My concern also is that if it fails, I don't have a clue how to work on the controls.
Gosh darn it, then you go to a class and learn!!
I've been to several classes on the Rheem unit
Well, being a Rheem, that was your first mistake LOL Sorry Ken, never a fan of Rheem on their separate hydronic side.
I went to a class and became certified to install my own
Thanks Brent, you've just given me a reason not to sell the brand you bought lol
There are other draw backs like, longer wait for hot water initially, you have to open the hot water faucet and leave it running, you can't let the water trickle, if you turn it on and off, you get cold, hot, cold, hot.
Ummm, and what water heater won't you have the problem with? Personally, if it's an extremely long run to the farthest outlet, I'd put a pump in with motion detector.
To the OP, being that you're on LP, it's a **** if you, **** if you don't trying to save money. As mentioned, because you have endless hot water, chances will increase that you will use more hot water than you have before, thus you will burn more gas.
As mentioned, the biggest issue on these units for people out in the "country" is the condition of the water. If you're on a well, almost a promise that you will need to clean the heat exchanger out at least once a year. A pain, but you vinegar usually does the trick.
Now, for what it's worth, I have a 75 gal LP direct vent sitting in the basement that has been there since the house was built in 1988, and I haven't changed it out yet LOL
Just make sure you look at the temp rise rating on the unit compared to the flow rate. Too many people go off of only the flow rate and end up getting in trouble.