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TACO · ZVC403-4The TACO space at AirGreenThe ZVC403-4 zone valve control for hot-water heating, offered on quotation by AirGreen in Montréal, Laval, Longueuil, the South Shore and the North Shore.
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TACO · Hydronic zoning · Updated October 26, 2026

TACO ZVC403-4: three hot-water zones, one boiler

The ZVC403-4 zone valve control takes calls from three thermostats, opens the right zone valve and starts the boiler and pump only once that valve is fully open. It is made for hot-water heating, not for zoning air in ducts.

Try the simulatorIs it the right control?
Three lights tell the whole story
Per TACO sheet 102-391: one green light for the control, a yellow and a red for each zone
  1. GreenPower is on and the fuse is good.
  2. YellowThe thermostat is calling: the zone valve is powered.
  3. RedThe valve is fully open: the end-switch relay is energized, so the boiler and pump can start.
Watch them light up in the simulator
3hot-water heating zones
Zone 3priority, set by an OFF/ON switch
40 VAin total, 24 VA per zone
3 yearsTACO limited warranty (terms in 05)
AirGreen × TACOZVC403-43 hot-water zonesPriority on zone 324 VA per zone, 40 VA totalGreen, yellow and red lightsMontréal · Laval · Longueuil · South Shore · North Shore
01 · The right control

Hot water or air: first, the right control

The ZVC403-4 fits one specific case. Answer a few questions: if it isn’t the right one, the tool tells you right away.

Your heating system moves…
In each zone, the water is controlled by…
Number of zones (including the indirect water heater)
Should an indirect water heater get priority?

Hot water: baseboards, radiators or floors fed by a boiler. Air: floor or ceiling grilles connected to ducts.

Our reading of TACO’s sheets
The ZVC403-4 fits
TACO ZVC403-4
TACO ZVC403-4
3-zone zone valve control with priority.
  • 3 of 3 zones used.
  • Priority switch set to OFF: the zones run independently.

See the ZVC403-4 product page

02 · Simulator

The simulator: three thermostats, one boiler

Make the thermostats call and flip the priority switch: the panel responds the way TACO’s installation sheet 102-391 describes.

Thermostats calling for heat
ZONE 3 PRIORITY switch
  1. 1The thermostat calls (terminals R and W).
  2. 2The zone valve gets 24 V: yellow light.
  3. 3The valve is fully open and its end switch closes: red light.
  4. 4The end-switch relay closes the boiler’s X-X contact and the pump contact: the boiler and system pump start.
ZVC403-4 panel
Zone 1
Valve open
Zone 2
Idle
Zone 3
Idle
Boiler + system pumpX-X contact + pump contact
Running
  • At least one valve is fully open: the end-switch relay is energized, so the boiler (X-X) and system pump run.

Simplified simulation, for explanation only. A heat-motor valve takes some time to open; here the opening is sped up. During priority, the sheet does not describe the other zones’ lights. When in doubt, sheet 102-391 prevails.

AirGreen × TACO

TACO’s control, picked for your heating.

TACO designs the ZVC403-4 and publishes its wiring rules. AirGreen checks with you that it is the right control for your hot-water heating, on quotation.

TACO

What TACO brings

  • Since 1920Started as the Thermal Appliance Company, hence T-A-C-O; headquartered in Cranston, Rhode Island.
  • The ZVC403-4Three zones, priority on zone 3, a yellow and a red light for each zone.
  • The wiring rulesInstallation sheet 102-391: wire, thermostats, valves, jumpers.
  • Manufacturer warrantyThree years from start-up, or three years and six months from shipment, whichever comes first.
AirGreen

What AirGreen brings

  • The right control firstThe section 01 chooser says no when it is not the ZVC403-4.
  • TACO’s rules, appliedThe simulator follows sheet 102-391 and says “on quotation” where it is silent.
  • Free quotationWe look at your system before proposing the control.
  • RBQ 5645-9605-01Subclasses 15.8, 15.10 and 16.

The result: a control picked for your hot-water heating, price on quotation.

Try the simulatorRequest my quotation
03 · ZVC403-4

The ZVC403-4 in detail

Values from TACO installation sheet 102-391 (effective December 20, 2013) and catalogue 100-87.

ZVC403-4 specifications
Zones3, with optional priority on zone 3
Power input120 V, 60 Hz, single phase, 1.5 A
Output to valves and thermostats24 VAC Class 2: 24 VA per zone, 40 VA total
Boiler contact (X-X)Main end switch, 24 VAC, 1 A
Pump contacts (2)1/6 hp, 5 A at 120 VAC
Valves24 V, 2-wire, 3-wire (TACO) or 4-wire
ThermostatsTerminals R and W; C optional
LightsOne green (power); a yellow and a red for each zone
Fuse5 A, TACO spare SR5A-005RP
EnclosureType 1
Listing“UL listed” per catalogue 100-87

Not an -EXP version

Post purge, pump exercise and expansion up to 20 panels are -EXP features in catalogue 100-87.

The -5 generation

TACO also sells -5 generation ZVCs (Bluetooth app, Modbus). Our shop carries the ZVC403-4; the -5 is on quotation.

More than 3 zones

TACO makes the ZVC404, ZVC405 and ZVC406 (4 to 6 zones). On quotation.

04 · Wiring

What the installation sheet asks for

A summary of TACO’s instructions for the ZVC403-4. Connecting to 120 V and to the boiler is a job for a qualified contractor; sheet 102-391 prevails.

Wire

Copper only. 120 V: 12 to 18 AWG, insulation rated 75 °C minimum. Thermostats and 24 V: 14 to 22 AWG.

Thermostats

Terminals R and W for each zone. Terminal C is only for 24 V thermostats that need a common.

Power-stealing thermostat

It may need a 1,000 Ω, ½ W resistor between W and C (TACO SRTR-001RP). Battery thermostat: fresh batteries.

2-wire valve

No end switch: TACO requires a jumper.

Pump on the priority zone

If a circulator replaces the valve on the priority zone (an indirect water heater, for example), a jumper links terminals 3 and 4 of that zone.

Fuse

A 5 A fuse protects the control (spare SR5A-005RP). A lit green light confirms power and fuse.

AirGreen × TACOTACO warranty: 3 years24 V valves, 2, 3 or 4 wireHot-water heatingPrice on quotationMontréal · Laval · Longueuil · South Shore · North Shore
05 · Warranty and rebates

Three-year TACO warranty, no rebate found

What the warranty printed on sheet 102-391 and the programs themselves say, checked October 20, 2026.

3 years
TACO limited warranty, from start-up
  • Or 3 years and 6 months from shipment, whichever comes first
  • Repair or replacement, at TACO’s option
  • Prompt written notice to the local TACO stocking distributor or to TACO; product shipped to the distributor, freight prepaid
  • Removal and reinstallation costs excluded
  • Does not cover a product not installed or operated per TACO’s instructions, or subjected to misuse, misapplication, petroleum-based fluids or certain chemical additives, or other abuse
  • The sheet mentions no registration
Limited warranty printed on sheet 102-391 (TACO, Dec. 20, 2013).
LogisVertDoes not apply

Guide v1.10 of September 15, 2026 covers heat pumps, geothermal system replacement, solar, insulation and a few appliances: no zone controls.

ENERGY STARDoes not apply

For controls, only smart thermostats are certified.

RénoclimatDoes not apply

The program page (October 13, 2026, rules in force since October 1) names no zone controls.

TACO at a glance. Founded in 1920 as the Thermal Appliance Company, hence the letters T-A-C-O. Headquartered in Cranston, Rhode Island; Canadian site in Milton, Ontario, per its ISO 9001 certificate. Pentair announced on July 28, 2026 that it would acquire TACO, which would keep its brand according to the announcement.
06 · FAQ

ZVC403-4 frequently asked questions

Does the ZVC403-4 work with a forced-air system?

No. It controls zone valves on a hot-water heating system. Air zoning uses motorized dampers in the ducts and an air zoning panel, which is a different kind of device.

How many zones can it control?

Three. For 4, 5 or 6 zones, TACO makes the ZVC404, ZVC405 and ZVC406: on quotation.

What does the priority switch do?

Set to ON, when zone 3 calls, the other zones stop until it is satisfied. Set to OFF, the three zones run independently. It is typically used for an indirect water heater.

What if the priority zone calls for hours?

After more than one hour of continuous call from the priority zone, the control gives power back to the other zones. It resets on its own once the priority zone is satisfied.

Why doesn’t the boiler start as soon as the thermostat calls?

It waits until the valve is fully open. The valve’s end switch is what makes the boiler’s X-X contact close: red light on.

What do the green, yellow and red lights mean?

Green: power and fuse are good. Yellow: the thermostat is calling and the valve is powered. Red: the valve is fully open and the end-switch relay is energized.

Which thermostats can be connected?

24 V thermostats wired to R and W, with terminal C for those that need a common. A power-stealing thermostat may need a 1,000 Ω resistor between W and C. The control supplies 24 V; the sheet makes no provision for 120 or 240 V baseboard thermostats.

Which zone valves does it accept?

24 V 2-wire valves, TACO 3-wire valves and 4-wire power-open, self-closing valves. A 2-wire valve has no end switch, so TACO requires a jumper.

Can a zone use a pump instead of a valve?

The sheet allows it for the priority zone, with a jumper between terminals 3 and 4 of that zone. If every zone has its own pump, TACO offers its switching relays (SR series) instead.

What is the warranty?

TACO’s: three years from start-up, or three years and six months from shipment, whichever comes first. Repair or replacement at TACO’s option; removal and reinstallation costs excluded.

Is there a rebate for this control?

None found as of October 20, 2026: LogisVert and Rénoclimat do not cover zone controls, and ENERGY STAR has no category for them.

What is the difference between the ZVC403-4 and the -5 generation?

The -5 generation adds a Bluetooth app and Modbus, among other things. TACO lists both generations on its site; we offer the -5 on quotation.

AirGreen · Montréal, Laval, Longueuil, South Shore and North Shore

Tell us about your hot-water heating

Number of zones, type of valves, indirect water heater or not: with those three answers, we prepare a quotation for the TACO ZVC403-4. Price on quotation.

Request my free quotation514 316-2973
Showroom1370 Joliot-Curie Street, Suite 712, Boucherville
HoursMon. to Thu. 8 a.m. to 6 p.m. · Fri. 8 a.m. to 4 p.m.
RBQ 5645-9605-01Subclasses 15.8, 15.10 and 16
See alsoTACO in the shop · Thermostats and controls

Sources checked October 20, 2026

  1. TACO — ZVC403-4 instruction sheet (102-391), effective Dec. 20, 2013, limited warranty included
  2. TACO — Zone Valve Controls catalogue 100-87, effective Dec. 8, 2020
  3. TACO — Zone Valve Controls page (modified June 9, 2026), read Oct. 20, 2026
  4. TACO — wiring guide 100-92, Nov. 27, 2014
  5. TACO — SR503-4 switching relay (102-379), Jan. 18, 2017
  6. TACO — -5 generation ZVC, product page and manual 102-575 of June 27, 2025
  7. TACO — company page (read Oct. 20, 2026) and ISO 9001 certificate Q 545 of Dec. 1, 2025
  8. TACO — “Pentair to acquire Taco”, July 28, 2026
  9. Hydro-Québec — LogisVert participation guide v1.10, Sept. 15, 2026
  10. Natural Resources Canada — ENERGY STAR certified products, read Oct. 20, 2026
  11. Québec.ca — Rénoclimat, page updated Oct. 13, 2026

TACO is a trademark of Taco, Inc. The warranty is the manufacturer’s.

Price on quotation · free quotation. The TACO ZVC403-4 below.

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The ZVC403-4, right below.

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