How to Bleed a Radiator & Why It's Essential
By: Nick Geary
Updated: 30th October 2024
Every family needs to bleed their radiators from time to time to keep their central heating running as efficiently as possible and keep those bills down. Here’s how to get it done properly.
When to bleed a radiator
It is quite easy to tell when a radiator needs bleeding as the top section will remain a lot cooler than the bottom section, or in severe cases the entire radiator will stay cold when the heating system is turned on. This happens because trapped air displaces the hot water that normally heats the radiator.
This air gets released when you bleed your radiator. The hot water will be able to flow freely when the air is released.
Sounding a bit too technical already? Boiler Guide has a network of Gas Safe engineers all over the country who can help. Complete our form and get quotes from engineers in your area who can test your heating system and bleed your radiators.
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Brilliant service. Was getting a headache from other plumbers with extortionate prices. Saves a lot of hassle ringing around. Really pleased. Thank you.
Berni Byrne
This was the hassle free way of finding a boiler company in my local area for a quote. I recieved 3 quotes and I was very satisfied. The job is complete and I'm now saving on my usage. I would highly recommend using Boiler Guide.
Mr Neil Cutsforth
Boiler Guide is the go-to to find the best boiler at a reasonable price and good installer. The experience has shown me to do your research properly when you are thinking of spending a lot of money. Boiler Guide was in touch to check if I found an installer. Thank you Boiler Guide
Shirley Feshitan
Brilliant service. Was getting a headache from other plumbers with extortionate prices. Saves a lot of hassle ringing around. Really pleased. Thank you.
Berni Byrne
This was the hassle free way of finding a boiler company in my local area for a quote. I recieved 3 quotes and I was very satisfied. The job is complete and I'm now saving on my usage. I would highly recommend using Boiler Guide.
Mr Neil Cutsforth
Submitted my request and I received a phone call within 30 minutes to confirm what I needed. Received a list of potential installers the next day who all rang me and arranged a time to come round. Great service and it saved time which I didn't have as my boiler had stopped working.
K Patel
I was very impressed with this service. Within an hour of completing the form online I had a phone call from an advisor who confirmed that I would like to proceed. In the next two hours I had made appointments with three companies, all of whom have now been and given their quotations, within 48 hours of deciding to get a new boiler. We have proceeded with one of these companies and now have a date for installation. Excellent.
Steve W
Boilerguide emailed me 3 potential companies and within minutes one called me and visited my home and gave me a quote which i accepted and i'm having a new boiler installed within a few days i'm delighted with the result thank you boilerguide
Ted Billingham
Submitted my request and I received a phone call within 30 minutes to confirm what I needed. Received a list of potential installers the next day who all rang me and arranged a time to come round. Great service and it saved time which I didn't have as my boiler had stopped working.
K Patel
I was very impressed with this service. Within an hour of completing the form online I had a phone call from an advisor who confirmed that I would like to proceed. In the next two hours I had made appointments with three companies, all of whom have now been and given their quotations, within 48 hours of deciding to get a new boiler. We have proceeded with one of these companies and now have a date for installation. Excellent.
Steve W
Boilerguide emailed me 3 potential companies and within minutes one called me and visited my home and gave me a quote which i accepted and i'm having a new boiler installed within a few days i'm delighted with the result thank you boilerguide
Ted Billingham
Submitted my request and I received a phone call within 30 minutes to confirm what I needed. Received a list of potential installers the next day who all rang me and arranged a time to come round. Great service and it saved time which I didn't have as my boiler had stopped working.
K Patel
An easy to use website. Boiler guide gave me all the information I needed to choose a reliable company to remove and install my new boiler even although it was Christmas week. I would highly recommend anyone to check out boiler guide if they're looking to replace a boiler or radiators.
Margaret Arbuckle
Boiler Guide were excellent. I was already stressed having just been told my boiler was beyond repair, no idea of cost. Boiler guide made it all much easier, located people local to me and trusted to give me quotes. Really took some of the stress away from searching online myself. Highly recommended. Thank you
Julie Walker
Boiler guide is an excellent, quick & easy way to source businesses to provide quotes to have boiler replaced.
Sandra Emmerson
An easy to use website. Boiler guide gave me all the information I needed to choose a reliable company to remove and install my new boiler even although it was Christmas week. I would highly recommend anyone to check out boiler guide if they're looking to replace a boiler or radiators.
Margaret Arbuckle
Boiler Guide were excellent. I was already stressed having just been told my boiler was beyond repair, no idea of cost. Boiler guide made it all much easier, located people local to me and trusted to give me quotes. Really took some of the stress away from searching online myself. Highly recommended. Thank you
Julie Walker
Boiler guide is an excellent, quick & easy way to source businesses to provide quotes to have boiler replaced.
Sandra Emmerson
An easy to use website. Boiler guide gave me all the information I needed to choose a reliable company to remove and install my new boiler even although it was Christmas week. I would highly recommend anyone to check out boiler guide if they're looking to replace a boiler or radiators.
Margaret Arbuckle
Super efficient in finding 3 local firms to quote. All 3 got in touch the same day to arrange appointments and all 3 came within the next day. Great to be able to compare products and prices and I signed up with the best for me straight away
Joanne Barlow
Obtained names of 3 installers in my area, all of whom responded and visited very promptly. All 3 very professional, polite and gave estimates at time of visit, followed up by e-mailed quotes. Also answered my questions at time of visit and subsequently via e-mail. Found Boiler Guide very helpful in reducing time that might have been wasted trawling through local lists.
Lindsay Nicoll
The guys that came round were very professional and polite told us everything we needed to know and left the area spotless thanks
S Harding
Super efficient in finding 3 local firms to quote. All 3 got in touch the same day to arrange appointments and all 3 came within the next day. Great to be able to compare products and prices and I signed up with the best for me straight away
Joanne Barlow
Obtained names of 3 installers in my area, all of whom responded and visited very promptly. All 3 very professional, polite and gave estimates at time of visit, followed up by e-mailed quotes. Also answered my questions at time of visit and subsequently via e-mail. Found Boiler Guide very helpful in reducing time that might have been wasted trawling through local lists.
Lindsay Nicoll
The guys that came round were very professional and polite told us everything we needed to know and left the area spotless thanks
S Harding
Super efficient in finding 3 local firms to quote. All 3 got in touch the same day to arrange appointments and all 3 came within the next day. Great to be able to compare products and prices and I signed up with the best for me straight away
Joanne Barlow
Boiler Guide phoned me as soon as I had entered my details. Within a few minutes, 3 very professional companies called me and arranged to survey the same day. By the evening I had received 3 quotes to replace my boiler. I was very impressed with the service I received from both Boiler guide and their appointed gas specialists.
Sarah Bicknell
Having had an issue with my existing 18 year old boiler. I found the Boiler Guide online. Excellent and quick service, plus excellent customer services. They contacted me to find out what I was looking for and then informed me that three quotations would be in touch. They also supplied the details of the companies. They contacted me, next day, to ensure that the selected suppliers had been in touch and either supplied a quotation or were due to visit. Takes all the hassle away!
G@Southampton
Excellent. A rep called almost immediately after my enquiry. She was pleasant, helpful and this was a bank holiday. 3 engineers called really quickly so this platform is a superb service that takes the faff out of looking for heating engineers.
Windsor Browning
Boiler Guide phoned me as soon as I had entered my details. Within a few minutes, 3 very professional companies called me and arranged to survey the same day. By the evening I had received 3 quotes to replace my boiler. I was very impressed with the service I received from both Boiler guide and their appointed gas specialists.
Sarah Bicknell
Having had an issue with my existing 18 year old boiler. I found the Boiler Guide online. Excellent and quick service, plus excellent customer services. They contacted me to find out what I was looking for and then informed me that three quotations would be in touch. They also supplied the details of the companies. They contacted me, next day, to ensure that the selected suppliers had been in touch and either supplied a quotation or were due to visit. Takes all the hassle away!
G@Southampton
Excellent. A rep called almost immediately after my enquiry. She was pleasant, helpful and this was a bank holiday. 3 engineers called really quickly so this platform is a superb service that takes the faff out of looking for heating engineers.
Windsor Browning
Boiler Guide phoned me as soon as I had entered my details. Within a few minutes, 3 very professional companies called me and arranged to survey the same day. By the evening I had received 3 quotes to replace my boiler. I was very impressed with the service I received from both Boiler guide and their appointed gas specialists.
Sarah Bicknell
Where does the air come from?
Air can be introduced into a central heating system in several ways. This could happen when new water enters the system from the expansion tank or as routine maintenance is carried out. It could also be ‘created’ by the movement of the pump as it turns.
Where to start when bleeding a radiator
If your home has 2 floors you should begin bleeding the downstairs radiators first. It’s also advisable to start with the radiator which is furthest away from the boiler. Once you’ve bled all the downstairs radiators you move on to the upstairs, again beginning with the radiator which is furthest from the boiler.
Don’t forget to make sure you have the central heating system switched off before you start the process of bleeding a radiator. This is very important because some water pumps – depending on where in the system they are fitted – will actually suck more air into the radiator and consequently the heating system if they are turned on while you open the bleed valve.
How to bleed a radiator
You will need a radiator key, dry cloth or towel and a container to catch any water that comes out of the radiator. If you don't have a radiator key, you can find them in any DIY shop and tend to cost between 50p and £3. Pliers may also work but there's a chance you could damage the valve so a proper key is highly recommended.
Before you begin, make sure that your central heating is turned off. Having the central heating on while bleeding radiators is very dangerous; the last thing you want is boiling water bursting out of the pipes.
You should see a square 'bleed screw' at the top of the radiator. This is the part you’ll need to turn in order to release the air and water from the radiator. You’ll want to put your container on the floor beneath this area to catch any water.
Use the key to turn the bleed screw anti-clockwise, the cloth will help with gripping. You should hear a hissing sound as the air escapes, use the cloth to catch any water.
When the hissing air stops and there’s a steady trickle of water, the radiator is fully bled. Use the key to tighten the bleed screw but don't do this too tightly as you could damage the valve.
Wipe down any water on the radiator to avoid rusting then move on to the next radiator, repeating the previous steps.
Once all of the radiators have been bled, you can turn the heating back on. It’s a good idea to check the pressure gauge on the boiler to makesure it’s at the optimum level (around 1.5), that the radiators are heating evenly and there’s no sign of leaking.
It may be necessary to bleed some radiators more than once. If this still doesn't fix the problem you may need a professional engineer to inspect the system.
An engineer may recommend that you replace some of your radiators which could not only improve both the comfort of your home but could also reduce your heating bills. Find out more in our Radiator Sizing Guide: Get the Best Radiators for Your Home.
Maintaining your heating
If your heating system is sluggish from trapped air or sludge it will be making your boiler work harder to heat your home and making your monthly energy bills more expensive. By keeping a clear system you can not only keep energy bills to a minimum but also prevent damage from occurring over time. As well as bleeding your radiators it's highly recommended that you:
Get the heating system serviced by a professional every year to prevent wear and tear and catch problems early
During summer months try to turn the heating on every now and again for a few minutes to prevent the mechanics of the boiler seizing up
Monitor your heating for small problems that crop up like pressure dropping regularly or small leaks and get a Gas Safe professional to check it over as soon as possible to prevent small problems from escalating
You’ll find plenty of advice to keep your heating system in top condition in Water Treatment in Heating Systems .
Boiler Guide has a network of Gas Safe engineers all over the country who can check your heating system, make sure it's running efficiently and provide quotes for replacement radiators or boilers.
We highly recommend comparing quotes from at least 2 heating engineers and not just accepting the first offer you receive. Our team at Boiler Guide can help you with this by providing you with up to 3 free quotes from Gas Safe registered engineers near you. This way, you can ensure you’re getting the best price.
Click the button below to start comparing quotes.
Get your best deal
Quickly compare 3 FREE quotes
4.7 /5
out of
27,102
reviews
1,8 million quotes provided in 10 years
This was the hassle free way of finding a boiler company in my local area for a quote. I recieved 3 quotes and I was very satisfied. The job is complete and I'm now saving on my usage. I would highly recommend using Boiler Guide.
Mr Neil Cutsforth
Boiler Guide is the go-to to find the best boiler at a reasonable price and good installer. The experience has shown me to do your research properly when you are thinking of spending a lot of money. Boiler Guide was in touch to check if I found an installer. Thank you Boiler Guide
Shirley Feshitan
Brilliant service. Was getting a headache from other plumbers with extortionate prices. Saves a lot of hassle ringing around. Really pleased. Thank you.
Berni Byrne
This was the hassle free way of finding a boiler company in my local area for a quote. I recieved 3 quotes and I was very satisfied. The job is complete and I'm now saving on my usage. I would highly recommend using Boiler Guide.
Mr Neil Cutsforth
Boiler Guide is the go-to to find the best boiler at a reasonable price and good installer. The experience has shown me to do your research properly when you are thinking of spending a lot of money. Boiler Guide was in touch to check if I found an installer. Thank you Boiler Guide
Shirley Feshitan
Brilliant service. Was getting a headache from other plumbers with extortionate prices. Saves a lot of hassle ringing around. Really pleased. Thank you.
Berni Byrne
This was the hassle free way of finding a boiler company in my local area for a quote. I recieved 3 quotes and I was very satisfied. The job is complete and I'm now saving on my usage. I would highly recommend using Boiler Guide.
Mr Neil Cutsforth
Submitted my request and I received a phone call within 30 minutes to confirm what I needed. Received a list of potential installers the next day who all rang me and arranged a time to come round. Great service and it saved time which I didn't have as my boiler had stopped working.
K Patel
I was very impressed with this service. Within an hour of completing the form online I had a phone call from an advisor who confirmed that I would like to proceed. In the next two hours I had made appointments with three companies, all of whom have now been and given their quotations, within 48 hours of deciding to get a new boiler. We have proceeded with one of these companies and now have a date for installation. Excellent.
Steve W
Boilerguide emailed me 3 potential companies and within minutes one called me and visited my home and gave me a quote which i accepted and i'm having a new boiler installed within a few days i'm delighted with the result thank you boilerguide
Ted Billingham
Submitted my request and I received a phone call within 30 minutes to confirm what I needed. Received a list of potential installers the next day who all rang me and arranged a time to come round. Great service and it saved time which I didn't have as my boiler had stopped working.
K Patel
I was very impressed with this service. Within an hour of completing the form online I had a phone call from an advisor who confirmed that I would like to proceed. In the next two hours I had made appointments with three companies, all of whom have now been and given their quotations, within 48 hours of deciding to get a new boiler. We have proceeded with one of these companies and now have a date for installation. Excellent.
Steve W
Boilerguide emailed me 3 potential companies and within minutes one called me and visited my home and gave me a quote which i accepted and i'm having a new boiler installed within a few days i'm delighted with the result thank you boilerguide
Ted Billingham
Submitted my request and I received a phone call within 30 minutes to confirm what I needed. Received a list of potential installers the next day who all rang me and arranged a time to come round. Great service and it saved time which I didn't have as my boiler had stopped working.
K Patel
An easy to use website. Boiler guide gave me all the information I needed to choose a reliable company to remove and install my new boiler even although it was Christmas week. I would highly recommend anyone to check out boiler guide if they're looking to replace a boiler or radiators.
Margaret Arbuckle
Boiler Guide were excellent. I was already stressed having just been told my boiler was beyond repair, no idea of cost. Boiler guide made it all much easier, located people local to me and trusted to give me quotes. Really took some of the stress away from searching online myself. Highly recommended. Thank you
Julie Walker
Boiler guide is an excellent, quick & easy way to source businesses to provide quotes to have boiler replaced.
Sandra Emmerson
An easy to use website. Boiler guide gave me all the information I needed to choose a reliable company to remove and install my new boiler even although it was Christmas week. I would highly recommend anyone to check out boiler guide if they're looking to replace a boiler or radiators.
Margaret Arbuckle
Boiler Guide were excellent. I was already stressed having just been told my boiler was beyond repair, no idea of cost. Boiler guide made it all much easier, located people local to me and trusted to give me quotes. Really took some of the stress away from searching online myself. Highly recommended. Thank you
Julie Walker
Boiler guide is an excellent, quick & easy way to source businesses to provide quotes to have boiler replaced.
Sandra Emmerson
An easy to use website. Boiler guide gave me all the information I needed to choose a reliable company to remove and install my new boiler even although it was Christmas week. I would highly recommend anyone to check out boiler guide if they're looking to replace a boiler or radiators.
Margaret Arbuckle
Super efficient in finding 3 local firms to quote. All 3 got in touch the same day to arrange appointments and all 3 came within the next day. Great to be able to compare products and prices and I signed up with the best for me straight away
Joanne Barlow
Obtained names of 3 installers in my area, all of whom responded and visited very promptly. All 3 very professional, polite and gave estimates at time of visit, followed up by e-mailed quotes. Also answered my questions at time of visit and subsequently via e-mail. Found Boiler Guide very helpful in reducing time that might have been wasted trawling through local lists.
Lindsay Nicoll
The guys that came round were very professional and polite told us everything we needed to know and left the area spotless thanks
S Harding
Super efficient in finding 3 local firms to quote. All 3 got in touch the same day to arrange appointments and all 3 came within the next day. Great to be able to compare products and prices and I signed up with the best for me straight away
Joanne Barlow
Obtained names of 3 installers in my area, all of whom responded and visited very promptly. All 3 very professional, polite and gave estimates at time of visit, followed up by e-mailed quotes. Also answered my questions at time of visit and subsequently via e-mail. Found Boiler Guide very helpful in reducing time that might have been wasted trawling through local lists.
Lindsay Nicoll
The guys that came round were very professional and polite told us everything we needed to know and left the area spotless thanks
S Harding
Super efficient in finding 3 local firms to quote. All 3 got in touch the same day to arrange appointments and all 3 came within the next day. Great to be able to compare products and prices and I signed up with the best for me straight away
Joanne Barlow
Boiler Guide phoned me as soon as I had entered my details. Within a few minutes, 3 very professional companies called me and arranged to survey the same day. By the evening I had received 3 quotes to replace my boiler. I was very impressed with the service I received from both Boiler guide and their appointed gas specialists.
Sarah Bicknell
Having had an issue with my existing 18 year old boiler. I found the Boiler Guide online. Excellent and quick service, plus excellent customer services. They contacted me to find out what I was looking for and then informed me that three quotations would be in touch. They also supplied the details of the companies. They contacted me, next day, to ensure that the selected suppliers had been in touch and either supplied a quotation or were due to visit. Takes all the hassle away!
G@Southampton
Excellent. A rep called almost immediately after my enquiry. She was pleasant, helpful and this was a bank holiday. 3 engineers called really quickly so this platform is a superb service that takes the faff out of looking for heating engineers.
Windsor Browning
Boiler Guide phoned me as soon as I had entered my details. Within a few minutes, 3 very professional companies called me and arranged to survey the same day. By the evening I had received 3 quotes to replace my boiler. I was very impressed with the service I received from both Boiler guide and their appointed gas specialists.
Sarah Bicknell
Having had an issue with my existing 18 year old boiler. I found the Boiler Guide online. Excellent and quick service, plus excellent customer services. They contacted me to find out what I was looking for and then informed me that three quotations would be in touch. They also supplied the details of the companies. They contacted me, next day, to ensure that the selected suppliers had been in touch and either supplied a quotation or were due to visit. Takes all the hassle away!
G@Southampton
Excellent. A rep called almost immediately after my enquiry. She was pleasant, helpful and this was a bank holiday. 3 engineers called really quickly so this platform is a superb service that takes the faff out of looking for heating engineers.
Windsor Browning
Boiler Guide phoned me as soon as I had entered my details. Within a few minutes, 3 very professional companies called me and arranged to survey the same day. By the evening I had received 3 quotes to replace my boiler. I was very impressed with the service I received from both Boiler guide and their appointed gas specialists.
Sarah Bicknell
About the author
Nick Geary
Nick has a wide range of experience writing about conventional and renewable heating solutions, and is always increasing his knowledge by researching any new heating technologies on the horizon.
