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Lawler #805 tempering valves

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geoboy
geoboy Member Posts: 30
Does anyone have any ideas?

To expand on the question, the two Lawler valves service the DHW needs of 318 1 bathroom condominium units. Each valve is protected by screens on the hot and cold water inlets. We do need to clean these screens quarterly as they become blocked with a rusty-colored debris that we periodically see in both the hot AND cold water. We presume it to be debris from construction, flushing of fire hydrants in the area, etc.

Interestingly, the coating on the valve's thermostatic element appears to be a lime-like, scaley-looking substance totally unlike the stuff in the screens.

I always thought that MWRA water had a relatively low mineral content and am therefore puzzled as to why our valves scale up so frequently. Is anyone familiar with the water chemistry in our area, and with the expected life of mixing valves in similar applications?

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  • geoboy
    geoboy Member Posts: 30
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    tempering valve scaling

    Long time lurker here, first time poster.

    We are a rather large condominium having a recurring problem with our DHW system. We heat our water in two stages, the first by geothermal (80-100 degrees - whatever the traffic will bear) and the second via a large off-peak electric hot water heater. We store the DHW in two tanks with a total capacity of 550 gallons at approximately 140 degrees F, then mix it down to 120 degrees using two Lawlor 805 mixing valves. (These valves are installed in parallel for redundancy). The "cold" input to the Lawlor valves is the abovementioned preheated water.

    In the past eighteen months, we have had to replace the innards of the Lawlor valves at 4 to 6 month intervals due to severe scaling, which renders the internal thermostats inoperative. Typically, the output temperature of the valve resets to some inappropriate value and becomes impossible to readjust. Replacement then becomes the only cure.

    My question is, has anyone else experienced this problem with these valves, and is there perhaps another type of mixing valve more suited to this application?

    BTW, we are located in the MWRA district in Greater boston.
  • mwsmith
    mwsmith Member Posts: 10
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    lawler, are vthe best i have used
  • bob young
    bob young Member Posts: 2,177
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    consider Holby
  • oil-2-4-6-gas
    oil-2-4-6-gas Member Posts: 641
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    Holby, & Taur Anderson are the 2 best for domestic in commercial applications # 1 IMHO is the Taur Anderson , the B&G, Lawler,ITT etc.. just don't compare
  • geoboy
    geoboy Member Posts: 30
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    Thanks for your replies. Sorry for the delay - I was away from the computer yesterday.

    Yesterday we had the offending valve disassembled and cleaned yet again. As before, rusty debris in the screens, scale-like material coating the thermostatic element. Fortunately, this time removal of the element followed by a good cleaning solved the problem.
  • geoboy
    geoboy Member Posts: 30
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    Thanks for your replies. Sorry for the delay - I've been out of the office.

    Yesterday we had the offending valve disassembled and cleaned yet again. As before, rusty debris in the screens, scale-like material coating the thermostatic element. Fortunately, this time removal of the element followed by a good cleaning solved the problem.

    I'll talk to my engineer about your suggestions.
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