Replacing a 3-way valve in a 2011 Navien CH210 combi boiler. This "first generation" model is a nightmare to work on. You need to clear the PV board and remove the pump just to get access to the 3 way valve. Note: If the unit is flush against a wall (like this one) it's nearly impossible to remove the rear screw of the 3-way valve because the 1-1/4" Isolator Valve Kit takes a lot of room up where that rear screw is located. The homeowner offered to take this video.