About the exam
ACS Domestic Gas Appliances Exam structure
An independent route guide to the principal ACS domestic appliance modules CENWAT, CKR1, HTR1 and DAH1, with shared appliance-safety preparation kept separate from CCN1 core.
Issuer and path
ACS Domestic Gas Appliance Modules Study Guide is administered through IGEM Standard Setting Body / UKAS-accredited certification bodies. Check official resources before booking, retesting, or relying on a stale requirement.
CENWAT
0 scored + 0 pretest
Domestic central-heating and hot-water boilers, circulators, combination boilers, storage and instantaneous water heaters.
CKR1
0 scored + 0 pretest
Domestic natural-gas and LPG cooking-appliance assessment scope.
HTR1
0 scored + 0 pretest
Domestic space-heating appliance assessment scope.
DAH1
0 scored + 0 pretest
Domestic ducted-air heater assessment scope.
Shared Appliance Safety
0 scored + 0 pretest
Cross-module source use, commissioning, combustion, unsafe situations and handback boundaries.
Before booking
Confirm current eligibility, the exact assessment or module code, approved provider or centre instructions, permitted references and any route-specific practical evidence.
Official Outline Coverage Map
Coverage is mapped to official outline item counts so content depth can be checked without hard-coding a single exam.
| Topic | Official outline items | Your questions | Your flashcards | Confidence |
|---|---|---|---|---|
| CENWAT Scope, Appliance Types and Components | 0 | 50 | 4 | Good |
| CENWAT Installation and Siting | 0 | 50 | 4 | Good |
| CENWAT Commissioning, Controls and Performance | 0 | 50 | 4 | Good |
| CENWAT Servicing, Faults and Handback | 0 | 50 | 4 | Good |
| CKR1 Scope, Siting and Ventilation | 0 | 44 | 4 | Good |
| CKR1 Installation and Commissioning | 0 | 43 | 4 | Good |
| CKR1 Servicing, Faults and Handback | 0 | 43 | 4 | Good |
| HTR1 Appliance Types and Siting | 0 | 44 | 4 | Good |
| HTR1 Chimneys, Flueing and Combustion | 0 | 43 | 4 | Good |
| HTR1 Servicing, Controls and Handback | 0 | 43 | 4 | Good |
| DAH1 System Layout and Airflow | 0 | 35 | 4 | Good |
| DAH1 Commissioning, Servicing and Faults | 0 | 35 | 4 | Good |
| Module Route, Prerequisites and Work Categories | 0 | 24 | 4 | Good |
| Source Use, Measurement and Reasonableness | 0 | 24 | 4 | Good |
| Unsafe Situations, Escalation and Handback | 0 | 23 | 4 | Good |
How to use this guide
How to prepare for ACS appliance assessments
Confirm the exact module and range, use the current assessment criteria and manufacturer instructions, then rehearse installation, commissioning, servicing and fault work under competent supervision.
1. Confirm scope and source
Identify the module, gas family, appliance, task and controlling current documents.
2. Make the area safe
Survey the appliance, services, chimney or ventilation, electrical interfaces and immediate hazards.
3. Test and interpret
Use the correct instrument, condition, unit and limit; investigate results rather than forcing them to pass.
4. Hand back or escalate
Complete final checks, records and user information, or follow unsafe-situation procedure when safety is not demonstrated.
CENWAT Scope, Appliance Types and Components
Range boundaries, boiler and water-heater types, system components and manufacturer-specific requirements.
Key rules
Rule 1
CENWAT covers specified central-heating and hot-water appliance types rather than every domestic gas appliance.
Exam cue: Identify the scope and evidence that control the cenwat scope, appliance types and components decision before selecting a rule or method.
Rule 2
Appliance type, flue arrangement, controls and system design determine the applicable instructions and checks.
Exam cue: Connect cenwat covers specified central-heating and hot-water appliance types rather than every domestic gas appliance. with appliance type, flue arrangement, controls and system design determine the applicable instructions and checks. and test the conclusion against manufacturer instructions and current criteria must be used together without extending personal certification scope..
Rule 3
Manufacturer instructions and current criteria must be used together without extending personal certification scope.
Exam cue: Identify the governing scope, interpret the evidence and apply the method before selecting a conclusion.
Common traps
Applying a neighbouring topic or route rule without checking whether it belongs to CENWAT Scope, Appliance Types and Components.
Prevention: Check the current official source, route and assessment boundary before relying on a memorised rule.
Memorising a label or number without being able to interpret evidence, explain the boundary or apply the method.
Prevention: Check the current official source, route and assessment boundary before relying on a memorised rule.
Memory anchors
CENWAT Scope, Appliance Types and Components
Range boundaries, boiler and water-heater types, system components and manufacturer-specific requirements.
CENWAT Scope, Appliance Types and Components: core principle
CENWAT covers specified central-heating and hot-water appliance types rather than every domestic gas appliance.
CENWAT Scope, Appliance Types and Components: application
Appliance type, flue arrangement, controls and system design determine the applicable instructions and checks.
CENWAT Scope, Appliance Types and Components: evidence check
Manufacturer instructions and current criteria must be used together without extending personal certification scope.
Next best moves
Quick check-up
Use a short quiz to confirm the rule pattern is actually sticking.
Check-up Questions
Which appliance falls directly within the published CENWAT appliance range?
What is the function of the expansion vessel in a sealed wet-heating system?
Answer all questions to submit.
Next step personalized recommendations
Open another topic next
Official resources
Verify the details with the official sources
Use these links for eligibility, scheduling, handbook rules, and issuer updates. Our guide helps you study; official sources tell you what the testing partner currently requires.
IGEM SSB assessment criteria directory
Current public appliance, core and specialist ACS criteria documents.
CENWAT criteria
Current CENWAT domestic boilers and water-heating assessment criteria.
CKR1 criteria
Current domestic cooking-appliance assessment criteria.
HTR1 criteria
Current domestic space-heating appliance assessment criteria.
DAH1 criteria
Current domestic ducted-air heater assessment criteria.
BPEC ACS scheme rules
Current certification, entry and extension-of-range rules for BPEC candidates.
Gas Safe Register qualifications
Current registration and category-scope information.
FAQ
Common ACS Domestic Gas Appliances questions
Is ACS Gas Appliances one assessment?
No. This directory groups separate appliance modules for study. Candidates book and pass the exact module or modules required for their work range.
Which modules are included?
The initial scope covers CENWAT, CKR1, HTR1 and DAH1. Other domestic appliance, metering, LPG or changeover categories require their own current criteria and product decision.
Does CCN1 cover appliance work?
CCN1 is the domestic natural-gas core. Appliance work normally requires the relevant appliance assessment and matching current Gas Safe work category.
Can revision prove practical competence?
No. Installation, commissioning, measurement, servicing and fault tasks must be demonstrated under the approved assessment arrangements.
Are the public criteria enough on their own?
No. Candidates must also use the current documents supplied or permitted by their certification body or centre and the relevant manufacturer instructions.
Why is full mock disabled?
There is no single combined examination format. Questions remain mapped to the separate modules, so the bank supports targeted and mixed practice without claiming to reproduce one official paper.