We’ve put together a few posts about 3in1 bathroom units over the years … the benefits, the types, the style. This post, we focus on the things you need to consider when selecting your 3in1 unit, as well as some simple calculations to make sure you are getting the unit that is right for your space.
But first, let’s briefly revisit why 3in1 bathroom units can be beneficial.
Why install a 3in1 bathroom unit?
- It helps remove moisture, which has some of it’s own benefits, including, preventing your bathroom fogging up, keeping your bathroom free from odours caused by damp, and maintaining the structural integrity of your bathroom by not allowing damp to reside.
- It’s a space saving, cost effective, and convenient way of fulfilling all the needs of your bathroom – lighting, heating, ventilation. Most units also come with one control panel for all functions, so no more trying to find the right switch on the wall!
- It can warm you instantly on a cold morning, with most modern units using infrared instant heat lamps.
- Most modern units will provide energy efficient LED lighting.
- More recent models, while not designed to be a statement piece in your bathroom, do keep design in mind, with sleek styles that blend seamlessly into your décor.

What features of a 3in1 bathroom unit do you need to consider?
While 3in1 bathroom units are designed to be an energy efficient form of lighting, heating and ventilation, it’s important to remember that energy efficiency will be compromised if you are not selecting the unit that is the right size, and has the right functions, for your space. Too small an exhaust, and it will not pull moisture effectively, or too many heat lamps, for instance, can mean you are expending more energy than is necessary,
To make sure you are correctly selecting the 3in1 unit right for your space, there are a few simple steps you can follow.
1. Heating
Most 3in1 models come with either one of two heating configurations – 2 heat lamps, or 4 heat lamps. In most cases, as you would expect, models with 2 heat lamps would be sufficient for small bathrooms, while 4 heat lamps will provide better heating in larger bathrooms.
What is considered a small or large bathroom? A standard bathroom is thought to measure around 3.5m x 2.5m, while a small bathroom can measure around 3m x 2m. A 3in1 unit with 2 heat lamps would generally provide sufficient heating for these size bathrooms. A larger bathroom, by Australian standards, is generally anything around 4m 5m or above. In this case, we would suggest opting for a 3in1 unit with 4 heat lamps. These measurements are provided as a guide only, but give you an idea of where 2 or 4 heat lamp units will operate most optimally.

2. Lighting
Most 3in1 bathroom units are designed with the inclusion of LED lighting options. Some cheaper models will still come with older style halogen globes, but we would always recommend opting for the more energy efficient LED models.
The lighting provided by 3in1 units is generally a standard ambient light, designed to provide that overall general lighting for your bathroom, delivered by an energy efficient LED source. For additional lighting needs, such as task oriented lighting around your mirror, for instance, we would recommend something like vanity or wall lights, or even a well placed pendant light. You can read more about bathroom lighting options in our post 8 Tips for Planning your Bathroom Lighting.

3. Ventilation
The effectiveness of the exhaust fan is the most important element to consider when selecting your 3in1 bathroom unit. By effectiveness, we mean it’s ability to remove steam and moisture from the room.
3in1 units will come with what is called an “extraction rate” (usually measured in cubic metres per hour). This measurement is the amount of air the unit can extract. As expected, the amount of air a unit needs to extract will be less for smaller bathrooms, and more for larger ones.
There is, however, a way to calculate the extraction rate required for your bathroom, and the first step is to calculate the size of the room. This can be done with a simple calculation.
Length x Width x Height = total room size (in m3)
The next step is to work out how many “air changes” the room will need to achieve, to effectively dispel steam and moisture. An “air change” is when the exhaust fan extracts the full volume of air in the room. A good guide for a bathroom is around 15 air changes per hour. Nearly all 3in1 bathroom units will provide this measure of air change as a measure of it’s capacity in m3/hr.
Now that you have your room size in m3 and you know the approximate number of air changes you need in a bathroom, you can calculate the required capacity, or extraction rate, of your 3in1 unit, and this can again be done with a simple calculation.
Total room size (in m3) x 15 air changes = Capacity required (in m3/hr)
Please note, these calculations are taken from our experience, the experience of other professionals, and recommendations made by manufacturers, and are in no way definitive, but to be used as a guide only.

What other things should be considered in the selection of a 3in1 bathroom unit?
While, these won’t so much affect your selection of 3in1 unit, they will play a part in it’s effectiveness, and so, are things to keep in mind.
- Installation and placement of your unit is important. We would recommend not installing your unit directly above the shower, for instance, as it will have difficulty completing air changes. The better placement would be central to both steam and the entry of fresh air. Central placement will also improve the overall spread of ambient light, as well as warmth from the heat lamps.
- The temperature of water will also impact the amount and the temperature of steam created, and by association how effectively your 3in1 unit can dispel. In simple terms, hotter showers means more and warmer steam!
- Materials used in your bathroom can also be something to consider when looking at your unit’s extraction rate. Bathrooms with lots of tile, glass, stone, and the like, will often mean a greater amount of condensation as they tend to be “colder” surfaces. When warm moist air hits cold surfaces, it condensates.
- The climate you live in can also have an impact. A cooler climate, for instance, will generally mean hotter showers, and more steam. It will also mean the surfaces of your bathroom are cooler than in say warmer climates, and so will produce a greater amount of condensation.
And, if all that math was just too much, you can contact the experts at Rovert Lighting & Electrical! We carry a wide range of sizes, styles and designs of 3in1 bathroom units to meet your bathroom needs!