New England Heating
May 13, 2021 6:30 PM Subscribe
Should I repair or replace my old gas furnace? If I replace it, what should I replace it with?
I bought a 111-year-old home in Newton, MA in September and have an issue with the gas furnace that powers our hot water heating system. It's not a critical issue, but there is some blockage in the burner tubes that could indicate a larger issue with the unit. We have baseboards on the first floor and radiators in our second floor and in the finished attic. We also have central air conditioning via two separate air handlers, one for the first floor and another for the second and third.
We've had a couple of plumbers out to look at the furnace, and they said that, while they could attempt a repair, given the 30+ year age of the unit, they recommended replacement. We also had a guy from MassSave, the state's energy efficiency program, out to review our house, and he said the same thing.
The thing is, I've been reading about heat pumps online and they seem really cool. My understanding is that the technology is advancing rapidly, both for air- and ground-source systems, and that it is getting better all the time. I am not interested in going with ductless units due to the appearance of the tubes outside the house, and the fact that we already have the hot water for heat and ducted AC, but I am keen on the the potential of the increased efficiency of a heat pump system to reduce my family's carbon footprint.
This leads me to a question as to how to address the issue with my current furnace. I am tempted to have it repaired, in the hope that heat pump technology advances enough in the next 3-7 years that we could upgrade to a non-gas system at that time. Of course, with the unit being so old, no repair technician can guarantee that it will last through the next winter, let alone several more years, and it could conk out in January and leave us in the old. Us, by the way, means me, my wife, our toddler, and the baby that we are expecting in July.
The more conservative approach seems to be to have it replaced with a modern, high-efficiency gas system, but I'm worried that, if I make a big investment in a system like that now, I could end up regretting it if better, more efficient heat pump solutions become available in the near future.
Hive mind, hope me, please. I'm looking for advice on which direction I should go here, and thoughts on what factors I should be considering when making this decision. Are non-mini split heat pumps already an option here in MA? My unicorn solution would be to go with Dandelion, but they are not operating in my zip code yet.
I bought a 111-year-old home in Newton, MA in September and have an issue with the gas furnace that powers our hot water heating system. It's not a critical issue, but there is some blockage in the burner tubes that could indicate a larger issue with the unit. We have baseboards on the first floor and radiators in our second floor and in the finished attic. We also have central air conditioning via two separate air handlers, one for the first floor and another for the second and third.
We've had a couple of plumbers out to look at the furnace, and they said that, while they could attempt a repair, given the 30+ year age of the unit, they recommended replacement. We also had a guy from MassSave, the state's energy efficiency program, out to review our house, and he said the same thing.
The thing is, I've been reading about heat pumps online and they seem really cool. My understanding is that the technology is advancing rapidly, both for air- and ground-source systems, and that it is getting better all the time. I am not interested in going with ductless units due to the appearance of the tubes outside the house, and the fact that we already have the hot water for heat and ducted AC, but I am keen on the the potential of the increased efficiency of a heat pump system to reduce my family's carbon footprint.
This leads me to a question as to how to address the issue with my current furnace. I am tempted to have it repaired, in the hope that heat pump technology advances enough in the next 3-7 years that we could upgrade to a non-gas system at that time. Of course, with the unit being so old, no repair technician can guarantee that it will last through the next winter, let alone several more years, and it could conk out in January and leave us in the old. Us, by the way, means me, my wife, our toddler, and the baby that we are expecting in July.
The more conservative approach seems to be to have it replaced with a modern, high-efficiency gas system, but I'm worried that, if I make a big investment in a system like that now, I could end up regretting it if better, more efficient heat pump solutions become available in the near future.
Hive mind, hope me, please. I'm looking for advice on which direction I should go here, and thoughts on what factors I should be considering when making this decision. Are non-mini split heat pumps already an option here in MA? My unicorn solution would be to go with Dandelion, but they are not operating in my zip code yet.
Dandelion isn't the only company doing ground-source heat pumps; they're just the ones who advertise the most on trendy websites. I suspect that you would be able to find someone who would be able to install such a system in your area.
The issue, of course, is that ground-source geothermal is generally more expensive than air-source, due to the need to excavate your yard for the ground pipes. They're more efficient than air-source as well, so you end up paying more up front but less in heating bills after that.
Ducted (central) air-source units do exist as well. My understanding is that you might be able to replace the AC unit with a heat pump, since a heat pump can do both and you've already got the ductwork installed.
Apologies if this is stuff you already know.
posted by Johnny Assay at 7:39 PM on May 13, 2021
The issue, of course, is that ground-source geothermal is generally more expensive than air-source, due to the need to excavate your yard for the ground pipes. They're more efficient than air-source as well, so you end up paying more up front but less in heating bills after that.
Ducted (central) air-source units do exist as well. My understanding is that you might be able to replace the AC unit with a heat pump, since a heat pump can do both and you've already got the ductwork installed.
Apologies if this is stuff you already know.
posted by Johnny Assay at 7:39 PM on May 13, 2021
Geothermal is really cool but really expensive, and sometimes not alll that much more efficient than top-of-the-line air-cooled systems.
Non-mini-split air-cooled heat pumps are totally a thing! They would take the place of the outdoor condensing units that your AC system uses. They'd enable you to run the ducted AC system in heating mode in the winter and through the magic of the refrigeration cycle, extract heat from the cold outside air to warm your house. You may need to also replace the indoor coils in your air handlers and the piping between the indoor and outdoor units in some cases, since heat pumps can run at different pressures than old AC systems did.
The big question is, if you swap out the AC condensing units for heat pump units, can you get enough heat with your ducted systems to keep your whole house warm without using the hot water system? It's very possible that your air handlers and ductwork aren't sized large enough to provide that much heat, particularly in a cold climate like yours. Maybe it would be fine but it's definitely something to ask about when you talk to a contractor about installing heat pumps.
Disclaimer, I'm an HVAC engineer but not licensed in your state, this is not professional engineering advice. :)
posted by beandip at 8:20 PM on May 13, 2021 [1 favorite]
Non-mini-split air-cooled heat pumps are totally a thing! They would take the place of the outdoor condensing units that your AC system uses. They'd enable you to run the ducted AC system in heating mode in the winter and through the magic of the refrigeration cycle, extract heat from the cold outside air to warm your house. You may need to also replace the indoor coils in your air handlers and the piping between the indoor and outdoor units in some cases, since heat pumps can run at different pressures than old AC systems did.
The big question is, if you swap out the AC condensing units for heat pump units, can you get enough heat with your ducted systems to keep your whole house warm without using the hot water system? It's very possible that your air handlers and ductwork aren't sized large enough to provide that much heat, particularly in a cold climate like yours. Maybe it would be fine but it's definitely something to ask about when you talk to a contractor about installing heat pumps.
Disclaimer, I'm an HVAC engineer but not licensed in your state, this is not professional engineering advice. :)
posted by beandip at 8:20 PM on May 13, 2021 [1 favorite]
I changed to geothermal 8 years ago. It was a big investment, but the changes it has made to our quality of life, the health of the house and the household economy are massive. I also installed solar panels, but I think even if you run the thermal system on the grid, you will see huge savings. I've kept my old gas bills so I can take them out and remind myself how much I save every now and then. Also from this year onwards I have been able to choose to have only electricity from renewable resources when I buy it from the grid during long winter nights. It definitely means something to me that I am doing my best towards stopping global warming.
The primary reason I chose to do this was that I want to be able to live here in my retirement with as few expenses as possible. When I did the renovation I was in a tenured position, but still I was thinking we are all precarious in the 21th century, and that turned out to be true for me.
Everyone in the extended family loves that we can take long, guilt free showers and baths and the house is almost too dry, meaning there are no problems with mold or smells. And the space which was liberated by throwing out the old furnace has become a cosy and bright new hallway, where I often sit and read during summer.
So, the pros are a secure, stable and cheap source of heating and hot water.
The con is that sometimes when it is very cold, the heating is just not warm enough. Luckily I can supplement with the existing fireplace, and it is lovely to sit around it during winter nights. I have an extra chimney and might install an extra wood burning stove to heat the other end of the house. I insulated the floor and roof when I installed the thermal system, but I did not buy new windows. I could probably keep up with the cold a little better if I did that, or if I put up some extra frames with double glazing during the coldest months.
posted by mumimor at 2:36 AM on May 14, 2021
The primary reason I chose to do this was that I want to be able to live here in my retirement with as few expenses as possible. When I did the renovation I was in a tenured position, but still I was thinking we are all precarious in the 21th century, and that turned out to be true for me.
Everyone in the extended family loves that we can take long, guilt free showers and baths and the house is almost too dry, meaning there are no problems with mold or smells. And the space which was liberated by throwing out the old furnace has become a cosy and bright new hallway, where I often sit and read during summer.
So, the pros are a secure, stable and cheap source of heating and hot water.
The con is that sometimes when it is very cold, the heating is just not warm enough. Luckily I can supplement with the existing fireplace, and it is lovely to sit around it during winter nights. I have an extra chimney and might install an extra wood burning stove to heat the other end of the house. I insulated the floor and roof when I installed the thermal system, but I did not buy new windows. I could probably keep up with the cold a little better if I did that, or if I put up some extra frames with double glazing during the coldest months.
posted by mumimor at 2:36 AM on May 14, 2021
Burning wood is at the other extreme of carbon footprint and might negate the benefits.
The carbon footprint of biomass depends a lot on how the wood is harvested and burned. High-efficiency pellet stoves, fired by pellets from sawmill & paper plant waste residue, have (from what I understand) a lower GHG footprint than fossil fuels. But it's a complicated issue.
posted by Johnny Assay at 5:00 AM on May 14, 2021
The carbon footprint of biomass depends a lot on how the wood is harvested and burned. High-efficiency pellet stoves, fired by pellets from sawmill & paper plant waste residue, have (from what I understand) a lower GHG footprint than fossil fuels. But it's a complicated issue.
posted by Johnny Assay at 5:00 AM on May 14, 2021
Burning wood is at the other extreme of carbon footprint and might negate the benefits.
Absolutely, and it depends on how much you will need to supplement your other energy sources. Here, there will be days or even weeks of very cold weather where the geothermal system isn't enough, but rarely months. This winter, where I have been home much more than usual because of corona, I think I have used two cubic metres of firewood. I think that is an OK level when all my other energy comes from renewables. Also, I have the wood already, enough for many years at this rate.
But as I wrote above, with better insulation, I could reach better results, and TBH, everyone should look at that, both for hot and cold climates. Zero energy houses are a thing, even in very cold climates. It's a bit more expensive to retrofit an old house, but not at all impossible, and maybe you have asbestos or other problems you can get rid of at the same time.
Another mistake I made, seen in retrospect, was that I kept the kitchen unheated. This works fine when everyone is here, and the stove and oven are going all day. But when I am alone, as I have been a lot during corona, it's not only a cold room, it cools down the rest of the house.
BTW, I didn't write the actual savings above because I am in Europe, and the conditions are very different. For instance, more than half of my electricity bill is carbon tax, in spite of the fact that I don't use fossil fuels. This is because how the tax was construed, they are working on changing it. The gas was also taxed, obviously, at a different rate. And then I got a tax rebate for installing the whole thing.
posted by mumimor at 6:46 AM on May 14, 2021
Absolutely, and it depends on how much you will need to supplement your other energy sources. Here, there will be days or even weeks of very cold weather where the geothermal system isn't enough, but rarely months. This winter, where I have been home much more than usual because of corona, I think I have used two cubic metres of firewood. I think that is an OK level when all my other energy comes from renewables. Also, I have the wood already, enough for many years at this rate.
But as I wrote above, with better insulation, I could reach better results, and TBH, everyone should look at that, both for hot and cold climates. Zero energy houses are a thing, even in very cold climates. It's a bit more expensive to retrofit an old house, but not at all impossible, and maybe you have asbestos or other problems you can get rid of at the same time.
Another mistake I made, seen in retrospect, was that I kept the kitchen unheated. This works fine when everyone is here, and the stove and oven are going all day. But when I am alone, as I have been a lot during corona, it's not only a cold room, it cools down the rest of the house.
BTW, I didn't write the actual savings above because I am in Europe, and the conditions are very different. For instance, more than half of my electricity bill is carbon tax, in spite of the fact that I don't use fossil fuels. This is because how the tax was construed, they are working on changing it. The gas was also taxed, obviously, at a different rate. And then I got a tax rebate for installing the whole thing.
posted by mumimor at 6:46 AM on May 14, 2021
The cost of a new geothermal vs the a gas fired heater to me are just so different, the pay back period is insanely long. You can probably get some guy to get you a decent gas heater for $2000, and then try again in a couple of years to see if the numbers have changed.
If you look at Dandelion's website, they estimate $30k total cost for that $150* a month for 20 years.
That's a terrible ROI.
posted by The_Vegetables at 7:52 AM on May 14, 2021 [1 favorite]
If you look at Dandelion's website, they estimate $30k total cost for that $150* a month for 20 years.
That's a terrible ROI.
posted by The_Vegetables at 7:52 AM on May 14, 2021 [1 favorite]
Sorry to be a picky cuss, but you have a boiler, not a furnace.
Heat Pump. Effectively, a heat pump is an air-conditioner in reverse. So you have a compressor, refrigerant, etc. Stuff breaks, stuff leaks.
If it's air based, then there is a limit to how cold the outside air can be in order to get the wonderful efficiency over straight electric heat. Physics. Ground based is better, as if you go deep enough (reasonably) then the ground temperature is at a relatively constant 10 degrees Celsius (50 F). I've always wondered about freezing right around these pipes in the ground, reducing the efficiency. But that's just me.
You mentioned "some blockage in the burner tubes." I presume, in your boiler, this is in the water tubes that is heated by the gas, oil, electricity or whatever. Yes? If so, this is due to crud in the water system. Perhaps there is some kind of flush that could be done.
Personally, I would go with gas. Simple, reliable, not too polluting.
If you are tempted to go with a heat pump, please check out the efficiency vs surrounding air (for an air-sourced one) and factor that and electricity costs with the cost of gas.
posted by mbarryf at 8:36 AM on May 14, 2021 [1 favorite]
Heat Pump. Effectively, a heat pump is an air-conditioner in reverse. So you have a compressor, refrigerant, etc. Stuff breaks, stuff leaks.
If it's air based, then there is a limit to how cold the outside air can be in order to get the wonderful efficiency over straight electric heat. Physics. Ground based is better, as if you go deep enough (reasonably) then the ground temperature is at a relatively constant 10 degrees Celsius (50 F). I've always wondered about freezing right around these pipes in the ground, reducing the efficiency. But that's just me.
You mentioned "some blockage in the burner tubes." I presume, in your boiler, this is in the water tubes that is heated by the gas, oil, electricity or whatever. Yes? If so, this is due to crud in the water system. Perhaps there is some kind of flush that could be done.
Personally, I would go with gas. Simple, reliable, not too polluting.
If you are tempted to go with a heat pump, please check out the efficiency vs surrounding air (for an air-sourced one) and factor that and electricity costs with the cost of gas.
posted by mbarryf at 8:36 AM on May 14, 2021 [1 favorite]
This thread is closed to new comments.
posted by jessamyn at 7:25 PM on May 13, 2021