I assume you mean boiler. Furnaces only heat air. Yes, boiler is a misnomer since most people don’t actually heat with steam anymore, but that’s to distinguish it from the potable/domestic water heater.
I do not believe that heat pumps can adequately heat water to the level you need for radiators, convector cabinets, baseboards, or anything like that. The one exception might be if you have radiant underfloor heating, since that runs at a lower water temperature, but it would require some engineering to figure out.
In general, heat pumps struggle somewhat to achieve the temperatures you need for the domestic hot water. A pre-heat tank that runs off the heat pump with either a separate booster tank (electric or gas), or instantaneous water heater(s) downstream seems to be the best bet there. Some systems use a desuperheater to extract the “hottest heat” from the refrigerant for the domestic hot water. It works great in the summer when all you have is waste heat, but in winter it’s also sapping heat you want for the rest of the house, and I’ve heard of systems that ran excessively trying to keep up the hot water temperature and causing higher electric bills.
Ground-source/geothermal would be the way to go there. Drilling vertical wells is usually preferable to running long horizontal loops if you don’t have a lot of space or don’t want to totally destroy your yard. Yes you still need to do horizontal runs to connect the loops to each other and back to the house but do you really have that much stuff in the ground it wouldn’t be possible? Granted it’s not cheap no matter what, probably $10,000-$20,000 for the wells/loops alone.
First: Why do you live there?
Secondly: No, you’d need one with a ground source (more common in Northern Sweden, than in the south where I live). And I think that is a lot more expensive, i.e. it’d take longer to recoup the investment. But also, maybe raise the value of your property?
I was in undergraduate school with a guy who worked for North Little Rock Electric. They have a generator on the Arkansas river. He told me they stored water overnight behind a dam, and it all went to hot water and toasters in the morning. Niagra Falls undoubtedly produces more.
An instructor in engineering school owned an A/C heating business. They sized heat pumps to the house, and defined how much air moved into each room with louvered vents. They ran the blower continuously.
A heat pump system is going to have a motherboard in the indoor air handler as well. While a capacitor is cheap, outdoor fan motors, reversing valves, and compressors can all fail, and those can cost big dollars.
My brother’s heat pump seems to have a refrigerant leak, so he’s looking at $$$$ to fix it. He’s in Alabama, so a heat pump makes sense, but my climate is almost as cold as Northern_Pipers. No heat pump here.
I’m likely to wind up in the NYState program; various required procedures are in process. Next up is that the contractor’s coming to look at the house. If I do wind up with a heat pump, I’ll try to report back here; but it’s likely to be quite a while.
The current oilburning furnace is functional but old and has needed significant repairs; eventually the boiler will go and it’ll need to be replaced anyway. Current system is steam and radiators. I do also have a wood stove, which won’t heat the whole house in extremely cold weather but does take a lot of the load; most of the firewood’s cut here on the farm (dead or dying trees, and an occasional one determinedly trying to grow in the wrong place.) The wood stove doesn’t need electric power to run. The oilburner does; I think nearly all modern oil or gas furnaces need electricity to run, as their safety devices need it even if the ignition doesn’t, so the furnace shuts down if the power goes out. They don’t seem to be expecting me to get rid of the wood stove (and I may well back out if they do.)
I would have sworn the manufacturer’s label said “furnace,” but you’re right, it’s a “boiler,” and it heats water both for the radiators and for running hot water.
Oh interesting. I am shopping for a new furnace (or boiler, if you prefer. But it doesn’t boil anything) for my hot water baseboard heating system. I tried a little to find a contractor that would replace it with a heat pump, but gave up. I guess i won’t find one.
I do have central AC, but it was designed to be add-on AC, not a heating system. It would not comfortably heat the house. (Narrow, high velocity pipes instead of full sized ducts that force air out of the ceiling, and not in rooms that don’t really need to be cooled, like bathrooms.) It also has a single zone, where my heating system has three.
Baseboard heat is generally more comfortable than forced hot air even in a hot air system designed to deliver hot air. In my case, switching would be a huge downgrade.
I’m feeling better about giving up and hiring a contractor to replace it with a new gas system.
Good. Because I need something that works when the power’s out.
I haven’t checked the label, but my steam boiler system is indeed casually referred to as a furnace, whatever the technicalities are. The people who clean and repair it say ‘furnace’ unless they’re referring specifically to the part that holds the hot water.
I wonder whether, if I do wind up with a heat pump, I’ll also wind up with air conditioning? Currently I have one window air conditioner, which of course doesn’t really do the job, but makes the kitchen usable and the downstairs inhabitable in hot weather (the bedrooms upstairs have to make do with opening all the windows at night, which has its limits, even though aided a little by not having as much heat right underneath them.)
I do rather like my radiators, and will miss them if I lose them (as will the cats). I’ve warned the contractors that there’s no ducting for a hot air system; I don’t know yet what they intend to do about that.
That would be a nice addition. When this house was built, and close to a hundred years later when I first moved here, there were only maybe a couple of days a year when opening the windows at night and closing them in the morning wasn’t sufficient to keep the house comfortably cool in summer – and my idea of ‘comfortably cool’ is cooler than some peoples’. But the past decade or two we’ve been getting more and more relatively long stretches during which the nights aren’t cool enough for that to work.
Aren’t most heat pumps bidirectional, in that run one direction, they’re basically a normal air conditioner during the summer, and when the weather’s cold, they turn it around and run it the other, and basically “cool” the outside?
I’d be very surprised if they’re not expecting to rip out all the radiators and piping and replace it with ductwork. You’d get air conditioning from that as a bonus.
It appears that there are some heat pumps that can run radiators, but it’s unlikely that existing cast iron radiators would be adequate due to the lower water temperature. To counteract that you need more surface area for heat transfer, and thus either larger radiators of the same type, or more efficient Euro style radiators with extra baffles and fins.
Many old buildings (think pre-1930) that had cast iron radiators for steam heat with coal boilers were upgraded in the 1960s to gas boilers. The system was converted from steam to hot water, but they had to install storm windows and insulate the attics to counteract the lowered heat output of hot water versus steam. The same considerations need to be made for converting gas hot water to a a heat pump for hot water (air-to-water heat pump).
Let’s say you replaced your windows, added insulation, and your radiators were already a bit oversized, so an air-to-water heat pump would provide adequate capacity. You still won’t get air conditioning from this. You can’t just run cold water through radiators. They’d sweat and drip all over your floors, and the pipes in the walls would sweat and drip as well, rotting out the framing. You’d either need a separate ducted system, or you’d need to replace all the radiators with fan-coil convector cabinets. They’d all need electricity for the blower, a condensate drain either to your home’s drain piping or through the wall to the exterior, and you’d need to insulate every last inch of water supply and return pipe to prevent condensation. They can be a little noisy and don’t necessarily look good in an historic home. One bonus there is that each unit can have its own thermostat.
It seems generally preferable for a heat pump to provide both heating and cooling, because it’s essentially replacing two components (the separate furnace and a/c) and not sitting idle for half the year. This is especially the case for ground-source heat pumps because it helps “recharge” the ground temperature on an annual basis. If you’re only dumping heat into the ground, or only sucking heat out of the ground, then at some point it could get “saturated” and unable to take in or give out any more heat. I’m not sure how big a concern that is. It usually seems to be a result of an undersized loop, and of course your particular subsurface conditions.
I would think it would be an unusual problem, because I would think in most cases the heating and cooling effect of the summer and winter would entirely overwhelm what any heat pump, or even a batch of them in the neighborhood, could produce. But I’m in no way an expert in the subject.
Getting duct work all the way around would be an interesting project involving tearing up a lot of the house, I would think. Much of the place is at least over a full basement (though tall people have to duck) but some of it’s over a very shallow crawl space, that I don’t think can even be crawled through by an adult human; and the construction is 1890’s. But the radiators and steam pipes were a later addition, and they managed that. So maybe it wouldn’t be as bad as I think.
You can now retrofit older homes with small-duct, high-velocity HVAC systems that use flexible plastic ducts that can be fished through walls instead of large metal ducts. Some friends just had such a system installed in their house. I haven’t had a report on how they like it yet, but I’ll see them at Thanksgiving, and can post here after that.
I’m afraid my knowledge of them is pretty much limited to knowing that my friends installed one. Sorry I can’t be more help, but I’ll grill them when I see them and after turkey day I’ll report back, unless someone who already knows more posts first.
