Oil boiler vs electric boiler vs heat pump choices. Help needed!

Here we go again.

To take it from the top: unless you have a very large lot and want to cover it with solar PV panels, you will not be able to heat your house with solar voltaic equipment. You may, however, be able to install enough panel area to cover your electrical needs -- including the heat pump water heater -- when the sun is shining. This is not to be opposed to solar panels, but rather just plain vanilla physics. Sorry about that.

Electric boilers are not a popular choice for hydronic heat, at least in your region, for one very simple reason: they cost too much to run. You have some of the highest electric rates in the country, and it just doesn't compute. They are also not a particularly green option, as the overall efficiency of an electric boiler from fuel to the generating station to warmth in your house is about 33%, contrasted with a good oil or gas boiler which is about 85% and up to 96% in some installations.

An air to hot water heat pump may, possibly, be an option. They are about as efficient, in terms of overall fuel use, as an on-site oil or gas boiler. However, in my opinion at least there is still some question as to whether even the most sophisticated of them can really deliver on your coldest days. If you were to choose that route, you would do well to get a written guarantee that the system would heat your building to at least 75 F on your design day without using any secondary (resistance) electrical heat, with an additional guarantee that if it fails to do that the installer will replace it with a fuel fired boiler which will, at no charge to you. This will require the salesman and installer to put their money where their mouth is, as it were -- and you may find that they are unwilling to do that.

The heat pump hot water heater, however, is a good choice -- but there are a couple of comments there, too. They do require service. A lot more service than either a fuel fired or electric heater. If you have concerns about the availability and adequacy of service, this may be a deal breaker. The other thing to remember about them is that their recovery is slow, unless they switch to the electric resistance auxiliary heat which most of them have. This may or may not be a problem, depending on how much hot water you use and how you schedule it.

Depending on how much boiler you really need (you should do, or have done, a full heat loss calculation for your house) you may be able to use a wall hung, direct vented, natural gas fired boiler. These take up much less space than your existing boiler, and don't require a chimney. This might be a very good option, but do check and see if you can get natural gas service for it.

I'm truly sorry to be a bit of a wet blanket with regard to the combination of on-site photovoltaic solar power and space heating. While it is quite possible -- and, in my view, desirable -- for a new-build house to be entirely heated by the sun (I've built a few in my time), that is direct solar space heating, not photovoltaics, and it is simply not feasible to do that for an existing structure. Your existing boiler has a power input of about 44 kiloWatts. In direct, full, sunlight, that would require around 2200 square feet of solar panel -- or, very roughly, the total area of your house. The problem is, of course, that there are times when the panels will not be in full direct sunlight. Night time, for instance, or on a cloudy day. A very rough rule of thumb for your area is that you need about 8 times that area to gain and store enough energy to carry through the night, or a string of cloudy days -- or, in this case, around half an acre of panels. Plus, of course, the necessary batteries and converters...

I don't know what your time frame is. Either way i would get the heat strips for the Bosch AHU and get them installed. They are low $$ Upgrading the wiring to the AHU will be a larger expense.

Then you can try heating with the Bosh and shut the boiler down and try it before you commit

I wouldn't go with a heat pump for heating in the northeast but that's just me.

You already have a hot water system. I would put in the heat strips and a new boiler if it was me.

You can use the HP for heat say Sept, Oct & November &March, April and use the boiler the rest of the time

I like multiple sources and backups & practice what I preach. My biggest concern about electric only and especially heat pump only, is a power outage, or a repair.
Say the power goes out or the unit quits, during a huge winter storm. By the time the tech gets there the outdoor unit could be completely buried/frozen.
The logistics to get a tech to the unit and shovel out where the controls rest or worse, the entire thing if you need to replace a motor would be a nightmare for me and I probably wouldn't service it Then you'll need to get all the frozen snow ice, off of the blades before firing it back up.
I strongly disagree with the statement "...oil is particularly expensive to heat with." And not just with the grammar.

How about oil, propane and electric resistance are particularly expensive to heat with?

@Jamie Hall I totally agree - seems like that extends beyond just energy too.

Back to the matter at hand: basically that heat pump (a nice one by the way!!!) is not big enough to solely cover your heating load. However, it's efficient enough that it is worth running for the whole winter, especially with solar power. Therefore, you'll need 10 kw of supplemental heat (or so - check my numbers with this: https://www.greenbuildingadvisor.com/article/out-with-the-old-in-with-the-new). Probably easiest to include it in the air handler, but the electric boiler option is doable too. So is keeping the oil burner, but you won't gain the laundry room, will keep the chimney, and you'll have to replace it one day. You can test it out this winter, set the heat pump's set point above the boiler's when it's around 30 degrees, and just shut the boiler down above that (for heating, not DHW).
I'd take a second look at a large, 80 gallon heat pump water heater, I think sound insulation is cheaper than a Sanden.
However, another twist is that if you go with a Sanden, it can be incorporated into the baseboards but it's limited to a small output I believe.

Some observations and comments:

What is your priority? Save oil/money, be more comfortable or gain space? Put these in order of importance and the answers will follow

Heat pumps and wood stoves frequently don't work well together. You need to figure out how to get heat to those cold areas. Is your current system zoned? How about the a/c? Warm air systems work best when turn on and left on. You don't want the thermostat calling for heat when the living room is already a toasty 78 degrees.

The demand for how water is killing your oil usage. I would concentrate on this before heating the house.

Hot_water_fan said:

@J_Cov You can use the electric boiler with zones. Another option would be to replace the hydronic baseboards with electric ones. That'd be easiest to zone since each baseboard can come with its own thermostat. You're correct that the load for the bedrooms will probably be low, so the efficiency hit shouldn't be too bad. Another pro would be that each electric baseboard would be independent, so lots of redundancy. It would probably rule out ever switching to an air-to-water heat pump in the future though.

One might find it hard to believe, but I have used electric baseboards in one of the places I care for. Now I'll grant that it's three and a half seasons (the water supply would freeze) instead of four, and they do suck up a pretty fair amount of power on a cold day -- but the ease of installation and low first cost, plus the ease of zoning (I have wall mounted 240 volt thermostats in each room) is really wonderful.