Central gas furnaces come too large for an apartment of your size. Most start at 40k btu/hr input (38k output), enough for small house, some may be available in as low as 25-30k.

Safe to say, even if your 55k wall heater is only 70% efficient once warmed up, it's oversized -> not efficient due to cycling on and off a lot.

When deciding what fuel to use, look at electricity vs gas costs, heatpump efficiency, climate, installed cost, cost of having a gas meter. Operating costs can be calculated and compared directly.

I would put new, smaller gas wall heater if you want to stay with gas, otherwise look into a ductless mini-split heatpump system.



A load calculation will be required to size either way*. For mini-split, you size it for worst case heating and it runs at a lower speed for cooling and mild weather heating. They have variable speed compressors and the best ones not only vary capacity to meet the load, but can maintain full capacity down to 0F or below.

They heat much better than most conventional central heatpumps which lose a lot of capacity as it get colder outside.

*Likely looking at 12 to 18 000 btu/hr, with two heads if it has a separate bedroom.

 

It depends on your fuel/electrical costs.


Electricity is cheap enough in my part of the world so that I went with a heat pump instead of gas (used to run on resistive electric heat, then gas, now heat pump) and my cost to operate has been about the same price as a mid efficiency gas furnace. You're in New Jersey which I don't think even goes below 0(?) so the payoff may even be bigger with a heat pump. Your unit is small enough so that a mini split system would work which means no duct work to run.

 

Would like to hear pro/con of heat pump vs a high efficiency gas furnace.

If you have gas available USE IT. That's it.
Same for dryer and water heater and stove.


If you ALSO need to provide air conditioning... do so.

 

ignorant heatpump bashing with nothing to back it up. if u have nothing to add, why bother?

if you think gas is a better choice, ask for utility cost and climate data relevant to the op's case and use it to make your own determination.


every application will be different. It often doesn't make sense to pay for a gas meter for a small heating load when you can get a mini-split running at 200 to 300%+ efficiency most of the time and putting out full heating capacity down to 0F or lower.

they'll often charge $20 to $30 a month just for a gas meter.

the only real choices btw for gas heat are 60% seasonal efficiency wall heaters or a super expensive water heater feeding rads or small high velocity hydro-air handler.

The smallest furnaces and boilers are way too large for a 600 sq ft apartment. and also many high performance homes. think very short cycles.

 

For a small heating load, heatpumps are better especially the mini-splits that do a good job of maintaining capacity in the cold and the heat can be similar cost. i would only go for gas for an application like this if electricity is prohibitively expensive.

The efficiency is comparable with gas even at 30 to 40% power plant efficiency as long as minimal resistance heat is used If all of the power is from hydro, the heat is effectively renewable.