It runs on Off-Peak electric electric rates and has 4 control zones independent of each other. We only heat the area that we are using and there is a 24 hour heat sink of less than 2 degrees. If we lose power, it takes 48 hours to lose up to 8 degrees. Emergency backup is provided by a generator.
These systems are available at a very reasonable price and there is very little maintenance required. They are one of the most reliable and trouble free systems ever created. I have been using them for over 15 years and can certify the results. These steam systems described here are a complete joke.
With regard to the electric hot water system you have, yes it is 100% efficient in terms of taking electricity delivered to it and converting it into heat inside the home. However, the fossil fuel efficiency in terms of BTU consumed within the home for heat divided by the BTU consumed at the generator (coal or gas generation only) is probably near 30%.
It doesn't matter to you, but it does matter in terms of national energy policy. If saving fossil fuel is the goal, then we need nuclear power. As has been demonstrated, wind and solar power require fossil fuel backup, and so are not 100% “Clean Energy” as advertised..
Steam has it uses. a system that is completely filled with water is vulnerable to bursting from freezing. People go on vacation and don’t think about their homes when they are away. if there is a momentary power failure or some other problem, the boiler will not fire up until someone hits a reset button and if the house if vacant...big problem. hot water systems can freeze up in certain areas of the house which receive little solar heat and/or a north wind. Then when they thaw out, there is a leak and water spills out, ruins floors and drywall beneath it, more feezing occurs because of lack of heating system circulation, etc. sometimes even electrical problems occur from moisture which can cause even more damage.
The most “robust” boiler system I can think of would be a steam system with a standing pilot. You can shut the elecric power off to the entire house in january and leave it off and there will be no damage to the heating system. The pilot will keep the boiler from freezing and the rest of the heating pipes/radiators will never burst because they have no water in them. Your plumbing will be ruined unless your have the sense to turn all your faucets on to a trickle or a steady drip. But that is not your heating system.
How does your electric boiler ONLY consume off peak electric rates? Do you use glycol? if so that reduces your thermal transfer efficency and will increase installation costs. The additional cost of purchasing a generator is no small price. There are tradoffs. every system has it’s positives and negatives.