We don't really have good heating (and air conditioning) to our second floor.
Possibly because there are only three registers (one in each bedroom and one in the bathroom).
Our heating and air guy has said that we could make another zone for the 2nd floor (we already have one for the basement and one for the rest of the house). He would install a thermostat upstairs.
He also suggested a "cassette" mini split - we could get two - one for each bedroom. They would fit in the ceiling. The cost would be different - with the mini split running about twice as much. The mini split would have remotes and thermostats in each bedroom.
Hard to give advice. You don't mention what kind of heat you have, any information about the distribution fan size, supply duct size and length, nor what duct size if any for return air. No idea if the current supply ducts have baffles and if the system has ever been balanced. I assume there is plenty of insulation in the attic?
If you have good duct size, you may just be able to use booster fans in the supply ducts. All my bed rooms and bathrooms only have 1 duct.
Seems odd to have a mini split for each bedroom, when you also have a central unit. There should be a better way to control the conditions other than throwing more capacity, unless the central unit is old and undersized.
One thing, you may be asking the wrong guy. Like asking a barber if you need a haircut. HVAC guys sell systems by the ton. Never saw a house that could 't use more equipment.
You might be able to find a home inspector or energy consultant to help you sort it out.
As Dick mentioned, your system may not be balanced. In most houses with a single system and more than one floor you have to "chase" the air around. In winter you throttle back the vents on the second floor and open the ones down stairs. In AC season you reverse and open the vents up and throttle them back down. Some care is involved particularly with heat pumps to not close too many vents and choke the system.
Many systems have internal dampers in the main ducts to allow you to make a single seasonal adjustment. Sometimes they can be installed later. It is possible to motorize them.
There should be a return duct upstairs.
Changing the dampers seasonally should only take a few minutes once you understand, even if you are doing individual ones in the supplys.
Another thing to think about is how well the house and especially the second floor is insulated. If the second floor is poorly insulated it is even more difficult to control the temperature. Often it is fairly easy and inexpensive to dramatically increase the ceiling insulation. Maybe improve the windows. Caulk and seal to cut air flow and the associated heat loos and gain. This is a huge topic with lots of ramifications and pitfalls. Much too complex to go into here. The point is the house may be easier to control and more comfortable and much cheaper to operate if the thermal package can be improved.
The problem is that most HVAC contractors don't sell insulation, but sell more equipment to overwhelm the problem. At an initial cost and increased operating cost.
OTOH, be careful, some "energy consultants" may be little more than snake oil salesmen.
You may be able to have booster fans installed in your existing ducts to help get more air flow upstairs.
I think you should consider a single mini split head in the upstairs hallway just to take some load off the main unit.
I think very few HVAC contractors actual install mini splits they mostly use them as the bait in a bait and switch game. They quote oversize mini split compressor with a head in every room when the price tag sends you into shock they conveniently have a much lower bid for a conventional system.
My house is a new construction circa 1994. First and only owner. Originally built with only central heating. Heating worked ok basically. AC was added early on and never really succeeded. It works ok for the first floor. But fails completely on the 2nd floor. The whole house suffers from not having a ac air return. Should have a return from high up on the 2nd floor and high up on the first floor. Short of redoing the house, I had a mitsubishi air conditioner unit installed. It is a room ac. two part unit one in the bedroom mounted high on the wall. AND an exterior unit (condenser) on the ground outside.
you didn't mention whether you have one heat pump or two. If only one, it seems like it could be challenged trying to heat and cool a basement plus the rest of the house. I've seen this setup fail too many times for various reasons.
If you have two units, one for downstairs and one for up, then you can probably get more comfort from the upstairs unit by any number of suggestions already stated.
I like the mini splits for their efficiency but think they are better used in existing structures where it's cost prohibitive or impossible to run ductwork or no space for the air handler, and there is no dedicated heat pump for that part of the house.
We have a propane furnace w/ a heat pump (I think 13 SEER).
Currently two zones - basement and the other two floors.
We have seven registers on the first floor and three registers on the second floor.
The upstairs return is in the first floor hallway and that's where the thermostat is located.
No problem w/ the first floor or the basement. The second floor on the other hand... Not enough cooling in summer, not enough heat in winter - though the heating isn't really a problem as we have a portable heater.
We have a propane furnace w/ a heat pump (I think 13 SEER).
I'm taking this as your propane furnace is the auxiliary heat source for the heat pump and not the fulltime heat. 13 SEER is low as far as efficiency. Newer heat pumps can be in the 18 - 22 range.
Currently two zones - basement and the other two floors. We have seven registers on the first floor and three registers on the second floor.
You don't say how many registers for the basement, given that it's on the first zone. 10 registers doesn't seem like a lot for a single heat pump to handle except the ones upstairs are a longer distance away from the source.
The upstairs return is in the first floor hallway and that's where the thermostat is located.
I'm guessing by "upstairs" you are referring to the first floor above the basement. The thermostat location is normally near the return to benefit from the air flow to help sense temperature better.
Again, like others have stated - any number of things can affect the temperature problem upstairs - insulation, duct sizing, enough air delivered, distance from source. It's not clear whether your single heat pump is able to properly heat and cool the upstairs areas. Sounds like you need an expert that's not trying to sell you a bill of goods to analyze things and make an informed recommendation.
One thing to check is see if your local power company has Energy Auditors either on the payroll or a list of subcontractor ones working locally. They might be an unbiased source of information. Even then you might need a second opinion.
If you have one system, you effectively have a three story house. Basement, main floor and upstairs. Several of us have spoken of "Balancing." Think of the air flow as being the source of the heat or the AC. Also remember that warm air rises. So the idea is you want to dump the warm air in low and let it rise, and dump the cooler AC air in high and let it fall. You need to subtract warm air from parts of the house that are too warm or even warm enough when heating and chase it to parts of the house that are not warm enough.
This is difficult for many people to grasp when I say to throttle back the vents on the main floor, slowing the delivery there (and in the basement) until the upstairs can catch up. The home owner says "No, the main floor is fine, it's the upstairs that has a problem." The heat for the upstairs has got to come from somewhere, so you may have to leave the heat running longer, with a little less going to the main floor until the upstairs catches up.
The lack of a return on the upstairs makes it m ore difficult, especially for AC.
This is a supply and demand problem. If the second floor is poorly insulated there will be huge demand for both heat and AC. So you have to solve that by either reducing demand or increasing supply. So, if your existing system is big enough, you can increase air flow to the upstairs, by robing it from the basement and main floor, or you can install another system.
The mini split systems are attractive and can be very efficient. And, being ductless, they can be easier to install. They can be zoned as well. Even a small one can have three or more zones. so I don't understand why your guy wanted to put in two, unless it was just easier for him and more money. While they don't use ducts, there are some problems. They must run tubing for the refrigerant to each unit and power wiring and wiring to the thermostat, and a condensate drain.
You have several possibilities. You can tweak your present system. Run a return duct to the upstairs, add booster fans in the ducts, add internal dampers, adjust the vents seasonally, Etc. You could also improve your insulation and sealing. This is often a good idea as it reduces cost in both seasons forever. And you can add an additional system or systems. Remember, you can add the systems later if all else fails.
Start by figuring out what the problem is and what's causing it.
On last thought....after a house is reasonably well insulated the principle source of heat loss is air leakage.
Unless someone is using a bedroom in the basement I would close all the basement vents. Basements generally stabilize at a livable temperature on their own without any open vents.
Look for dampers in the ducts going up stairs commonly found in the basement just off the main duct all you will see is a small handle on one side and a pivot point on the other. Like a gas valve the handles indicate the position of the damper make the handle parallel to the duct for the upstairs vents.
The insulation is good. The walls are well insulated as is the ceiling in the attic area. The attic insulation is on the order of 6" thick.
As far as the ducting - who knows. There is roughly square duct that goes from the system to the second floor (behind the closet). That duct is probably 12" square. The smaller ducts that lead from that to the wall registers in the second floor - IDK - they are behind a knee wall.
We've tried adjusting the first floor registers and we do have somewhat reasonable air flow in the second floor registers. The basic problem is that it stops conditioning the air (heating or cooling) when the first floor thermostat is satisfied.
Our HVAC person has come up w/ two solutions. Put another zone in (which the board on our system could handle) along with replacing the damper system and putting a thermostat on the second floor. This would let our existing system do the job. The other proposed solution is a mini split w/ two cassettes. This would just condition the air on the second floor.
Our HVAC person has come up w/ two solutions. Put another zone in (which the board on our system could handle) along with replacing the damper system and putting a thermostat on the second floor. This would let our existing system do the job. The other proposed solution is a mini split w/ two cassettes. This would just condition the air on the second floor.
Even though your existing board would handle a third zone the problem I see is how much more that single unit will potentially run. An example would be if the upstairs thermostat kicks the system on but before it's satisfied the downstairs also calls for air. The upstairs gets satisfied but the downstairs runs a longer before cutting off. Then the process starts again and again. It seems like that one unit will get a real workout.
Installing the mini split system would mean closing off the vents for upstairs for the heat pump. Instead, I have to wonder if you wouldn't be better served by adding the appropriate sized heat pump for upstairs with thermostat and return duct. If it's not possible or cost effective to install a second heat pump, then I think going the mini split route makes sense.
Bottom line, I think you would be asking too much of your single heat pump no matter the damper arrangement. It doesn't seem like a more efficient way to heat and cool your house and it might run it to an early grave.
Several years ago I installed many heating / central air systems, boilers and contracted electrical and plumbing jobs as a second job. (They called me an Engineer on my main job!). Yeah I was bonded and insured and held a contractor's plumbing license. Indiana State doesn't have licenses for electrical or other contracting work.
I have seen many issues caused by fairly obviously things. One issue you may have is return air from your upstairs rooms caused by close fitting doors. I have seen temperature changes caused by carpet installation. A room with one 6" duct need about 30 sq/inches of return air - typically this is about 1" cut off the bottom of a door.
As has been stated heat rises so with the upstairs floors heated by the rising heat from the first floor so lack or return air may not be apparent until the air conditioning fails to function properly. Quick test to determine if this is an issue is to leave all the upstairs room doors open for a period of time to check.
The first thing I would check in your home is the position of the dampers - unfortunately there is no one perfect setting as during the heating cycle you would like the upstairs ducts to be partially closed and the first floor wide open. During the cooling cycle the upstairs should be wide open and the first floor partially closed.
As others have stated the basement need little heating or air normally to stay comfortable.
As a footnote, in the 70's I had one customer call me after I had installed his furnace about a year earlier. He said it just wasn't working right in the evening - when the wife and him said to watch TV it just became too cold to stand.
So I went to his home to inspect things being quite puzzled with his situation. I walked in looked at the thermostat and said "You have two choices!, (he had a large Tube type TV setting right under the thermostat).
You can either move your TV away from the thermostat or pay me to move the thermostat and rewire it. He looked puzzled so i led him to the TV and had him put his hand over it. The heat radiating was similar to a small electric heater. He like many people, did not really understand how a thermostat works - after I explained, he moved the TV! He called later and thanked me, said it worked perfectly.
I did way over ten thousand Home Inspection over the last thirty five years. On every one of them I checked to see if the doors were undercut and yet I failed to mention it above. You are correct and its easy to see if it's bothering the system. Good on you.
