Replacing Undermount Drawer Runners: A Compatible Replacement for Alno Kitchens (System 32)
An undermount runner is fitted concealed beneath the drawer base and typically uses System 32 for fixing inside the cabinet carcass.
When repairing or modernising older fitted kitchens, such as models from Alno, replacing the drawer mechanism is a common task for the fitter. The runner is the running gear of the drawer – when mechanical parts wear out after years under load, the only solution is a professional replacement of the runner slides. Because many kitchen manufacturers rely on standardised hole patterns, swapping them over is straightforward with accurate measurements.
This technical guide takes you through the removal of the old runners, measuring for the correct replacement part, and the installation and adjustment of the new components.
Difficulty level: Intermediate (basic technical understanding required) Time required: approx. 15 - 25 minutes per drawer
Required Tools and Materials
No specialist tools are required to replace the runners. Standard fitter equipment is sufficient:
- Cordless screwdriver or manual screwdriver with cross-head drive (PZ 2)
- Folding rule or tape measure (readable in mm)
- Bradawl (if new fixing points need to be marked in the carcass)
- New Undermount drawer runners
- Suitable chipboard screws (typically 3.5 x 16 mm or 4 x 16 mm, countersunk)
Preparation: Determining the Correct Replacement
Before installing the new runners, the exact specifications of the existing drawer must be established. An incorrect nominal length or incompatible kinematics will result in the drawer box not closing or incorrect gap alignments.
1. Measure Nominal Length and Installation Depth
The nominal length (NL) describes the length of the runner itself. It is measured from the rear edge of the front fascia to the back wall of the drawer. Standard dimensions in kitchen cabinets range from 400 mm to 550 mm. The clear carcass internal depth (installation depth) must always be at least 3 mm to 5 mm greater than the nominal length of the runner.
2. Define the Extension Type
A distinction must be made between two extension types. A single extension extends to approximately 75 % of its length. The rear section of the drawer remains inside the carcass. A full extension, on the other hand, allows access to 100 % of the drawer contents. Upgrading to Drawer runners full extension is straightforward during replacement, provided the nominal length matches.
3. Mechanism: Soft-Close vs. Push-to-Open
These two mechanisms are mutually exclusive in their pure form and must not be confused when ordering:
- Drawer runners with soft-close (Soft-Close): An integrated damper decelerates the drawer over the final few centimetres and pulls it shut smoothly and silently.
- Drawer runners push to open (Tip-On): A spring mechanism pushes the handleless drawer open when pressure is applied to the front.
4. Consider Load Capacity
For standard cutlery drawers, a dynamic load capacity of 30 kg is sufficient. However, for a wide pull-out holding heavy pots or stacks of plates, Heavy duty drawer runners with a load capacity of 40 kg to 50 kg should be selected.
Step-by-Step Guide: Replacing Undermount Runners
Step 1: Remove the Drawer
Pull the drawer out fully. Reach underneath the drawer base, directly behind the front fascia. The locking clips (usually made of plastic) are located there. Press the levers on the clips inwards or outwards on both sides (depending on the model), lift the drawer slightly, and pull it forwards off the runners.
Step 2: Remove the Old Runners
Loosen the chipboard screws securing the old carcass runners to the side walls. Note which holes in the runner the screws were located in, so you can maintain the vertical position for the new runners.
Step 3: Carcass Inspection and Hole Pattern Check
Most kitchen cabinets, including those from Alno, use System 32. This means:
- The distance between drilling centres is exactly 32 mm.
- The diameter of the pre-drilled holes is 5 mm.
- The frontmost hole is positioned 37 mm from the front edge of the carcass as standard.
Check whether the drilled holes are stripped. If this is the case, the new runners must be screwed into adjacent, intact holes in the system line.
Step 4: Mount the New Carcass Runners
Position the new runners against the carcass wall. The front edge of the runner aligns with the 37 mm dimension. Fasten the runner in the frontmost hole first. Align the runner horizontally and fix it in the rear third. Use at least three to four screws per runner (front, centre, rear) to ensure proper load distribution. Ensure the screw head (countersunk) sits flush within the metal of the runner, as protruding heads will obstruct the running profile.
Step 5: Replace the Locking Clips on the Drawer
Because locking systems vary by manufacturer, the new clips supplied must be fitted under the drawer base.
- Turn the drawer upside down.
- Unscrew the old clips in the front corners.
- Position the new clips precisely in the 90-degree corner between the front fascia and the side wall.
- Screw them firmly into place.
Step 6: Insert the Drawer
Pull the carcass runners in the cabinet out completely. Place the drawer horizontally onto the runners and push it back smoothly until the clips audibly engage into the runner pins with a 'click'.
Step 7: Adjust the Gap Alignment
Modern undermount runners offer extensive adjustment options directly on the front locking clips to align the front fascia gap perfectly with neighbouring Kitchen cabinet pull outs.
- Height adjustment: A small slider or thumbwheel on the clip allows the front to be raised by approx. +2 mm to +3 mm.
- Side adjustment: On many models, the drawer can be shifted approx. +/- 1.5 mm to the left or right.
- Tilt adjustment: On tall drawer fronts, there is often an additional lever at the rear of the runner to correct the tilt of the front fascia.
Specific Kitchen Cabinet Widths
During installation, the carcass width is relevant for pull-out stability, but not for runner selection (runners are determined solely by depth). Whether working with a narrow Kitchen cabinet pull out 30 cm for spices, a standard Kitchen cabinet pull out 50 cm, or a wide Kitchen cabinet pull out 60 cm for cookware: the installation of the undermount runner on the side panels remains identical. Only with very wide pull-outs of 800 mm or more is the use of an additional side stabiliser (synchronisation rod) recommended to prevent racking when opening from one side.
Avoiding Common Installation Mistakes
- Incorrect setback: If the runner is not installed exactly 37 mm from the front edge, the front fascia will not sit flush with the carcass. It will either protrude or hit the cabinet frame prematurely.
- Confusing runner types: An undermount runner cannot simply be replaced with a side-mounted ball bearing runner. The timber dimensions of the drawer (internal clearance) are calculated differently for undermount systems. Switching runner types requires a completely new timber drawer box.
- Oversized screws: Using 5 mm diameter screws in holes intended for 3.5 mm will damage the runner and obstruct the rollers inside the profile.
- Failing to clean: Wood shavings that fall into the runner tracks during pilot drilling will permanently damage the plastic rollers. Always vacuum or blow out the runner before inserting the drawer.
FAQ – Frequently Asked Questions
Can I replace roller runners with undermount runners? No, this is not possible without modifying the timber components. Drawer runners roller runner are mounted on the side or bottom edge and require approx. 12.5 mm of space per side. Undermount runners sit beneath the base, and the drawer side panels conceal the runner. The carcass and drawer dimensions are not compatible.
What should I do if the soft-close mechanism no longer works? When Drawer runners with self closing no longer dampen over the final few centimetres, the oil-filled damping cylinder in the runner is usually defective (leaking) or the tension spring has snapped. Repairing the cylinder is not possible; the runner must be replaced completely.
Which screws do I need for System 32? For the 5 mm drill holes in System 32, dedicated Euro screws (6.3 x 13 mm) are often used. If the runner only features small holes (approx. 4 mm), standard chipboard screws (3.5 x 15 mm) must be used. In this case, do not screw into the large 5 mm holes as the screw will have no grip; new pilot holes must be drilled in the wood.
Related Categories and Products
For further components relating to professional cabinetmaking and kitchen fitting, explore the relevant product sections:
- Drawer systems
- Kitchen cabinet pull out 40 cm
- Kitchen cabinet pull out 20 cm
- Kitchen cabinet pull out 15 cm