| The installation of the boiler must comply with the requirements of the current issue of BS6798. 3.1 Frost Protection If the position of the boiler is such that it may be vulnerable to freezing it should be protected as specified in the current issue of BS5422. It is recommended that a frost protection thermostat be fitted. 3.2 Pump The pump, with integral valves, should be fitted in the heating flow pipework from the boiler, it should be set to produce a temperature difference of 11oC (20oF), between the flow and return, with the boiler thermostat set at "MAX", which is about 82oC (180oF). The pressure loss of the boiler can be found from diagram 3.1. High resistance microbore systems may require a higher duty pump. 3.3 Bypass - Fully Pumped and Sealed Water System A bypass is usually unnecessary on systems using a 3 port diverter valve since one port will remain in the open position at all times. This allows satisfactory operation of the pump overrun. However if thermostatic radiator valves are fitted to all radiators or two port valves are used a bypass is required. The bypass connection must be at least 2 metres away from the boiler. The flow through the boiler must not be allowed to fall such that there is a temperature difference greater than 20oC between the flow and return. 3.4 Water System For an open vented system the boiler must be supplied from an unrestricted water supply taken from a feed and expansion cistern fitted at a maximum height of 27metres above the boiler. The cold feed must be 15mm minimum size. It is important that the relative positions of the pump, cold feed and open vent are as shown in diagram 3.2. The unrestricted open vent from the boiler must rise continuously to discharge over the feed and expansion cistern. 3.5 Domestic Hot Water System General. The domestic hot water service must be in accordance with the current issue of BS5546, refer also to the current issue of BS6700. 3.6 Cylinder For all systems supplying domestic hot water the cylinder must be indirect. It is recommended that the cylinder be fitted with some form of temperature control. 3.7 Gravity Domestic Hot Water with Pumped Heating Important: If domestic hot water is to be provided by a gravity circulation to the cylinder the blanked off connections must be opened and used, using 22x28mm connections, see diagram 3.3. |