Viper Gas resources
The purpose of a flue test is to prove a few points about the flue:
1. Flue draws all the products of combustion up the flue.
2. The flue does not leak from any joints or connections.
3. The flue terminates in the correct position.
4. The flue does not leak through any other flue system.
Before carrying out the test a few points MUST be covered.
1. Explain to the customer what you are about to do (in case they panic)
2. Close doors and windows (put the flue under its worst conditions)
3. When testing a flue with a fan in the area (it may not be necessary to turn the fan on as the problems that may occur with back pressure are checked when conducting a spillage test)
The purpose of a spillage test is to prove a few points about the appliance:
1. The appliance draws all the products of combustion into the flue.
2. The appliance and flue design are working correctly.
3. The appliance has no fumes entering the room
4. The appliance is safe to use
Before carrying out the test a few points MUST be covered.
1. Explain to the customer what you are about to do (in case they panic)
2. Close doors and windows (put the flue under its worst conditions)
3. Turn the extractor fans on in the room and test
4. Turn extractor fans on in any other room in the house and leave the door between the rooms open, and re test
5. When testing a flue with a fan in the area test with the fan on and with the fan off.
Pre-Test Checks & Preparation
Visual Inspection: Check the chimney for damage, blockages (soot/debris), or internal dampers that must be fully open.
Seal the Area: Close all doors and windows in the room where the appliance is located.
Check for Extracts: Turn on any extractor fans or hoods that might interfere with flue draw.
Warm the Flue (If Needed): If there's no initial "pull," use a blowtorch to warm the flue for about 10 minutes, then re-test with a lighter smoke match before the main test.
Performing the Smoke Test
Insert Smoke Pellet: Light a specific smoke pellet (producing at least 5m³ of smoke in 30 seconds) and place it in the appliance's catchment area or at the base of the flue.
Seal the Appliance: Seal the appliance opening to direct smoke up the flue.
Inspect for Smoke:
Inside: Check the appliance area and all adjacent rooms (including lofts/bedrooms) for any smoke leakage.
Outside: Confirm smoke exits only from the correct chimney pot.
Spillage Test (Secondary Phase)
Once the flue flow is confirmed, a spillage test is often conducted with the appliance running:
Warm-up: Run the appliance at maximum heat for 5–10 minutes.
Smoke Match Test: Place a smoke match (or "puffer") near the draught diverter or canopy. All smoke should be drawn into the flue, with only an occasional wisp allowed.
Worst-Case Scenario: Retest with internal doors open and any extract fans (kitchen, bathroom) running on maximum speed.
4. Result Actions
Pass: Smoke is consistently drawn into the flue and exits the correct terminal without leaking into the building.
Fail: If smoke spills or leaks into rooms, the appliance must be turned off and disconnected immediately until the fault (blockage, poor ventilation, or flue damage) is rectified.