People living near the Alfer metal foundry owned by Baxi Heating, have been holding their noses but not their tongues and complained about foul smells coming from the Preston site.
In response to residents complaints, South Ribble Council sent environmental protection officers to the area and confirmed the source of the odour is coming from the Alfer foundry, used to cast moulds in aluminium for boilers.
The smell is created during the cooling down process, which takes place when aluminium moulds have been cast. This odour is then extracted through a roof stack.
Residents have complained of being unable to open their windows or go outside because of the smell.
A spokesman for Baxi said 'Baxi is currently completing investigations into reports of odour emissions from the aluminium foundry at its Club street site in Bamber Bridge. The company would like to reinforce the fact that any emissions would not be hazardous, and it will continue to work closely with local council officers to ensure a safe and comfortable environment is maintained'.
In line with pollution control requirements, the stack is regularly tested and the council keeps records of the results.
Councillor Carol Chisholm, cabinet member with responsibility for public health and housing, said: 'Our records show that Alfer's emissions are within national emission limits. We can confirm that this odour presents no danger to anyone, although we have advised Alfer that they will need to improve their extraction arrangements.'
'We will now write a formal letter to Alfer requesting that they tell us in writing what action they intend to take to rectify the odour issue.
'Once we have a response, we will be able to decide whether their course of action and the timescales they suggest are acceptable or whether further negotiation is required.'
Seven million boilers are sold in Europe every year to power domestic central heating systems. One in every ten boilers sold is manufactured by a Baxi Group company.