Over the years Pulsa coil was installed in most of the apartment and this type of system does not need discharge pipe,therefore they are exempted from Section G3 building regulation requirement.
The major drawback of the pulsa coil system is the leak from the internal copper tank. This cannot be repaired as the internal copper tank is is contained within the outer steel case which is impractical to dismantle. Apart from the leak, it has an element ,pump and elctronic board.
Most of the time I found the element cuts off itself due to leak, the pump get stuck because of lime scale built up inside the tank.
The popularity of the system were declined as it tends to breakdown quite often.However Boiler4u is specialise in repairing the system subject to condition of the boiler.
When it come down to replacing there are limited choice available:
1. ETS 160 electric thermal storage by Advance appliance
2. Coral Aquanox direct by Elson hotwater
3. Pulsa coil BP
I have installed number of advance appliance by replacing Glendhill pulsacoil, so far I have not heard any complaint.