Building defects database - Flue: ventilation

Record details

Figure 4.41 This shows the kitchen extract fan and the only permanent air vent in the room. Already, I have a number of concerns: the extract fan is in the same room as an open flue; the air brick is close to extract fan - would the fan affect the supply of combustion air? Additionally, the kitchen is relatively small and contains the gas cooker. Imagine a cold winter’s evening when the boiler is going full blast, the oven and most of the gas rings are cooking a roast dinner and the occupants switch the fan on. How would these interact?
Figure 4.41 (a) The timber wall cupboard in this refurbished bathroom contains an older, room sealed, balanced flue, gas fired multipoint water heater - see (b). This is an older model and because of this, it is likely to need compartment ventilation. In this case, there is none. By itself, this does not make the installation dangerous, but it is below standard. This will reinforce the importance of checking whether it has been properly maintained. In this case, it has not.
Figure 4.41 (b) The multipoint water heater revealed. There is no ventilation to the compartment and not enough space around the casing for proper maintenance and repair.
Figure 4.41 (c) This is the outside view. The fan discharges through the upper airbrick and the PVC ventilator provides the permanent ventilation. In this situation, there are enough ‘trails of suspicion’. I would advise the client to get the system inspected and tested and not to use the boiler until this has been done.