I think that there is an error in the specs posted by Frigomar on their site. The units were first available as 230/50hz only and more recently released with the 115 volt option. All my units are 230/50.
If you compare the power draw on the 597 or 598 NT to the NT-A 115 volt versions you will see that they show the same amp draw. So, for any of you that are in the 115v world be advised not to rely on the amp draw shown on the website. Go to the spec sheet instead where the information looks to be correct. Here is the link:
In the spec sheet they had previously, they showed wattage draw at various power levels. For instance, on the 597 NT they showed wattage at 70, 50 and 35 hz as 560, 355 and 245. So a 230 volt unit would have a draw of 1.1 amps when running at the lowest speed of 35 hz.
BTW at this point I should mention that I thought that I would have an option to set the units to run in the ECO mode. So far, that seems not to be the case. You set the desired temperature and the unit comes on and slowly spools up to full speed and runs there until the temperature is made. It then modulates down to find a speed that maintains the temperature.
The chart below show water requirement in cubic meters per hour and pressure drop in the condenser in meters. Just try to find the pressure drop in the condenser of any marine A/C unit. Without it you are just guessing on pump size. After making all the calculations, I determined that the Koolair PM500 was a suitable pump for the 597 running at 50hz (at 60hz it's perfect for the 598). The pump draws only 37 watts.
So, finally an answer to the question. Lowest speed on the smallest unit 597NT looks like 245 watts plus pump 37 watts for a total of 282 watts. 2,5 amps at 115v or 1.25 at 230v
SELF-CONTAINED UNITS REQUIREMENTS- first two numbers are water flow requirement minimum and maximum in cubic meters per hour. Second two numbers show the pressure dropfor min and max flow in the condenser cooling coil in meters of head
597NT - 10 kBTU/h 0.6 - 1 - 1.3 - 3
598NT - 16 kBTU/h 1 - 1.2 - 4.2 - 6
599NT - 27 kBTU/h 1.2 - 1.3 - 7.2 - 8
Another BTW for anyone considering these Frigomar units. From what I can see, the 597 is the same unit as the 598 except that it has a smaller condenser and cooling coil and is limited to run at 70 hz as opposed to the 100 hz that the 598 NT will run at. The 598 will spool down to very close to the lowest setting of the 597. I'd suggest getting the 598 unless you have some very compelling reason to go with the 597.