Open to any agencies and willing to pay heat as part of the deal. 

If this doesn't fix it then there is probably one of the heating elements out.If that doesn't fix it easily then I would send PM and owner a letter and tell them they have 14 days to cure or you will call a plumber that advertises on TV (They will be expensive) and take it of the rent. 

I buy houses in Columbia Heights - Petworth area with as many bedrooms as possible (I'll turn a living room, a dining room with an egress window, basement rec room, a heated porch, etc. into bedrooms as well.) and rent by the room.  

UmañaR&R heating & cooling was great when I had used him before.

It has central heat and air, has a metal roof, an unfinished basement that has potential to add a lot of value to the home, etc.

The heat could be put on Home Depot and perhaps you'll be able to return the dishwasher despite Home Depot claiming you breached the two day delivery return date. 

Currently, it is just an open space that I plan to heat, cool, floor, drywall, insolate, and insert piping to make it a 1 bed 1 bath studio.

Currently it is a steam boiler system that heats the entire building.

For an apartment building I bought I wanted to put in heat and air for each apartment rather than every 2 units share one HVAC unit (and I get the electric bill). 

I see it all the time where people will advertise an apartment for rent with heat and hot water included in price, but not mentioned in the description of the listing.