Protecting people and Property
An emergency repair is one that is necessary to protect people or property.
If a reasonable person would get it fixed faster then its an unreasonable delay. But it also doesn’t mean Would they live with the problem until tradesmen and parts were available.
That doesn’t mean that, that it must be replaced that night.
Suppose a landlord is unreasonably slow or unwilling to do the work. In that case, the Residential Tenancies Act gives the tenant the authority to arrange for the repairs to be carried out by a tradesperson and seek reimbursement.