Choosing a Heat Pump System
TomKzz
| Posted in Mechanicals on
Hi everyone,
I’ve been here before…. Since then I have had an energy audit done on my house and therefore sizing is no longer a mystery. Now I’m looking to select a system from 4 decent options.
Two are dual fuel (Trane, Carrier) and two are electric only and would be installed with backup resistance coils (Mitsubishi, Moovair). No need to discuss sizing as this has been sorted by an energy audit I had done.
Of note:
– The Trane [2-stage gas], Mitsubishi and Moovair are all communicating, variable systems.
– The Carrier would work with a standard ecobee thermostat and works on a fixed fan speed when the heat pump is being used.
– The Trane would depend more on gas as its cold climate performance is the worst of the bunch.
– The Moovair is 2.5 ton, slightly larger than the other heat pumps, as it qualifies for rebates whereas the other manufacturers don’t have a rebatable system of this size.
– Cost of the systems from cheapest to most expensive: Carrier, Trane, Moovair, Mitsubishi
– My confidence in the installer is high for Carrier, Mitsubishi and Trane, but questionable for Moovair
NEEP Links:
– Mitsubishi: https://ashp.neep.org/#!/product/31987/7/25000///0
Which system do you think is the best for comfort, value, and reliability? Location is Toronto, Canada.
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Replies
I never saw the appeal of the dual fuel systems. Seems to me like you are betting a lot of money that one fuel is a lot cheaper than the other fuel today and you think that it is somehow likely to change making the other fuel much cheaper than the other. Seems unlikely at best that the prices could change enough to recover the extra costs.
Do you have city gas service in the home? If so it is likely to be the low cost heating fuel.
Ask the Carrier to bid greens speed with Infinty controls if you want their best system.
Ask the Mitsubishi dealer to quote a hyper heat model.
Walta
Thanks for the reply.
That's not how I understand dual fuel. It's less about changing utility rates, but more to do with which energy source works better at different temperatures. Gas is cheaper and works better when it's colder. I believe it's supposed to be a 'best of both worlds' solution and reduces gas use significantly thanks to the heat pump working efficiently during cold but not super cold weather.
Also, the dual fuel systems are significantly cheaper than the all-electric ones based on the quotes I received. My house already has natural gas service. My 28 year old existing furnace is a single-stage lennox.
In deciding between dual fuel and all-electric systems, I weigh the cost and benefit and also think about how technology will change in the next 10-20 years. The mitsubishi electric system is $7,000 more expensive than the least expensive dual fuel (Carrier). I imagine in a decade, better heat pumps will be available for cheaper, as more companies invest in producing better compressors and inverters.
Currently, gas prices are at an all time high but it's still cheaper to heat with natural gas when it gets really cold.
Carrier's Greenspeed is also $$$$$ but it's mostly due to marketing as the cheaper system has the technical ability but Carrier has just handicapped it. I don't really want to pay the Carrier marketing tax.
The Mitsubishi is the hyper heat yes.
I have the 2 ton Mitsubishi hyper heat, but not the P-series. It's great! It wasn't nearly as expensive as you've been quoted but this was almost 2 years ago. A heat pump is much cheaper than gas here so the dual fuel seemed like a waste, but I understand the appeal and electric utilities probably love them. A heat pump using gas generated electricity can actually use natural gas more efficiently than the best furnace can, so if gas is cheaper it's because of how it's delivered (and billed) to your house.
There should be no price difference between a dual fuel system or a heat pump only. If you look at the material cost, they are comparable and install for the heat pump is much simpler. You need to find a better contractor.
The Moovair looks awfully like a Midea DLFSAAH unit, if indeed that is the case, I would not worry about. The Midea cold climate units pretty good, they also OEM most Carrier hyper heat systems.
Hey we meet again! Thanks for your 2 cents. Yeah I agree, the all-electric should be the same or less! Unfortunately there are limited contractors installing all electric systems in my area, so I imagine it's a supply and demand thing and not at all related to materials or time.
The Moovair could be good based on the equipment and specs, but the guy who came to propose it is a one man show and has only installed one of them before, so I'm super hesitant about using him.
If the question is about lowest operating costs city gas is almost impossible to beat below 50° and how much heat do you need above 50°.
For some the goal is to cut off the gas line for environmental/political reasons but avoiding the $30 a month connection fee does have some appeal.
You need to do the math using your utilities rates but it seems unlikely you can save enough money on fuel to pay for the extra equipment a dual fuel system requires.
The other problem with dual fuel is the occupant. The gas furnace blows toasty 130° air and the heat pump blows tepid 90°. When the HP is the only option, the occupants become accustom to 90° and live happily but give them a blast of 130° air and they will figure out how make that happen all the time.
Note I think buying the low-end of the heat pump line is a mistake because they do not work as well or as efficiency.
My variable speed heat pump supplies all my heat above 9°F
Walta
"If the question is about lowest operating costs city gas is almost impossible to beat below 50° and how much heat do you need above 50°."
This is extremely utility dependent! It's not really related to the cost of the actual gas, it's more the cost of electric vs. gas infrastructure. If we can generalize at all, I'd posit that the higher the fixed monthly fee is, the higher the balance point. If distribution is a variable cost, then the balance point is lower and possibly doesn't exist. Another generalization in my opinion would be the higher the AC usage is in a location, the lower it'll cost to heat with a heat pump even with the same winter.
I'm not sure we can generalize and I'm not sure we need to either, particularly in the context of my question. I'm just trying to pick the best system for my home in Toronto.
The Trane and Mitsubishi are fully variable and have fine cold temp performance. The Carrier is fine enough, but is a lower level offering from that brand. These brands are established and either can be paired with auxiliary heat, electric or gas of your choosing, or you can skip that for the Mitsu. Flip a coin!
The Trane's cold temp performance looks quite a bit worse than the other three (see chart attached to one of my messages below). Are you saying it doesn't matter as I'll have gas ? Because I do like the low noise specs on it.
Agreed on the fully variable aspect. I feel like Carrier handicapped that system by not letting the blower vary its output in concert with the heat pump. This is the main reason I haven't just gone ahead with it already.
How are the Trane thermostats? I liked the idea of having an ecobee but I don't think I can do that with the Trane, Mitsubishi or Moovair, as they are proprietary systems (correct me if I'm wrong).
In Toronto, heating is more important than cooling. Even though we do get hot summers, they are relatively short. As a result I worry about a Mitsubishi system with no backup.... it would have to be larger to handle the load and then would likely be oversized for cooling.
So my current hvac system is 28 years old, so I will be spending money on SOMETHING soon... It just so happens that the dual fuel systems are cheaper than the electric-only ones. They shouldn't be. But they are. Both system types qualify for the same $5,000 rebate with the exception of the Trane - the rebate on that system is only $4,000 since it doesn't have very good cold climate performance.
I don't need to cut off my gas line, at least not now. I'm not looking at this from an absolutist point of view. But I do care about efficiency and the environmental aspects which is why I'm looking at replacing my furnace and A/C with something that includes a decent heat pump. 50F is only 10C so definitely need some heat. Heat pump would work great at this temperature I think?
At current rates it would make sense to use gas on the coldest of days, around 12 F and lower, but heat pump above that. I could also adjust that point based on costs or comfort.
Regarding "the occupant" that's me and my family. Due to my current single-stage gas furnace, I have my thermostat programmed to run the fan for a while every hour to recirculate the air and rebalance the room temperatures. During those times there is NO HEAT, just air, and it doesn't bother us. So, it can only get better from here.
Regarding buying low-end, mistakes and efficiency: Are you saying that the Carrier, Trane and Moovair heat pumps are low end? I don't normally buy low end stuff. But I also don't necessarily need the top end either. Technology is always evolving and I do care about overall value. The "top end" most expensive heat pump today likely won't rank at the top in a few years once technology evolves further, but my dollars will have been spent.
It sounds like you want to talk about your setup. What heat pump do you have and what is your location and house type?
Interesting discussion guys.
I found an interesting matrix that helps people find the economic switchover point, and I mapped my costs to the chart. I have a 22 dollar fixed monthly charge for gas (which I'll have to pay anyway, as I have a gas water heater and gas bbq), but the other charges are variable. For my current rates this switchover point turns out to be 10 F. If gas should become cheaper again then this point will go up and I could decide to use more gas (or not, depending on my priorities at the time).
(Edit: I don't know why this site is reducing the size of my image. Here is the original: https://s3.amazonaws.com/greenbuildingadvisor.s3.tauntoncloud.com/app/uploads/2022/12/08130649/48563_1670522809_hybrid-costs.png)
In Toronto, a balance point of 10 F is close to not mattering! Looks like 90% of Heating Degree days are below 39, so a daily average >25F.
I also overlaid the performance of the 4 heat pumps....
What do you make of this?
Again here is the link to the full size image: https://s3.amazonaws.com/greenbuildingadvisor.s3.tauntoncloud.com/app/uploads/2022/12/08131106/48563_1670523066_4-system-comparison.png
The first graph is based on a heat pump of unknown efficiency a chart for HSPF of 13.5 would be very different than 6.5 HSPF!
The second chart is about how much heat a HP can produce at a given outdoor temp. You are looking for data about how many BTUs per kWh at a given temp.
Walta
You're not wrong, but if you're going to just point out all the flaws with the charts/data I was able to find, but not provide anything better, you're not really adding much to this conversation.
… do you have gas? If you do just get a gas furnace and call it a day. It is the cheapest and will be so for quite some time. Unless you plan on getting solar panels and then the math might skew towards the ashp.
Hey thanks for your input. Yes we have gas service. The existing furnace is a 1994 Lennox single stage. I also inherited a relatively new hot water tank rental from the sellers which unfortunately I'm bound to for a while, and I do enjoy my gas BBQ, so probably not going to ditch my gas service anytime soon but I would love to reduce consumption. I also want better humidity control in the summer so a nice variable heat pump seems to be a good idea to me. Which system of the 4 would you select or is there some other system I should consider?