Induced Draft Counter Flow Cooling Tower Problem

You don't mention the incoming temperature, if that is higher than design limits then you will get higher outlet temps.

You do say that the range of 10°C is within design parameters, so the tower is achieving the temperature reduction that it is designed to do, so the problem is most likely incoming temperature or total heat load.

it is working as designed, just stop hitting it with high inlet temps, DUH

Are you sure the direction of air flow for all fans is correct? If you have one or more fans running in the wrong direction, the temperature will be affected.

Inspect your cooling tower fill also. It should be breaking the water into fine droplets. If you are getting pouring water you could try to add more fill or decrease flow.

I saw a problem once where the scrubber balls from the condenser were plugging the holes in the deck causing water to cascade over the side or stream out in thick columns that wouldn't break sufficiently.

I hope your operators are sufficient to ensure fan direction is correct, you might be able to change the pitch of the blades to get a bit more air flow, but if the weather is a temporary issue it would be better to leave them.

Drew K

Please check your fill it might have scaled and also check the air flow it may be reduced due to the choking of fills

What does <...High...> actually mean (rhetorical question - NNTR)?

The water temperature can never go lower than the wet-bulb temperature of the air passing through it, for it is this that determines whether any evaporation takes place. With the given figures, if the wet-bulb is <...27 C...>, then that is the minimum achievable cooling water supply temperature, and in practice it will be a bit warmer than that.

If cooler heat transfer fluid temperatures are required, then a refrigeration loop is needed downstream of the tower to provide those temperatures, and that's all there is to it.

If in doubt, consult a qualified Heating, Ventilation and Air Conditioning Engineer.