heat.

Source: wall_w: D-Central ASIC power-requirements dataset; noise: dc_miner noise_level meta; BTU derived (W x 3.412142). Bible: MINING_ECOSYSTEM, KNOWLEDGE_GAPS_EE 4.3 (fan airflow gap).

Antminer L3+ forced-air garage / workshop (or ducted whole-room)

800 W · 2,730 BTU/h · 0.80 kW thermal · 75 dBA stock

Lowest power here (800 W, ~2,730 BTU/h) makes it the gentlest single-room contributor, but 75 dBA stock means duct it out of earshot or fit quiet fans. Scrypt/Litecoin, not Bitcoin.

Source: wall_w: D-Central ASIC power-requirements dataset; noise: dc_miner noise_level meta; BTU derived. Bible: KNOWLEDGE_GAPS_EE 4.3.

Antminer S17 / T17 (underclocked) ducted whole-room (or forced-air garage)

1,800 W · 6,142 BTU/h · 1.80 kW thermal · 75 dBA stock

Underclocked to ~1,800 W (stock S17/T17 pulls 2,200-2,520 W) it lands near ~6,142 BTU/h with lower fan speed and somewhat less noise than full tilt — but still 75 dBA stock. Best ducted; these boards are also failure-prone, so treat as a heat appliance, not an investment.

Source: wall_w: underclocked target (stock S17/T17 2,200-2,520 W, MINING_ECOSYSTEM); noise: dc_miner noise_level meta (stock); BTU derived. Bible: KNOWLEDGE_GAPS_EE 4.3.

Antminer S19 Pro ducted whole-room (or immersion->hydronic)

3,250 W · 11,090 BTU/h · 3.25 kW thermal · 75 dBA stock

A serious furnace at ~11,089 BTU/h — enough for a ~325 ft2 space — but 75 dBA and a 240V circuit put it firmly out of the living room. Duct the exhaust into the room and keep the unit elsewhere, or go immersion for hydronic reuse.

Source: wall_w: D-Central ASIC power-requirements dataset; noise: dc_miner noise_level meta; BTU derived. Bible: KNOWLEDGE_GAPS_EE 4.3.

Antminer S19j Pro ducted whole-room (or immersion->hydronic)

3,050 W · 10,407 BTU/h · 3.05 kW thermal · 75 dBA stock

~10,407 BTU/h covers a ~305 ft2 room. Same story as the S19 Pro: 75 dBA and 240V mean duct it or run it in a garage/utility space, not a bedroom.

Source: wall_w: D-Central ASIC power-requirements dataset; noise: dc_miner noise_level meta; BTU derived. Bible: KNOWLEDGE_GAPS_EE 4.3.

Antminer T19 ducted whole-room (or forced-air garage)

3,150 W · 10,748 BTU/h · 3.15 kW thermal · 75 dBA stock

~10,748 BTU/h, ~315 ft2. The T19 trades efficiency for a lower entry price, which makes it a popular heat-first pick — still 75 dBA, still 240V, still duct-or-garage.

Source: wall_w: D-Central ASIC power-requirements dataset; noise: dc_miner noise_level meta; BTU derived. Bible: KNOWLEDGE_GAPS_EE 4.3.

Antminer S21 immersion->hydronic (or ducted whole-room)

3,500 W · 11,943 BTU/h · 3.50 kW thermal · 75 dBA stock

Highest air-cooled BTU here (~11,942 BTU/h, ~350 ft2) AND the best efficiency, so it earns its electricity longest. At 3,500 W / 240V / 75 dBA the smart home play is an immersion tank feeding a hydronic loop — heat without the jet-engine noise.

Source: wall_w & 11,942 BTU/h: Bible MINING_ECOSYSTEM (S21 3500W table); noise: dc_miner noise_level meta; BTU derived. Bible: KNOWLEDGE_GAPS_EE 4.3.

Bitaxe Gamma (contrast row) not-for-living-space (negligible heat — silent desk miner)

18 W · 61 BTU/h · 0.02 kW thermal · 38 dBA stock

NOT a heater: ~18 W is ~61 BTU/h — a warm laptop, not a furnace. Listed only for contrast: at 38 dBA it is whisper-quiet and lives on a desk. If you want sovereign solo-mining without heating a room, this is the trade-off against the kilowatt-class Antminers above.

Source: wall_w: typical Bitaxe Gamma (BM1370) draw; noise: dc_miner noise_level meta (38 dBA); BTU derived. Bible: ecosystem/open-source.

Plan your build

Crunch the payback: Mining heat-savings calculator · heating-fuel cost comparison dataset
Tame the noise: Miner noise planner (set-back distance & enclosure)
Build a quiet box: Bitcoin Space Heater XL DIY case · S9 Space Heater Edition · S19 Space Heater Edition · S17/T17 conversion kit
Go deeper on heat reuse: Heating your home with Bitcoin miners · Mining heat reuse & the Bitcoin space heater
Model family hubs: Antminer S21 · Antminer S19

Method: an ASIC converts ~100%% of its electrical draw into heat, so heat (BTU/h) = wall watts × 3.412142. Wall power aligns with our ASIC power-requirements dataset; stock noise is pulled live from our miner database. Grounded in the D-Central Mining Bible. CC BY 4.0 — D-Central is the author. Verify circuit, ducting and venting against your specific install before running an ASIC as a heater.

Related products, repair, and setup paths

Last reviewed June 23, 2026.