Buying Replacement Parts Online: How to Check You Have the Right One

Trade parts are some of the best value in surplus stock. Valves, cartridges, sensors, filters, springs and service kits often come from cancelled orders, overstocked wholesalers and business closures, new and boxed at a fraction of the trade price. The catch is that they have to be exactly the right part. Here is how to make sure.

Start with the part number, not the photo

Many parts look identical and are not. Two valves can share a body and differ in thread, pressure rating or voltage. Two shower cartridges can look the same and fit different valves.

The most reliable way to match a part is by its number. Most manufacturers use one of these:

• MPN (manufacturer part number) — the maker's own reference, usually printed on the part, its label or its box.
• Model or series number — identifies the product family, but on its own may not pin down the exact variant.
• EAN or barcode — identifies the exact retail product, size and pack quantity.

If you can, take the number from the old part or the equipment's manual, and match it character for character. Small differences, a suffix letter or an extra digit, often mean a different specification.

Where to find the number

• On the old part. Stamped, etched or on a label. Clean it gently if it is hard to read.
• In the manual or parts list. Exploded diagrams list every part with its number.
• On the equipment's rating plate. For machinery and appliances, the model and serial number lead you to the right parts list.
• From the manufacturer. Most will tell you the right part number if you give them the model and serial number.

Check the details that matter

Once the part number matches, a few details are still worth a second look:

• Voltage and frequency for anything electrical, such as solenoids, motors and controllers.
• Thread type and size for fittings and valves. UK, European and US threads differ.
• Pressure and temperature ratings for anything carrying air, water or gas.
• Pack quantity. A listing for springs or seals may be for one, or for a pack.
• Superseded numbers. Manufacturers sometimes replace a part with a new number. The new one usually fits, but check.

New, surplus or used?

Surplus parts are usually new and unused, often still in the maker's packaging. They are cheap because a business over-ordered or closed, not because anything is wrong with them. Used parts can be fine for some jobs, but for anything safety-related, such as gas, pressure or brakes, buying new and fitting through a qualified person is the sensible choice.

A word on fitting

Some parts are a straightforward swap. Others, particularly anything involving gas, mains electrics, pressure systems or vehicle safety, should be fitted by someone qualified. Buying the right part is only half the job.

Browse trade parts

We list surplus trade parts with the manufacturer's part number in the title wherever it is known, so you can match them before you buy. Most sit in business, office and industrial, home, furniture and DIY and vehicle parts and accessories. If you cannot tell whether a part fits, send us the number and we will check what we can.