Hi guys. When I moved into my house a couple of years ago, I was delighted to discover that it came with TWO Navien CR-210A units. They are hooked up master/slave, supplying both hydronic heat and hot water to the tap with circulation.
While I like the units in principle, the day to day reality has been disappointing. Here's a list of some of the problems I've had:
1) Both units had ignition problems (error 3). We replaced the circuit boards.
2) One unit had an intermittent problem with the flow adjustment valve. We replaced the entire unit.
3) I've had two flow adjustment valves that failed (error 34), requiring new valves.
4) Both units have been through a handful of flow sensors (error 36). They seem to last 3-6 months.
5) One unit gets intermittent air flow faults (error 10).
With the recirculation system, the units short cycle constantly. Each new ignition causes a nasty belch of exhaust as the units clear themselves. My elderly neighbor complained about the fumes. The gas company showed up and red tagged the units. Testing revealed that the units are venting "as designed" and we simply turned them back on after a chat with the neighbor.
I've finally had enough. I'm not a plumber and I'm tired of dealing with this mess, not to mention the expense of constant repairs.
So, what should I use to replace my broken heaters? I need hydronic heat, hot water, and (ideally) a new circulation system. It has to fit into the existing (smallish) utility room. I've got PVC venting at the moment. I know very little about plumbing, so please use small words and be specific.