Space heat for a whole house plus hot water to run up to 3 showers and a dishwasher.
Condensing boiler with on demand water heater.
Proline xe condensing tankless water heater family state s condensing tankless gas water heaters are available in residential and commercial line ranging from 120 000 btu h to 199 000 btu h with options for natural gas and propane.
I think you best option would be to use a small mod con boiler that has a 10 to 1 turn down with an indirect water heater connected to it that has enough storage capacity for the shower.
Condensing water heaters pull heat from the exhaust cooling it to much lower temperatures.
It uses a unique microprocessor electronic control module that automatically adjusts blower speed and gas flow rate to closely match the boiler output for space heating or domestic hot water demand.
Condensing gas tankless water heaters delivers high efficent hot water in the same small box of regular efficent on demand water heaters.
The water that goes through the pipes is heated and then it s ready for use.
The prestige is a 95 afue fully modulating stainless steel wall mounted condensing boiler.
The proline xe combi boiler provides industry leading continuous hot water delivery with its on demand high efficiency design.
All at the same time.
Provides homeowners with an endless supply of hot water energy savings a space saving design and environmental benefits takagi and rinnai offers ease of installation now with more venting options right out of the box.
M series natural gas condensing boiler tankless water heater with 160 000 btu input.
Prestige excellence 110 condensating gas boiler water heater with 86000 99000 btu and 1100000 input modulating.
Also idk of any single on demand water heater that would be able to handle the gpm needed for a car wash type shower.
Superior space heating performance the proline xe combi boiler offers up to 74 more heating capacity than other combination boilers.
All residential models are energy star qualified and utilizes pvc venting.
Indoor residential condensing natural gas combination boiler with 199 900 btu h input modulating.
Navien ncb e and nfc are the ultimate high efficiency condensing combination boilers with the capacities to supply both heat and domestic hot water for larger homes enough.
The heating exchangers for condensing are made of stainless steel which is highly corrosion resistant and has a long service life much energy and wasted gas are saved because of the design.
Tankless water heaters work very simply.
Condensing water heaters are a newer innovation in tankless water heater technology that claims to offer multiple promising benefits that increase efficiency as well as the durability of the heater.