With this form of heating you can have the pick of mixer shower types, however bear in mind the position of the shower relative to the bottom of the cold water tank. Both the hot and cold water pressures are determined by the height (or head) of this tank above the shower. Provided there is at least 1 metre (or 3ft) between the bottom of the tank and the shower head, you should have a reasonable flow rate and pressure for the shower to function. However if the flow and pressure are unsatisfactory you can either raise the tank or install a pump.

As a rough guide, a good modern combination boiler, with an average mains pressure, should deliver approximately 1.5 bar pressure of hot water, which is good enough to power a decent mixer shower. If however, you feel that the flow and pressure from your combination boiler is insufficient for your showering needs then you could consider installing a pumped electric shower (see above) which can run off the cold mains water.

As an unvented system operates at mains pressure this is usually more than sufficient for all your bathroom needs. If you are in doubt as to the pressure of your unvented system then contact your local water board, they can provide max. and min. mains pressure values for your street.