Water Heater Busted...

[Kent88]

No, looking back over it now it does appear that it is a water loop that goes between a heat exchanger in the outdoor unit and the storage tank. Glad you pointed this out to me before I ordered this for myself .

That does seem like a weird way to set it up. Why not have the heat exchanger indoors on top of the tank and run a refrigerant that can't freeze all the way there? I guess I'd know if I was an engineer, or had an engineer explain it to me.

You probably saw the Freeze Protection bullet points. It does reference some kind of freeze protection heater. That seems strange, as the entire unit is a heater that is supposed to work effectively at temperatures as low as -20F. It should be able to sense when the outside temperature is below freezing and just run the system slowly to keep the water moving, which should keep it from freezing. I wonder if there is a backup heater in the outdoor unit for cold snaps where the temperature might be below spec?

Or perhaps -20F is just the threshold for where you'll be able to get the hot water like you want, but perhaps it can still (with an efficiency penalty) pick up heat at lower temperatures without getting the water as hot as you want, but still well above freezing.

 

[IslandLizard]

it does appear that it is a water loop that goes between a heat exchanger in the outdoor unit and the storage tank.

The only reason I can see to use water and not a real refrigerant is to prevent the involvement of an AC contractor during installation who also needs a CO2 setup. Most don't do CO2, R-410A being most common now. Liquid CO2 for refrigerant may well be an industrial niche market, I don't know, I've read/heard about it in the past.

It does reference some kind of freeze protection heater.

Oh yeah, the heat tape instructions...
I switched off at the purging of the closed water loop. Altogether this unit is not a simple installation.

I watched the AC/heating guys install my unit, only to swap the whole (outdoor) compressor unit out for another new one the very next day as the first one seemed to perform below specs.
They also do checkups (scheduled by me) and perform maintenance, they know what they're doing. It's definitely outside any DIY realm.

After 5 years of perfect use, we started to get issues that boiled down to the evaporator coil (it had developed small leaks). Although still covered under the 10-year manufacturer's warranty, it still cost us close to $1000 all in, as all the testing, dye injection, top-up refrigerant, re-installation labor, and whatnot, was not covered "unexpectedly." There was a class action lawsuit about that very evaporator issue, but never found out the skinny on how it ended. In my view that evaporator is some outsourced Chinese manufacture, costing less than $400 shipped to the local warehouse door. I still regret not driving to the hearing in Philly to give them my 25 cents of input. Then again, maybe best not to, I may have ended up in contempt and/or in jail.

 

[Kent88]

Getting off-topic, my parents-in-law only use mini-splits for AC, which works great for the spaces that the units are in, but they made some interesting decisions in placing them. Just two units, one in their bedroom and the other in the living-room/dining-room/kitchen. For those spaces it works great.

I wish they had one with the inverter, because their only other source of heat is in-floor heat that is really slow to respond when the thermostat is adjusted.