Heating Costs of Heat Pumps and Woodstoves
jberks
| Posted in General Questions on
This article came up in my feed this morning:
https://www.cbc.ca/news/canada/new-brunswick/heat-pumps-firewood-offer-cheapest-nb-heat-1.6721594
I thought this would spark good debate amongst the HVAC nerds here.
Anyone care to poke holes in this?
Jamie
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Jamie,
So if the figures are right - or even close - switching from oil heat to a Mini-split is the equivalent of adding four times the existing insulation to the house.
My natural gas is cheaper and electricity more than the article, the cost of heat pump is a bit less but close to natural gas. Definitely WAY cheaper than oil, propane or electric baseboards.
Seems accurate based on that location and those prices. Electricity has the benefit of being generated from multiple fuels, the energy portion should always be pretty competitive. Delivery is a different story.
Since that article is from a Canadian publication, I'll assume all the figures are in $CA. My cost, after converting to $CA, is about $19.23 per million BTU, after allowing for the 80% efficient furnace (something that will be replaced with a 90+% efficient furnace when it dies, but it came with the house and is still in good shape). My electric rate is similar to the rate used in the article, after adjusting for exchange rate, and using my "off peak" rate, which is nights and weekends (simplifying a bit) which is when the furnace runs the most. I will assume my rate with a heat pump would be similar, although I'm not sure if New Brunswick sees average temperatures a bit warmer than I do due to atlantic currents.
That would put a heat pump, for me, at around 37% cheaper to operate than my existing natural gas furnace, or about 26% cheaper when I eventually upgrade to a 90+% efficient gas fired furnace. A quick check of my last gas bill, which conviently lists the last 12 months of consumption info, says I use about $2,088CA worth of gas at my current rate (which is about 74% higher than it was last year). That means I'd save around $772 a year with the heat pump. I'd save around $543/ a year compared to a 90+% efficient gas furnace.
A new 96% efficient gas furnace, a basic one, would be about $1,720, so about a 7.5 year payoff assuming rates stay the same. A hyperheat heat pump, using some basic numbers here since they're more difficult to quickly price out for me, would be around $7,000 for an equivalent ~80kBTU system. That would give about a 9 year payoff over my current 80% gas furnace, but near 13 years if I already had that 90+% efficient furnace installed.
Putting in a heat pump would make sense if you were already getting close to needing to replace your exisiting furnace. I'm not so sure it would make sense if your existing furnace were already a 90+% efficient model though, since I'm not so sure the heat pump will last 13 years or so. On a new build, with all new everything going in, a heat pump likely makes sense -- especially if it also means you won't need to pay for a connection to your natural gas utility.
The big thing I didn't allow for is that a heat pump will probably cost a fair bit more to "upgrade to" than it would cost to swap out an existing gas furnace for a new unit. On a new build, that wouldn't be an issue, and I'd actually expect a minisplit system to be cheaper to install compared to a ducted HVAC system for a furnace -- and remember that a heat pump gets you air conditioning "for free" with a new build!
Wood heat for me would be free. I'm on almost 24 acres and have a nearly endless supply of firewood from dead wood, so that's not really a fair comparison for most. I actually have looked into using the wood for heat though, and the cost of the outdoor boiler (an efficient gasifier type unit) would actually cost significantly more than the heat pump mentioned above after allowing for buying the boiler, installing the underground lines for the water loop, and putting a water to air heat exchanger coil in the furnace. I'd love to put the system in, and do something useful with all the free wood, but I can't justify the installation cost to put the system in.
Bill
Wood is free in the same sense that oil, gas and coal are free -- all of the cost is in the effort to gather them and transport them to you in a usable form. They're just sitting in the ground after all.
Someone I know who heats with wood that he gathers on his own land, and who seems to be good at it, told me that he figures 16 hours of labor per cord to cut, haul, split, stack, dry and haul again into the house. Good firewood is about $300 per cord delivered so that's $20 per hour or so, not counting the cost of acquiring and maintaining the equipment.
Where it really pays off though, is if you can cancel the gym membership.
DC,
"Wood is free in the same sense that oil, gas and coal are free -- all of the cost is in the effort to gather them and transport them to you in a usable form."
The difference is that wood allows the possibility of the work being done by homeowners. Here cutting and collecting firewood is almost a recreational activity. It takes a couple of days in the summer, and is seen as an extension of yard work for many of us.
The question of carbon differs depending on there you are too. Most of the wood here is salvaged from recently cut land, and would otherwise be machine piled and burned anyway.
The wood is here already, as dead wood (dead branches that fall, dead trees that fall). Most of my land is woods. That makes it "free" in the sense that I don't have to buy it from someone else, or from a utility company, as is the case with electricity or natural gas (my other two options). Basically I can my own gathering and transport instead of paying others to do it, as Malcolm mentioned.
I do remember reading in a forum dedicated to wood fired hydronic heating systems, that the owners of those systems were big on insulating their homes, just as most of us on GBA are. The difference is that on here, our motivations are usually cost and energy savings. On the wood heating forum, the motivation was more insulation meant less physical labor. They would talk about how many cords of wood the extra insulation saved them over the season. They could, quite literally, FEEL the difference :-D
In my case, I have to cut and clear a lot of the dead wood that falls in the grassy parts of my land, or on the driveway (which is about 1/3 mile long). I cut it into logs and store it on racks, but I don't have anything else to do with it. If I could make that wood do something useful, that would be great, but for now it sits, waiting until maybe I find a deal on a "previously expierienced" wood boiler someday...
Bill
Bill,
I would defiantly reconsider burning wood if I had to buy it. A cord is over $450 CDN here, which makes it compare poorly with even electric baseboards.
Malcolm, the one thing we in the frozen North tend to have (Northern US and Canada both are similar in this regard) is a lot of heavily wooded areas. Get yourself a big wooded lot and nature will set you up with plenty of wood! Mother nature always sells her wood on an "as is, where is, no guarantees expressed or implied" basis though, and the customer service I have found to be quite lacking -- I had a free delivery of firewood a few years ago placed right across my driveway in fact! Very inconsiderate of the winds and the tree :-)
I have often seen firewood sold on places like Craiglist, I'd think Kajiji probably has some listings too. You usually have to buy full cords though. Maybe you could get some better prices that way? I can usually find wood for about half what you mentioned, but maybe there is more of it available near my area. You don't have to go too far from me to get to farmland, so I'm pretty far outside of the major cities.
Bill
Bill,
Most years I have enough wood for the next winter by June. A lot comes from trees that go down on the power lines, which they leave by the edge of the road knowing locals will take them. Right now I'm staying even with my woodshed full and only two months of wood stove use left.
What about a wood burning fireplace insert? That might be cheaper? We have one in my house with a ceramic afterburner and the smell/ air quality is not bad. To distribute the heat throughout the house I just turn the HVAC fan on. The fireplace insert and HVAC are not connected. But the blower for the insert is about 20 from a central return.
I live near DC so our winters are a fair bit milder, but our polar vortex (down to 7 deg F) the wood fireplace insert was able to carry the whole heating load for the house without an issue.
I don't have a fireplace, so a fireplace insert isn't an option for me :-)
Bill
Bill --
You should check out this wood boiler:
https://www.mbtek.com/collections/solid-fuel-boilers/products/pro-11
Less than $2,000! I have no idea if it's any good, but if anyone could make it work you could.
I am a big proponent of wood heat for a variety of reasons, but it does not work for everybody. For my leaky 1965 house I spend about $200/year on truck and saw gas to heat the place compared to +/- $2000/year when I was on a gas furnace.
The big benefit is when the power goes out, as it does frequently up here in the north. Heat and the ability to cook.
Our infrastructure works very well when it works, but is very fragile when you look deeper. We have 1 main hydro line feeding the area, 1 highway in and out, and 1 gas line. Both the highway and the hydro line have been down for various reasons in the last several years and with major weather and fire events becoming more frequent it feels good to be somewhat self sufficient. We lost internet for 2 days last year because a beaver fell a tree on a line!
The downside is local air quality.
My grandmother came from St John's Newfoundland and the guy in the article reminds me of my relatives from that neck of the woods......tough, resourceful people...
I have possibly mild COPD so woodburing appliances indoors dont make a lot of sense for me. But from an enviornmental perspective, while I assume cutting down live trees for firewood is rarely a good idea; using wood that is already down or must be cut for other reasons is a more interesting and complex equation...I seem to recall some lively discussions on the topic; with one side arguing that the wood was decaying anyway so there is no net addition to atmospheric carbon, and the other side arguing that burning wood acclerates the process and emits a great deal of carbon at a time when the world can ill afford it...I don't recall how it all eventually worked out.
I know in the the developing parts of the World, burning wood for heat, cooking and sterilizing water is one of the leading causes of respiratory problems in villages and a big reason why many forests are being cut down so quickly....
You are correct in that wood burning is not a solution for the masses, especially in urban settings. But it makes sense in rural areas.
Falling live trees for firewood is no good, both in that the wood needs to season for 2 years before burning, and on the carbon front. But naturally killed wood can either be burnt or it will begin rotting in several years, as well as creating fire loading of the forest.
Most of the people burning wood for heat are getting that wood often from their own land, in which case it's nearly always from dead trees and fallen branches. Sometimes you'll have a tree taken out to make room to build something, but usually the wood used for heating is coming from "natural causes" like storm damage. If you have 20+ acres, you get a surprising amoung of dead wood from storms, and from trees falling over from rot at the base.
People who buy their wood I would think could find wood from similar sources, since tree trimming crews have to dispose of a lot of that after storms. There may be some trees being harvested just for firewood, but I'm not aware of any of that in my area. I think the wood pellets for pellet stoves are sourced from waste wood too.
Bill
In Maine, as in many places I suspect, firewood is part of the forest products based economy. People conduct harvests (of varying quality and with varying goals) but more often than not there will be low grade hardwood removed that needs to go to market. Firewood and pulp is that market. I would argue the overall outcome of the forestry operation is a better place to analyze the carbon and environmental aspects than the isolated use of wood burning. A systemic approach if you will.
And we probably find that some harvests are tough on the ecosystem and others are much better-- firewood extraction not usually being the primary decider...
I've been heating one house with wood for over 40 years. Most of my wood has been taken from my property, but to call it 'free' is a misnomer. Sure it grows there, but it takes a lot of work to get it from tree form to logs that burn. That time that could've been spent doing other productive stuff. Still, we love to burn wood, but it has its drawbacks too. I won't bore you with those.
As I have aged, it has become more and more difficult to cut it, split it and haul it. When a large tree falls or I have it cut down, I hire the work out. Then, I hire the guys to use my splitter to split it. When all is said and done, it'd be less expensive for me to buy a $250 cord than pay these guys.
With the next house, we'll still have a fireplace but it will only be used on special occasions. That home will be electric. My wood burning days are coming to a close. It's sad but true.
I hear you. I am dumb enough to still enjoy it, but it will not last for ever. I will hopefully have heat pumps installed by then so that wood is only needed during extreme cold spells