DANGERS OF CARBON MONOXIDE IN TINY SPACES

The lack of air space in tiny spaces, especially where there’s a stove present actually increases the potential dangers of carbon monoxide (CO) should any unfortunately escape from the stove. It is vital therefore that a good quality CO alarm is permanently installed where it can best detect this poisonous gas. Always follow the manufacturer’s instructions and do not do what many people do, simply prop it up in a corner. Recently the consumer magazine Which? found that many CO detectors for sale on a well known auction site were not fit for purpose, with some failing to work at all. We would always strongly recommend buying a CO detector from Honeywell or fire Angel.

ALWAYS BURN THE RIGHT FUEL

One of the best ways to ensure an efficient well-performing stove that gives out great heat and reduces the potential for CO escape, is to use fully seasoned wood with a moisture content of less than 20%. Foraging for wood is a great way of keeping heating costs down but you must always ensure that the wood that you burn is fully seasoned, in other words, very dry. It needs to clack when you knock two logs together or crack when you snap smaller branches. The best way to ensure that the wood that you use is properly seasoned is to make a small investment in a wood moisture meter. Check out the BurnRight website here for more information www.burnright.co.uk.

REGULAR SWEEPING

Just because your shepherd hut or shed is off grid in the middle of nowhere, this should be no excuse for ignoring the basic safety assurances that having your stove and chimney regularly swept can provide for you. Depending on the frequency of use this should be a minimum of once a year if you burn fully seasoned wood but it’s always worth checking how your fuel choice and flue are performing by checking the flue, preferably via an inspection hatch in the connecting flue or by dropping down the baffle in the stove and inspecting the flueway (the entrance to the flue above the baffle). It should be easy to learn how to safely sweep your flue yourself, especially if you have a relatively short flue.

ATTENTION TO DETAIL

For future reference information about the stove (nominal heat output etc) and other aspects about the performance capabilities of the flue and hearth etc should be detailed in a permanently fixed durable notice plate near the stove.

COMMISSIONING: IMPORTANT SPILLAGE TESTS FOR STOVES IN TINY SPACES

The chances are that it won’t be practical to meet the building regulations’ requirement for a full height flue with a minimum height of 4.5m (15’) from the top of the stove in a temporary structure and you’ll end up with a flue that’s smaller. That’s not so much of a problem if you have a specialist stove with a 100mm (4”) diameter flue outlet which will require significantly less height to deliver sufficient updraught. However, flues with a bigger diameter of 125mm (5”) are going to be more problematic and you should always aim for a flue with a height as close as possible to 4.5m (15’). As previously stated a stove with a 150mm (6”) flue outlet is likely to have a heat output which would much greater than that required for temporary structures and will also need a much higher flue to ensure the safe removal of the combustion gases.

Reduced flue heights, whether they’re 100mm or 125mm diameter, are inevitably going to affect the performance of the flue draught, especially in adverse weather conditions. Poor updraught will allow smoke and combustion gases to escape into the tiny space, particularly when lighting and possibly when refuelling the stove. This could also mean that before all of the fuel has burned away the updraught could become ineffective possibly leading to smoke spillage. It is vital therefore that the installer performs the standard spillage tests below and takes any remedial action required to ensure that any issues are resolved before ‘signing off’ the installation.

BS8303 (2018) SPILLAGE AND INTERFERENCE TESTS

Below is a synopsis of the BS8303 spillage tests that all stove installations should undergo before it goes into general operation. These tests are especially important for stoves installed in tiny spaces which, because of the nature of the installation and likely reduced flue height, can exacerbate potential issues with smoke release into the room.

TEST 1 Cold Conditions Spillage Test

This test is used to determine that a suitable flue draught has been established in line with the stove manufacturer’s requirements which will ensure that during the start-up operation, as well as refuelling, spillage does not occur.

1. Close the door and any windows, as well as any internal door(s) to the space the stove is located in and ensure all closable ventilators (eg window trickle vents) are closed and if there are any devices that extract air from the space ensure that these are also turned off.
2. Preheat the flue to establish a sufficient updraught by either lighting a small fire burning kindling or using a blow torch or electric fan heater.
3. Ensure that the stove’s air-controls set to the maximum combustion air open position. Light a smoke pellet (preferably 5m3/30 sec) and place inside the stove firechamber and shut the stove door.
4. Check that all of the smoke enters the flue and none of it enters the room through any part of the stove, its connecting flue pipe or the external air supply duct joint.
5. Note: If smoke does enter the room then repeat stage 2 above. However, this time build a much greater kindling fire, or significantly increase the time the blow torch is used to warm the flue so that an improvement in the flue draught is generated. Again, light a smoke pellet and place inside the stove firechamber and close the stove door.
6. If the second spillage test still fails, then progressively open a window in the space where the stove is installed. If the flue starts to draw the smoke, then this will indicate that the stove has not previously been provided with sufficient air for the flue to function correctly and therefore a permanently open air vent, as specified in Document J (or equivalent), may be necessary to correct the problem. When the air supply has been corrected then repeat the previous tests.
7. If smoke continues to spill after opening a window, this would indicate a more serious problem (for example a flue of insufficient flue height) which must be rectified and then the commissioning process repeated.

TEST 2 Hot Conditions Spillage Test (Refuelling)

This test requires a smoke match / pen and is used to determine that the flue draught is consistent between cold and hot operation.

1. Once the initial flue draught has been verified as sufficient, light a good sized fire in the stove according to the instructions in the manufacturer’s handbook, using the recommended fuel load and air control position(s). Allow the stove to reach normal operating temperature before refuelling.
2. Close the door and any windows, as well as any internal door(s) to the space the stove is located in and ensure all closable ventilators (eg window trickle vents) are
3. closed and if there are any devices that extract air from the space ensure that these are also turned off.
4. Open the stove door, and with a smoke match / pen (15 second burn time), pass over the top and sides of the firechamber opening and observe and record if the smoke / combustion products are drawn into the chimney or spill back into the room. Once the smoke match / pen is extinguished, close the appliance door.
5. Next, if appropriate, open any internal doors which interconnect the room in which the stove is installed to spaces where any extraction fans are present and turn these on to the maximum setting and allow to run for ten minutes. Repeat the smoke match / pen test at 3 above and observe and record if the smoke / combustion products are drawn into the chimney or spill back into the room.
6. If this spillage test fails, then progressively open a window in the room where the stove is installed. Again using a smoke match / pen observe and report If the flue starts to draw the smoke, then this will indicate that the stove has not previously been provided with sufficient air for the flue to function correctly and therefore a permanently open air vent’, as specified in Document J or equivalent regulations, may be necessary to correct the problem. When the air supply has been corrected then undertake the same test.
7. Fit an appropriate flue draught testing device to the connecting flue pipe and re-light the fire as previously. Repeat the test(s) in points 1 – 4 above. Check that the flue pressure meets the stove manufacturer’s minimum requirements.

TEST 3 Extraction Test

This test requires a flue draught / temperature gauge. This test is to ensure that the stove manufacturer’s recommended operational flue draught pressure for this stove is met. In some cases spillage can still occur, so it is important to carry out other essential smoke spillage tests as outlined above.

1. Fit a flue pressure and flue gas temperature testing device to the connecting flue or in the position indicated by the stove manufacturer.
2. Close all external doors and windows, as well as the internal doors to the room the stove is located in and ensure all closable ventilators (eg window trickle vents’) are shut and any devices that extract air from the dwelling are also turned off.
3. Light the appliance and ensure the optimum operating temperature is reached according to the stove manufacturer’s instructions.
4. Record the flue draught and the flue gas temperature and confirm that these are within the stove manufacturer’s recommended parameters.
5. Next, if appropriate, open any internal doors which interconnect the room in which the stove is installed to spaces where any extraction fans are present and turn all of these on to the maximum setting and run for ten minutes. Record the flue draught and the flue gas temperature. These should not be lower than the previous readings obtained without the extract system(s) running and should not fall below the manufacturer’s safe minimum pressure recommendations.
6. Once the tests confirm the satisfactory operation, remove the test device and if required seal any test point aperture in the flue pipe.

Please note that if at any stage during commissioning the flue draught reading taken differs from the stove manufacturer’s recommended minimum, then action should be taken to improve the updraught before proceeding with further testing.

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