Conventional versus Combination Boilers - The Pros and Cons:

A Conventional boiler is purely a heating appliance – there will be an external hot water cylinder, control valves and radiators.

Worcester-Bosch Ri conventional boiler

Why would you want one?

  • More than one hot water outlet can be supplied simultaneously (dependant on a separate storage cylinder)
  • You desire a longer service life for a boiler than 10-12 years.
  • You would prefer to have a stored hot/cold water supply in the house
  • You may have recently invested in a new hot water cylinder/tanks
  • You want an electrical immersion heater as hot water backup in case of boiler failure
  • The water flow rate (sometimes erroneously described as pressure by plumbers) is too low for a combination boiler (but see low water mains pressure solutions as there are solutions available)
  • All conventional boilers are now condensing technology, mandatory in the UK
  • Perceived reliability advantage.


A System Boiler;

Is a conventional boiler (above) with the circulation pump mounted within the boiler casing, most of these are designed to be fitted to a sealed radiator system (in other words, one without a header tank).

They also incorporate some sealed system components, such as an expansion vessel, shown in the ATAG boiler below.

ATAG i32S System Boiler

A Combination boiler contains all the necessary controls and equipment to provide instantaneous hot water and also central heating – apart from radiators and pipe, everything else is in the boiler.  There are now over 7 million households in the UK equipped with Combination boilers.

New for 2019, Worcester Bosch Greenstar 8000

Why would you want one?

  • Convenience. Hot water is always available, 24 hours a day
  • Economy. Only heat the hot water you use.  Ideal if you are at home infrequently.
  • Consecutive hot water demands can be made without running out
  • You don’t require to run two hot water taps simultaneously
  • No water tanks in the roof or hot water cylinders are required.
  • It’s a one box compact solution, ideal for small properties
  • All combination boilers are condensing versions, now mandatory in the UK
  • It offers mains pressure showering without a pump (ideal for flats or loft conversions)

Customer Testimonials

Excellent Work

Excellent work , the workers were very efficient, considerate and tidy. They worked with the least disruption possible for an elderly lady. Any unexpected problem was dealt with safely and professionally. The finished heating is to a high standard. K.T. Kent

Jennie 05/05/2017

Very good job

The job was very professionally undertaken on time and budget with no adverse issues raised. Customer satisfaction appeared to be a high priority.

Martin, Kent 25/04/2017


Truly excellent, as much technically as aesthetic: clean, prompt, going well beyond expectations.

Nicholas, Kent 14/04/2017

Commercial plumbing

A small to medium sized company capable of installing & maintaining a highly technical modernisation of our heating & h/w systems. The planning, execution & result was truly ‘excellent’.

A J, Surrey 04/04/2017

Very knowledgeable

We needed a replacement boiler & Simon talked us through the options, which manufacturer & what size to go for & saw through the installation, not leaving until he was satisfied that all was in order. All in all very, competent and professional.

Stephen, Kent 16/02/2017

Highly recommended

Not the cheapest but very knowledgeable which gave me confidence that the job would be well done and correctly done. I was not disappointed.

Geoffrey, Kent 06/02/2017

Good standard of work with an ongoing commitment to customer satisfaction

This firm installed a 12 zone Honeywell Evohome central heating and hot water control system for us in October 2014. The quotation was clear and detailed, and the price reasonable. The installation work was personally overseen by the boss, Simon, who also set the rather complex (but powerful) wireless control system to work and gave clear advice on how to get the best from it. He had in-depth knowledge and experience of the control system that is probably second to none. The firm also installed and connected to our boiler a plinth fan heater nicely hidden under a kitchen cupboard Read more…

Mike 28/11/2016

Employed this trader many times

Started and finished on time. Workmanship as good as ever. prices reasonable.

Peter, Surrey 24/05/2016

Smart solution, neatly implemented

Great technical solution to the tricky replacement of a 1980’s warm air unit. Starting with a clear and comprehensive quotation. Careful and tidy installation with minimal disruption. Excellent communication throughout the work.

Martin, Surrey 21/03/2016

Clean + tidy

HWCH installed our boiler a few years ago and have looked after it ever since so I was happy to leave them in the house unaccompanied. We came home to find the installation complete and no mess or trace they had been.

Bryan, London 15/12/2015

Prompt and efficient. Very professional.

My son recommended this firm as I was very apprehensive about having a new boiler. Mr Davies was very clean and helpful and explained everything. The two men who did must of the work were efficient, polite , clean and considerate to me . As far as I can tell I have an efficient job carried out in one long day which helped me.

Jean, Surrey 19/11/2015

Very good job – as always

We have used the company for many years for 2 rental properties & our family home. We cannot fault them.

Stephen, Kent 19/06/2015

Knowledgeable, friendly and efficient

HW and CH knowledgeable, friendly and efficient company we would certainly recommend them.

John, Kent 01/06/2015

Reliable & professional company

Hot Water & Central Heating responded very promptly & installed a new boiler in a quite awkward location. Very helpful

Jerry, London 27/05/2015

Professional & efficient

I have known HW & CH for several years. They installed two large boilers in a church and hall and maintain them annually. I gave recently used them at my home where they did a very clean, neat and efficient job. Supplied excellent product and were very professional.

David, Kent 16/01/2015

Diligent & Efficient

Simon of HWCH takes his job very seriously but is a pleasure to deal with. He assessed our (complicated) situation carefully, recommended the right solution and carried it out promptly and efficiently.

Jay, London 15/01/2015

Expert & professional installation

An intimate knowledge of a rather complex Honeywell Evohome heating control product, combined with an excellent installation crew on the day resulted in a very satisfactory installation. Some tricky rerouting of underfloor pipework was accomplished without fuss, mess or extra charge, highly recommended.

Richard, East Sussex 04/07/2014

Very impressed

Very impressed with work rate and efficiency. Would have no hesitation in recommending them.

Neville, West Sussex 16/03/2014