Questions you need to know before a Boiler Installation or Replacement

You just tell us your desire, where you want to install your new boiler and we take care the rest.



If you want to save money in a long run and make a good decision, in our guide we show you what to look out for before a new boiler installation.


All of our professional engineers are gas safe registered, you can have peace of mind that we can take care your new boiler installation project, every steps what we take will comply with the new building regulations.



1. The first thing before a New Boiler Installation or replacement:


  • Find a GAS SAFE registered LTD like MML Plumbing.
  • We will give you a free estimate before boiler installation or replacement!
  • We will check out your pipework if it’s the right size.
  • We take pressure test before the boiler installation to see if the new boiler will work with the gas pressure what you have in your old boiler now.
  • In the end of the free estimate we give you advice what boiler can be installed and what to look out for.
  • Also we give you peace of mind that your new boiler will comply with the new building regulations.
  • We self-certifies the new boiler.
  • We notify Gas Safety about the installation.
  • Gas Safety will notify to the Local Authority.
  • We register your warranty at the boiler manufacturer.
  • And a Building Regulation Compliance Certificatewill be send out to you within 2 weeks.
  • After you have to write the Building Regulation Notification Number to the benchmark commissioning checklist, what you will find on the back of the boiler installation manual.


2. What we need to know before we install a new boiler or replace your old boiler:


If you have any future plans regarding your home like:

-you want to install a new fireplace in the living room?

-you are refurbishing your kitchen and move the cooker in a different location?

-you plan to do a roof extension with a new bathroom?

-do you want to put an extra radiator in the bedroom to the near future?


*we have to know every small details, because if you move the cooker for a different place and the pipe is to small, the gas pressure won’t be enough for the cooker and won’t work.



3. The gas engineer need to know about your hot water and heating needs!


Are people in the house regularly using more than one tap or shower in the same time?

Do you have low cold water pressure in the house and you are using a shower pump?

The combination boiler are not compatible with a shower that has an electric pump, so we have to get rid of the shower pump.

If you have one bathroom and we will install a new combi boiler than the pressure will be good so you won’t need shower pump anymore.

If you have more than one bathroom, and people in the house constantly using the showers in the same time than the best boiler for you will be a system boiler with a hot water cylinder.


4. Do you have any problem with your system, performance issues?


Did you had any issues in the past with the heating system or with the old boiler?

We think about the radiators didn’t heat up properly, pipe were noisy, boiler were noisy in the past?


If your radiators didn’t heat up properly in the past we might need to clean out your system using power flush. Another method is the magna cleanse system cleaning if your pipework are not strong enough for power flush.

After a new boiler installation or boiler replacement we clean out your system anyway.

Sometimes in your home the pipework are not strong enough, specially if you had and old gravity feed hot water system. This is a low pressure system.



5. What brand boiler do you want to install?


Don’t just think about the best boiler out there! When we install a new boiler we choose good brand boilers, but also we think about how much the parts will cost you in the future or how accessible are the parts if we have to come and replace a new parts in the future.

It would really make a huge difference if the parts are accessible. When some repairs need to be done, and the job would take 4-5 hours instead of 2 hours.

We also use boiler brands where the parts are good quality, not everything is plastic but brass or stainless steel like a heat exchanger.


6. Disposal of condensate water:


-the condensate water produced by your boiler need to take away to a drain.

If we can we have to run the condensate pipe inside the house. If this is not possible, we can still run the pipe outside, but we have to increase the size to 32mm from 21,5mm and the pipework need to be isolated from freezing temperature.

We have to find the right place where we can disposal the condensate water.


7. About the heating system:



Old heating system need at least a basic cleaning with chemical before the new boiler installation. After the cleaning process we have to add inhibitor for the system for future protection, this prevents the corrosion and scale build-up in your system.


Also we need to install a magnetic filter (normally this will include in our boiler package) to the boiler in the return heating pipe so your new boiler have long life and you won’t loose your manufacturer warranty by not installing a magnetic filter.


Heavily sludged heating system might need a power flush. The sign of a sludged system will be cold spots on the radiator, system noise and will take long time for your system to heat up.


It is particularly important that we install a scale reducer for your new boiler in the hard water area.


After your new boiler installation we have to balance your heating system so each one of your radiators can heat up properly.


8. Using a plume management kit


In some cases we have to use it. What this does is diverts the pluming gasses so that they don’t cause damage to neighbouring properties.

We want to hear your opinion if you will like the look how the flue pipe will run outside the house. Will it bother you or the neighbours?


9. Heating controls:

In new boiler installations the new government legislation requires at least one energy saving measures. This can be load-compensating thermostats, flue gas heat recovery, smart heating controls or weather-compensating thermostats.


10. Safety and performance checks:


After we installed the new boiler, we record the results in the back of the boiler manuals in the benchmark list.

After we register with the boiler manufacturer so your warranty can be activated. Manufacturers for new boilers can give a 3-5-7-10 year warranty.


We cover North London, Barnet, London city centre, East London, West London.

If you have any questions, please do not hesitate to reach us on 020 3877 0586.

Online estimate are 24/h. You can send us an email about the job and we will get back to you with an estimate asap.

Boiler Installation 10%-OFF.  Free Estimate before New boiler Installation. Gas safe registered engineers. 10 year parts and & labour warranty!