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Low hot water pressure with LAARS Endurance

FredQuimby Member Posts: 3
edited March 2015 in Domestic Hot Water
I have a LAARS Endurance combo heat and hot water system. It was installed about 8 years ago. In January the hot water pressure slowed to a trickle making showering an impossibly (The low flow was still maintaining the right temperature). I called the only LAARS certified tech in my area and he came out and diagnosed the problem. He replaced the heat exchanger which he said was clogged, and also replaced the flow valve from an internal metal unit to an external plastic unit. Hot water pressure was back better than before.

45 days later my hot water pressure is dropping drastically again. Can anyone offer any suggestions? It cannot surely be the same problem already?



  • Abracadabra
    Abracadabra Member Posts: 1,948
    I'd guess there's something up with the new "external plastic" flow restrictor that was installed.
  • FredQuimby
    FredQuimby Member Posts: 3
    LAARS certified tech spend couple hours on the phone with LAARS. They cannot figure out what is going on with it. 8 Years old and more headaches than you can imagine.
  • Pabloblanco
    Pabloblanco Member Posts: 2
    Did you figure out the problem? I'm having the same problem. Cleaned the exchanger with vinegar overnight but it didn't help. Also replaced the mixing valve.
  • Jamie Hall
    Jamie Hall Member Posts: 15,344
    Clearly a flow restriction somewhere -- try and diagnose where. Are either or both of you on city water? Or wells? For @FredQuimby -- if you are on well water, is it possible that the water has significant sediment in it? That could clog the exchanger surprisingly quickly -- and it's a problem which could come on equally quickly in the well.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Pabloblanco
    Pabloblanco Member Posts: 2
    edited April 2017
    I'm on a well. I soaked the exchanger in vinegar overnight, a bit of gunk came out, I then blew it out with an air compressor. Now the internal pump is on all the time. Wondering if the flow sensor switch is bad. I replaced it a few years ago with the new design switch.
  • FredQuimby
    FredQuimby Member Posts: 3
    This system became a nightmare that still exists since my original question 2 years ago.

    I was never able to get a complete solution to my original problem. However I did get a pain in the **** work around by installing clean out valves on the hot water lines coming out of system. Now I routinely flush the system with Witlam descaler (they sell a pump and solution kit). I need to do this every couple months otherwise the problem reoccurs. The Witlam descaling solution is not cheap but it does not corrode the exchanger.

    I have since found out that 2 of my neighbors have similar systems and similar problem. One neighbor got so fed up with dealing with it , she bypassed the hot water part of the Laars system and installed a regular hot water heater instead .

    To Jamie, yes we are on well water. I live in a small complex so my neighbors with the same problem are drawing from the same well also. Maybe that's why were having such problems.

    I wish everybody the best luck with this system.

    Never again would I buy LAARS.
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