Sediment in hot water lines with tankless heater

[ryguy]

I have been having problems with sediment (looks like large pieces of sand and tiny rocks in varying colors of brown and black) accumulating in my faucet aerators and shower heads. I installed a whole house filter at the water main thinking that the water coming into the house was simply "dirty". Then I cleaned all the aerators in the house, and even decided to clean out the lines for my washing machine. That's when I realized the problem is with my hot water only, because the cold line to the washer was super clean but the hot water line was full of the sediment. It is so bad at this point that I am cleaning out aerators on a weekly basis, otherwise there is no pressure or hot water at the faucet or shower head. The washing machine keeps giving me an error code becaue the hot line is full again and no hot water is getting to it. I have an electric tankless water heater and I thought that there wasn't supposed to be any sediment with a tankless heater. My home is less than five years old and I live in Tucson, Arizona. The water has been tested and the hardness is less than 10. Anyone have any idea what is causing this problem?

[Dana]

Accumulated crud in the lines keeps moving?

Deteriorating galvanized plumbing?

Whatever it its, it's not the tankless, which has extremely low water volume. It might lime up and restrict flow in hard water areas, but it can't develop a layer of sludge the way tanks sometimes do.

[AAnderson]

All tankless manufactures recommend softeners if the water has more than 11 grains of hardness (roughly 210 ppm total dissolved solids). Calcium will precipitated out in hot water which is why you are experiencing the debris you are in appliance pre filters and aerators...

[macmikey]

My plumber said it was from the old tank heater and the crud it created.

He comes out, on schedule, to flush the system, run a vinegar solution through it and then flush it again. He also replaces my whole house filter and maintains the faucets for me as well.

I go around about every 2 weeks or so and clean out all of my faucets and other filtery kind of things to prevent blockages.

The routine maintenance is required for the warranty on the Rinnai or you may not get service on it. It does not reduce the crud, but does guarantee that the heater itself is not going to be damaged by it.

Mike

[AAnderson]

My plumber said it was from the old tank heater and the crud it created.

He comes out, on schedule, to flush the system, run a vinegar solution through it and then flush it again. He also replaces my whole house filter and maintains the faucets for me as well.

I go around about every 2 weeks or so and clean out all of my faucets and other filtery kind of things to prevent blockages.

The routine maintenance is required for the warranty on the Rinnai or you may not get service on it. It does not reduce the crud, but does guarantee that the heater itself is not going to be damaged by it.

Mike

Mike, define crud? Do you mean small white particles that looks like broken sea shells? This is calcium that has precipitated out of solution under heat and pressure, a problem is you have hard water. A whole house filter will not remove dissolved solids.

[4fuzzies]

I'm a little worried since this thread was posted in 2009 and there doesn't seem to be a consistent answer. We too have the sediment in our hot water lines that looks like sand and up to 2mm sized pieces of mineral. We too were convinced to put a water filter on the incoming water. This did nothing for the problem and just killed our water pressure. It seems to be worse in the winter, we clean the shower head 3 times per week as apposed to once a month in the summer. Our water heater in a natural gas powered rinnai tankless that was installed in 2009. Our heat unit is an Apollo hydroheat system. We had no problems from 2005 when we moved in, until the summer of 2010. Then we lost hot water. The plumbers that put in the rinnai came out and cleaned the in line filter and the faucet aerators. We thought at the time that the sediment was from when the city changed the meters on the water lines. The problem went away until fall 2010 when the heaters kicked on. That's when we were told we need the whole house filter. It fixed nothing. We still have sediment in the lines that makes me feel like when I run the bath for my kids, I'm not getting them any cleaner. We call out plumbers... they say its the Apollo unit. We cal out hvac guys they say either they can't touch the Apollo units or its a plumbing problem, call a plumber. We have had several different companies come out. No one has an answer. We have to run the sink in the bathroom if we want to take a hot shower, otherwise because the lines and showerhead are so plugged, not enough water flows through the rinnai to turn it on. We did not have any problems the first winter after getting the new rinnai tankless. For what it is worth, our house was also plumbed using the now illegal Quest pipe. Please help. This thread is the closest thing we have found to an answer in 2 years.

[jadnashua]

Have you demineralized the tankless system? It's fairly easy if it was setup properly with the appropriate fittings, otherwise, it can be a pain the first time (assuming you install them now). This involves pumping a weak acid solution through the thing for a period of time to disolve the minerals. Depending on the hardness of your water, your total water use, and how hot you have the tankless set would all affect how often it needs to be done. The internal passages could be restricted a lot, and the minerals also act like an insulator. Depending on the heating, some could break off during use and may be the source of the mineral chunks.