Used heater? is too much btu bad?


Jun 5, 2015
Littleton, CO
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


LifeTime Supporter
Aug 19, 2014
Pacific NW
250k btu for your pool is medium to smaller sized I'd say. 400k would be more like the max size.

I used to have a Jandy Laars Lite2. The main issue you will have is finding parts to keep it running.
The membrane keypad was going out on mine. Ebay had one but they wanted $ 300 for it.
If yours has a leaking heat exchanger, expect to pay somewhere around 800-900 more to replace it.

If the bottom of it is rusted out, it's a fire hazard and not worth the risk.

Pool Clown

In The Industry
Sep 5, 2008
Silicon Valley, CA
The heater you want to put in is almost twice the size of the current one. The new heater is going to need quite a bit more gas than the old one did.

Is a 250K btu heater too small for 28K gal pool? Probably, but that isn't the issue here. Your issue is gas delivery or supply. You need to confirm that the new heater will have enough gas VOLUME supplied to it. If the current gas line (from the gas meter to the pool heater) is too small in diameter, or has an extended (more than 150') run, you need to take that into consideration.

The owners manual should include a gas piping schedule showing how far you can run a certain size diameter pipe to satisfy the demands of a certain size (BTU) heater. Starving the heater for fuel in non forced air heaters will probably not give you any symptoms right away. Long term problems may cause sooting and in turn running hot.