Water from tankless water heater now smells!

I have a Navien tankless water heater for about 5.5 yrs which I descale ever year or so with 2 gallons of white vinegar. Well, when I did it last Friday, I came back after letting the pump run for about 40 minutes to an oily substance in the bucket. I flushed the unit for 15+ minutes, but it appears this substance is now in the unit and maybe pipes. I was hoping the substance would just dissipate over time, but now my hot water smells and you can sometimes see a little bit of oily substance in it. On Saturday you could smell it a little but my Monday it was really strong. So on both Tuesday and Wednesday, I flushed the unit with 2 gallons of water combined with 2 tablespoons of Dawn. This seems to help a little, but certainly has not resolved the issue. (I ran it for about an hours the first time and 35 minutes the second time.) FYI, I bought a new pump, hoses and bucket since the old ones are covered with the oily substance. So I have questions for you all? Do you think the oily substance is from the little 1/4 hp utility pump I was using? If that is the case, the substance is probably mineral oil from what I've read. Has anyone ever had anything like this happen to them before? What was the resolutions? Any ideas on what I can use to flush the system? I'm planning on trying vinegar again tonight. Is the unit salvageable or do you think this substance damaged the unit beyond repair? Do you think this substance has made it into the pipes? If that is the case, what are my options? Thanks in advance. submitted by /u/ss_lbguy [link] [comments]

Feb 20, 2025 - 16:03

I have a Navien tankless water heater for about 5.5 yrs which I descale ever year or so with 2 gallons of white vinegar. Well, when I did it last Friday, I came back after letting the pump run for about 40 minutes to an oily substance in the bucket. I flushed the unit for 15+ minutes, but it appears this substance is now in the unit and maybe pipes.

I was hoping the substance would just dissipate over time, but now my hot water smells and you can sometimes see a little bit of oily substance in it. On Saturday you could smell it a little but my Monday it was really strong. So on both Tuesday and Wednesday, I flushed the unit with 2 gallons of water combined with 2 tablespoons of Dawn. This seems to help a little, but certainly has not resolved the issue. (I ran it for about an hours the first time and 35 minutes the second time.)

FYI, I bought a new pump, hoses and bucket since the old ones are covered with the oily substance.

So I have questions for you all?

Do you think the oily substance is from the little 1/4 hp utility pump I was using? If that is the case, the substance is probably mineral oil from what I've read.
Has anyone ever had anything like this happen to them before? What was the resolutions?
Any ideas on what I can use to flush the system? I'm planning on trying vinegar again tonight.
Is the unit salvageable or do you think this substance damaged the unit beyond repair?
Do you think this substance has made it into the pipes? If that is the case, what are my options?

Thanks in advance.

submitted by /u/ss_lbguy
[link] [comments]