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AirGreen × TOSOT · Sold and installed by AirGreenTOSOT four-zone at AirGreenFour heads on one outdoor unit, with Lomo 23 and LomoPlus UltraHeat compressors.
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TOSOT · Multi-zone · Four zones · updated November 5, 2026

TOSOT four-zone: four heads against one compressor

Four heads often add up to more than the compressor that feeds them. Build your four rooms: you see which compressors take the combination, and what TOSOT says about it.

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  • 5four-zone compressors online
  • 130%heads ÷ compressor ratio TOSOT recommends at most
  • 35,040 BTU/hcooling for four 12,000 heads on the 36,000 Lomo 23 (sheet read on October 28, 2026)
  • 6four-head combinations on the 42,000 LomoPlus UltraHeat, with our sizes
01 · Heads against compressor

Build your four rooms: which compressors take these heads?

Pick the head for each room. For the LomoPlus UltraHeat units, you see the ratio between your heads and the compressor, as TOSOT calculates it; for the Lomo 23 units, the output TOSOT gives the system.

Room 1 · BTU/h

Room 2 · BTU/h

Room 3 · BTU/h

Room 4 · BTU/h

Your heads: 9,000 + 9,000 + 12,000 + 12,000 = 42,000 BTU/h. 5 of 5 compressors accept it.

  1. ListedLomo 23 · 30,000TM30H4O · TOSOT sheet read on October 28, 2026System output per TOSOT: 29,600 BTU/h cooling, 31,600 BTU/h heating.
  2. ListedLomo 23 · 36,000TM36H4O · TOSOT sheet read on October 28, 2026System output per TOSOT: 34,040 BTU/h cooling, 42,000 BTU/h heating.
  3. ListedLomo 23 · 42,000TM42H3O · TOSOT sheet read on October 28, 2026System output per TOSOT: 39,000 BTU/h cooling (only this table was recorded).
  4. ListedLomoPlus UltraHeat · 36,000TM36H5O · list in the TOSOT sheet of November 4, 2024Heads 42,000 BTU/h ÷ compressor 36,000 BTU/h = 117% (within TOSOT’s recommended range, 50 to 130%).
  5. ListedLomoPlus UltraHeat · 42,000TM42H5O · list in the TOSOT sheet of November 4, 2024Heads 42,000 BTU/h ÷ compressor 42,000 BTU/h = 100% (within TOSOT’s recommended range, 50 to 130%).

LomoPlus UltraHeat: combination table in the TOSOT sheet of November 4, 2024, limited to the head sizes AirGreen offers (9,000 to 24,000 BTU/h); the ratio compares the sum of the heads with the compressor size, as TOSOT’s note does. Lomo 23: combination tables in the TOSOT sheets read on October 28, 2026, system output at AHRI test conditions (95 °F cooling, 47 °F heating). The final choice is made on site.

AirGreen × TOSOT

TOSOT four-zone units, live

Each product page: outdoor model, AHRI number and the heads offered.
02 · Did you know

Three details in the sheets that matter with four heads

01

The compressor is shared

Four 12,000 heads add up to 48,000 BTU/h. On the 36,000 Lomo 23, the sheet read on October 28, 2026 gives the system 35,040 BTU/h in cooling and 42,720 in heating: the four rooms share that total.

TOSOT sheet TM36H4O, combination table.

02

The circuit changes with the family

At 36,000 BTU/h, the LomoPlus UltraHeat needs a circuit of at least 36 A (MCA), protected at 60 A at most (MOCP); the 36,000 Lomo 23, 23 A and 35 A per its sheet read on October 28, 2026.

TOSOT sheets TM36H5O (November 4, 2024) and TM36H4O.

03

No 24,000 wall head on the 42,000

TOSOT’s brochure reserves the 24,000 size for cassette, ducted and floor-ceiling heads on the 42,000 BTU/h compressors, not wall heads.

TOSOT “Heat Pumps” brochure in English.

03 · Side by side

The five four-zone compressors side by side

How many four-head combinations each sheet takes, with the sizes AirGreen offers, and what it publishes.

Compressor4-head combinationsHeads in total (BTU/h)Published system outputCircuit
Lomo 23 · 30,000TM30H4O336,000 to 42,000cooling 29,600 to 29,700 · heating 30,800 to 31,600 · sheet read on October 28, 2026MCA 20 A · MOCP 30 A
Lomo 23 · 36,000TM36H4O736,000 to 48,000cooling 34,000 to 35,040 · heating 40,800 to 42,720 · sheet read on October 28, 2026MCA 23 A · MOCP 35 A
Lomo 23 · 42,000TM42H3O836,000 to 51,000cooling 35,480 to 40,010 · sheet read on October 28, 2026MCA 24 A · MOCP 40 A
LomoPlus UltraHeat · 36,000TM36H5O436,000 to 45,000not published · list only, sheet of November 4, 2024MCA 36 A · MOCP 60 A
LomoPlus UltraHeat · 42,000TM42H5O636,000 to 54,000not published · list only, sheet of November 4, 2024MCA 38 A · MOCP 60 A

Combinations counted with 9,000 to 24,000 BTU/h heads. MCA: minimum circuit ampacity; MOCP: maximum overcurrent protection.

04 · Multi-zone

The multi-zone pages, each with its question

R-410ADual zoneYour pair of heads, compressor by compressor.R-410ATri-zoneYour line-set plan, checked against the sheet.R-410AFive zonesWhat TOSOT really publishes for five rooms.R-410AUltraHeat dual zoneWhat the compressor keeps in deep cold.R-410AUltraHeat tri-zoneThe head trios TOSOT accepts.R-410ALomo 23 dual zoneStarting with a single head.R-410ALomo 23 tri-zoneThe compressor’s ceiling with three heads.TOSOTAll multi-zone unitsBoth compressor families, from 2 to 5 rooms.
AirGreen × TOSOT

The right model is chosen at your place, not on a grid

We look at the room, the insulation and the electrical panel, then we propose the model, the quote and the LogisVert amount that applies.

Book my free estimate514 316-2973
  • Sold and installed by AirGreenMontreal, Laval, Longueuil, South Shore and North Shore.
  • RBQ 5645-9605-01Subclasses 15.8 Ventilation, 15.10 Refrigeration and 16 Electricity.
  • LogisVertHydro-Québec never solicits by phone or door to door for LogisVert.
Sources

Sources and reading dates

  1. TOSOT, submittals TM18H5O, TM24H5O, TM36H5O and TM42H5O, dated November 4, 2024, tosot.com, read on November 5, 2026 (specifications, indoor-unit combination table and note on the capacity ratio).
  2. TOSOT, submittals TM18H4O, TM24H4O, TM30H4O, TM36H4O and TM42H3O, undated, read on tosot.com on October 28, 2026 (specifications and combination tables); these files were no longer online there on November 5, 2026.
  3. TOSOT, “Heat Pumps” brochure in English, undated: note on the 24,000 BTU/h size with the 42,000 BTU/h compressors.

LogisVert amounts come from Hydro-Québec’s list on the date shown; only Hydro-Québec confirms the grant. AHRI numbers are those on our product pages, unchanged.