I'm wondering recommendations for sizing of a tankless gas water heater that will only service the washing machine, dishwasher and kitchen sink. The washing machine is a front loader and the dishwasher is a nice quality Siemens. Although unlikely it's possible the washing machine and dishwasher (or kitchen sink) would be used simultaneously.

I have a Noritz tankless water heater servicing the rest of the house and it's doing a great job so this one is only for the areas listed above.

Thanks!