Crikey? Strewth mate. Haven't you heard the late Crocodile Hunter say it? It's a bit like "golly" and is kind of twee, which is why I like it I guess....I was born in Ontario but have lived in Australia and New Zealand since 1974, moving back to Canada only last year....so I kind of picked up a lot of sayings.... If you want mad and eccentric, you can't go past a kiwi- NZ'er.... Take this for example: http://www.asciimation.co.nz/beer/ Or this guy: http://www.interestingprojects.com/cruisemissile/ Aussies have their mad inventors too, but they're not half a patch on the Kiwis, who have produced some brilliant export earners with their innovation. Personally, I think it's the Scottish Engineer influence (lots of the early European settlers in NZ were Scots) Here is a link that might be useful: THE JET POWERED BEER COOLER

@Ladenson - for clarity, as people are talking about different things, I was referring to the type of air-to-water heat pump that would use your existing hot water baseboards, i.e. would replace your existing boiler, not minisplits - no headers indoors. This is common in some markets (esp Europe). It's not quite so simple as your baseboards may not be sized right (heat pump output temperatures tend to be lower) for the coldest temperatures, meaning you'd have to resort to 'backup' more often. In some places, hybrid systems are used (heat pump plus natural gas/propane boiler) - heat pump delivers most of the heat, the gas-fired part kicks in only when higher temperatures needed. Or electric resistance can 'upgrade' the heat to the needed temperature. It can work and be better financially depending on local conditions/fuel and electricity prices; propane is expensive and your electricity reasonably priced, so possible it would make sense. You'd need someone with experience with these systems though and may not be available locally, up-front cost higher than a propane boiler. I'm probably in a similar climate to Maine, i.e. no A/C requirement and heating can be required in every month of the year (typically little save hot water for the two warmest summer months, but we can get cold nights even in summer). It's only the coldest month (roughly, perhaps 15-30 days) that would require much 'extra' heat. Doesn't make financial sense (for me) because of cheap natural gas - more expensive propane might change the calculation.

I presumed that you have central A/C in the house, you can’t tie into that. The reason is that if a car is left running in the garage the fumes could get pulled back into the house. No idea what a mini-split system costs - depends mostly on size. You will need at least one 220v circuit for whatever you end up doing. 120v just doesn’t provide enough power for any significant level of heat, unless you have a very small garage. There are small “window” A/C units that are 120v but I’m guessing you have at least a two car garage... If budget allows, I’d suggest taking a good look at a mini split system.

Thanks everyone for the ideas above! Very thoughtful. Unfortunately, a lot are non starters because of some unusual features of our old house. I don’t want to sound like I’m being negative by rejecting everything though! First, I appreciate the comments about an old house and inadequate ducting. On further thought, the bedroom isn’t really significantly warmer than the rest of the house.... maybe just a degree or two. So I probably spoke too soon when I complained about it being at the end of a run. The bigger issue is just that son wants it in the 60s to be comfortable, which means blasting two big units all night to cool 2500 sf total, when he’s only using 150 sf of that. So I don’t think the solution is fixing duct lines or insulation. Second, I’d like to avoid any permanent units (like a mini split) because the home is exposed block walls and architecturally significant. I think the architectural society would come with pitchforks and chase me out of town! Ceiling fans are the perfect obvious solution.... except the middle of the ceiling Is where the one vintage air register is, and there is no power running through the ceiling. And even if I were open to moving it, there is no power running through the ceiling and no way to get it there. Because, as mentioned above, the walls are exposed block. Lighting is all from plug in lamps. So we cant run wires through the walls because there’s no drywall. I guess that also means no booster fan in the duct. So given the extremely limited flexibility my vintage house provides, it sounds like my only solution is a free standing unit. Which I kind of assumed! Thanks all!