cooling tower freeze protection

[dpoppeli]

A 30 year old existing condenser water loop system has a full 6" cooling tower bypass with control valve fairly close to the pump (below roof) as well as a small 1" bypass with steam-heat and auxilary pump closer to the tower end of the lines (still below roof). The installation is in Indiana. Intent of the equipment is to obviously have the ability to run the system during winter/shoulder months and I would like to start operating it this way. My concern is that I could still freeze up the pipes or basin when the tower bypass is activated since water will be circulating below roof in this mode and I would think that there will be stagnant water in the above-roof lines/sump. Is this a valid concern? at minimum shouldn't the piping be insulated to the tower? It seems like electric basin heater is more foolproof (Marley quoted 9kW and 12kW heaters) but I don't want to spend the money if it's not needed.

 

[imok2]

If you have steam avialable try the steam bypass and see if it's functional, then determine if the 6" by-pass works. once all is functional set the control to maintain a minimum of say 65*f but ck with the chiller mfg to see how low you can run the cond temp and se say 5*F above. At the set point you should be in 6" bypss mode and the steam line or heat x changer should be activated I would also relace the condensate trap every year and install a freeze stat in the condenser line to disengage the chill water pump which should shut down the entire system should cond. water temp get to low.

 

[imok2]

PS The water in the piping above the basin will drain to the basin an whatever is left will expand in the piping and result in no damage,as for the water in the basin, it too will expand upward and should not damage the basin.