I have forced hot water heat, heated with gas. I like both of those. But my boiler was installed in 1959, when the house was built, and it’s time to replace it.
I also have a gas hot water heater, next to the boiler.
What are my options these days? What do you recommend, or disrecommended? Why?
The other heating system i considered is a geothermal heat pump, but our house is built on ledge, and i don’t think we can do it.
Drilling enough well to do geothermal would be very expensive. We have only one gas appliance in our new house, the boiler. You have a couple options, boiler or boiler-instant hot water generator. Lochinvar among others makes both. We paired a Lochinvar boiler with a heat exchanger hot water heater (electric). It allows us to have hot water recirculation which would be difficult if not impossible with an on-demand hot water system and reduces our propane use.
The brands I’ve seen most in my 30-year career are Lochinvar, Triangle-tube, and Weil-McLean, FWIW.
One piece of advice–do not oversize your boiler. You really want it running full-out for maximum efficiency (although less-so than with older boilers).
I have an oil burner and hot water heat with baseboards. I’ll explain the setup briefly, we have an old log cabin with a modern stick build addition. The log cabin has the oil burner in the basement to heat the log cabin with baseboards, but we only window units for A/C there. The addition has a split system for bot heat and A/C upstairs and no heat in the basement.
Soon I’ll get a split system for the log cabin to provide heat and A/C upstairs, remove the baseboard heat upstairs, and use the oil burner to provide heat for both basements. The oil burner would be hard pressed to provide heat all around by itself, and we’d still need A/C. So the split systems have been the solution. Those use heat pumps, just extracting heat from the air instead of the ground.
Since you have gas you could consider gas forced hot air. You’ll need to add ducting, the same ducts can be used for A/C also. The great advantage to hot air heat is quickly heating up rooms or the whole house. If you’re out during the day for example, you can turn the heat way down, wait until you get home to turn it up, and heat up the room or the whole house in minutes.
I assume you are in New England, others may not realize ‘ledge’ is not a ledge, it’s lots of large rocks though, often the size of cars. Depending on the state of the ground geothermal might be entirely possible but it’s a risk to start digging and then finding house sized boulders in the way.
This is what we have had for 11 years now, and it works very well. It also saves fuel cost compared to having a tank water heater. Our heat is hydronic (hot water under the floors) rather than forced hot water heat, but I don’t think that should make any difference to the functioning and economy of the instant hot water generator.
I recommend getting a capacity that would support two people showering at the same time, or one person showering plus running the washing machine at the same time.
I have air conditioning, retrofitted to a house built without ducts. It’s high velocity mini-ducts, because there really isn’t any good place to run ordinary ducts.
Also, i really prefer hot water baseboard heat to forced air. No drafts, no hot and cold spots. The only downside is that modern forced air can also humidify in the winter, and my system can’t. But given the existing infrastructure and the benefits of baseboard heat, I’m not going to change my system. I’m just updating the boiler, and perhaps the hot water. And i plan to stick with gas.
I am, and it’s clear that they had to blast to make room for some of the foundation. I suppose I’m probably on glacial moraine, and not on bedrock. But there are lots of very large rocks under the house, and under the yard. And some of those might be as large as the house.
I’m in the UK and have had a combi bioiler for many years.
No trouble and reasonable costs. 
What is a Combi Boiler and How Does it Work? (boilerguide.co.uk)
My house is large, there is already plenty of room for the boiler and whatever stuff it needs, and i have four bathrooms. So based on that article, the combi boiler isn’t my best choice.
It suggests a “system boiler”, which sounds like what my contractor recommends. He actually recommends installing a system boiler but not including the hot water storage tank until my current got water heater needs to be replaced, and then replacing the stand-alone hot water heater with a tank heated by the system boiler.
And yes, I think the contractor is pretty good, but I’m looking for second opinions, as this is a major decision.
With multiple bathrooms, combi-boilers probably won’t be a good fit. They kind of max out around 5 gallons a minute. We did a pretty fancy master shower (3 body sprays, rain head) and it alone can pull 5 gpm. I assume “system boiler” means “boiler.” Then it kind of comes down to price, contractor preference, and warranty. Most plumbers/HVAC folks are partial to certain brands.
Naw, a “system boiler” heats the hot water for the taps, as well as the hot water for the heating system. But that water is then stored in a hot water tank. It replaces the stand alone hot water heater as well as the heating boiler.
OK–that usually is a standard boiler and the tank has a heat exchanger in it, or there’s an external heat exchanger. The tank is pretty much just another zone on the system. Sounds like you’ve got it pretty sussed out. The costs are kind of crazy–the Lochinvar Knight is available for $2500-$5k, but it’ll be 4 times that (or more) installed.
I just saw something on the current season of This Old House, which was a standard tank water heater but instead of being heated by fuel, it was heated by a heat exchanger, and it was installed in the basement of the remodeled old house. It is supposed to draw incremental heat from just the surrounding air (I don’t understand really how that works) and heats the water in the tank. It makes me wonder how long it takes to heat more water as the hot water is used up, but it might be worth investigating as a long-term saving in fuel.
The question is are you more interested in efficiency or comfort?
There are all kinds of high efficiency systems out there to replace your boiler. From what I have been able to determine, most of them are complete crap.
My house was similar to yours, built in 1960, and had a gas fired boiler furnace with baseboard hot water heat. The boiler furnace also supplied the domestic hot water, but that’s a separate issue.
I like baseboard hot water heat. I think it is the most comfortable type of heat. So for me there was no question, I wanted to replace it with another gas fired boiler type of furnace.
In my case, my original boiler furnace also supplied the domestic hot water, so instead of a separate tank like you have, the furnace simply had a second coil of water pipe going through the furnace core. The furnace keeps its core hot, the hot water through the house is heated by going through the core, voila! Endless hot water. The furnace can heat the entire house, so it has no problem heating the incoming cold water up to hot water temperatures for use in our bathroom and kitchen. There’s no tank like in the systems you describe.
The benefit is that you always have hot water. My kids could all take long showers, but since the furnace is heating the hot water on demand, we would never run out of hot water.
The down side of this is that the furnace core is always kept hot, even in summer. So it’s a much less cost-effective way of generating hot water. It’s not hugely expensive, but there are cheaper ways of getting your home’s hot water.
But I personally preferred this system, especially since another benefit is that the hot water would last as long as the furnace, where separate water heaters only tend to last about 10 years or so these days.
The furnace is now about 15 years old and it’s still working great. I’ve never had a problem with it. It’s also about 1/3rd the size (physical size) of the original furnace while providing the same BTU output.
I personally prefer comfort and convenience to cost. YMMV.
What’s that system called?
My guess is that anything I get now will be at least as efficient as the old one.
You may want to look into point-of-use water heaters to supplement a hot water coil build into the boiler. I don’t have a huge house, just 2 bathrooms, and I have an additional hot water heater next to the boiler, electric in my case. In the winter the heated water from a coil in the boiler feeds into the hot water heater so it uses little electricity to operate. In the summer the boiler is off, not using oil or heating up the house at all, and the electric water heater supplies all the hot water. You may want to do something similar instead of a large hot water storage tank that requires the boiler running year round. You can have a separate gas water heater so you can turn off the boiler in the summer, and if you don’t want an inefficiently large how water storage tank than you can add additional point-of-use water heaters for more capacity and faster response.
Is it more efficient to run a hot water heater than to run a boiler-that-heats-water? That’s not immediately obvious to me. It’s not as if my current boiler stays on all the time. It cycles on and off, as it is needed. And that’s ancient technology. I assume the modern ones are similar.
I don’t actually have a huge house, by the way. It just has a lot of bathrooms. And i doubt we’ve ever used more than two showers at the same time. But i would like to be able to shower when the washing machine is running, or the dishwasher.
It’s called a combination boiler since it does both the heat and the hot water.
It’s a conventional furnace though, not a wall mount type of thing like in the article upthread. Ours is made by Burnham.
This is ours. The green tank above the furnace is the expansion tank for the baseboard heat. There’s no water tank.
With mine, there is a noticeable drop in temperature in the shower if you run the washing machine or dishwasher at the same time.
The boiler will cycle, hopefully, it’s way undersized if it doesn’t cycle. It will be inefficient to use for heating water in the summer when you don’t need the boiler on for heat. It’s also not as efficient at providing hot water far from the boiler, if you have bathrooms or kitchen far from the boiler there’s heat loss in transporting the water, and then leaving hot water in the pipes that will cool off and needs to be run out later.
Having to run the boiler in the summertime for hot water is the thing that bothers me the most. It’s wasting energy in the boiler, and some of that wasted energy is released as heat into the house which has to be removed with more energy wasted in air conditioning.
A point-of-use water heater helps with that. Reviews on those things are mixed, but it’s something that can be added later.