Installation manual

30 RIVA PLUS MANUAL

13. 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 us the central heating ﬂ ow

restrictor supplied with the boiler. The ﬂ ow restrictor ensures that there will be enough back

pressure to make the central heating ﬂ ow switch in a low head loss piping system like primary

secondary.

Installation of ﬂ ow restrictor: The ﬂ ow restrictor is installed inside the pipe tail

that attaches to the boiler. Place the ﬂ ow restric-

tor into the gasket for the central heating supply

pipe tail. Place the gasket on the pipe tail so the

ﬂ ow restrictor seats into the pipe tail. Then in-

stall the pipe tail onto the boiler.

There are two methods for accomplishing a Primary Secondary piping system. The ﬁ 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 exter-

nal 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 ﬂ ow switch will operate properly.

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.