Had a pool put in about 2.5 yrs ago. Builder put in a Laars LT400 heater for pool/spa. At the time, I figured this was a good heater having had an older Teledyne heater heating a spa only at another house I owned with no issues. Have consistently had problems with the spa heating to full temp. Have been back and forth with the pool company and gas utility who each blame each other, but I have been told my problem is due to the "safety" design of the heater requiring at least 5 water columns of gas pressure to the heater. Have had it measured a few times and we are getting over 5 water columns until the heater jets kick on, then it dips just below 5. Seems the computer in the heater then gets freaked and shuts the heater off causing only a partial heat of the spa. Wierd thing is that this happens most, but not all, of the time. Sometimes it fires right up to a toasty 103-104 degrees water temp, other times, kicks off at 98. Tonight it go to 101, then settled at 99.

Based on conversations with my pool guy, I really don't think it is a malfunction of the heater itself, but a problem due to the "safety" features deigned into the unit

That all being said, I am looking into a replacement heater due to our gas pressure issue and looking for recommendations. We use an Aqualogic PS-8 control system with salt cell, Jandy 60 sq ft DE filter and Jandy Pro Stealth pump and valves.

Thanks
Geep