Are you going to pay the 20K to upgrade your service from the pole, plus a larger capacity panel or sub panel. Electric tankless in your location will need 160 amps, and be limited to 1-2 fixtures at a time, due to low incoming groundwater temperature in the winter. Gas is the only real option, and you may need to upsize the gas service to run the wateer and heat. Never give up your gas heat for electric either. Never. It’s more expenive and is subject to power grid issues. In fact, add gas logs for potential winter storm outages.

Is this townhouse a 100+ year old brownstone with 10+ foot ceilings? Are you planning to upgrade the insulation and windows to modern day standards? Old houses in NYC have high heating and cooling loads. Your tenants are not going to be happy when they see their heating electric bill.

How is the house currently heated? Is it a one or two pipe steam system or hot water? Are you planning to keep the old radiators? If so what is your plan for cooling?

I am not an HVAC professional, but I have never heard of a tankless heating system. Can you provide a manufacturer and model number?

I think KT is talking about a tankless electric water heater. Which is logical, since you don' t use tankless boilers to heat with radiators. And you don't get rid of gas boilers, ever. None of that post makes any sense in the real world. Yes, to do this nonsensical electric conversion thing would likely require an Electrical revamp. That would be an industrial 3 phase electrical tap for the building, since it is multi family. That's way way more than pulling a new service from the pole. You already crossed the 100K line before breakfast. Most old buildings have 60 amp services, and can't even run a hair dryer and a coffee pot at the same time. Which is why they use gas heat and cooking.

Someone is about to ruin their tenant’s lives, lose sll tgrir money, and end up with a halfass halfdone house.

New York City has passed a law banning heating using fossil fuels for new construction of new buildings 7 stories or less starting in 2026. If the original poster wants to do a renovation and install an all electric HVAC then heat pumps would make the most sense. If it were my 2 family townhome I would be investigating high efficiency gas boilers. I think old brownstones should retain the charm of their ornate radiators to go with their high ceiling and elaborate moldings.

For cooling their are thousands of old homes in NYC with mini splits bolted to the side of their masonry exteriors. It is not a pretty sight. For a total renovation it may be possible to run the required duct work for a central AC system.