"Assuming 240VAC, that's:
P = E^2 / R = 240Vrms^2 / 1600 = 36 watts
That's way too high dissipation for a solenoid valve.
Are you sure those are 240VAC solenoids and some other AC voltage? Are the solenoids run by 240VAC or some other voltage? "

Ummm, where is the "L" in your equation. If it is 1600 ohms DC resistance it is likely to have considerable inductance. There is also usually some type of metal core which takes it even higher.

That reminds me of a time I threw together a thermostatic control for a window unit air conditioner in a hydroponic grow room. I put the box together with a little transformer and a relay, a DC operated relay. Come to find out once it started it would not stop. I used an electronic thermostat so there was no worries about leveling it or anything, plus he liked the ability to set the timer. Turns out the SOB used a small triac and with DC it would never shut off so I had to start over. Wasn't so bad, just get a different relay and eliminate the rectifiers and filter.

But, the DC relay would not run on AC, and that had to be because of the inductance. I wound up using one for an air conditioning condensing unit, you know, like in back of the house. Typical 24 VAC job, which is what the thermostat was designed for. Put a long ass wire on it too because he wated to be able to place it wherever. he had something like 4,000 watts worth of lights and the thermostat has to be a bit away from them, and also away from the window unit.

In the end it worked but I had learned the hard way you just can't interchange relay with DC and AC coils. And damn, 1600 ohms is alot for just about any wire. Much more than that and it almost ain't wire !