Installation manual

36 RIVA PLUS COMBI MANUAL
14. Piping
All external piping components are to be supplied by the installer. It is very important to use
a primary secondary piping scheme when an external circulator will be used. Also, when the
boiler is piped in a primary secondary manner, it is necessary to use the central heating ow
restrictor supplied with the boiler. The ow restrictor ensures there will be enough back pres-
sure to make the central heating ow switch in a low head loss piping system like primary
secondary.
Installation of ow restrictor:
The ow restrictor is installed inside the pipe tail that attaches to
the boiler. Place the ow restrictor into the gasket for the central
heating supply pipe tail. Place the gasket on the pipe tail so the
ow restrictor seats into the pipe tail. Then install the pipe tail
onto the boiler.
There are two methods for accomplishing a primary secondary piping system. The rst is
to use two closely spaced tees for the boiler supply and return. An example is shown below
in Figure 14.1. The run legs should be sized so that there is no excessive head loss on the
external circulator that is installed. In most circumstances 1 ¼” piping will be the best choice.
When the boiler is piped in this way, the external circulator will not have any hydraulic effect on
the Riva boiler. This is essential to ensure that the ow switch will operate properly.
Figure 14.1
The second method is a hydraulic separator. Hydraulic separators are available commercially;
however you can also construct your own. An example of a hydraulic separator is given in Fig-
ure 14.2. It is important that the separator be at least 2” in size to ensure proper performance.
Figure 14.2
Must be less than 8"
Boiler
Return
Boiler
Supply
System
Return
Sy
stem
Supply
1 ¼”
¾”
2"
No more than 8"
At least 16"
1 ¼”
¾”
System
supply
System
return
Boiler supply Boiler Return