Am I looking at a new heat exchanger (NPE240A)

[Jay Vining]

Going to start a couple separate threads here but will put them in appropriate places.


TLDR

Well pumped sand a couple nights ago. So much so that when a regen started it hit the pre-filter so hard it blew the bottom out and started flooding the basement. In the hurry of waking up from a dead sleep to the sound of the trash pump running I whipped the raw water to bypass the filter train.

Water heater pre filter was plugged solid with white sand. Backflushed, flushed according to manual, backflushed with no pre filter etc. Can get flow out of the hot outlet for a short period then it plugs off. Will flow backwards (in hot out cold) fine. My assumption here is that I'm looking at a new exchanger on a 16month old unit..... for 800 bucks am I better off just buying a whole new unit? I am unfamiliar with how much more stuff the sand has ruined in here. No trouble codes or anything ( I haven't fired the burner long at all in fear of baking it in there).

Thanks!

 

[FDNY/RETIRED]

Like I start all my threads. I am a homeowner and not a certified plumber or Navien tech. So much smarter people might be better to listen to. With that said, and
this is how I look at your situation. My sister use to live in Vermont and she had the same type of problem has you. Not with a Tankless unit. But first parts were replaced which cost money and turned out to be a bad move. She finally had to have a boiler and water tank replaced. So with that in mind, and if you do not have an exploded view. take a look at this http://bostonheatingsupply.com/Navien/NPE Parts and Diagram.pdf

Look at the 5.5.2 Burner Assembly/exchanger page. Anything that is water related is a problem . Then go and look for your model that says water way parts 5.5.4 page. Minus maybe o-rings and clamps. Anything on that page is a potential problem. Biggest ones IMHO circulation pump, Buffer tank and related parts. Also the (WAV) water adjustment valve, to name a few. Now you could try cleaning them out has a unit. Or taking everything apart and doing it one by one. In reality I think your screwed and hate to say it. But if it was me a new unit would be the way to go. Even if I was told it could be fixed.
So let me ask you this, because I know my sister was able to get her insurance pay for allot of what need to be fixed and replaced. I don't know if your covered by home insurance for things like that. It might be a separate Ryder on your insurance. But it is something to look into. I know it hurts a unit that new having to be replaced. I feel for you and the situation your in. Hopefully someone will be along and either agree with me. Or give you better advice. Best of luck.

 

[Sponsor]

 

[Bannerman]

Water heater pre filter was plugged solid with white sand.

As you said this influx of sand and filter failure occurred when the (water softener ?) was undergoing regeneration which you said woke you out of a deep sleep, why was hot water being used during the night to cause sand to enter the WH?

If no hot water was being drawn, there should have been no sand that actually entered the WH heat exchanger.

If sand/silt/sludge is a problem from your well. suggest installing an Atlas Filtri Hydra spin down type filter to trap the majority of silt so it can be easily flushed to drain. Flushing can be automated if needed when there is considerable debris that enters.

When considering cartridge type filter housing, it is advisable to not utilize those with a clear sump housing as that material is brittle and is prone to a higher failure rate compared to filter housings that utilize an opaque sump housing.

 

[Jay Vining]

Thanks for the help.

I am going to get one of those blow downs in there...this one looks real nice. Also changed from the clears to the blue poly housings.



Unfortunately state farm won't touch it because its a well. I would need an additional ryder. Which of course I didnt have lol. But I do now.

 

[Fitter30]

Install a differential pressure switch across a filter with a alarm in case this happens again.
https://pureaqua.com/differential-pressure-switch-dp-series/
Think your going to be chasing sand through softener for a while. Agree with Bannermanthat sand shouldn't be in the wh but suplly needs to be flushed.

 

[Jay Vining]

Okay so I was able to work some more on my wed thurs off.
Got everything cleaned out. I marked the levels of the bottles when I filled them and neither lost or gained level. I guess in hindsight I was lucky that it happened at what seemed like the second the katalox kicked over to regen. I then had my failure almost immediately.

I did get the navien pulled apart as far as I was comfortable doing ( pipes, check valve, recirc tank etc.). There was alot less sand INSIDE then I would have thought....though there was some. I flushed it out and threw it back together and flushed it a few more times, now that I had clean water coming in.

Put it back in service and its working well. I do have a weird thing now where the hot water doesn't seem accurate. Not cold water sandwich, but the temp walks cooler then hotter. I had read that the check valves could be a common issue here. Its cheap enough and easy enough. Although I cleaned it, I have no way to test it.

Am I on the right track there?

 

[Arya.H]

In this way, I'd like to recommend this sediment filter whole house for you! A pre-filter to be installed to make sure that new heat exchanger can work well. Because when the water has large impurities, it will definitely influence the working efficiency of heat exchanger. So firstly, you should buy a prefilter to make sure the impurities won't affect.