Your rental property’s boiler FAQs: Answered by a Gas Safe engineer

We caught up with Adam Knight, one of BOXT’s Gas Safe registered engineers with over 18 years of experience, to answer the company’s most frequently asked questions from landlords. 

Let's get started.  

Hey Adam, great to meet you. Are new boilers tax-deductible?

Yes, most new rental property boilers are tax-deductible, provided they're a like-for-like replacement rather than a significant home improvement. However, it’s worth seeking professional tax advice before proceeding. 

Do I need a CO2 alarm?

By law, any room used as living accommodation with a fixed combustion appliance (like a boiler or gas fire) must have a carbon monoxide (CO) alarm. While gas cookers are excluded by law, it is recommended. 

How do I choose the right boiler?

This will come down to the number of bathrooms and radiators in your property. But as a rough rule of thumb: 

• 1-10 radiators with one bath or shower will require a 25kw boiler 

• 10-15 radiators with up to two baths or showers will require a 30kw boiler 

• 15-20 radiators with two or more baths or showers will require a 35kw boiler 

For more support, speak with our team of professional engineers. 

Is an annual boiler service a legal requirement for UK landlords?

Yes, all rental properties in the UK need their boiler servicing annually. In addition to keeping your tenant safe, this will keep your manufacturer's warranty valid and help you to spot any potential issues before they become more expensive to fix. 

If you’re considering getting a new boiler installed, BOXT is offering a free boiler Service Plan with every new installation purchased between 1st February 2026 and 31st March 2026, for your peace of mind. T&Cs apply* 

Do you have any advice for landlords who own multiple properties?

Yes, absolutely. From my years of experience installing and surveying boilers for landlords, I found that their biggest challenge is keeping track of which boilers in their portfolios have been serviced. BOXT has made this process much simpler with its customer app. The app allows users to browse through their properties, store essential documents for each boiler online, and provides annual reminders for upcoming service dates. 

If this sounds like something you'd be interested in, take a look at our monthly boiler Service Plan specifically for landlords. As part of this, they'll also review other gas appliances in your property, such as cookers or fires. And on successful completion, they'll issue your CP12 form, also known as your 'landlord certificate'. 

Save £75 when you upgrade your boiler with BOXT?

Just tap the button below to learn more. As a member of the NRLA, enjoy an exclusive £75 discount on any boiler installation with the code NRLA75**. And with the BOXT Price Match Promise*** you’ll always get BOXT’s best deal. 

*Service Plan is free for 12 months then automatically renewed at £8.99 a month for homeowners or £11.99 for landlords, unless cancelled. Offer ends 31st March, 2026. Terms and conditions apply. https://www.boxt.co.uk/boxt-free-boiler-service-plan-terms-conditions  

**Terms and conditions apply. For more information, visit https://www.boxt.co.uk/boilers/nrla. Please note that the offer cannot be used in conjunction with any other offers. There may be better promotions available - visit our www.boxt.co.uk to find the best deal for you. 

***For more information, please see https://www.boxt.co.uk/the-boxt-price-promise