Need to descale my tankless heater can you use a sump pump

Discussion in 'Tankless Water Heater Forum' started by loki993, Oct 26, 2012.

  1. loki993

    loki993 New Member

    Joined:
    Aug 7, 2012
    Location:
    Michigan
    I have to descale my tankless water heater. I've lost a bit of flow on the hot side apparent and its affecting the water pressure ion the shower.

    I have what I need but I didn't want to go spend the only on a pump if I didn't have to. I went to my dads house and he has a half horse sump pump he said I could use. Now I'm not sure but I'm afraid that it could be too much flow/pressure to do the descale.

    Can you cause damage to the unit by using too powerful a pump or should I be ok using the sum pump?
     
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Joined:
    Feb 6, 2011
    Occupation:
    Retired
    Location:
    NW Ontario, Canada
    Most sump pumps are between 30 and 90 GPM while descalers generally are a tenth of that. Also descaling pumps are resistant to the acid used. Not sure what the acid might do to a sump pump.
     
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  4. loki993

    loki993 New Member

    Joined:
    Aug 7, 2012
    Location:
    Michigan
    Im just using vinegar, nothing serious, the pump should hold up. Im just worried that it may be too much pressure.
     
  5. Killer95Stang

    Killer95Stang Member

    Joined:
    Mar 24, 2012
    Location:
    Southern CA
    A 1/2 hp unit seems like a huge overkill to descale a tankless. I'll be using a 1/6hp pump I picked up at HF... I'll check in to post the results once I'm done....
     
  6. Killer95Stang

    Killer95Stang Member

    Joined:
    Mar 24, 2012
    Location:
    Southern CA
    So.. Yesterday I completed my 6 month descaling of my Rheem Condensing Tankless water heater. I used the 1/6hp pump below that I purchased at HF with my 20% coupon. I then sourced two 6ft washing machine hoses, since they already have the needed FPT hose ends installed. I used a clean 5 gallon bucket filled with 3.5 gallons of white distilled vinegar. I first bypassed my tankless from the house water system using my installed service valves, then drained the waterheater. I connected the hoses to the WH and circulated the mild acid solution for 45-60 minutes. After, I flushed the WH twice with clean water using the same pump and bucket, then cleaned the small filter of loose debris.

    All said and done, the process was pretty uneventful. I ended up spending about $70.00 for all the supplies needed, which is way cheaper than buying one the $169 pre-made kits.

    [​IMG]
     
  7. loki993

    loki993 New Member

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    Aug 7, 2012
    Location:
    Michigan
    Yeah I think its overkill too, but the pump didnt cost me anything. I was trying to avoid the biggest cost of the job which is the pump. However Im not going to risk damaging the unit to save some money. Maybe I can run across a pond pump on clearance somewhere.
     
  8. saphman

    saphman New Member

    Joined:
    Jan 18, 2012
    Location:
    Northwest Florida
    I agree with you. I have the 1/6 hp pump I bought at lowes. It has just the right amount of pressure and flow.

    Another option to descale is using "SULFAMIC" acid powder. This is available through LOW ENERGY SYSTEMS and comes in a 5lb bag. There is a copper protector solution that you add with the powder to a gallon or so of water that is red. When the descaler has circulated and done it's job the water turns clear. It is better than vinegar IMHO.
     
  9. lifespeed

    lifespeed Member

    Joined:
    Apr 27, 2007
    Location:
    California
    The sulfamic acid certainly sounds well-suited to the job of descaling. How about a link to this "copper protector" solution?
     
  10. Mac Cat

    Mac Cat New Member

    Joined:
    Feb 18, 2017
    Location:
    Texas
    This operations only affects your hot water. You should also remember to un-plug your tankless water heater (you don't want it to kick on while you are flushing it out!) And, what ever you use, remember it's in your drinking water, so make sure it's clean.

    I used 1/4 hp motor without any problems. It was $55 and while the output port was 1 1/4" wide, it had a cap on it that reduced the output side to work with a garden or washer hose. The pressure didn't seem to be a problem and volume was very manageable.

    I first flushed the tank with clean water, using a clean kitchen trash can (13 gallon size, I think). It's taller than a bucket and takes less water to fill over the top of the sump motor. There are no switches on sump pumps, so it just goes on when you plug it in.

    For the second pass, I pumped all the water into a second plastic tub and dumped it out. Then I filled it back up with white vinegar, which is about $2/gallon at the grocery store. I used 4 gallons. I ran the pump for an hour.

    The vinegar is fairly weak acid, it won't hurt you or your pipes or you pump (most pumps have plastic and/or hard rubber impellers, so the acidity and the shot time you use it, is not important.

    Remember to flush again, with clear water. If you just drain out the vinegar, you may have get cloudy hot water and you will detect a little of the left over vinegar smell. It's harmless and all goes away after a shower or a washer load of clothes.

    Main thing is, you can buy the parts for about $70, including new washer hoses (4-5' long is plenty).
    Last year, there were dozes of kits to choose from. Too many of them included disinfectant powders and chemical.
    The year, their were very few kits to choose from and they average $150 each.

    The kits are fine, but all you need is a pump (1/6 to 1/4 hp). I'd buy a new one to use, because if your sump pump is as nasty as mine, I doubt you'd want to drink water after using it.

    I use 100 % white vinegar (5% solution). There are stronger vinegars (9% and higher), which you don't need, but they work about the same.

    (Last year, someone recommended diluted vinegar on one of the web sites. That isn't right.)

    As for frequency, that depends on the quality of your water. If you have a water softener or a household sized charcoal filter, you don't need to do this step very often. Annually is good, but every 6 months is too often. If you have that kind of scaly water (like we do in Texas), you should consider additional water filtering, too.

    I love my tankless heater. It's been so much more reliable than my 50 gallon tank, which had little scale, but after 15 years, it just started springing leaks everywhere around pipe joints.

    There is also a thread going on about scale deposits and how to control them. Scale likes copper, but I've seen it in brass and even plastic supply hoses. I've also heard it can be extra hard on houses with mostly plastic pipes, where it will build up heaver in the few places that copper is exposed.
     
  11. Mac Cat

    Mac Cat New Member

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    Feb 18, 2017
    Location:
    Texas
     
  12. Mac Cat

    Mac Cat New Member

    Joined:
    Feb 18, 2017
    Location:
    Texas
    That's a 1/2 hp sump pump, which is really too big to run in some buckets or small trash cans. But, notice that it comes with adaptors to smaller output size. Yes, the pressure will be a little higher, but that shouldn't hurt your tankless system. Many of these pumps have adjustable output, using a adaptor with a smaller size or intake port covers (*more typical of water fountain pumps).
     
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