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My ~2400 sq ft house was built in 1987. We are still rocking the original oil furnace (yes it's 33-34 years old...), which serves the 1 bedroom in law suite in the basement as well as the main floor. We have electric baseboard on the second floor (and a couple in the basement as well).
I want to put heat pumps in throughout the house but a) I might want to do it in two stages and b) I think the indoor units are a bit of an eyesore. If we did ductless, we would need 6-7 indoor units. Also two of the bedrooms are fairly small so the units would likely be oversized in there. We sleep with doors closed for lots of reasons, so we do need units in every bedroom.
I just discovered ducted heat pumps and am thinking we could do the basement/main floor with the ducting we already have and then put in ceiling ducts and run ducting through the attic for the second floor.
(We do have backup heat in the form of a wood stove on the main floor and the aforementioned electric baseboard, which we wouldn't remove.)
I've reached out to one installer but am also interested in your feedback. When I got quotes for ductless heat pumps last year no one suggested going ducted. I'm also having trouble finding other companies who install ducted (in the southern midcoast).
I live in NY state and have a mix of ducted and ductless mini splits in my house. After having lived with them for a few years, I mildly favor ductless but fully understand the eyesore comment. I removed my oil boiler and heat solely with this system, so it definitely works well for both heating and cooling. I have no backup heat, although I do enjoy using my high-efficiency fireplace on the coldest days (always nice having a 75 degree room in the house when it's 0 outside).
The ducted was not much more difficult to install than the ductless, and compared to one of my really complex ductless units, it was much easier. The key difference is that if you're using an HVAC company that mostly does ductless, they might not have the expertise for ductwork. Designing and installing ductwork is a fine art, though many avoid the issue by using flex duct. In this case, the only "hard" part is finding a supply house that can build a manifold to interface the ducted unit with the flex duct since the ductless mini splits are very wide, very skinny rectangles unlike regular HVAC systems which are mostly just very large squares.
The reason I am lukewarm towards the ducted units is that, for whatever reason, they have terrible control units. The thermostats that come with them, for most brands, are just mind bogglingly stupid. In the summer, the fan runs all the time regardless of whether the thermostat calls for cooling, and the scheduling component of the thermostat is useless. I know you may be thinking "but every brand is different"; I'm only aware of a single brand that has an interface for a normal thermostat- Mitsubishi; the rest use the stone-age controller. Ductless controllers are universally dumb too, but at least they have an IR interface so can be used with a smart controller like the Cielo Breeze. Luckily my manufacturer created a new thermostat for the ducted units that is equally as dumb but at least has an IR receiver, so I use 5 Cielo Breeze units to control my whole house and I'm happy with it.
You're definitely not crazy, though. I had the same problem- installers who do regular HVAC weren't big on mini splits, and mini split installers don't care for ductless. In my opinion, a good installation will use a mixture- sometimes the ductless units make more sense (1 big room, or one floor of open floorplan), and sometimes the ducted makes the most sense (lots of little rooms with a shared attic above them). Since you can connect both types to the same outdoor unit, why not mix and match.
I don't have one of these systems, but have read a fair amount about them, so have some knowledge. A couple of thoughts that I hope will be helpful...
- As typically configured with a small number of big wall units anyway, they work best in tight, well-insulated houses - like new-ish houses, because if the outside walls and windows lose heat quickly, it'll be cold far from the nearest distribution point, and that goes double when there are interfering walls.
- I think you're discussing the option for using an air handler in e.g. the attic or basement, with a heat exchanger in it and also a fan to push the warmed/cooled air to individual rooms through air ducts? The small grills definitely look the nicest, but I heard from a builder I was talking with as we did a walkthrough of his project where they had the ductless units downstairs and then an air handler in the attic and ducted outlets upstairs- he told me that latter configuration can be significantly more expensive.
- In terms of aesthetic options, they do also have other ductless "heads", like the floor mounted units, which are still big but maybe attract less attention down lower - form factor similar to an old school radiator, and the ceiling "cassette" units - big also, but with little protruding into the room...
What you are contemplating is as common as can be.... at least in most of the country.
I like the comments on the attitudes of different installers... but that is all normal. They make their living with certain lines of products, and are official dealers with specific factory connections for parts, training. etc. And the staff know just certain HVAC types... most don't know anything about what they don't normally sell or install. So the advice to search around for the right contractor is good advice IMHO.
Be advised that you WILL need some source of backup heat for any heat pump. The standard type is inside the indoor heat exchanger and central air handler, and consists of electric resistance strips that are basically like your upstairs electric baseboards but inside the air handler where the air can carry the heat all over. You can also have gas backup heating sources instead of the resistance heat strips, using propane from a tank or natural gas from a gas line. In that case, a gas furnace is installed (in place of your oil furnace) and the heat exchanger from the heat pump is mounted in/on the furnace blower. Done every day.
Doing the upper floor with ceiling ducts from a central unit may be problematic for your situation. We have full ducted in our house, with the gas furnace & heat exchanger in the basement and ducts on main and 2nd floor. But the chase to carry the heating air to the 2nd floor, and the return air back down, was built into the house new. You might be able to do the return air down the staircase if it is open from top floor to 1st all the time. But you would need a supply duct/chase from basement to attic and that might not be easy at all. Most houses don't have closets stacked vertically, where a new chase can be easily installed.
The alternative is to put a 2nd heat exchanger in the attic with the ceiling ducts up there, fed from a 2nd, smaller heat pump, and make that a separate zone from the basement and 1st level system. Again... done every day. (Our 3 story house in the Outer Banks had 3 separate systems.)
Be aware that heat pumps need to be kept clear of snow and trash and leaves, and when the temps get really cold, they become quite inefficient. Hence the use of backup heat sources.
I don't understand the comments on the limited thermostat functions....??? If a fan runs all the time in summer, it is either intentionally set to do that or something is wrong. Most of the new t'stats are used for many system configurations, and are field configured by the installer for the specific system through a 'secret' menu (that you may be able to find if you look around the internet hard enough); he may have put in the wrong digit in a programming field!
We had two mini-split heat pumps installed in our home in May 2021. This i s our first winter with heat pumps.
From all of our research they are good in Maine for the shoulders [Spring and Fall]. We kept them running right up to last week.
It is not that they do not produce heat, rather the warmth is very subtle and the air they blow feels cold.
As of about 10 January, we are back to woodstove only heating in our home.
Exactly and it's that way with all heat pumps..... Once the outside air gets too cold, they extract less and less heat from the outside air and so can warm the inside air less and less, and it becomes a 'chilly' heat for lack of a better word. Our first heat pump, in northern IN, back in the 80's could work as low as 10F, but the air from the registers was mighty cool and uncomfortable.
Since heat pumps gets more and more inefficient as outside temps go down, they have to run more and more and the overall efficiency advantage gets lost.. plus there is more wear and tear on the heat pump. So that is when backups kick-in for central ducted, either electric or gas... for comfort, and for no worse efficiency. Our gas backup kicks in at 30 or 35 F (I can't recall the setting)... that cutover temp can be programmed in the t'stat via the secret menu that was mentioned.
And in cold, humid conditions, the outside air coils will freeze up, because the coils at at a lower temp than the outside air. So they have to stop, and reverse flow and/or use extra heating strips in the pump to thaw themselves out.. more inefficiency, and wear and tear. A heat pump will perform better on a dry 15F day, than a 33F high humidity day, simply due to the lack of freezing up on the dry colder day. So if you are near the coast with more humidity, then a good backup heat source is more important.
Last edited by nm9stheham; 01-16-2022 at 07:00 AM..
If you buy wood green and season it yourself it will probably be cheaper than the mini split when it gets below 20, plus with the wood stove if you wait until it’s below freezing you don’t have to F with the draft as much, win win.
if you have to buy seasoned wood then it will be cheaper for lower temps. My mini split is not terrible
Efficient by today’s standards but it still works to -5F but you notice it start to struggle at 5F.
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