I found a used gas heater, Jandy Laars Lite 2 - for under $200, and without wasting words, I feel fairly confident it is functioning. My heater is about to Crud the bed- over 15 years old, lots of nasty noises, etc. So, I'm thinking of this Jandy - my pool is 28k gallons in ground, in Denver Colorado - I guess avg. air temp during months I'd be heating to be at 60 - from what charts I can find, I need maybe 150k btu. Is this 250k btu going to cause issues if its too big, or does it only use what it needs? I stumbled across someone saying that you buy as big as you can afford - but I can stumble across anything on the internet if I try hard enough. Any advice is appreciated - I do understand that used heater = big risk, but $150 I can risk, new heater at 1-3k - ouch. Thanks in advance