I have a Noritz NR98-OD that is 4 years old. It has been flushed yearly by the same company that installed it, with the most recent one being yesterday. They spend about 1 hour on-site so I assume they are doing the flush for about the entire time.
This years invoice indicated they used "Flow Aide" to flush the system, I'm not sure if they always have used that or this is just the first year it was detailed on the invoice, as no other invoices say Flow Aid. After the guy left, I went outside and opened the pressure relief valve and a a bunch of yellow and then brown water came out (for around 5 seconds each time I opened the valve). I did this a couple times until everything was clear. I had a similar experience on last years flush, and that was the end of colored water.
But, I was still getting brown water later in the day yesterday. It was still after the initial fire up and only lasted a few seconds, then the hot water would run clear. If I turn the hot water off, then wait 10 seconds and turn it back on, the water is still clear. But, if I wait a couple minutes (until at least the fan turns off) I'll then get some brown water again, then it goes clear.
Yesterday I ran all my faucets on hot for 5 minutes to flush out the pipes and let water run through the system, but later in the day I still got some brown water. I don't quite understand why this only occurs after the initial fire up.
Before I call these guys back, I wanted to get myself informed on what may be going on so I know how to talk tot he technician if they try to give me "it's normal", because it's certainly not normal based on past history of flushes. I'm wondering if this could be a symptom of not flushing the unit with the power on and gas off (How Noritz says to do it). A lot of the video's I've seen online say to flush with power off and gas off.
PS - City water, no brown water on cold side (never in 10 years I've been in this house), all PEX pipes with brass bypass valves at the unit, tankless is set to 120F and always has been.
Last edited by HDClown; 02-05-2014 at 07:14 AM.
Sometimes the valves used for isolating the unit can collect crud, then when it's turned off & on again some of that crud gets into the water stream. It should clear up after a few days use, but if that's not the case, there may be something else going on.