Older dual DI cart question

I have an older Unger dual DI cart. Its the one with the 2 DO cartridges. Does anyone know if it can be laid down on the job or in the truck between jobs?

Yes in the truck. No during operation.

It won’t mess up the DI?

Do you have one? If so when you refill the cartridges do you refill the end cartridge and then after that keep refilling the end cartridge and switch the old one to the first cartridge spot? Or do you just go ahead and do both at the same time?

Nope. Only problem would be running it on its side… Water will flow through without maximum contact with resin.

1 Like

Yeah i have one. Home build but same components. And i just swap them both out at once.

Great thanks! Have you tried only changing out the end cartridge? I’ve heard guys doing that with other dual DI systems and getting longer life out of the resin.

Nah. I think being stingy about saving resin is a waste of time. Just refill and go. The time spent figuring out if your yield is higher is better spent cleaning windows at $150/hour.


I know it depends on the tds of the water coming in but how many houses can you average with fresh resin?

No clue. Don’t keep track.

Bottom line for me- does pure water increase my PMH and protect my people from unnecessary ladder work on this job? If yes, we’re using it. If no, we’ll leave it on the truck.

I think with pure water costs a lot of guys are spending dollars to save cents… Buy the right system for you local water conditions and then just get to work… There are MUCH more important things to track than your cost per gallon of pure water.


Just to clarify I was asking only to understand how often I might have to change it out. I wasn’t asking to figure the cost per gallon.

1 Like

Oh gotcha. It’s tough to say. Maybe every couple of weeks? Too many variables to predict.

You ever on well water?
Whats average typical tds?
Do a lot of tdl’s?
Run more than one pole off it?

I’ve had ours last a month one time and then tap out in a week the next. Best practice is to have two extra cartridges on hand, filled and ready to go. Minimizes down time if you tap out on site.