| Many boilers are indirectly heated by the central heating unit. A three way valve directs the hot water from the normal circuit to the boile...
| Many boilers are indirectly heated by the central heating unit. A three way valve directs the hot water from the normal circuit to the boile...
| Many boilers are indirectly heated by the central heating unit. A three way valve directs the hot water from the normal circuit to the boile...