Chillers: What HP to Get?

[Enigma]

I've just been surprised with a one week vacation to Kelowna in August. I am mortified! (Though I tried to hide my horror from hubby)

I figured i would battle out my first summer reefing with fans and bottles of frozen water (to float in the tanks). My 18-year-old son (my critter sitter) can't be asked to do that. I'm going to need a chiller, and everything will be moved into one tank well beforehand.

The new tank is a 40B and the sump/fuge is around 15 gallons. So, I need to plan for +/- 55 gallons.

I have no idea what temperatures to plan for. We live in a 1960's bungalow, with crummy insulation and windows, and no a/c.

The EcoPlus 1/10hp would fit in the stand beside the sump. I don't think the 1/4hp would fit very well.

What kind of temperature spike should I plan for?

[Aquattro]

On that size tank, if you even need a chiller, the smallest you can find will probably work. Depends on whether you turn your house heat on during the summer :)
You could even reverse your lighting period while you're gone, have lights on in the cooler hours at night. But I've used a 1/4hp on a 180, you don't need anything that big.

[Enigma]

Thank you!

Our crummy old house heats up like an oven in the summer. Murphy's Law being what it is, if we get a temp spike it'll be while my eldest is here trying to manage things for that week.

[Enigma]

I got a very fair deal on a JBJ Arctica 1/5hp chiller off of Kijiji. I love it. While it may be overkill size wise, it was such good value that I couldn't pass it up. It is very quiet and is doing a very good job at keeping my tank below 79F.