The Ins and Outs of Chimney Testing

The Ins and Outs of Chimney Testing

As chimney sweeps, there’s much more to our jobs than making sure the chimney is clear of debris. At SweepSmart, we also perform several safety checks and tests to ensure that your chimney is fit for use.

As qualified chimney sweeps, we’ve included a list of tests that we carry out in order to identify any potential problems. If you don’t trust that your current chimney sweep is looking at these potential hazards, it may be worth finding a new chimney sweep.

 

 

Chimney Pressure Test (Smoke Test 1)

The chimney pressure test is a pressure smoke test to check the air tightness of the chimney. Chimney pressure tests are required when installing a new appliance into an existing chimney or reopening a chimney following a house move. This service is popularly used if smoke is suspected of leaking into the property or part of an adjacent building.

Once the flue has been warmed, a number (based on the flue size) of smoke pellets are placed in the fireplace. Once the smoke can be seen at the top of the chimney, the chimney pot is closed or sealed. While the smoke is contained within the chimney breast, several inspections are performed and the chimney structure is investigated in great detail to ensure that the flue is sufficiently airtight. Any smoke seen evacuating from parts of the chimney will indicate a failure.

 

 

Chimney Draw Test (Smoke Test 2)

The chimney draw test checks the ventilation in the room to ensure the chimney is evacuating smoke freely.

This test should determine whether there is enough ventilation in the room to ensure the chimney is evacuating all products of combustion freely. Although this test can identify leaks, it’s not a test to determine whether a flue is airtight. The difference is the top and opening are not sealed during the test, hence not creating pressure that would identify leaks. This is performed after every sweep, servicing an appliance, and commissioning a new installation.

During the chimney draw test, all doors and windows in the room are closed and the flue is warmed. After 10 minutes, a smoke pellet is lit in the fireplace. The smoke is observed for any leakage back into the room and a door or window is opened to see if the additional ventilation speeds up the smoke. The smoke is then observed evacuating from the top of the chimney.

 

 

 

Chimney Leakage Test (with a measuring device)

The leakage test determines whether the flue or chimney meets the allowable leakage rates for flue systems. A Wöhler DP 600 Leakage Tester is used to determine the exact leakage rate to ensure a flue within the recommended allowances. This test is generally needed to test the airtightness of manufactured flue systems such as rigid flue systems, flexible liners etc.

Similar to the smoke pressure test, the top and bottom of the flue are sealed. Air is manually pumped into the flue and the probe measures the amount of pressure that’s established and determines the leakage rate. Once the device has completed the test, a printout of the results is produced. The tightness of the flue liner needs to be relatively greater than on chimneys and the leakage rates for different flues are specified in BS EN1443.

 

Flue Draught Test

The flue draught test is a device used to measure the flow rate within the flue. The draught test is part of the commissioning process when a new stove is installed. A draught test will also be performed in conjunction with a Smoke Test 2 and Extraction Test to find the solution if problems are being experienced.

A draught testing point is provided by the stove manufacturer or is created in a stove pipe.

The flue is warmed to operating temperature and the probe of a flue draught gauge is inserted into the testing point. After 30 seconds the draught reading is recorded. The reading must be within the stove manufacturer’s specified range. The constant flow of gases is required for safe and efficient combustion. Remedial work is required to achieve the specified draught reading.

 

 

 

Flue Draught Extraction Test

A draught extraction test is performed with all mechanical extractions turned on such as kitchen extraction fans and tumble dryers to check if any interference is caused. The draught extraction test is part of the commissioning process when a new stove is installed. A draught test will also be performed in conjunction with a Smoke Test 2 and Extraction Test to find the solution if problems are being experienced.

Continuing from the flue draught test with the appliance alight, we open any internal doors interconnecting the room in which the appliance is installed and extraction fans are present. We turn on all extract fans within the property to the maximum speed setting allowed and run the extract systems for ten minutes. During this time, the flue draught is being recorded.

The reading should ideally be the same as when the extractors were turned off, however it’s likely that there may be a small dip in the recorded draught. This is allowable provided the draught does not fall below the minimum specifications of the stove manufacturer. Modern homes may contain forms of mechanical ventilation such as, bathroom extract fans, cooker hoods, tumble dryers etc, either in the room in which the appliance is installed or in another room of the property.

 

 

Core Ball Test (Liner Pass Test)

The core ball test is used for proving the minimum diameter of flue. The call ball test is carried out to ensure a flue has been constructed correctly and is free of obstruction. It is also used to check whether a flexible liner will pass down a flue. Any blockages, such as nesting birds, or debris can be identified and cleared before a liner is passed to prevent damage.

A coring ball test is a heavy ball, which is lowered on a rope from the top of the chimney to the bottom. If an obstruction is encountered, the area should be identified so the blockage can be removed and the test repeated.

 

 

Refuel Spillage Test

The refuel spillage test checks that smoke will not spill back into the room when the door is opened on a stove when adding fuel.

To carry out the refuel spillage test, we allow the appliance to reach its normal operating temperature before closing all external doors and windows. We then carefully open the appliance door and touch the tip of a smoke match to a burning ember in the firebox. The smoke match is then positioned 50mm above any flames in the centre of the firebox and two-thirds of the firebox depth in from the front.

Once the smoke is extinguished we then close the appliance door and repeat this test with all extraction fans running and internal doors and record the results for comparison.

 

 

4 PA Test

The PA test measures the differential pressure between the room where the fireplace is installed and the surrounding ambient air.

The Wöhler DP 600 Leakage Tester can perform the 4 Pa-test. The device sucks the theoretically required combustion air and simulates the fireplace whilst measuring the differential pressure.

To carry out the 4 PA Test, we need to switch on all mechanical fans and extractions and open an outside window or door. We then test the appliance to ensure that there are no backdraft conditions before leading the hose outside through a window seal or into the stairways through the door rebate or the keyhole. The second capillary hose will stay uncut in the fireplace room. We then start the machine to begin measuring.

To start recording, we open the window/door for about 30 seconds, so that the zero line can be registered, then close the window/door for about 30 seconds, before repeating the process for 4 minutes.

The 4 PA test is carried out in properties where fitted external air vents aren’t permitted such as heritage or listed properties. This data can be used to provide evidence that there’s enough combustion air. It can also be used as part of an investigation in a Carbon Monoxide incident as data is required to provide evidence.

 

 

 

As you can see, chimney sweeps have far more responsibilities than sweeping soot out of chimneys, so it’s important that you choose a reputable chimney sweep to carry out any work. It’s almost impossible to check the work of a chimney sweep, so it’s very important that you find one you trust.

 

If you need advice from a reputable chimney sweep or would like to book an appointment for any of the services above, get in touch today. Our friendly team would love to help.