As of December 2019 the FCX will no longer be available in the U.S.



How to:

Cold Air Trap

Construction Filter

Thermal Siphon heat exchanger


TACO Switching Relays

Retrofitting the Riello to an older FCX

Rewire Heat Wise Burner for post-purge

Install a hour meter

Becket Wiring Changes

TACO 502,3,4... Control with Johnson 421 Digital Temperature Control

TACO 502,3,4... Wiring Detail for Actuators and Thermostats

Tekmar 402 Wiring Details - Zone Valves

Tekmar 402 Wiring Details - Cross Manifold

Probe Locations - Tekmar 402, Johnson 419, Delta T Pumps


Hot Water Safety Shutdown - Causes and solutions

VRG130 - Mixing Valve Alignment

Handling the Condensate - Piping and Traps

Best Practices

This PDF contains basic installation recommendations on Fuel, Pumping, Piping, Controls, Stacks. Setup and Tuning.   Also included are:

A basic plumbing diagram for a simple radiant and DHW system, with a typical parts list. 
A detailed wiring diagram using a Taco SR502 using the Johnson 419 heat controller is included.
A DWH diagram showing the domestic side of the BS series indirect water heaters.
A detailed wiring diagram showing how to interface the FCX with the Tekmar 400 series of controllers including  modifications to the FCX wiring.
A symbol Key

Plumbing Schematics:

Rule #1: Return water temperatures control efficiency (the lower the return water temperature the more condensing). The colder the better, so certain practices should generally be avoided: no 4-way mixing valves or blocks, no circulating injection loops, and no hydraulic separators. Tempering of return water by any means is to be avoided. In most residential and small commercial systems these are rarely necessary even when multiple pumped circuits are used. If there are reasons to incorporate injection based or hydraulically separated systems, there are ways to accomplish this but will require additional plumbing.

The following examples detail some of the options of how to interface the low temperature (mixed circuit) with the high temperature circuit. Again, "be cool" with the return water.

Radiant + DHW (basic)

Baseboard - Alone

Baseboard + Unit Heater + DHW

Radiant, baseboard, with 2 mixing valves + DHW (Optimized)

Domestic Plumbing Option for BS Tanks