Problems after removing how water storage tank

Discussion in 'Boiler Forum' started by dyaco, Feb 27, 2013.

  1. dyaco

    dyaco New Member

    Messages:
    2
    Location:
    CT
    I recently had my hot water storage tank fail and removed it from the system completely. I replaced it with a passive mixing valve straight off the boiler. My boiler is oil fired and was installed in the late 90s. This unit also feels the baseboard heat in the 2 story 1800 sqft home.

    things seems to be running fine for a couple of months. However is seems within the last few months my water temps have been fluctuating greatly.
    temps at the showers and faucets seem to take forever to warm up, sometimes the shower only gets luke warm and sometimes scalding hot. It does seem like the water pressure drops slightly when the temp drops to luke warm to barley tolerable cold

    I have tried adjusting the dial on the mixing valve and that outdoes seem to help much. There are only two people in the house, and I have the same problem with running nothing but the baseboard heat for hours and hours before. I am not sure if the cold New England weather would affect it at all.

    I'm at a loss here guys. can anyone shed some light. any help is much appreciated
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    I'd need a bit more info to understand exactly what you've cobbled together there, but if I do understand what you've done, your boiler may not live long.

    The tank acted like a buffer to help maintain a (small) supply of water and help heat the incoming cold water so you had a decent 'nominal' temperature output. Bypassing it means the outlet temp is entirely dependent on the volume used and the incoming water temp. Try to use more, it's in contact with the heat exchanger a shorter time, and it's cool. First draw after a long time, quite hot. Mixing valves don't react immediately. Your best bet would be to add an indirect WH tank as a priority zone on the boiler for your hot water supply.

    Maybe with a little more understanding, something else would come up. What brand and model boiler do you have?
  3. dyaco

    dyaco New Member

    Messages:
    2
    Location:
    CT
    I actually had the repair done by a licensed plumber. The storage take was just a storage tank, no heating element and it was not on a separate zone. 40 or 50 gal cap i believe. It did have a circulating pump on it.

    My understanding is that he took a tap of the main line from the street as the cold in to the mixing valve and the "hot out" from the boiler that used to feed the tank into the hot side of the mixing valve. If I remember right the plumber explained to me that the storage tank is not common and most with my setup use the mixing valve is more commonly used.

    I have a Weil-McLain P-WTGO-4
    IMAG0878.jpg IMAG0881.jpg IMAG0883.jpg
  4. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,309
    Location:
    Maine
    Your plumber should have dropped the tempering valve below the coil. Hot water sits on the spring and weakens it. A replacement cartridge for the tempering valve will fix it for a while but the problem will return
  5. CameronRobertson

    CameronRobertson The Storage Man

    Messages:
    3
    Location:
    Dee Why , Australia
    Any option of putting any hot water storage back in? I'm no plumber, but I'd try to stick with the original system as much as possible if it was a system that worked. Additionally, I personally would prefer a reserve tank just in case of those situations where I'm just rushing for a shower and don't have time to switch the heater on, or I just plain forgot. It also takes care of the situation where everybody wants to have a shower one after another and somebody uses up all the hot water as it's getting heated up.
  6. Dana

    Dana In the trades

    Messages:
    3,027
    Location:
    01609
    Abandoning the internal could and installing indirect-fired hot water heater operating as a priority zone off the boiler would let you run the boiler at a lower standby temp/higher efficiency, and install a retrofit heat-purge controller (eg. Intellicon 3250 HW+ or simililar.) This boiler has enough output to deliver "endless hot water" showering capacity when the indirect is operated as the priority-zone. Heat purge boiler control would minimize standby losses by parking the boiler at a lower temp at he end of a call for heat, and letting the boiler to drop down to the low limit (140F recommended for this boiler) before firing on subsequent calls, and would likely cut 12-15% off the oil bill.

    It's not a cheap hack, but it's probably the right thing to do (short of changing hot water heating fuels.) Odds are pretty good that you could heat your house with a max temp at the boiler of 160F, but probably have to set the MINIMUM temp of the boiler to 160F to have reasonable hot water performance. The higher standby temp adds up to a higher standby loss, and I'm guessing that the boiler room is still the warmest spot in the house most days, despite the high loss rate out of the uninsulated foundation.
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