u/Fit_Yak7907

I have a 2 family house in NY that is very old with a brick exterior and little insulation. Each unit is about 950 sqft. Last winter was brutal. I have hot water heat and in some rooms, it was still pretty cold. Overnight, some pipes froze, even though the heat was on pretty high. I was thinking of getting a mini split to supplement the heat and use for AC in the summer. I had 2 different HVAC companies to give quotes. One of them recommended a window heat pump instead, but they seem just as expensive as the kind you install on the wall. Any recommendations on something easy and not so expensive?