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Conservatory Radiators Don’t Work: Why Standard BTU Calculations
A conservatory can be one of the hardest rooms in the home to keep warm. Large windows, glazed doors, and glass or polycarbonate roofs can create much more heat loss than you'd expect from a typical brick-built room.
This is why you can use a BTU calculator, choose a radiator based on the result and still find your conservatory feels cold in winter.
The problem isn't always the radiator. It can be the way the room's heat loss has been assessed.
If you're looking for the best radiator for a conservatory, it's worth considering the glazing, roof, insulation and available wall space before choosing the radiator size and heat output.
Why Are Conservatories Difficult to Heat?
A typical bedroom or living room usually has a combination of insulated walls, a ceiling and a relatively limited amount of glazing. A conservatory can have much more of its external area made up of glass or polycarbonate.
The main factors affecting conservatory heat loss include:
- Large areas of glazing: Windows and glazed doors can lose heat differently from insulated walls.
- Glass or polycarbonate roofs: The roof can have a significant effect on heat retention, particularly in older conservatories.
- External exposure: Conservatories can have several externally exposed sides, increasing heat loss.
- Draughts: Older doors, frames and seals can allow cold air into the room.
For this reason, a conservatory shouldn't automatically be treated like a standard bedroom when working out its radiator size.
How Many BTUs Does a Conservatory Need?
A BTU calculator for a conservatory is a useful starting point, but the accuracy of the result depends on the information you provide.
Consider:
- Room length, width and height
- Total window and glazed door area
- Conservatory roof construction
- Number of external walls
- Insulation levels
- Whether the room is open to the main house
- How regularly the room is used
Our BTU Calculator can help you estimate the heat output required before choosing a radiator.
Don't automatically add a fixed percentage to the result. Every conservatory is different. A modern, well-insulated conservatory can have very different heating requirements from an older room with extensive glazing and a polycarbonate roof.
It's also important to compare radiator outputs using like-for-like specifications, as stated heat output can vary depending on the operating temperature used for the test.
Should You Simply Buy a Bigger Conservatory Radiator?
Not necessarily.
A larger radiator won't solve problems caused by poor insulation, draughts or an inefficient roof. At the same time, an undersized radiator may struggle to keep the room comfortable during colder weather.
A better approach is to:
- Calculate the required BTU/Watt output.
- Measure the available wall space.
- Check the radiator's stated heat output.
- Consider the glazing and roof construction.
- Choose suitable heating controls.
This gives you a better balance between heat output, comfort and running costs.
Alma Double Oval Vertical Designer Radiator 1600mm x 360mm Anthracite
In stock
- 🔥 BTU Output: 2798
- ⚡ Watt Output: 820
- 🛡️ Warranty: 5 Years
Alma Single Oval Vertical Designer Radiator 1600mm x 480mm Anthracite
In stock
- 🔥 BTU Output: 2357
- ⚡ Watt Output: 691
- 🛡️ Warranty: 5 Years
Aura 2 Column Horizontal Radiator 600mm x 1010mm Anthracite
In stock
- 🔥 BTU Output: 3273
- ⚡ Watt Output: 960
- 🛡️ Warranty: 5 Years
Aura 2 Column Horizontal Radiator 600mm x 1010mm White
In stock
- 🔥 BTU Output: 3273
- ⚡ Watt Output: 960
- 🛡️ Warranty: 5 Years
What Is the Best Radiator for a Conservatory?
Once you know the approximate heat output you need, the next challenge is finding a radiator that fits your room.
Conservatories often have plenty of glazing but limited uninterrupted wall space, so the radiator's shape can be just as important as its output.
Vertical Radiators for Conservatories
A vertical radiator for a conservatory can be a practical choice when you have only a narrow section of wall between windows or glazed doors.
Using height rather than width makes vertical models particularly useful for:
- Conservatories with large windows
- Rooms with bifold or glazed doors
- Narrow sections of solid wall
- Smaller conservatories
- Modern extensions with limited wall space
Browse our Vertical Designer Radiators if you're working with a narrow wall.
Horizontal Radiators
If you have a longer uninterrupted wall, a horizontal radiator may be the simpler option.
They can work particularly well along the solid wall connecting the conservatory to the main property or beneath a suitable window.
Browse our Horizontal Designer Radiators to compare different sizes and styles.
Column Radiators
For traditional conservatories and period-style interiors, column radiators can combine useful heat output with a classic appearance.
Explore our Column Radiators, including 2 Column Radiators and 3 Column Radiators.
Conservatory Radiators
If you're specifically looking for a radiator for a conservatory, our Conservatory Radiators collection is a useful place to start.
Once you know the required output and maximum available dimensions, you can narrow down the styles and sizes that suit your room.
What If Your Conservatory Has a Glass Roof?
The roof can have a major effect on how comfortable the room feels.
If your conservatory remains cold even when the radiator is running, look at the whole room rather than immediately buying a larger radiator.
Check:
- Roof insulation
- Window and door seals
- Glazing performance
- Draughts
- Radiator output
- Airflow around the radiator
If you're planning a conservatory roof replacement or insulation upgrade, reassess the heating requirement afterwards. Improving the thermal performance of the room can change the amount of radiator output required.
Aura 2 Column Horizontal Radiator 600mm x 1100mm Raw Metal
In stock
- 🔥 BTU Output: 3393
- ⚡ Watt Output: 994
- 🛡️ Warranty: 5 Years
Aura 2 Column Horizontal Radiator 600mm x 830mm White
In stock
- 🔥 BTU Output: 2893
- ⚡ Watt Output: 848
- 🛡️ Warranty: 5 Years
Aura 3 Column Horizontal Radiator 600mm x 650mm Anthracite
In stock
- 🔥 BTU Output: 2842
- ⚡ Watt Output: 833
- 🛡️ Warranty: 5 Years
Luna Single Flat Vertical Designer Radiator 1600mm x 376mm Anthracite
In stock
- 🔥 BTU Output: 2001
- ⚡ Watt Output: 586
- 🛡️ Warranty: 5 Years
Can You Heat a Conservatory with a Radiator?
Yes. A correctly sized radiator can provide effective heating in a conservatory when it is suitable for the heating system and the room's heat requirement.
A central heating radiator can be suitable where the conservatory is connected to your home's central heating system. If you want independent heating, an electric heating option may also be worth considering.
The best choice depends on the construction of the conservatory, the existing heating system and how you use the room.
How Can You Make a Conservatory Easier to Heat?
Before replacing your radiator, consider whether you can reduce heat loss from the room itself.
Improve draught-proofing: Check doors, windows and seals for noticeable draughts.
Improve roof insulation: An older conservatory roof can contribute significantly to heat loss.
Upgrade glazing: Modern glazing can improve thermal performance compared with older installations.
Use thermostatic control: A suitable radiator valve can help regulate room temperature.
Keep the radiator clear: Avoid placing furniture directly in front of it and always follow the manufacturer's recommended clearances.
Luna Single Flat Vertical Designer Radiator 1600mm x 376mm White
In stock
- 🔥 BTU Output: 2001
- ⚡ Watt Output: 586
- 🛡️ Warranty: 5 Years
Luna Single Flat Vertical Designer Radiator 1600mm x 452mm Anthracite
In stock
- 🔥 BTU Output: 2254
- ⚡ Watt Output: 661
- 🛡️ Warranty: 5 Years
TRH Best Double Vertical Designer Radiator 1800mm x 375mm Textured Anthracite
In stock
- 🔥 BTU Output: 4298
- ⚡ Watt Output: 1260
- 🛡️ Warranty: 5 Years
TRH Keyworth Vertical Radiator 1800mm x 450mm Matt Black
In stock
- 🔥 BTU Output: 3685
- ⚡ Watt Output: 1080
- 🛡️ Warranty: 5 Years
How to Choose the Right Conservatory Radiator
Before ordering, check these five things:
1. Calculate the required heat output
Use your room dimensions and construction details to establish a sensible BTU/Watt target.
2. Measure the available wall space
Check the maximum height, width and depth available before choosing a model.
3. Consider the glazing and roof
Large glazed areas and less-insulated roofs can increase heat loss.
4. Choose the right radiator shape
Vertical models are useful where wall width is limited, while horizontal models suit longer walls.
5. Compare actual heat output
Two radiators with similar dimensions can produce different amounts of heat, so check the product specification rather than choosing by size alone.
Frequently Asked Questions
Why is my conservatory cold even when the radiator is on?
Large areas of glazing, poor roof insulation, draughts or insufficient radiator output can all contribute to a cold conservatory. Check the room's overall heat loss rather than simply increasing the radiator size.
What size radiator do I need for a conservatory?
There is no standard radiator size. The required output depends on the room dimensions, glazing, roof, insulation and external exposure. Use a BTU calculator as a starting point, then choose a radiator that provides the required output and fits your available wall space.
How many BTUs does a conservatory need?
It depends on the size and construction of the conservatory. A heavily glazed room can require more heat than a similarly sized, well-insulated room. Our BTU Calculator can help estimate the required output.
What is the best radiator for a conservatory with lots of glass?
A vertical radiator can be particularly useful where there is limited solid wall between glazed panels. If you have a longer uninterrupted wall, a horizontal radiator may be more suitable.
Are vertical radiators good for conservatories?
Yes. They make good use of narrow wall sections, which are common in conservatories. However, the radiator still needs to provide sufficient heat output for the room.
Can I use a column radiator in a conservatory?
Yes, provided it is compatible with your heating system and provides the required heat output. Column radiators can work particularly well in traditional-style conservatories.
Does a glass roof affect radiator sizing?
Yes. The roof is an important part of the conservatory's overall heat-loss profile. Glass and polycarbonate roofs can perform differently from properly insulated solid roofs.
Should I buy the biggest radiator that fits?
No. The aim is to choose a radiator with the appropriate heat output. Simply buying the largest model won't necessarily solve problems caused by poor insulation, glazing or draughts.
Can I use central heating in a conservatory?
Yes. A conservatory can be heated using a central heating radiator when the radiator and heating system are appropriately designed and installed.
What can I do if my conservatory is still cold after fitting a new radiator?
Check the radiator's actual heat output, roof insulation, glazing, draughts and airflow around the radiator. If the room has been altered since the original calculation, such as through a roof or glazing upgrade, recalculate the heating requirement.
Find the Right Conservatory Radiator
A conservatory isn't simply a normal room with a few extra windows. Glazing, roof construction, insulation and external exposure can all affect how quickly it loses heat.
The best approach is to calculate your approximate heat requirement first, measure your available wall space, and then choose a radiator based on its actual heat output.
Explore our Conservatory Radiators, or compare Vertical Designer Radiators, Horizontal Designer Radiators and Column Radiators.
Before choosing a size, use our BTU Calculator to get a useful starting point for your conservatory heating requirements.
