Can I Install A Combi Boiler In My Loft?

Can I install a combi boiler in my loft? A customer asked me this the other day so I thought that I’d write a blog post on the topic. A combi boiler is a combination of a high-efficiency water heater and a central heating boiler in one. Combi boilers are the most popular type of boiler that we install because they provide both heating and hot water directly from the mains. They don’t need a separate hot water tank, so they don’t take up much room.

If you’re reading this article, then you’re probably thinking about moving your boiler into your loft but you’re not sure whether or not you can. The simple answer is: yes, you can relocate your boiler into your loft space. However, there are some points that you should consider first before deciding either way.

This blog will hopefully give you some insight into what goes into installing a combi boiler into your loft.

The Main Things You Should Know:

1. Relocating Your Pipework

You will have to relocate your pipework from your original positioning of your boiler, to your loft. This may prove to be difficult depending on its location as it might result in you having to lift up floorboards or carpets to be able to redirect the pipes.

It can get even more complicated if your existing pipes are buried into the walls or inside concrete floors. If that’s the case, then it can get very messy (and time consuming) locating the existing pipes runs to the point where your walls will have to be chased and then plastered over and then repainted. If you’ve ever had any building work done at home, then you know how much dust and mess this kind of work creates.

Another point to consider when relocating your pipework is that you may have to run a new a waste pipe as it is unlikely your loft will be near the existing drainage system.

Boiler Pipe Work
Piping up a brand new boiler

2. Drilling A Hole For Your Flue

Depending on the size of the boiler, the flue must be positioned a certain distance away from the nearest door, window or air brick. You normally need to allow 30-60cm but the Gas Safe Registered Plumber that you’re using will know the rules and regulations. When installing a boiler in your loft, it is important that you have somewhere to fit a flue for your boiler. This may require you to drill a hole in the wall or roof to fit it and this can get expensive. The plumber will need access to your roof which could mean that you need to invest in a tower or sometimes even scaffolding. If you need to erect scaffolding on to the public pavement, you’ll need to request and pay for permits.

This all adds to the cost of installing a combi boiler into the loft of your home so must be considered.

Installing a New Boiler Flue Pipe
Installing a new boiler flue pipe

3. Regulating The Temperature In Your Loft

You should also consider the fact your combi boiler may be more exposed to extreme weather (both hot and cold) in your loft than in your kitchen. This means it will be very important to insulate your loft as in the winter, your boiler and pipes will have to deal with very cold temperatures which could cause frost damage. Most new boilers have frost stats built in but you may also need to install a separate frost thermostat if you choose a boiler which doesn’t have one.

On the other hand, in the summer your loft could become the hottest room in your house (due to the fact that heat rises), so you need to make sure you have good insulation or alternatively you could invest into an attic fan to help regulate temperature in the warmer months.

4. It May Take Longer For Hot Water To Reach Your Taps

Have you ever turned on a hot water tap and have had to wait a long time for the hot water to start coming through? This is normally the result of long pipe runs (or sometimes a blockage). If the hot water source is a located a long way from the hot water outlet (a tap or shower) then you need to wait for the hot water to travel that distance before it starts to come through the outlet. 20 seconds is a long time when you’re waiting to wash your hands!

It’s really important to consider the distance between your loft and your hot water outlets for convenience sake. The further away your hot taps are from your boiler, the longer it could take for your water to heat up. This may be inconvenient for you if your loft is far away from your bathroom and kitchen.

We’ve discussed key points that you need to consider when considering whether or not to move your boiler up in to the loft. Now let’s look at the pros and cons..

Pros Of Installing A Combi Boiler In Your Loft:

1. Space

The first obvious benefit of installing a combi boiler in your loft is the amount of space you will be saving in your home where you originally had your boiler positioned. Usually a boiler is installed in a kitchen and hidden within a kitchen unit or cupboard. So, moving the boiler means that you could potentially free up an entire cupboard. More room for storage!

2. Space (Again)

Another benefit of installing a boiler in the loft is that you have more space in your loft so can get away with installing a larger sized boiler. In some installations, we’ve had to change the boiler manufacturer and even size due to the fact that we didn’t have enough room to install it. Some combi boilers are big and bulky and stick out a lot as they have built in hot water storage tanks (check out the Vaillant ecoTEC Plus Combination Store 938 Gas Condensing Storage Boiler). So, you don’t have to worry about the size of the boiler as you probably won’t be restricted if you’re moving it into the loft.

3. Aesthetics

Another benefit is, by putting the boiler in the loft of your home, which is unlikely to be used that much, it means you won’t have to see all that horrible pipework that boilers come within your living space. Let’s be honest, as hard as we try to make the pipework look good it’s an awkward area to keep clean so will always look dusty over time. Having no pipes to clean will make your living space look more aesthetically pleasing.

Powerflush Installation Plumber in Dartford Kent
MultiPlumb install combi boilers in South East London & Kent

Cons Of Installing A Combi Boiler In Your Loft:

1. Cost

I went over this at the beginning of the article but one of the main drawbacks of Installing a combi boiler in your loft is the cost involved. You may need to spend more money than you were originally planning to as you may need to erect scaffolding or a tower so that the plumber can drill a hole for your flue in your roof. Moving the boiler means redirecting the pipework which will also add to the cost.

2. Performance

You also have to consider that performance may become an issue if your loft is far away from your kitchen and bathroom as your boiler will be further away from water outlets. This means there could be a slight delay in accessing hot water straight away.

3. Checking Pressure

It is less convenient when checking the boiler pressure if your boiler is in the loft as you will have to go all the way up there. However, it is possible to install a pressure gauge elsewhere in your home. You could also consider having a wireless room thermostat to control your settings from there.

4. Temperature Regulating

Another disadvantage is that it is necessary to keep your loft insulated to prevent damage to your combi boiler and pipework in extreme hot and cold temperatures. This could require you to spend even more money on good insulation, a frost thermostat or an attic fan. Regulating temperature in your loft for the boiler is very important as not doing so could affect its performance and even the guarantee.


Installing a combi boiler in your loft may prove to be more difficult and costlier than you originally thought it would be, so take the time to consider all points made above.

Having your combi boiler installed into your loft may be really convenient for you, especially if your loft isn’t too far away from your bathroom and kitchen. The extra space could be very useful to you and make your home look more aesthetically pleasing. Your loft conditions may in fact mean you won’t have to make many extra expenditures, for example if your loft is well insulated you won’t need to invest more money into making sure it is.

However, if you are on a budget, installing a combi boiler may prove to be a bit more difficult as you may end up spending more money than you had planned to. In this case, you should the take time to carefully plan your expenditures and see what changes you may have to make to your loft which could cost you extra.

Should I install my combi boiler in my loft?

Use this information as a guideline only but like I mentioned earlier, always consult an experienced, qualified Gas Safe Registered plumber to help you make the right decision for your home. It is not as simple as it sounds so leave it to us professionals!

Ask the plumber the right questions such as:

“Will my boiler performance be affected?”

“How difficult will it be to redirect my pipework?”

“How far away will my hot water outlets be from my new boiler position?”

“Is my loft insulated well enough?”

Asking these questions will mean that the plumber knows that you’ve done your research, so they won’t be able to misguide you in anyway. Make sure you have answered these before you come to a decision.

If you liked this blog post and found it useful I’d be grateful if you could help by sharing it with your friends and family on Twitter or Facebook.

If you have any questions feel to free to comment down below and I’ll answer them personally.

If you live in South East London or Kent and need some advice in terms of whether or not to install your boiler in your loft, then feel free to get in touch. We’d love to hear from you.

Richard Costello

Richard Costello, from Dartford in Kent, is the owner of MultiPlumb and has been involved in the plumbing industry installing bathrooms and boiler systems for over 15 years. If you have any questions or suggestions for future blog posts feel to get in touch at

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