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  • Users: WilliamTz
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  1. WilliamTz

    Temperature Control Unit... Glycol heating and coolgin

    Hello Engineers, I have a small glycol system at -5degC in a primary/secondary pumping arrangement. The glycol serves process vessel jackets through a Temperature control unit, to cool and heat the process inside of them...see attached sketch....each approx 15kW. The glycol control valve at...
  2. WilliamTz

    Duct sizing

    Hello I am upgrading an old 1980's Office that uses circular duct throughout for HVAC. I want to retain the old circular duct downstream of the air handler as much as possible up as far as new VAV boxes I intend installing.. I usually use 1pa/m when sizing ductwork and that is how I intend...
  3. WilliamTz

    Pretreating outside air

    Hello Quesiton: In an air handling system with outside air and return air is it cheaper to treat the outsdie air first (dehum) before mixing with the return air. Or will the same dehum/reheat energy be used if you just mix and treat the mixed air? Thanks!
  4. WilliamTz

    MTHW for HVAC heating coil

    Hello Has anyone any suggestions regarding trying to control an air handler off heating coil temperature when using MTHW at 135degC Control is very difficult and the temperature tend to over shoot.... its the huge difference between the water temp and the desired air temp is the problem I...
  5. WilliamTz

    Cooling tower

    Hello If I have a number of cooling tower in parallel all connected with an equalization line can I delete the automated outlet valve and just rely on the inlet automated valve shutting off when the tower is not being used? Regards W
  6. WilliamTz

    I have a problem with vibration and

    I have a problem with vibration and pipes shaking in a boiler room. 3 x boilers 4mW, 5mW and 2 mW. Pipes range from 200mm to 450mm headers. Water temps at 138degC 6 bar pressure min. Primary pumps next to the boiler all on a header . The 2mW boiler was added recently. When running after a while...
  7. WilliamTz

    Faulty non return valve on pump

    Hi I got 4 x Condenser water pumps in parallel....2 new and 2 old.... non return valves on each Occasionally I loose condenser water flow through the chiller when running of the new pumps I did notice water flow noise coming from the two old the condenser water pumps, when they were off off...
  8. WilliamTz

    Pump performance unstable.

    This is a follow on from a previous question...see attached sketch I have a large condenser water system. Cooling tower , pumps etc. Back to 3 chillers When ever all the pumps atop the water continues to fill into the towers from the FLOW IN side and it overflows the towers. Is this due to...
  9. WilliamTz

    Pump Cavitation

    Hi I have installed 2 x large pumps 75KW (111L/s) under 2 x open circuit cooling towers The pumps are on VSD's If I switch on and ramp up the pumps slowly 1 pump or 2 pumps at the same time everything works very well...no noise, with no apparent cavitation If however I ramp up a pump to full...
  10. WilliamTz

    Pump curve

    Hello If I suspect my pump is generating low Differential Pressure and off the pump curve (see attached in red area) would it be worth closing off the discharge valve to increase the system pressure drop and force the system curve back onto the pump curve. I suspect my pumps are currently not...
  11. WilliamTz

    Pipework vibrating around pumps

    Hello I have a fierce problem with a pipework header off a set of 5 pumps with respect to vibrations being transmitted form the pumps...see attached picture...water pressure 6 bar 140 degC. A few weeks ago the coupling between the motor and pump shafts was worn and needed rubbers replaced...
  12. WilliamTz

    Pump change over and non return valves

    Hello I have 3 x large centrifugal pumps arranged in parallel feeding into a common header, running off in one direction. 1 duty / 2 standby. 90kw motors on each pump and a variable speed drive on each. Each pump has a non return valve on it (just a normal flap working under gravity). System...
  13. WilliamTz

    Cooling tower pipework

    I have some large cooling tower currently being installed....4000kW of cooling Would you typically have expansion bellows on the pipework in/out of the towers..? 200dia, 400 dai typically
  14. WilliamTz

    Boiler isolation valve

    Hello, Does anyone know the manufacturer of a good quality steam rated butterfly valve both manual and actuated (open/close) It is for a hot water system with water at 140degC. I have used valves rated to 150degC in the past but they seem to fail after a couple of years hence I would like to go...
  15. WilliamTz

    Steam Valve - butterfly

    Hello, Does anyone know the manufacturer of a good quality steam rated butterfly valve both manual and actuated (open/close) It is for a hot water system with water at 140degC. I have used valves rated to 150degC in the past but they seem to fail after a couple of years hence I would like to...

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