hybrid tankless fix/solution

Discussion in 'Tankless Water Heater Forum' started by greatwhite, Feb 6, 2009.

  1. greatwhite

    greatwhite New Member

    Messages:
    5
    Hello. i am a genius that bought a too small indirect superstor 30 a couple of years ago and now needs more water. i was going to add storage tank installed in reserve storage configuration with superstor as heat source based on ease and relative cost.

    what does anyone think of this instead: i can get a gas tankless on demand for around $200 after the $300 tax credit. (ss flue will add about 100-150 to cost).

    instead of adding storage tank as before, I would plumb cold into tankless and hot output (set to 122F) into cold in of superstor. keep superstor heating "coil" connected as before. now i have a 30 gallon store of hot water that will prevent lag i have heard about with tankless heaters and when superstor's reserve "gone" hot water (up to 5.8 gpm) will go on indefinitely. than current setup with indirect will heat tank to make up for any stand by loses.

    i would not bother will all of this if i had sized the tank with a look to future when i installed it, but now that i have it, i just cant see disconnecting and running tankless especially given lag concerns. Also for a few dollars more, I essentially will have unlimited hot water (finally).

    any comments/input you have will be greatly appreciated.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,353
    Location:
    New England
    A couple of questions first. What is the temperature setting on the indirect? The combination of setting that hotter and adding a tempering valve (if you don't have one) would extend the safe amount of water in the system.

    How much hot water in one session do you want?

    Is the tank on a priority zone? This means that when the indirect calls for heat, it is the only zone that gets it, letting the full output of the boiler work towards keeping the water hot.

    How big is your boiler?
  3. greatwhite

    greatwhite New Member

    Messages:
    5
    thanks for reply

    i have tempering valve; indirect set at 140 tempered down to 120, tanks is indirect superstor30, dhw on own priority zone (i didnt add part in original post that "rigging" with the tankless with the superstor should greatly reduce the amount of "off" time for hydronic heat while dhw in use or tank is in recovery.) boiler is 140K. tank it is suppled with 180f water, designed for i believe 6 gpm (one inch pipe with own 007).

    problem is when i put in suprstor, it was just me and my fiance, on a limited budget. I had 30 gallon storage tank linked to old old bolier coil and it worked fine for us so i figured 30 gal indirect should suffice. life changes best of plans and now 5 adults (me and her, plus 3 family members) live together and all work so hw used one afetr another after another. after third shower, family has to start staggering times to allow dhw to recover. as problems go, it not that bad and i avoid all together by scheduling when i shower when they dont. however for few hundred bucks, its worth it for me to try to remedy. eitehr way, i figure when i have kids, i will have to addrss b/c baths etc.(what if i have girls, oh my)
  4. mattbee24

    mattbee24 In the Trades

    Messages:
    100
    Location:
    Fremont, OH
    Something must not be working right. According to the specs on the superstor30, you should get 154 gal of hot water the first hour. That is at a 90 deg. rise with 180 deg boiler water. What kind of shower heads are you using? It might be as simple as changing your shower heads to low flow. If you would go with say 2 gpm shower heads that would give you plenty of hot water. Even if you used all hot water without any of the cold being mixed in, you have 75 min. of hot water. (of course it's really more than that since you go over the hour mark) That's 15 min. showers each with no down time.

    Of course, I could just be reading the specs wrong, or have absolutley no idea what I am talking about. That has been known to happen with me!

    Hope this helps,

    Matt
  5. greatwhite

    greatwhite New Member

    Messages:
    5
    is is an old regular flow one. i had low flow but it su*ked.it not so bad, ie i anm getting 3, 10+ min showers in a row. just would be nice to not have "worry" or wait. i am going to "time" head with buxket and stop watch wheni get home.

    the more i think of it it could be the way P/s piping is set up now. water in the primary loop is 180f when it gets to "off" ramp for heater. i do not have temp on "out" pipe of secondary loop coming from water heater. i think primary loop pump may be too big and water not getting to indirect( ie it is stay in the primary loop)
  6. Ladiesman271

    Ladiesman271 Homeowner

    Messages:
    221
    Do you have a pressure balanced shower valve installed? That is a potential problem area.

    After a few people take a shower, measure the hot water temperature at the closest sink. Then measure the highest hot water temperature you can get out of the shower valve.

    Also, measure the steady hot water temperature after you flush all of the standing cold water out of the hot water pipes. The idea is to see what temperatures you get after various hot water run times.

    The 140 degree water temperature before tempering may be a bit too low for the tempering valve to work properly. Try 150 to 180 degrees tempered down to 120 to 140 degrees. Heck, you have an 180,00 BTU boiler. Use what you have before you go off on a sidetrip!


    The following does not include the indirect storage tank, but it gives you an idea on temperature settings.


    .

    Attached Files:

    Last edited: Feb 6, 2009
  7. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine

    If I am reading this correctly are you saying that you have the indirect coil piped through the boiler coil? If you do than that's why you are not getting enough hot water. The indirect should be piped as a separate zone off the boiler feed and return piping. The feed and return pipes need to be 1" copper also to get maximum flow through the indirect coil. It sounds to me like something is not piped correctly. Also the tempering valve may be bad and installed in the wrong location.
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