tankless-luke warm shower

Discussion in 'Tankless Water Heater Forum' started by wt, Jan 30, 2009.

  1. wt

    wt New Member

    Messages:
    1
    I recently installed a tankless hot water heater. I have a shower panel with a single handle adjustment with a mixing valve. The only way I can get the shower hot is by restricting flow at the gate valve on the cold supply line. I have adjusted the shower anti scald valve all the way to its hottest setting. All other fixtures in house will produce hot water. I did notice in a second bathroom that has an older valve setup that when only the hot water is turned on all the way that the flow is not as strong as it used to be prior to hooking up the tankless unit. It does come out hot but the flow rate is less than if you turn on only the cold side. Could the imbalance in flow rate at the mixing valve be the reason for not getting a hot shower? Can I put a circulation pump on the hot line to increase the pressure to match that of the cold line? Do I put the pump after the tankless unit or before it? Thanks for your help.

    Water pipe sizing
    Last edited by a moderator: Feb 8, 2009
  2. Sounds like an undersized unit.

    No fixes for that.


    You're exceeding the demand that tankless will provide.



    Use a water saver showerhead.


    Did you buy the bosch from lowe's/home depot?
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,820
    Location:
    New England
    Almost all tankless systems have a flow restrictor in them. So, not seeing as much volume in the hot side verses the unrestricted cold side is entirely normal. I do not know for sure, but wouldn't be surprised that the valve will not allow all hot input, and because the cold is full flow, you may never get hot enough. The pressure balance function may be restricting the hot flow.
  4. Ladiesman271

    Ladiesman271 Homeowner

    Messages:
    221
    To get an informed answer first make sure that your heater is perfoming right.


    1. Measure the temperature of the hot water at the sink closest to the shower after the hot water has run for a while.

    2. Measure the temperature of the cold water at the sink closest to the shower after the cold water has run for a while.

    3. Measure how many gallons per minute you get from your shower head with your normal settings.


    The make and model number and type (gas/electric) of the tankless is also needed.
  5. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Ain't tankless heaters great? :D Note the number of threads about tankless problems compared to threads about tank water heater problems.
  6. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,308
    Location:
    Yakima WA
    I wondered how long you could keep quite on this one. :D Gotta love tankless. Without them and Whirlpool WHs it would be lonesome.
  7. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    I had a nightmare last night. House piped in CPV and ABS with a tankless water heater, Champion toilets and Moen valves throughout. AHHHHHHHHHHH.:eek:
  8. Delta faucets now has a disclaimor

    Delta faucets have been in so much controversy
    due to the tankless water heaters that they are now
    sending out a disclaimor in every box telling
    the customer that a pressure balanced faucet
    and a tankelss water do not work well together....


    they empahtically state that this is not their
    faucets problem, it is the gap and hesitation
    in the tankless heater that causes the trouble..


    their pressure balanced faucet is
    doing what it was intended to do
    so piss off.






    gee, I wonder if that is what is going on here>>>:D..
  9. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas
    Got one of each... they work well together for me and my family of six.... But then again I installed both! :p

    Water pipe sizing
    Last edited by a moderator: Feb 8, 2009



  10. I missed this....so is Delta putting this in their boxes, or the tankless heaters?


    I never read the instructions on anything; I learn more by trying to figure it out on my own.

    I just bought a kidney from india and I think it's working. I'm pissing blood but that's normal for the first 96 hours!
  11. sjsmithjr

    sjsmithjr Geologist

    Messages:
    295
    Location:
    Knoxville, Tennessee
    Well, it's on the Delta website:

    "Often the outgoing water pressure from a "tankless" water heater is relatively low. As a result, these devices are not generally recommended for use with pressure balanced units due to the possible differences in water pressure from the hot and cold lines. For example, if you were to have 20 PSI on the hot supply line and 50 PSI on the cold, since pressure balancing adjusts to the low pressure, your resulting operating pressure in the shower will be reduced."

    Maybe Greg should give Delta a call and let them know that their wrong too. The Boy Scout's all trades certified and got it all figured out, you know. :rolleyes:
  12. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas
    Sure, they can call me! Delta can even come out and check what I have. It works and YOU can't take that fact away! HAHA. The key to a tankless system being trouble free is proper sizing of the unit in the first place. Buy too small a unit and you WILL have problems. Installation issues is the second area of problems. Wrong gas line sizing, wrong water pipe sizing and tankless location will cause problems too. The third area of issues is region... too cold inlet water temp, too low water pressure and just plain too cold of region can all cause problems.

    Selling, installing, and using a tankless system requires some brain power! Don't be dissin' a Boy Scout.... :cool:
  13. sjsmithjr

    sjsmithjr Geologist

    Messages:
    295
    Location:
    Knoxville, Tennessee
    I see. So the blind squirrel gets a nut and things like working in your field for over 20 years, extensive experience, the ability to troubleshoot multiple systems, etc. etc. goes out the window.

    Why wait to be discovered? I really think you should give Delta a call and explain to them the error of their ways. Why stop there, though? HD and Lowes are obviously in need of schooling as well. Sounds to me like your sitting on a gold mine!
  14. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Here greg just so you have the benefit of seeing it with your own eyes...

    http://www.deltafaucet.com/customersupport/faq/Water+Pressure/

    Perhaps you need to realize that your tankless experience down in Texas is going to be a lot more pleasant than a person might have in Houlton, Maine where they might be looking at an 87 Degrees F rate of rise spec and wondering when some water is going to start coming out of their pressure balanced shower.

    To ignore that is simply having a vision problem...

    [​IMG]
  15. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Is tankless performance outside of the extreme south of the country a real world question?

    When you get away from there tankless loses its practicle and green appeal.
    It becomes more a situation of I want my 20 GPM carwash shower to work and I want an unlimited supply of water for it!
    I don't care what it costs!
    Last edited: Feb 2, 2009
  16. CarlH

    CarlH New Member

    Messages:
    175
    Location:
    Northern VA
    I think the OP got the most likely answer to their problem, which is the combination of a flow restrictor on the tankless and pressure balance valve are the cause of the luke warm shower. Also, Delta recognizes this potential problem. Note that Delta used the word "Often" and not "Always". And I would have thought that a pressure balanced valve would have helped out the situation. I guess I learned something new today.


    Greg,
    It is situations like these where a tankless heater gets a bad rap. Whose fault is it in this case? Does it matter? What is the OP going to do to resolve the problem? Get a tankless with a higher capacity/flow? Change the shower valve? Either way it may be an additional expenditure that was not expected.

    Also, note that there are different makes of Tankless heaters on the market and they vary in their performance and reliability. Sounds like the Rinnai that you have is a decent unit and seems to be working out well for you. I'd be curious to hear how that unit works out for you in the long term, good or bad. Now that you've had it for a few months, have you noticed much of a change in your gas consumption? Does the gas consumption begin to rise before a routine cleaning?
  17. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    No Greg, I'm just saying in your replies to other posters that are telling of their experience in their area with tankless and comparing it with your experience brings little to the table.

    As for Delta doing a CYA... the problem is not theirs...
    Cutting back flow rates to maintain temperature is the nature of the beast with tankless and they are stating they are not responsible fir ineffiecencies of a water heating system...
  18. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas
    I agree that the bad rap may be a needless case of chasing rabbits and red herrings. I think that manufacturers may be overstating some of the spec. This in turn could lead to undersizing issues. That "global warming" thing we are seeing now isn't helping :cool:

    Our 1 year anniversary with our Rinnai will be in August. I will be doing a 30 minute descaling and filter clean at that time. I did look at the filter last November out of curiosity and it was clean. I do believe also in "you get what you pay for" in that the Rinnai represents one of the top 3 or so of quality tankless manufacturers. No, I am not on their payroll either ;)

    Being a long time (20+ years) Mac owner and authorized service provider... I don't advocate what sjsmithjr talked about! I charge extra, read triple, when I work on junked up system like that.
  19. sjsmithjr

    sjsmithjr Geologist

    Messages:
    295
    Location:
    Knoxville, Tennessee
    Well, actually, the part a guy with over 20 years experience in his field, a guy with extensive experience and the ability to troubleshoot multiple systems is from your business' website. That's you in your field.

    A lot of the plumbers dispensing advice here have the same or better qualifications in their fields. They're not troglodytes nor are they basing thier opinion on one install; you know, the guy who got a lot of parts at a good price and got it to work for him under one set of conditions.

    I am happy to hear your's is working well for you. Now if it were to experience a catastrophic failure of a critical component, how long would it take to get the part? Around here it would be "days" even with an expedited order.
  20. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas
    Will deal with downtime, if and when it happens. I hear Fedex has this thing called overnight shipping. May try it down here in the backwoods of Texas. :D

    More FUD
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