Gas fires are ideal when you are going from a back boiler and fire unit to an up to date condensing boiler they can mostly with a adoption to the opening go straight back into the same place without replacing the marble or surround, but of course you could upgrade your fire surround and marble. We tend to use a few different fire manufacturers such as valor, robinson willey and a great local surround , marble and fire manufacturer be modern
 
We also do a range of wood burning stoves as the photo above.

People often don't use their fires much after having a new central heating system fitted as modern boilers and controls make systems much more efficient so the need for a gas fire is much reduced this means they are much more decorative