Oil-filled radiators are usually generate the most comfortable heat for a portable, and tend to be the safest. BUT they don't work terribly well in rooms with very high ceilings or have major drafts. As long as you aren't dealing with those two problems, they'll do exactly what you're looking to do. Heat pumps are the most efficient way to heat, but I've not come across a portable model yet. That said, if you're planning on doing this regularly it might make sense to have mini-split heat pumps installed in the bedrooms. You would also then be able to do the reverse in the summertime -- cool only the rooms you're in. Generally, heat pumps put out 3x the heat for the same amount of watts compared to a portable heater. So if your portable heater needs to run for about 5 hours/day, it'd use the same amount of electricity that a heat pump would in 15 hours. Adds up over time.

I have to correct Skin...Trane does not really offer builder grade HVAC compared to the other HVAC brands. XR series condensers are not builder grade and any suggestion that it is is entirely incorrect. Relatively speaking, you are going to pay more for the smaller size condensers compared to larger sizes. You can assume that online equipment is low end especially from brands like Goodman. Like most things, you get what you pay for. Unfortunately due to price pressure, today's HVAC is not same quality as to 10 yrs ago. Very sad to see Carrier close up shop in Indianapolis and ship 1400 good American jobs to Mexico. Based on the feelings of plant employees, I wouldn't want any HVAC coming from Carrier during this transition period. IMO

Ductless heat pumps are often relatively limited in the space they can heat and it is not cost effective to add one to every room. A ductless heat pump mounted in the living room will rarely provide enough heat to auxiliary rooms that are farther away, such as bathrooms, bedrooms and kitchens. I have heard about infrared heating products are a great compliment to ductless heat pumps.

Hi Elmer I read through your comments strongly supporting NG over HP option due to its cost advantage. Do you know a 10 KW solar system can be installed in CA today for $15000 after tax incentive , which will generate approx. 15000 KwH of electricity per year ? I am exactly doing this for my 1995 built 3375 sq ft home in bay area as this appears to be the cheapest route to bring down my energy cost as compared to other options like improve insulation, change windows or upgrade 1995 installed 80% efficient NG furnace etc. Till my NG furnace is alive and kicking, I plan to use it minimally in the morning to take the chill out of the home and rely on supplemental electrical heating ( resistive ) to keep the house warm . Resistive heating is inefficient, but ok as stop gap option particularly if my electricity is coming from solar. When it's time to bid farewell to these antique NG fired machines, I plan to take HP route for my home heating and air conditioning. Even without any of these actions and just install of solar, my current electricity only bill will be reduced from $2800 / year ( 10000 KwH ) to zero. That will pay for solar install cost in just 5 years. Add to it cost saving from an electric car ( which I don't have at this time ), payback is even shorter. My yearly NG heating consumption is 700-750 therms. The baseline consumption of 20 therms / month or 250 therms / year will always remain due to NG cooking appliance and NG water heater. But the rest 500 therms / year NG consumption can be eliminated when I replace central ducted existing NG Furnace / AC system with ducted heat pump (no splits). There will be more upfront cost to install heat pump as compared to NG furnace / AC option , but I am hoping this differential to be in the range of $2-3K , particularly if I go with heat pump option like MrCool Universal ( will work well in temperate Bay Area weather ) instead of fancy Fujitsu or Mitsubishi heat pumps. And saving of $1000 from eliminating consumption of 500 therms / year should help offset this cost sooner rather than later. Due to these considerations, I decided to go for 10KW Solar System that gives me enough capacity of solar generated electricity to meet these loads. Time to give a fresh look to all ( almost ) electric home with recent price reduction ( actually since June, 2020 ) in solar install cost.