HeatMaster 25 C

Gas fired condensing combined boiler and high output water heater

  • Also available in propane.
Short Energy Label Heating
Short Energy Label DHW
  • Gas
  • Boilers
  • DHW Production
  • Standard
  • Concentric
  • Floor installation
# GTIN : 5400891032206
# P/N : A1002007
Label 2
  • Floor standing boiler with large primary water volume, adaptable to all types of existing installation
  • Responds to high peak demand and high continuous flow
  • Exceptional domestic hot water flow: >35L/min
  • NOx rating (EN483) 22.8/kWh
  • Seasonal Efficiency 96.8%
  • Stainless steel Tank-in-Tank DHW cylinder with proven long life reliability
  • Anti Legionellae: hot water stored at consistently high temperature
  • Stainless steel self-cleaning heat exchanger
  • High efficiency boiler charging pump
  • Concentric balanced flue or conventional flue options.
  • Can also be used as a stand alone water heater.
  1. Concentric flue gas/air inlet box
  2. Flue gas exhaust tube
  3. Combustion chamber
  4. Stainless steel heat exchanger
  5. Stainless steel “Tank-in-Tank” hot water production tank
  6. DHW circuit tube
  7. Condensate recovery dish
  8. High efficiency circulator pump
  9. NTC sensor (heating circuit)
  10. Pressure sensor
  11. Electrical panel (with spare fuses at the back)
  12. ACVMax Control panel
  13. DHW tank dry well (Sparge tube with temperature sensor)
  14. Automatic air vent
  15. Gas pipe
  16. Gas valve
  17. Connection for DHW safety valve (to be installed)
  18. Modulating air/gas premix burner with fan
  19. Air inlet

Constructive characteristics

HeatMaster 25 C
Capacity (total) L 200 L
Capacity (primary) L 120 L
Capacity (domestic hot water) L 80 L
Capacity expansion tank(s) L - L
Chimney: Max pressure drop in flue pipe Pa 130 Pa
Chimney: max length of concentric flue pipe m 20 m
Chimney connection Ømm 80/125 Ømm
Connection - heating Ø" 1 F Ø"
Connection - DHW Ø" 1 M Ø"
Connection gas Ø" 3/4 M Ø"
Connection - safety valve Ø" 1/2 M Ø"
Max operating temperature °C 87 °C
Water pressure drop boiler at Δt = 20°C mbar 3 mbar
Max service pressure heating (primary) bar 3 bar
Max service pressure (DHW) bar 8,6 bar
Height when tilted mm 1855 mm
Weight (empty) kg 174 kg

Heating characteristics

HeatMaster 25 C
Pre-heating time from 10 to 80°C (Heat source: boiler) min 27 min
Heating time from 10 to 90°C min 40 min


HeatMaster 25 C
Input max (heating) HCV kW 27,8 kW
Input max (heating) LCV kW 25 kW
Combustion efficiency % 97,5 %
Efficiency at 30% load (EN677) % 109,0 %
Efficiency (max output) 80/60°C % 98 %
Efficiency (min output) 80/60°C % 98 %
Efficiency DHW mode ΔT 30K % 99,2 %
CO emissions max output ppm 27 ppm
CO emissions min output ppm 6 ppm
Mass rate of combustion products (gas) kg/h 42 kg/h
NOx weighted (GCV) (EN15502) mg/kWh 26,3 mg/kWh
NOx class (EN15502) 6
Nominal power DHW kW 25 kW
Output power max (80/60°C) kW 24,3 kW
Output power min (80/60°C) kW 4,9 kW
Gas flow rate (min output) m³/h 0,5 m³/h

Domestic hot water performance

HeatMaster 25 C
Peak flow at 40°C L/10’ 233,5 L/10’
Peak flow 1st hour at 40°C L/60’ 748 L/60’
Continuous flow at 40°C L/h 617 L/h
Peak flow at 60°C L/10’ 145 L/10’
Peak flow 1st hour at 60°C L/60’ 478 L/60’
Continuous flow at 60°C L/h 400 L/h

Electrical Characteristics

HeatMaster 25 C
Voltage V 230 V
Frequency Hz 50 Hz
Protection IP 20
Electrical consumption W 95 W
Electrical power requirements A 0,8 A

Eco Design Fields

HeatMaster 25 C
Space heating energy efficiency class A
Seasonal space heating efficiency (35°C) % 93 %
Declared load profile XXL
Water heating energy efficiency class B
Water heating energy efficiency [ηwh] (EU 814/2013 Art 2 (15) Ann.IV-3) % 74 %
Sound power level indoors LWA dB 60 dB
Energy Label
Product Fiche


HeatMaster C, TC

11.41MB – en

ACVMax - Installers handbook for heating systems controlled with ACVMax (3.06-3.16)

21.45MB – en

ACVMax - Installers handbook for heating systems controlled with ACVMax (Software version 4.04 or more)

25.98MB – en

HeatMaster 25 / 35 / 45 / 70 / 85 / 120 TC (V15) - Installation, Operation and Maintenance instructions

13.00MB – en


ACV Guide to Ecodesign and Energy Labelling

969.34kB – en

ACV Products Overview 2019

40.33MB – en


Energy Label

Product Fiche

BIM Files

BIM Files

Find an installer

Get in touch with an installer for a free, no obligation estimate.

Call ACV

Need some answers? Talk to a specialist

Tel. +32 2 334 82 20