Retrofitting an electric opener to a manual unit

What is actually in a retrofit opener kit

A typical kit contains four things. A chain or rod actuator in a housing that clips or screws to the sash head or the frame head. A bracket set that ties the actuator to the other half of the assembly. A low-voltage cable tail, usually running back to a control unit or transformer. And a control, either a wall keypad, a handheld remote, or a receiver that pairs with both.

What it does not contain is a supply. The transformer needs a mains feed, and that connection is work for a qualified electrician. It also does not contain anything that improves the sash, the glazing, the hinges or the perimeter of the unit. It adds a motor to whatever is already there.

Some ranges also offer an integrated version where the actuator disappears into the sash head rather than sitting proud of it. Those are usually factory-fitted options on a new unit rather than retrofit parts, which is worth knowing before you get attached to the neater look.

Finding out exactly which unit you own

Nothing can be ordered until the model and the size code are known, and guessing from the outside does not work. Every major manufacturer puts a data plate on the unit, normally on the top edge of the sash, visible when the window is rotated or swung open. It carries the type designation, the size code and the year of manufacture.

On VELUX units the plate is on the sash head and the code reads as a type such as GGL or GPL, followed by a size such as MK04 or SK06 and a glazing code. Fakro, Keylite and Roto all use their own conventions but put the same information in the same sort of place.

Photograph the plate. That single image answers the compatibility question in one step, and it is the first thing we ask for when somebody rings about a conversion. Without it, every conversation is speculative.

Age is the first filter, and it is a hard one

Manufacturers publish compatibility charts for their opener kits, and those charts have a cut-off. Kits are made to suit the frame and sash profiles currently in production and a defined run of earlier ones. Go back far enough and the fixing points, the sash head profile and the electrical architecture all differ, and no kit exists.

As a rough guide, a unit made in the last fifteen years is very likely to have a kit available. A unit from twenty-five or thirty years ago very likely does not, and the timber, the seals and the glazing on a window of that age are usually approaching the end of their working life anyway.

Where a unit falls in the middle, the data plate settles it against the manufacturer’s chart. There is no fudging this. A kit that was not made for the profile will not clamp to it properly, and forcing it produces a sash that binds.

Centre-pivot and top-hung take different kits

The two hinge arrangements load the actuator in different ways and are not interchangeable. A centre-pivot sash rotates about its middle, so the actuator has to push the top of the sash outwards while the bottom swings in, and the stroke required is short. A top-hung sash lifts its whole bottom edge away from the frame, so the actuator has to carry the weight of the sash through a longer stroke.

Kits are specified accordingly, and a top-hung kit is generally the more heavily built of the two. On the larger top-hung sizes some ranges require a twin-actuator arrangement, which doubles the cabling and the cost.

Where a unit is a combined type that can be used both ways, the kit is chosen for the mode it will actually be operated in, and the other mode is normally restricted to cleaning with the motor disengaged.

Flat-roof units are a different problem entirely

A flat-roof rooflight that lifts on parallel arms or a scissor mechanism is not the same proposition as a pitched roof window. On most flat-roof ranges the opening mechanism and the actuator are a single integrated assembly designed and built together, and there is no separate manual version of the same product to convert.

In practice this means a manual flat-roof vent, usually operated by a winder or a pole, rarely has a retrofit path. Where the manufacturer does offer one, it is model-specific and the parts come from them rather than from a general kit.

The honest answer for a flat-roof manual unit is often that conversion is not available and the choice is between living with the winder and replacing the unit with a powered one. We would rather say that at the first phone call than after a site visit.

Getting a supply into a ceiling that is already finished

This is the real cost of a retrofit, and it is not on the price of the kit. A new-build or refurbishment installation runs the cable while the ceiling is open, which is covered on wiring an electric rooflight at first fix. A retrofit has to get a cable to the same place through finished plasterboard and insulation.

There are usually three options. Through the loft void above, where one exists, dropping down beside the unit through a small opening that is made good afterwards. Along the underside of the ceiling in surface trunking or conduit, which is quick and cheap and visible. Or by lifting a small run of plasterboard along a line and reinstating it, which is the tidiest and the most disruptive.

In a converted loft with a warm roof build-up there is often no void to work in at all, and the cable has to run in the room. That is a conversation worth having before the kit is ordered, because it changes what the job looks like when it is finished.

Solar opener kits and the trade-off they buy

Several ranges offer a solar-powered retrofit opener: a small panel on the outside of the sash, a battery in the unit, and an actuator that draws from it. There is no cable and no electrician, which removes the whole problem described above.

The trade-off is real. The panel needs daylight on it, so a north-facing slope with a large tree over it will underperform. The battery is a consumable with a finite life and will need changing at some point in the unit’s service life. And the actuator on a solar kit is generally sized for the smaller and mid-range sashes rather than the largest.

Where the roof orientation suits it and the sash is not enormous, a solar kit is frequently the sensible retrofit answer purely because it sidesteps the cable. The wider case is set out on solar powered rooflights without a mains run.

What conversion does to the opening angle

A manual sash opened by hand or by pole goes as far as the friction hinges and the stops allow, which on many roof windows is a considerable angle. An actuator has a fixed stroke, and the powered opening angle is normally smaller than the manual one.

This surprises people who converted a unit specifically to get more air. The motorised angle is repeatable and controllable, and small angles are easy to hold, but the maximum is usually less than the sash could physically achieve on its hinges.

Check the published stroke and the resulting angle for the specific kit before ordering. If the reason for the conversion is escape provision or a large summer opening, that figure matters more than anything else in the specification.

Seals, hinges and what a motor exposes

A motor closes a sash to a fixed position with a fixed force every time. A person closes it until it feels shut. Those are not the same, and a tired gasket that a homeowner has been compensating for by leaning on the handle will start showing itself once a motor is doing the closing.

Before converting, look at the perimeter gasket for flattening, splitting or hardening, and at the hinges for play. Gaskets are replaceable items on most ranges and are worth renewing at the same time as the conversion, since the sash is coming into your hands anyway.

Where the timber round the glazing has gone soft, or the sealed unit has failed and is misting internally, a conversion is throwing good money after bad. That unit needs replacing, and the replacement can simply be ordered as a factory electric one.

Integrated blinds and pairing them afterwards

If there is already an electric blind on the unit, or one is wanted, the control side needs thinking about at the same time. Most systems will happily run a blind and an opener on the same remote or keypad, but only if they are from the same control family.

Mixing an opener from one manufacturer with a blind from another usually means two remotes and no possibility of a single command that closes both. That is liveable but irritating, and it is entirely avoidable by choosing the opener to match whatever control system is already on the unit.

Where a blind is being added later on the same visit, the sequence is straightforward and covered on electric blinds fitted inside the rooflight.

The electrician’s part of the work

The actuator and its control run at low voltage, and connecting the transformer or power supply unit to the fixed wiring of the house is electrical work that a qualified electrician carries out and certifies. We do not present ourselves as doing that part.

What we do is the rooflight side: assessing the unit, confirming the kit, fitting the actuator and brackets, setting the stroke and the end stops, and setting out where the cable has to arrive and where the transformer will sit so that it is accessible later. The two trades are sequenced so that nobody is waiting on the other and the roof is not left open at any point.

The wider question of who is required for what is dealt with on do electric rooflights need an electrician.

When replacing the unit is simply the better buy

Add up the kit, the cable route, the electrician’s time and the making good, and a retrofit on a large or awkward unit can approach the cost of a factory-built electric window fitted into the existing opening. At that point the comparison is not close.

A new unit brings current glazing performance, new seals, a fresh flashing kit, a manufacturer’s warranty on the whole assembly rather than on a bolt-on part, and an actuator designed into the sash rather than clamped onto it. It also resets the clock on the timber and the hinges.

The case for retrofit is strongest where the unit is recent, the glazing is good, the access for a cable is straightforward, and the sash is a mid-range size. It weakens on every count as those conditions fall away.

What a retrofit will not improve

It will not make the unit warmer. The U-value is a function of the glazing and the frame, and neither changes.

It will not make the unit quieter in rain, will not stop condensation forming on cold glass, and will not make a small window bigger. It will not correct a perimeter detail that was wrong when the unit went in, and if there is a wet mark on the ceiling near the unit, adding a motor is not the response to that.

It will not, on its own, add a rain sensor. Most kits offer one as an additional item and some ranges bundle it, but it is a separate component and worth confirming rather than assuming. What a sensor does and does not do is set out on rain sensors and what they actually do.

How a retrofit day runs

On a straightforward pitched-roof conversion the work is done from inside. The sash is opened and secured, the existing handle assembly or ventilation flap is removed where the kit requires it, and the actuator housing is fixed to the sash head with the manufacturer’s bracket set.

The cable is then run to wherever the transformer is going to live, which is chosen for accessibility rather than convenience on the day. The electrician makes the final connection and certifies it. The unit is then cycled through its full travel several times, the end stops are set so the sash closes onto the gasket evenly, and the controls are paired and tested from every position they will be used from.

Before we leave, the sash is checked for even compression on the gasket all the way round, the rain sensor is triggered if one is fitted, and the manual override is demonstrated to whoever will be living with it.

Guarantee, warranty and who stands behind which part

Two separate things cover a retrofit and it is worth being clear about the boundary. The kit itself carries the manufacturer’s warranty on the component, on their terms and for their period. Our ten-year workmanship guarantee covers the installation work: how the actuator is mounted, how the sash closes onto its seal, how any cable route through the roof build-up is detailed, and any perimeter work we carry out around the unit.

We do not guarantee the future performance of an existing unit we did not install. Where the sash, the glazing or the flashing is already marginal, we will say so before starting and put it in writing rather than absorb it silently into a conversion.

As with every job, the figures come in two stages: a range by email once we know the type designation and the ceiling situation, then a fixed price after a survey, when the cable route and the condition of the existing unit are known rather than assumed.