I am a new owner of an old house. My house has what I believe is referred to as an indirect water heating system, where the water from the street passes through the boiler first, and then is piped into the hot water heater. The house heats via radiators.
The house had been winterized prior to me owning it, so the water was turned off, the hot water heater tank emptied, etc. When I first moved in, about 6 weeks ago, the water from the hot taps was merely tepid. We had a cold snap for a couple of weeks, so the boiler was running a decent amount, and eventually the water got hot enough that I needed to mix in some cold to take a shower. As the weather has warmed back up, the boiler isn't running nearly as much, although I do notice it come on if I run the "hot" water for a few minutes to do dishes, and gradually the water has settled back to being barely tolerable for showering. It's not cold, but it's pretty close.
I'm pretty sure the burner is fine for now, because I just had it serviced a few weeks ago, although it is pretty old. The water heater is 10 years old, so it seems like a fairly obvious culprit in need of replacing. Both temp controls are turned all the way up to 150 degrees. So, my questions are as follows:
1. It seems clear that, at minimum, I need to install a new hot water heater. I don't have gas to the house, so I need to go electric. And I assume that this indirect type system is something that I should replicate to save energy in the colder months. How much more complicated ($$$) does this setup make the installation of a new tank? Or is this a fairly common setup?
2. Since the furnace is very old (probably 1960's with a newer boiler), and since there is a good "tax credit" (free money) thing available this year, I'm tempted to replace the furnace as well. Should I look into a boiler/tankless water heater combo? From what I've been reading online, there doesn't seem to be much advantage to doing so without gas available. I do plan on installing a propane tank outside next year for a gas range in my kitchen, but I'm guessing I'd need a huge one to heat the house with, which is probably impossible to do code-wise even if I wanted to.
And please correct me if I'm not understanding something correctly, all of this stuff is new to me and it's a lot to learn at once.