Navien NPE-240S

[Wannabe...]

I've been running the Navien NPE-240S for about 4 years now and I've been happy with it. With that said, I haven't flushed it since it was installed. Recently, the hot water flow has decreased significantly. But it seems to be only at the shower furthest from the water heater. I was thinking maybe it was an obstruction limiting the flow in the valves of that shower, but most likely, I've got build up in the hot water heater limiting the volume of hot water the unit is able to produce. Looking at the flushing procedures for the manual, it seems I can do this myself easy enough, but the manual points to an "Navien Easy Valve Kit" and recirculating pump for the flushing. I see the easy valve kit online, but not a pump. Questions: Do you agree with my assessment on the buildup possibly being the source of low flow at the shower? Can anyone point me to a source for a complete flushing kit including the recirculating pump?

Thanks.

 

[bingow]

NPE-240A newbie here (9 mos). I bought a 1/6hp pump from Harbor Freight that worked just fine. Google "Navien flush kit" and you should find several generic kit options that include the pump, but I have no info on their quality. As for scale buildup being the cause, it's likely after 4 years if you have any hardness. We use a softener for our very hard water, but even so it was recommended to flush once a year minimum. You might inspect and clean every filter first, which is a part of the complete flush procedure. YouTube has good videos.