The outflow pipe from the water heater is warm just above the heater, so it is heating, but the rest of the pipe (6-10 ft) to the cirulating pump is cool to the touch. The pumps themselves were almost too hot to touch, and the pipe just beyond them was also very warm. I could feel some vibration so it appeared the pumps were running. We have now turned the system off and everything is cool (except right at the water heater). Could there be a vapor lock or something like that where the pumps are working hard and heating up but the water isn't circulating?

You've probably never been in a home with properly sized ductwork. Don't feel bad, it's estimated that as much as 3/4 of the heating and cooling systems in the US are oversized. 2 stage and modulating furnaces are better, but I've lived in a home with both, and both can be very comfortable and the single stage equipment doesn't make it feel more dry that I can tell. BUt you are correct, multistage cna reduce the sense of dryness you might get with a less than ideal system. THe RH of hot air is lower than cooler air, but cool air can make things feel drafty. That's why radiant heat is popular. You essentially have very, very low air velocities and much of the heat energy is indirect infrared heat which make you feel warmer, similar to direct sunlight. Keep in mind too, that unless you have an outdoor rest control for hte boiler or to sped up or slow the circulator, most hydronic air handlers are single stage for heating. So the heat is no different than a furnace. Worse, as you reduce BTU's to the coil, the airflow speed is usually ocnstant, so air temps get cooler. My point being, that a properly designed and installed furnace won;t make it feel dry even if single stage. But yes, oversized furnaces and those with restricted airflow can. Vairble capacity will always make the system more comfortable, but it will cost more. Radiant heat overall is superior, but the installed cost is much, much higher. That's why it fell out of favor. Same reason drywall took over the market and plaster disapeared. ITs' primarily a matter of cost. It's also why stone and brick homes aren't built anymore and concrete homes are the minority.

you’re either referring to the law (in Washington State, anyway) regarding rental properties, or you live in some place that has uber nanny legislators. And seriously? YOU don’t think YOU are smart enough to know what temperature YOU want YOUR hot water in your home? Any who, I don’t want the dishwasher to turn the electrical heating element on. Electricity (unless your using magnetic induction) is an inefficient way to heat water. It is better for my house to use hot water from my tankless HWH. I have a tankless HWH that will produce 190° hot water if I set it correctly. I have a dedicated line from the manifold that natal led between the heater and the Case Acme temperature regulator. I send 160° water to my dishwasher, and washing machine. (I also have a dedicated line that supplies 160° to a separate faucet on my sink that takes the place of the under sink contraption that crapped out a while back. (120° is the legal limit? Don’t tell InSinkerator. I doubt those gadgets they make can even go down to 120°.) I would use 180° water but I am afraid the water temperature alone might melt some plastic ware and also damage some synthetic fabrics. Here’s a thought, when it comes to how YOU choose to live in YOUR house, man up, and grow a pair.

You are going to use existing radiators? One pipe system or two-pipe? Does your steam system work well (silently, no leaks, even heat)? I don't think that steam is well-suited to temperature set-backs. Is that what you like to do? You have natural gas? If no gas, a heat pump might be a good bet. New England is a climate-diverse area if you are in the extreme part wrt cold, a heat pump might not be appropriate. I think, hot water can give you a more efficient boiler compared to steam. The end efficiency of the hydronic heat boiler depends a great deal on the overall design of the heating system. You must have sufficient radiation to bring down the temperature of the return water to condensing temperature. If your system as a whole can't deliver this, don't install a condensing boiler. It is the wrong tool for the job and will not function well. You might stick with steam if your system can't support an efficient hot water boiler and you don't want to spend a lot to install new rads or ducts. Lastly, finding good steam workers can be tough. If there is a youngster in your area that can handle your system until you die, you will be in luck. There are lots of boiler people at terry love.com and at heatinghelp.com (the wall). Beware, there are lots of steam chauvinists there that will not budge for an efficiency argument. condensing boiler explanation