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Laars Endurance boiler and Watts LF70A mixing valve

I'm still having a heck of a time getting DHW from my Laars Endurance EB110 combi boiler ... both DHW pressure and max temp are the pits ... I've replaced all parts in the DHW system ( heat exchanger , flow switch , mixing valve , etc ) and no luck ... I am getting only 1gpm and only 110 degrees at best in my bathroom from hot faucet ... cold with same 1/2 inch piping is 4 gpm , street pressure is fine ... there is a 4 gpm flow restrictor in the cold water line in to boiler DHW ...
so one question I can't get answered from Watts is , if I remove the thermostat from the LA70a mixing valve , will that then seal the cold water inlet to the valve so that just the hot from the heat exchanger will flow thru the mix valve ? or do I have to take the mix valve out of the line to see what happens to the HW temp at faucet ?
I've been screwing with this beast for a year and guess I may have to chuck it unless someone has magic cure
the service guy at Laars has been helpful but has no solutions ...he must have the worst job there is !!


  • unclejohn
    unclejohn Member Posts: 1,833
    I do not think that removing the guts from the valve will work. If you have done all that other work it should be no trouble putting a shut off in the cold to the mix valve and see what happens. Or pipe around the valve.
  • GroundUp
    GroundUp Member Posts: 1,907
    Pulling the guts will allow full hot flow- those LF70A tempering valves are a total POS, there's a reason they're $30. Pull the guts to see if that solves your problem- if so, replace it with a real thermostatic mixing valve
  • leethird
    leethird Member Posts: 2
    GroundUp is the winner ... I pulled the thermostat , and tho it's counter intuitive ( because it looks like the spring gizmo that the thermostat moves within the valve is covering the hot in to the mix valve ) , he is correct ... I now am getting 150 +/- in bathroom which has almost 50 foot run feet of run ( and getting 170 at a hot faucet 8 feet from boiler ) ... so that solves temp issue , and when i mix more cold ( at 4 GPM ) to get usable temp , that helps the pressure issue ... there you go !
    Thanks for the input that nudged me to try this !!!
  • GroundUp
    GroundUp Member Posts: 1,907
    Good deal, glad it worked out. I once spent a very long night in a basement fighting one of those valves and made an executive decision to pull the guts, which worked and allowed me to go home. There is a local guy who installs them everywhere and then a year later I get called to replace them with real mixing valves lol, been down this road several times