I told the seller what I needed the equipment for and it cannot do the job — is he liable even without a written warranty?

The warranty does not have to be written down

That is the point of calling it implied. Article 1562 provides that Where the buyer, expressly or by implication, makes known to the seller the particular purpose for which the goods are acquired, and it appears that the buyer relies on the seller's skill or judgment (whether he be the grower or manufacturer or not), there is an implied warranty that the goods shall be reasonably fit for such purpose. The absence of a warranty clause is therefore not the end of the enquiry, and neither is the seller's insistence that he only distributes what the factory makes: the parenthesis in the article removes that defence expressly.

Reliance is where the argument actually happens

Two elements have to be shown, and the second is the contested one. Making the purpose known can be done by implication, so describing the site, the load or the output you needed will usually do it. Reliance means you left the selection to him rather than specifying a model yourself. The evidence is ordinary commercial correspondence: the enquiry setting out what the machine had to do, the seller's recommendation of a particular unit, his technical proposal or sizing computation, any demonstration he arranged. A buyer who named the exact model against his supplier's advice has a much weaker case.

The second limb, and its neighbours

The article also implies a warranty of merchantable quality where goods are bought by description from a seller who deals in goods of that description. That is a lower standard than fitness for your purpose: it asks whether the equipment is fit for what such equipment is ordinarily for. Article 1564 adds that a warranty as to quality or fitness may be annexed by the usage of trade, and Article 1565 covers sales by sample, implying that goods from a dealer will be free from defects rendering them unmerchantable that would not be apparent on reasonable examination of the sample.

Choose your remedy, and mind the six months

Article 1567 gives you the election between withdrawing from the contract and demanding a proportionate reduction of the price, with damages in either case, so you are not obliged to return equipment you can still partly use. The timing is unforgiving: under Article 1571 actions arising from these provisions are barred after six months from the delivery of the thing sold. Do not spend that period in informal service calls. Put the failure in writing early, keep the commissioning and test records, and have the shortfall documented by someone who can explain it technically.

Related provisions

• Civil Code, Article 1562 — Implied Warranty of Fitness and Merchantability
• Civil Code, Article 1561 — Warranty Against Hidden Defects
• Civil Code, Article 1567 — Buyer's Options for Hidden Defects (Redhibition/Quanti Minoris)
• Civil Code, Article 1571 — Prescription of Warranty Actions (Six Months)