Hey, y'all. First, let me say I appreciate this forum so much. While this is my first post, I've read so many posts that have helped me along the way...
Here is a short version (OK... it is till long) of my situation, and I'm hoping you all can help:
I just bought a home two weeks ago that has a 33k gallon gunite pool with spa. This is the first pool or spa that I have ever owned. I'll do my best to give the details... One 2hp pump runs both the pool and spa. I have an Aqualite Goldline control system and I can switch between pool and spa mode. The heater is an 8 year old Jandy Lite 2 LD400P. All plumbing is standard 1.5" PVC. Two waterfalls are ran by a separate 2hp pump.
I'm sure there are a million other details that could be helpful, and if I knew them I'd tell you!
So, to make a LONG story shorter, the pool was neglected for quite some time. When I moved in I couldn't see the bottom and there were frog eggs on top, if that gives you an idea. The bottom was full of leaves and dirt. It was like a pond...literally. The pool, though, is beautiful so I got to work. I'm semi-handy, but not pool savvy. I had to replace all of the electronics... the control motherboard, the display and control unit, the salt cell, and the ignition control module on the heater. I bought a Dolphin M400 robotic cleaner and he and I got to work... The place is gorgeous now and the water is crystal clear. PH is right around 7.3 and everything seems to be great.
Except the spa...
I know the heater is old, but I've had it working great. I used it for the first time yesterday (that's when the ignition control came in and I could finally do that work...) I ran the spa for just a bit and got it up to about 95 to make sure everything was working, and then it was time for bed. Today, I wanted to run it for a while to make sure all was well so I heated the pool for a bit. In about 3 hours it took the pool up about 5 degrees, which seemed reasonable to me. All seemed well.
Tonight, I decided I'd like to finally break in this hot tub. The heater ran great until the spa hit about 98 degrees... or about 10 minutes in... whichever variable you want to consider important. At that time, it began to "clang." I had read that could be a water flow issue, so I cut it off. I've checked everything I know to check and all looks well. The "chimney" (I'm sure there is a proper term for that) is clear and exhaust seems to be flowing nicely. Water pressure at all of the jets is excellent. The filter is clean and was backwashed yesterday.
The difference in yesterday and today has to do with the blower motor. Yesterday I cut the blower motor on as soon as I cut the pool heater on. Today I didn't have the blower motor running when I got the terrible clanging. I was going to turn it on after I got to the desired temperature setting, which was 100 degrees.
I'm wondering, does the blower motor need to run from the beginning of the heating cycle? If it is off, is it restricting water flow and overheating the exchanger?
I know the answer could also be scale buildup in the heat exchanger, along with a million other things associated with an old heater, and that it may be time to buy a new heater. I can live with that... I bought this house knowing I'd have to spend some money, but that it'd be worth it.
Before I bust out a few thousand bucks for a heater, though, I thought I'd turn to you smart folks...
Sorry for the longwinded first post! Thanks for the help!