Need Recs for - On Demand Heat and Hot Water System All-in-One

[Indio]

After 8 years, of many maintenance calls and parts replacement, my natural gas Triangle Tube on demand, hot water tank eroded and rusty water, from a 12 gal tank, leaked. I had a service call to fix a CO recall on the venting for the unit and the company that looked at it said they have never seen a unit look this bad. I've had so many repair issues with it that the plumber or gas boiler company visited annually to replace pressure valves, venturi fan, etc. I asked the CO repair company to turn off the gas/water line and completely drain the tank while I figure out my options.

After speaking to the TT warranty manager, decided to look at full replacement options. Looked at installing point of use electric hot water for shower only, but electricity prices here are some of the highest in the country .18 kwh, even with arbitraging supplier/delivery service rates, and going up. Looked at outdoor tankless water systems but I live where winters can be below freezing for consecutive weeks. Geothermal and solar supplementation for electric system is out of my price range.

Basically now I'm looking for an on demand, energy star rated, energy efficient system for heat and hot water for 2 bathroom house about 1300 sq ft. Backup generator is only other appliance that uses natural gas, not stove or dryer. Fully aware that all heating hot water units need annual maintenance. I don't want to over spec the systems because I may be moving within next five years, but realize that I may be at the whims of the current supply chain issues.

Any suggestions of combi boiler systems that you've had for a few years and are happy with performance?

[KarefulKactus15]

It's crazy how common stuff in one area is so uncommon in others.

I have no recommendations. Just marveling that systems like that are the norm some places. 

I can comment on converting to electric, I don't see that working out financially ever.  The amount of wiring change change to match what a 200k btu gas system can do is pretty intense and the price moreso.   New breaker box of probably 2x size, and the power company may not even be able to support it.     I had a house on that same scenario. To update the breaker box required a new transformer for that tap, but that transformer couldn't be upgraded without upgrading the transformer that did the whole subdivision...etc etc... You see where this goes.  A 220v on demand hot water heater would have cost $17,000 by the time the electric service was set right.

Hopefully someone has some good suggestions.  A nice new system with a warranty and less breakdowns will be a nice upgrade for you.

[Indio]

Thanks for the input @Kroaler .

Fortunately, I upgraded the house electrical system and panel 20 years ago. When the generator was added and the automatic transfer switch installed, it was refined further prioritizing specific appliances and outlets. The existing electric panel can definitely handle a new heating system but I'm not sure which manufacturer to go with.