Combination boilers are usually suited to homes with one bathroom but if the water presure and flow rate are both high enough to cope then a large capacity combination boiler will run two showers at the same time.
Do I need a boiler service?
An annual boiler service is recommended to keep your boiler in a safe working condition and to help spot any problems that may cause carbon monoxide poisoning.
It is also mandatory for landlords to provide a CP12 Gas Safety Certificate every 12 months.
If you have a new boiler installed then the manufacturer will insist on a annual boiler service to keep the warranty valid.