View Full Version : Frying Transformers...

07-01-2005, 06:44 AM
I recently replaced some old metal pipe that ran from the water supply to two sprinkler valves for my lawn with PVC. I also replaced the valves with two new ones and wired them to the existing automatic timer/controller. Everything worked fine for a couple of days, then one of the valves stopped turning on. I was in the middle of a project and didn't have time to investigate, so I just ran that one manually for a few days. Then they all (6) stopped working.

I measured the voltage coming from the transformer that powers the system and found that there was none, where there should have been 24 V. I replaced the transformer with a new one. Again everything worked fine for a couple of days and then the new transformer went dead.

Can anyone tell me what they believe is causing these transformers to fry?

07-01-2005, 06:51 PM
Are all of the heads on at the same time? COuld the new ones take more current than the old ones, and are overloading the transformer? Do you need a larger transformer? I've never worked with sprinklers, so keep that in mind!

07-01-2005, 07:48 PM
If there is a short circuit and the controller does not have an overload button it it, that will destroy a transformer.

07-04-2005, 05:10 AM
At the risk of stepping over the line as far as brands/manufacturers, and potential advertisers to this website, for which we could get in trouble discussing, could you tell me what brand of sprinkler/irrigation timer you are using? That could tell a lot....

07-04-2005, 12:48 PM
Not usually a factor since all of them have transformers that will operate the panel and at least two valves simultaneously, even though good practice puts only one valve on a circuit.

07-04-2005, 01:41 PM
Most timers have the capability to operate a pump start relay or a main valve in addition to one zone valve. But there are some wimpy transformers on the market, so it is important to check the milliamp rating.