Filling it half way is not an issue. If you are going to be gone for 6-8 hours, use the timer feature to have it re-boil for when you will be back. The vacuum sealing feature increases energy efficiency a fair bit vs. the regular models, but it holds temperature as well as any thermos, gradually declining. I mainly bought the vacuum model because it only requires an average of 480 watt hours per day to maintain the 208F setting (same as running a 60W bulb for 8 hours).
wyardley wrote:One interesting thing to note is that there's two different models, one of which is cordless (using 2 AA batteries in a small compartment opposite the power inlet), and the other which is not cordless. Cordless model is ~ $180-190 vs. $150-160.
The cordless model is the same as the regular model but with the ability to run the pump off AA batteries. It's intended to be boiled and then taken outside, on a picnic, etc. The vacuum insulation doesn't really keep the water hot enough for black tea or pu'erh for any reasonable length of time, but you could certainly make green tea for hours in this fashion. When I was buying mine I didn't think it was worth the extra cost.
Coppery Cup wrote:I have had this model for almost a year (not the cordless one) and I like it quite a bit-my only significant complaint is that it does not have a 160 degree setting for the white teas that I buy. I would not have gotten the 4 liter, but I had to get it to get all the features I wanted.
The water you dispense is actually slightly below the indicated temperature anyway, so you could always dispense higher temperature water into a container and pour it from there to cool it down.
It's worth noting that the first bit of water drawn from one of these boilers is usually substantially cooler than the indicated setting because it's been sitting in the water line outside the boiler. On my CV-DSC40 the first draw is 40F below what is subsequently dispensed. If you want to draw a small amount of hot water, you should probably pour some off first (I heat cups with it).