What is the Boiler Replacement Process?

Book Appointment
See Services


Plumbing & heating specialists
Call us now

Subscribe to our newsletter for tips and industry news

It’s a heart-sinking moment when your boiler stops working. It feels as though everything is on hold; bathing, washing up, cleaning. So getting an engineer in quickly is a must. However, when you then receive the news that your boiler actually needs to be replaced, and can’t just be fixed, your heart can sink even further.

But we’d like to give you a little boost at this moment and reassure you that this doesn’t need to take as long as you think it will. When you choose a plumbing and heating company that deals with this stuff day in, day out, you can take heart that a new one will be up and running as soon as is possible.

What happens when you need to replace your boiler?

Well, your heating engineer will go through a few details with you first. For example, he/she will check how many bathrooms you have – or intend to have – and check your water pressure. They’ll also be keen to understand your usage levels and timings etc. as well. Once that’s established, you can then start your new boiler journey…

Homeowner Checking Boiler

Step-by-Step: The Boiler Replacement Process

Step 1 – Choose your new boiler. You’ll need knowledgeable advice to pick the right replacement, so we recommend you choose your adviser carefully. A qualified and experienced plumbing and heating engineer is your best bet.

Step 2 – The old boiler needs to be removed. Every job is different, but nothing can happen until that beast is out.

Step 3 – Your system then needs to be flushed and cleaned. It’s a requirement of British Standards, but the type of system you have will dictate what happens. You may just need a chemical flush, or you may need a power flush. And this is not a stage to miss, because a clean system will help to avoid damage to your new boiler in the future.

Step 4 – There may be upgrades to your pipework. Your installer may have recommended that your new boiler is sited in a different place, in which case you need adjustments made to your pipework. Plus, your new boiler may need adjustments and changes to be made to your pipework anyway. It’s likely boiler technology has improved significantly since your last boiler was installed.

Step 5 – Your boiler is fitted. This is when you start to feel real progress is being made.

New Boiler Replacement

Step 6 – Additional accessories are fitted. You may need a system filter, for example, to protect your boiler from any debris in your system. Plus you may need new controls. But all these things should have been agreed at the point of specification, so you shouldn’t be in for any surprises.

Step 7 – Testing. Once everything is installed, the engineer will commission the system by checking all aspects are working correctly. Combustion analysis is also undertaken to ensure the boiler is operating safely

Step 8 – Handover training. Once the engineer is happy the system is fine, he/she will take you through how the controls work, how to operate your new boiler, and any basic maintenance actions you should take.

Step 9 – Guarantee registration. One final step we recommend is that you then register your product with the manufacturer and ensure the guarantee is in place.

Step 10 – Enjoy your warm home with oodles of hot water!

To speak to someone about replacing your boiler, or to find out more about the boiler replacement process, please call us on 01908 034194.

Are you a landlord looking for a plumber?

If you’re a landlord and you need experienced and swift action taken to replace an old cranky boiler, please don’t hesitate to give us a ring on 01908 034194. We’ll work quickly to get the problem resolved and keep your tenants happy.

View more contact info

Areas we cover

  • Aylesbury
  • Bedford
  • Leighton Buzzard
  • Northampton
  • Olney
  • Towcester
  • Woburn Sands
Call us

What Our Customers Say

I’ve used Grand Union 3 times and every time the service is excellent and the price very reasonable. Engineers are very good at letting you know what they are doing and there are no hidden charges. They even managed to do a job at short notice. They work tidily and even followed up with a message to check my heating was still ok the following day. Highly recommend

Claire Edwards

Excellent service from Mitch!
Responsive, courteous and informative.
Work swiftly done too, with clear explanations throughout.
Thanks again, Mitch.

Used grand Union plumbing to service my boiler and couldn’t of asked for a better service. They were on time and actioned the job in a clean and professional manner. Very nice to see they were operating in a covid secure manner without being promoted too

100% will be used again in the future

Tom Holland
Highly recommend Grand Union Plumbing & Heating. We called Mitch after getting nowhere with the first 2 heating engineers we contacted. In contrast to them, Mitch quickly diagnosed the fault, ordered the part and replaced. Totally professional and good value for money.
Mike Kennedy
I found Grand Union on local heroes. Id given up on British gas and NPower/homeserve.
Mitch was honest from the get go. Came round and gave me quote got the worl done within a couple of days once parts came.
Very highly professional. Very friendly. Perfect on time. Clean. Safe. What else can I say. I will be using only Grand Union here on and cannot recommend enough.
Amazing service Mitch Andy and Cory all amazing guys came out Xmas Eve went above and beyond to get me sorted and were amazing with my children letting them watch and so polite couldn’t recommend highly enough 10/10
Steaves Jen
Highly recommend the team to fix any plumbing or heating issues. They arrived as scheduled and it was great to have such a high standard of service. Will definitely be my contact for anymore plumbing issues and for boiler services.
Owen Thomas
Contacted them after having three boiler services being cancelled by a Big Five company only resulting to a wait till May for the 4th appointment. From the first day I contacted them Andy came around in a week’s time and provided excellent customer service and serviced our boiler very efficiently and quickly. The appointment ran a bit late due to another emergency call but both Mitch and Andy were apologetic and polite. Appreciate there excellent customer service on top of a job done well. Will be calling on them in future again for sure. Thank you.
Kaanita Khan
Would highly recommend Grand Union plumbing, really knowledgeable team. They were able to identify the problem with our heating pressure gauge, and release valve really quickly and stop our leak straight away. Thanks
Emma Thompson
Love these guys, have been using them for years and will keep using them for years in the future. They’re helpful, do amazing work each and every time, and are respectful of your home, both Andy and Cory took their shoes off when they came into the house recently, Cory put down dust sheets when he was fitting my new radiator in the bathroom (tiled floor wipes clean, but still put it down).
100% recommend them for any and all plumbing works and looking forward to having them do more work for me later in the year.
Ian Kockelbergh

It’s not very often that you find a quality tradesperson who is reliable, honest, and competitive on his pricing. Mitch has done a number of jobs in our house, including installing a new boiler, water tank and radiators. All to a brilliant standard. I will happily recommend Mitch and Grand Union Plumbing!


I have called Mitch out twice since moving into our new house a month ago. Both times he has managed to fit in an appointment fairly quickly to resolve our issues. He has been professional and friendly, offering advice on other issues that I have seen. I would definitely recommend his services.

Simon Edwards

We have used Grand Union Plumbing several times as we had a really tricky fault. We found Mitch to be really excellent. Very happy to recommend, 10/10

Annette McDade

Called Mitch out on very short notice, extremely reliable and great rates, would highly recommend Grand Union Plumbing and Heating. Also provided advice with other queries aside from the job at hand- with no reluctance. Great service, thank you for your hard work and honesty Mitch.

Dushan Gnanakumar
Great service, polite, attention to detail. Would highly recommend.
Ajvinder Dhatt
Had a leak that needed fixing asap and Mitch gave me advice over the phone to deal with it until he could get to me, then came out within the hour on a weekend! Would highly recommend
Hannah Manners
Great company would highly recommend for any heating & plumbing issues
Terry Adolpho

Definitely recommend these guys. Had a job done by them and they wasted no time to get it done and made sure I was completely happy before any payments. Nowadays companies just want to rush and take your money. Big thumps up

Tevaugh Grant
We always use Grand Union for serving and any other unforseen problems. The service and professionalism is 1st class. Would definitely recommend!!
Stephanie Horne
A great company to do business with… I used them recently for an emergency with a domestic heating system which was rectified very efficiently. A second problem (some months later) and there was no decision to make, called them and they sorted it in no time with minimum fuss, mess and very reasonably priced.
Trevor Gordon

Have used Grand Union twice now. They are very quick to respond to enquiries, reasonably priced, tidy workers and very friendly. I can’t fault them. Definitely my go to guys now for any plumbing needs.
Highly recommended

Emma Verrall
Great service from Mitch. Have used a few times for boiler service, repairs and outdoor tap installation. Always very prompt service, turns up on time and reasonable prices. Would definitely recommend!
Jon Hood

I found Grand Union Plumbing through the Gas Safe Register. I had a boiler service and gas safety certificate. Mitchell was very professional and the prices were very reasonable. I would definitely recommend and use again.

Rebecca Hughes
Mitch was very helpful when fitting my new boiler – he was very fair about price and I couldn’t recommend Mitch enough. Thanks Mitch!
Reece Hussain


Use our calendar appointment request form and we will confirm back to you as soon as we can! We look forward to hearing from you.

Request appointment
Call us

Request a call back

If you have any questions regarding our services, would like to arrange a quotation or would like to book a call out please contact us using the form below. You can also request an appointment through our contact form. We look forward to hearing from you!