Feedback/Recommendation: Tankless water heater experience

Discussion in 'Tankless Water Heater Forum' started by OldSalt, Feb 10, 2018.

  1. OldSalt

    OldSalt Member

    Joined:
    Feb 3, 2017
    Occupation:
    IT Consultant
    Location:
    Northern Idaho
    I wanted to pass on my experience with installation and use of a Tankless Hot Water Heater:

    • Background: New construction, new Rinnai RUR98IP (similar, RUR98E* and RUR98IN) tankless water heater installed by plumber. He was inexperienced with tankless w.h..
    • Overall experience: Very good. Instant hot water with re-circulation, which puts hot water at every tap within two minutes (2200 sq ft house, 3 full bath, powder-room, kitchen, laundry with deep sink, exterior hot water tap). We have electric furnace/heat pump heating, and use propane for everything else (oven, stove, clothes dryer, fireplace). Average monthly propane cost (i.e. hot water was the biggest user) was 25 gallons. (Increased to 75 gal with addition of 30,000 BTU fireplace for main heat during cold weather below 30F, which is our heat pump's lock out temp.) We don't schedule hot water recirc for certain hours of the day, because "flipping the switch" on recirc delivers hot water everywhere in 30 seconds to 2 minutes max. Bottom line, VERY economical.

    • Installation experience: Total nightmare. Problems included:
    1. Original plumber installed unit as "cross over", i.e. retrofit, even though we had a dedicated hot water re circulation line. Required 10 minutes to circulate hot water, versus less than 2 minutes using a dedicated (3/4") line, as recirc cross-over mode requires hot water to pass through a 1/2" faucet line "choke point". Plus, he didn't set the internal dip switches for cross-over.
    2. What the 30 year experienced plumber could not figure out, took me two minutes of reading to understand (plus one quick call to Rinnai technical support, which was excellent). I properly reinstalled the unit with an expansion tank and check valves, and set the dip switches.
    3. I've had the system apart and in pieces about six or eight times since original install. The largest problem I had was water quality. The water here in Northern Idaho is hard (not as hard as Southern California, but the result is similar). I had to clean out the intake filter once a week. I had cold water in the hot water lines. I added a whole house filter. I replaced it with a strainer. I had to clean sediment out of shower heads, faucet heads, and my clogged check valves (i.e. source of cold water in hot water lines). We had this sediment problem almost from the first day of operation, but I assumed the cause was the old city pipes.
    Biggest lesson learned, and this likely applies to EVERY tankless hot water system.

    RECOMMENDATION: ADD A 50 MESH WATER STRAINER TO THE OUTLET SIDE OF THE TANKLESS WATER HEATER.

    SECOND RECOMMENDATION: INSTALL THE FRIGGIN STRAINER ALREADY!!

    I don't care what your water quality is, EVERY water heater will develop sediment. With tank'ed systems, the sediment generally settles to the bottom of the tank, while the hot water outlet is at the top of the tank. With tankless systems (at least, for the Rinnai), the hot water outlet is at the bottom of the unit, and there's no "tank" to hold the sediment. From the day the unit starts operating, debris WILL flow into your hot water pipes, and into your plumbing hardware. That includes your tankless hot water heater, if it's a recirculating unit. The Rinnai unit has a thimble sized strainer on the INTAKE side to protect the unit. However, a second, larger strainer is required on the outlet side to catch the junk that the unit introduces to your system.

    All tankless water heaters require an annual backflush (for me, 3x or 4x annually), which is easily performed with an submersible water pump in a 5 gal bucket of white vinegar, two washer/dryer hoses, and using the backflush cut out valves. (My unit came with the valves installed, but kits can be purchased to add them if needed.) Our water was only warm to lukewarm after a year, when I first backflushed our unit (i.e. while I was diagnosing the sediment issue and adding the water jar style strainer). After the backflush, it's the full default 115F degrees, almost too hot to the touch.

    I haven't seen that output line strainer on any manufacturers diagram (but my survey wasn't comprehensive), and I find that incredible. I can't imagine installing one of these units, with or without re circulation, without a strainer. The added bonus of the clear jar strainer is that I can "see" when it's time to backflush the unit, based upon the trapped sediment. My plumbing faucets and hardware fixtures are now mostly sediment free.

    That's my review. I'll include links to strainers and my strainer storefront in my next post (just kidding, really!). Hope this helps some of you.

    - Scott
     
    Reach4 likes this.
  2. Ladiesman217

    Ladiesman217 Member

    Joined:
    Dec 31, 2010
    Location:
    MA
    Water quality is regional.

    I have a tankless gas fired water heater.

    I cleaned my water input filter this year for the first time in about 20 years. The filter was still fairly clean. It had a few metal filings caught in the mesh as well as some crap. I installed a new filter.

    I also did the vinegar flush for the first time in 20 years. The vinegar was still pretty clear after the flush.

    Recently I did have to replace a defective thermostat as well as service the water valve. The old thermostat water probe looked like new. No mineral buildup at all on the probe. It was hard to tell the difference between the new and old probe going by looks only.


    Back to your posting. Since you say that you have to clean your input water filter "one a week", why don't you have a strainer installed on the cold side of the water heater?
     
    Last edited: Feb 11, 2018
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  4. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    I would be looking at a water softener. What is your hardness? The strainer could still be a backup. Does your Rinnai Operation and Installation Manual mention hardness?

    That strainer thing was surprising to me. I don't have a tankless, nor to I expect to get one. But to see that you could catch stuff is interesting and surprising. How about a photo of what you catch over an interval.
     
    Last edited: Feb 11, 2018
  5. OldSalt

    OldSalt Member

    Joined:
    Feb 3, 2017
    Occupation:
    IT Consultant
    Location:
    Northern Idaho
    1) Blessed you are, on your water quality. I'll bet you've never bought bottled water in your life. :)
    2) re: Suggestion for a cold water side strainer
    Answer: Misunderstanding. The first thing I did was add a whole house filter on my water main. The sediment seemed to pass through it, so I was an evil customer blaming the filter company. Then to "prove it", I yanked their system out and installed a strainer with a clear jar, and ...uh... apologized to the first company. The light bulb took a heck of a long time to turn on, for me, that the sediment problem was caused by the water heater (and of course, chemically hard water).

    Bottom line: Protecting the rest of your plumbing from the water heater output is as important as protecting the water heater from debris entering on the cold water input side, regardless of the quality of your water supply. (Then again, with your 20 years experience, I wouldn't change a thing.)

    That's my 2 cents.
     
  6. OldSalt

    OldSalt Member

    Joined:
    Feb 3, 2017
    Occupation:
    IT Consultant
    Location:
    Northern Idaho
    +1 on the water softener, but for various reasons on this particular house (which I did not design - bought it as an abandoned no-permit build, and renovated and completed the build), it'd be tough to install one here. I think it would fit in the current water heater closet, but am not sure. Then I'd have some excavation work and perhaps permit issues to dump the tank drainage at backflush. I think I can do it, but I'm going to put that project off for a while (you know, to give the hard water time to rot my hot water heater and every new plumbing fixture in the house :oops::rolleyes:).

    This forum is no fun without pictures. :)

    ** WARNING!! MY TANKLESS SYSTEM LOOKS LIKE A NUCLEAR POWER PLANT BUILT BY A THREE YEAR OLD. **

    It's been "modified" a few times." :eek: The control wire and gas line running across the middle of the closet were done by my highly skilled plumbers. I've been too lazy (a.k.a. busy) to re-route and tuck them, but I'll get around to it eventually. There's a whole lot of ugly in my closet.

    20171019_141129.jpg

    20180211_134334.jpg

    Rinnai_filter_debris.jpg

    20180211_134311.jpg

    20180211_134258.jpg

    20180211_134321_001.jpg
     
    Last edited: Feb 11, 2018
  7. OldSalt

    OldSalt Member

    Joined:
    Feb 3, 2017
    Occupation:
    IT Consultant
    Location:
    Northern Idaho
    One more pix:

    20180211_134236.jpg

    Note: That smaller strainer for the tank outlet side should be clear plexi-glass. However, it appears to have reacted negatively to heat, even though it's spec'd for something like 300 or 500 degrees. The water there is not that cloudy.
     
    Last edited: Feb 11, 2018
  8. Ladiesman217

    Ladiesman217 Member

    Joined:
    Dec 31, 2010
    Location:
    MA
    I love pictures. One picture is worth a million words.

    I am not sure why the sediment gets to the water heater input screen. You do have a whole house sediment filter installed on the cold input.

    Perhaps you should add a second sediment filter at the water input to the water heater. That would cut down on the large size sediments at the water heater input.

    This unit is flushable. There is a special filter for water heaters. WSP50P with Siliphos.

    https://www.homedepot.com/catalog/pdfImages/da/dac6baa1-cab3-4237-a8ae-d09c0f1f5ce7.pdf

    https://www.homedepot.com/p/ISPRING...PIPHorizontal1_rr-_-303709880-_-303568130-_-N

    https://www.amazon.com/iSpring-WSP-50-Reusable-Sediment-Filter/dp/B072YVNRZN

    https://www.bing.com/videos/search?...BE03E052751B002BCC46BE03E052751B&&FORM=VRDGAR


    [​IMG]



    [​IMG]
     
    Last edited: Feb 12, 2018
  9. Ladiesman217

    Ladiesman217 Member

    Joined:
    Dec 31, 2010
    Location:
    MA

    Nestle has a water bottling plant in town that takes town tap water (state water), filters it, and sells it as bottled water under well known brand names. No lead in my water pipes, so tap water is clean enough for me.
     
  10. OldSalt

    OldSalt Member

    Joined:
    Feb 3, 2017
    Occupation:
    IT Consultant
    Location:
    Northern Idaho
    That picture was before I added the second, W.H. outlet strainer. The last time I checked the intake screen, there was one or two flecks, and I expect that was due to what was already in the hot water line. I'll be checking it this week, and I expect it to be clean. Between the screen on the main and the W.H. outlet, I think I'm catching about all of the debris.

    In fact, I had intended to add a strainer on the W.H. intake line, in front of the Rinnai strainer, because I was so frustrated with the situation. The shower head output would

    Thanks! I love it. I had a tough time finding the cheap strainer I purchased, I was going nuts. (Seems that there's so much garbage on the internet, that any search returns a million hits of everything EXCEPT what you're searching for). Also, I'm not happy with the plexiglass going opaque, apparently, on contact with hot water.

    I looked into the flushable unit. 50 mesh is about 300 micron. So, from what I've seen, I'd have to go with a courser or finer mesh (500 or 200 microns), but I'll book mark this for a later purchase. I like it.

    This is the first I've heard about Siliphos. I'll look into that more, as well. Might help with the hard water.
     
    Last edited: Feb 12, 2018
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
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    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    FWIW, once you dissolve minerals in an acid, the acid typically still is 'clear'...it does not show particles as they are dissolved. You might see some initially if the flushing caused some to break off rather than be dissolved, but eventually, they would be dissolved.
     
  12. OldSalt

    OldSalt Member

    Joined:
    Feb 3, 2017
    Occupation:
    IT Consultant
    Location:
    Northern Idaho
    Not sure who you addressed this to, but yes, understood. I had a load of crap in the bucket (initially flushed out using the water main pressure) from residual build up, but very little sediment during/after the actual vinegar flush. Also, side note, I bought a cheap pump to try the procedure for the first time, but will probably buy a better quality pump. Seems like it kept losing pressure throughout the cycle (I let it run 2-3 hours, because the system was so limed up), and I suspect it's due to the internal components, seals, failing because I was pumping an acid rather than what the pump is most commonly used for, swimming pool water. Will have to buy a stainless steel pump for this 3x or 4x a year purpose.

    Tankless hot water heaters have turned out to be a WHOLE lot more complex than I had expected. Still, considering that we're on propane, and how little propane we use to keep hot water "instantly available", I'm pretty happy. I live in Northern Idaho near a lake, and it gets sort of could here once in a while - and the water gets colder than ice (so it seems). This unit cooks the water hot, just fine.
     
  13. Ladiesman217

    Ladiesman217 Member

    Joined:
    Dec 31, 2010
    Location:
    MA

    I also bought an inexpensive pump to flush my tankless. I suspect that your pump is as good as new.

    https://www.amazon.com/gp/product/B000X05G1A/ref=ox_sc_sfl_title_6?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

    My pump also appeared to "slow down" as it ran through the flush cycle. Two gallons of vinegar in bucket, pump water out of heater, then I ran the pump for an hour. I let the vinegar sit in the heat exchanger for a few hours, dumped 1/2 of the vinegar and added a new gallon of vinegar, then ran the pump for another hour to finish up.

    I also thought that the pump was going bad due the vinegar acid medium. After thinking about it, a few days later I tested the pump. I put the bucket in the tub, filled the bucket with water, and timed the water flow from the pump. Plenty of water pressure and flow from the pump through the 1/2" washer hose.

    Flow rate drastically decreases when the output fitting size is reduced from the 1 1/4" pump output to the 1/2" washer hose and heat exchanger size. In addition, my tankless has a 3 1/4 gpm water flow restrictor in the water input pipe as well as a backflow device in the water valve. Too much back pressure will reduce the flow by quite a bit.

    https://images-na.ssl-images-amazon.com/images/G/01/th/content_26/Q1_2011/c26-B000X05G1A-3-l.jpg

    My service manual descale procedure does not require a high pump flow rate As a matter of fact, water flow is not even required. The instructions say to fill the heat exchanger with vinegar and wait for at least 45 minutes, then flush. Too much work for my taste. The pump and bucket vinegar method with low flow works just fine to dissolve the mineral deposits in the heat exchanger. Just give the vinegar enough time to work.

    If you pay a plumber to do a descale, I wonder if they spend the time to do a full descale? I also wonder if the washer hose that I use is too small in diameter.

    https://www.bosch-climate.us/files/201109161944490.TWH-V-16_125-80_Descale_heat_exchanger.pdf
     
    Last edited: Feb 13, 2018
  14. OldSalt

    OldSalt Member

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    Occupation:
    IT Consultant
    Location:
    Northern Idaho
    I used about 3.5 gallons in a five gallon bucket. I saved half of it, and planned on reusing it, adding a new gallon of vinegar next time. I thought that the vinegar ph (i.e. =2 or 3) is probably nearly the same as new, so why use new stuff, but I might be wrong.

    I'm a notoriously cheap guy. I'll use the existing pump until it cries uncle. If it's using rubber or silicon seals, moderately high ph acid like vinegar shouldn't hurt it anyway. I can't see how mild acid in the seals or plastic could do more damage than simple water.

    Yeah, the change in pressure was so gradual that it had me wondering if the pressure really had changed. However, this 1/2 HP (maximum 2500 GPH) pump should have been blasting even with the inlet/outlet reduction to 1/2". Online reviews had other buyers upset, indicating similar problems. I just think my pump is cheaply made, that either the seals are inadequate to the pump motor size, or the pump itself is failing (e.g. maybe electrical, or maybe the impeller is coming lose from the shaft, something like that.) I'm not an engineer, but I played with engineering in the Navy. :cool:

    https://www.amazon.com/gp/product/B0170M5OM4/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
    41D+41z6g4L.jpg


    Good question for a plumber on the forum who regularly performs this service call. If I were a plumber with the tools and experience, I believe I could probably do this in an hour, i.e. pop off the valve covers, hook up the hoses, pull a ready five gallon bucket of vinegar from the truck, plug in the pump, watch it run for 1/2 hour, flush with water, close valved and covers, and present my bill. A half hour would probably be enough in most situations. I can't see a plumber spending hours on this, or perhaps two trips to the residence to let the pump run for a while while he worked a second call. LOL, probably 90% of homeowners never have this done any how.

    I can't see the 1/2" hose being a problem, particularly since BOSCH doesn't even proscribe a real "flush". It's more of an acid rinse, followed by a ph neutralizing solution (which I found REAL interesting; what's more "neutral" than pumping tap water through it for five minutes after the vinegar?). Germans do things differently than the rest of us. :)

    I know for a fact that the tap water pressure behind the initial flush (i.e. I opened the hot outlet side and left the cold side charged, and filled two 5 gallon buckets with water) cleaned out loads of stuff, that the Bosch funnel procedure wouldn't have touched. I also don't see how running vinegar through the system for 1-3 hours would be worse for the water heater than 15 minutes of soaking, with the Bosch routine.

    Anyhow, thanks for contributing here.
     
    Last edited by a moderator: Feb 15, 2018
  15. Ladiesman217

    Ladiesman217 Member

    Joined:
    Dec 31, 2010
    Location:
    MA
    Now that I think about it, the old standard washing machine hose that I used for the flush is too small in diameter. The inside diameter is only 3/8". That small diameter restricts the pump flow rate way too much. Too much back pressure for the pump.

    For the next flush I probably will buy a 5/8" standard water hose and cut it to length. I will have to install another female hose connector on one end to make an appropriate female to female hose.
     
  16. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
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    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    Did the pump get hot after running? THat may account for things slowing down some.
     
  17. Ladiesman217

    Ladiesman217 Member

    Joined:
    Dec 31, 2010
    Location:
    MA
    No, the pump is submerged in the vinegar and can not easily overheat.

    The effective head makes the difference in flow. There is some type of air purge and output back pressure bypass valve in these pumps. The more back pressure on the output line, the more fluid that exits the pump bypass output which feeds back from the base of the pump into the bucket. I think that bypass keeps the pump cool even if you get no flow from the pump output line due to a blockage or too much effective head.

    It is clear that the effective head of this flush setup is near the limits of these pumps. A 1/2" washing machine hose only has a 3/8" inside diameter. Perhaps a 10 foot long 3/8" id hose adds too much effective head to the pump output. The use of a 5/8" id input and output hose should reduce the effective head enough to notice the difference in flow.

    The 3 1/4 gpm flow restrictor in my water heater's cold input pipe also adds to the effective head in my setup.
     
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