Delta and Tankless HWH Solutions

Discussion in 'Shower & bathtub Forum & Blog' started by Greatwhitewing, Apr 19, 2011.

  1. Greatwhitewing

    Greatwhitewing New Member

    Messages:
    27
    Location:
    MA, United Staes
    Hi, first post but did do some searching.

    Have an oil fired Burham with a tank-less HW system. Short run of 1/2 copper tubing to the shower. My boiler is old and will need to be replaced in the near future. Hoping it lasts till next spring. My boiler runs about 180 with a tempering valve that looks pretty tired and crusty.

    My 20 year old Moen had very poor regulation and was showing its' age so I replaced with a Delta series 17 valve with temp control and volume handle.

    I am still getting poor temp regulation and I understand from reading and talking to Delta it's the pressure differences between hot and cold supplies.

    I have some questions about possible solutions.

    1. Would adding an indirect HW tank solve it? please explain how?
    2. Can I put the Buderous LT series tank beside my Burnham till I get the G125B or GB125BE boiler later?
    3. Can my problem be the old tempering valve?
    4. Semi-clogged coil?
    5. What type of good quality single handle valve would be a better choice?
    6. Is an Inline remote pressure balancing valve located near the shower a viable solution?

    looking for short term cheap solutions with a long term boiler replacement in mind.

    Thanks for your input
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,058
    Location:
    New England
    Many heaters like you have utilize a flow restricter to slow the water down so it can get hot enough. That may be a problem in itself. The tempering valve may be shot as well. Depending on design, the coil may have some restriction in it caused by mineral buildup that would also limit the heat transfer as well.

    Most any indirect could be installed to provide you with a large quantity of hot water, the brands are pretty much interchangeable - each has it's internal design features and capabilities, but they all generally will work with any boiler. An indirect is often installed on a priority zone to ensure you get all the shower time you want.

    New shower valves come in two general types, thermostatically controlled and pressure balanced. Each provides antiscald capabilities. The thermostatically controlled one may contain both technologies, depending on the design. Different pressure on a pressure balanced valve can limit the total throughput or shut it off entirely, if it gets bad enough. It could affect a thermostatically controlled valve in different ways, depending on the brand. In one hotel in London, the pressure varied all over the place, but the Grohe thermostatially controlled valve kept the output temp pretty consistent, but the flow did change. After experiencing that for a week, I bought a Grohe when I remodeled and have been satisfied, but I don't have the same pressure variations you have.
  3. Greatwhitewing

    Greatwhitewing New Member

    Messages:
    27
    Location:
    MA, United Staes
    Jim, do you have any knowledge if something like this would help?



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    Last edited by a moderator: Nov 25, 2013
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,058
    Location:
    New England
    This would likely compound the problem you have...as stated, there are two different technologies that can meet the antiscald federal requirements: pressure balanced and thermostatically controlled. While I can't say this with certainty, my gut feeling is that a thermostatically controlled valve would work better at maintaining temp than a pressure balanced one. A pressure balance valve assumes that the hot and cold supply temperatures are constant, and tries to maintain the selected balance. A thermostatically controlled valve adjusts the hot/cold flow rates to try to maintain a constant temperature...two different ends to the same means - keep you from scalding yourself. The valve you linked is an in-line pressure balance device, similar to what is in your Delta valve. Depending on the series, you may be able to utilize a different cartridge in the Delta and get a thermostatically controlled valve. On some rough-in valves, you can use three different cartridges, I think you have a pressure-balanced version with separate temperature control and volume controls. I put a similar one into my mother's house as she lives alone on a conventional water heater, and a thermostatically controlled valve wasn't a big advantage and she didn't want to spend extra for it. I think in your case, this may be a worthwhile upgrade.

    If the thermostatically controlled valve would work in your rough-in, you'd need new trim and cartridge. You may want to talk to Delta again and ask them if that would work better in your circumstances than what you have. As stated, the Grohe thermostatically controlled valves in that London hotel kept the temp constant when the volume and pressure was going all over the place. There are also multiple ways to do a thermostatically controlled valve - some use wax, some use a bimetal spring, and there may be others. To maintain the antiscald capability, it must respond in (I think) a second or less.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,689
    Location:
    Cave Creek, Arizona
    You already have a "pressure equalization" device in the shower valve. All a second one would do is restrict the volume AND pressure to the valve. We cannot tell if the temperature fluctuations are due to pressure imbalances, although it is not likely, or that the temperature TO THE VALVE is changing, and we cannot give an answer without being there and doing our own testing. ANY of the conditions you asked about could be causing the problem. Your options # 5, and 6 would NOT be solutions.
    Last edited: Apr 20, 2011
  6. Greatwhitewing

    Greatwhitewing New Member

    Messages:
    27
    Location:
    MA, United Staes
    HJ, I performed a flow test separately of the HW and CW. I filled a bucket with HW and it took just over 35 seconds, then filled the same bucket with CW and took under 25 seconds. Seems like a big difference but expected more.

    If I am having large HW temp changes as you suggested why did I NOT have anywhere near the same problems with the old Moen that had NO compensation at all???

    Doesn't make sense to me plus Delta told me it was large pressure differences beyond what the valve could compensate.

    I talked the parts guy at a profession plumbing supply and he was convinced the valve I posted earlier WOULD solve my problem.

    Not saying who is right or wrong but I am getting wildly differing answers with this and boiler selection questions. One guy says indirect water heater is best way to go and another says that it's not, use a storage tank off the tank-less?????

    Pretty hard to figure out who to listen to.


  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,058
    Location:
    New England
    In general, I wouldn't wish a tankless system on anyone except maybe an enemy. Yes, they can work, but I don't think they are worth it in many situations. An indirect water heater looks like a regular electric WH, except it is heated as a zone off your boiler. When the water cools down, it's just the same as a call for heat to the home, the boiler kicks in and reheats the indirect. It would certainly work. Now, is it the best solution, hard to say without being there to analyze your system needs and desires. You indicated you were going to replace the boiler next year. With an indirect, there should not be any more restrictions in flow than there currently is in the cold supply line, assuming you keep the pipe sizes the same through both. This is not necessarily true with your current system (internally, the pipe could be smaller than the supply), and may also be true for many tankless systems. Many in-tank heaters of a boiler and some tankless systems use a flow restrictor.

    The only temperature variation from an indirect would be like from any tank, slow cooling off as you dilute the hot water that's in the tank already during use. There should not be any drastic/rapid changes.

    Your valve already has a pressure balanced valve internal to it. Adding a second one is not likely to help. If the actual supply temperature is varying radically, something is wrong, and the valve won't fix it. As said before...a pressure balanced system does NOT CARE about the actual temperature, it is trying to keep the flow constant during use. If your hot temperature water increases, it has no way of knowing that...only if the flow (pressure) changes does it try to adjust and keep the hot supply/cold supply ratio the same. It WILL NOT keep the temp constant if the supply temps are changing. A thermostatically controlled valve has a chance, it depends on how rapidly it does change. The two types of valve are fundamentally different: PB, constant flow ratio; thermostatic, constant temp output. They both can achieve a similar safety feature, but comfort wise, the thermostatic valve wins since, say on the tank, as the hot water gets used up in a tank, it can cut back on the cold. A PB valve would just let the output get colder, only keeping the relative flows the same between the hot and cold supply.
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