Adding Forced Air Heat to NYC Condo with Central Air

8 years ago

Hello,

We live in a 100-year-old, pre-war building in NYC. Last summer we remodeled the condo and updated the unit's central air conditioning ducting and installed a new thermostat. The central system is cooling only, and is powered by an in-unit air handler attached to a common cooling tower on the building's roof. (Forgive me if I'm getting the terminology incorrect).

Heat is supplied by the building's central boiler that produces steam that travels to two, wall-mounted radiators. These radiators have all the features and issues you would expect: uneven heating, noise, drying the air, unpredictable performance, etc. They are also unattractive and take up space. The steam heat is included in my monthly HOA/maintenance fees, so I don't pay additional costs to operate that.

Question: I would like to remove the radiators as part of Phase II of our remodel, and add a centralized heating source to leverage the new ducting from last summer's Phase I. My question is what type of unit I should be looking at. The air handler/AC unit is 20 years and need of replacement (the previous owner never performed any maintenance on any of the critical systems). I'd like to find a new, quieter more efficient AC unit that can also produce heat. Since its inside the condo, I would presume the heat source would either be electric, or perhaps water-heated from the building's boiler. Seeking suggestions on what to look for.

We also intend to add a steam humidifier and perhaps some advanced air filtering.

Thanks in advance.

Kris

Featured Answer

ionized_gw

8 years ago

Radiators do not dry the air any more than any other heat source. All other things being equal, the only things that affect the final relative humidity are the absolute humidity in the air and the air temperature.

What makes indoor air dry in winter is excessive air exchange with outdoor air. The moisture that is produced by ordinary living (breathing, cooking, bathing and cleaning) leaks out. Poorly designed and installed ducted, forced air, heat can make matters worse by inducing pressure differentials turning the forced air system into a power vent. If you have excessively dry air, put money into air sealing your structure. It will pay off handsomely in summer and winter.

Steam heat radiators that are installed well in a good design and maintained properly can be silent, or nearly so. There is something wrong with your system. I am not saying that you can easily fix it, but there is something wrong.

A competent steam contractor will know how to add a steam heat exchanger to your current cooling duct set-up. High temperature steam is ideal for a relatively compact heat exchanger. The main problems might be how to run the pipes and if there is room for the heat exchanger. You may not be able to move enough air to heat even though you can move enough in the current ducts to cool sufficiently. It may not be practical for those considerations. If cost is no object, you might be able to add radiant heat to the floors via a steam to water heat exchanger with an associated circulator pump and expansion tank.

You may be able to find a contractor on a forum that has a lot of "steam heads" posting. Try heatinghelp.com and terry love.com.

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Comments (7)

mike_home
8 years ago
It is not clear what type of AC you have now. You mention a cooling tower. Is the AC a chilled water system? The answer to that would determine whether a combined heating and cooling system is feasible.

It may be possible to install a heat pump to make use of the new duct system. The location of the heat pump and how it ties into the air handler needs to be investigated.

NYC has some of the highest electric rates in the country. This means you will go from free heating to heating costing hundreds of dollars each year. I may be more practical to buy new good looking steam radiators and the building's association to fix the steam issues.

A steam system can work well if it is serviced by someone who knows what they are doing. It does not have to be noisy, can provide even heat, and actually adds humidity to the house.
Kris Koeller thanked mike_home
Kris Koeller
Original Author
8 years ago
Hi Mike, sorry if I wasn't clear.

You are correct that its a chilled water system run of a shared cooling tower.

I understand the potential for higher cost. From what I learned the state of repairs & maintenance of the steam system has been caught up in HOA politics for years, and while I could certainly get involved and try to bring about a resolution, I'd rather take personal control of my heating situation, even if there's a cost. The HOA dues are not expensive, so I'm not too beat up about missing out on the "free" steam heat.

The other issue is that the layout of the apartment is basically a 1,600 square foot rectangle, with the two radiators at one end of the rectangle, and the master bedroom and master bath at the other end, with a kitchen and living room in between. Thus the heat, even when working well, cooks the occupants of the living room in attempt to warm the back room. Its not feasible to add additional heat in the back, thus the desire to use the ducting that supplies all parts of the house (quite well, I might add).

The other option would be to add electric radiant heat to the flooring when its replaced. I would reckon that's also costly to run, but makes for comfortable heating.

I appreciate your input and time spent on my question.

Cheers,

Kris
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mike_home
8 years ago
I can see how the heat can be uneven in the apartment. There is a good chance there were additional radiators in the apartment which were removed in a previous renovation. It would be interesting to see if other apartments have these radiators and if the piping to your apartment still exists.

I have no experience how you would tie into an air handler that has a chilled water system. My advice would be to bring in some HVAC contractors who have worked on these type of systems. I find that when there is an unusual design problem it is good to get several opinions on how to solve it.

The other option is to install a mini split. It is basically a heat pump that does not use a duct. A cassette is mounted on the inside wall which connects to a small outside unit that sits outside. It can use it for heating and cooling. I am not sure how practical this would be for your building, or if it would be allowed. Mitsubishi and Fujitsu are two of the most popular brands.
Kris Koeller thanked mike_home
Kris Koeller
Original Author
8 years ago
Thanks again. I've engaged a few HVAC specialists, and will report back what I find.

Thanks!
homepro01
8 years ago
I would figure out what is wrong with the current radiators and upgrade the rads. I would love to have radiant heat in my home. I grew up with radiators and the heat is more even and gentle. I prefer them over a ducted heating system.

Good luck!
Kris Koeller thanked homepro01
mike_home
8 years ago
These are good suggestions, but the original poster does not want to get involved with the home owner's association in trying to fix the 100 year old steam plant. He would rather spend the money making his apartment comfortable.

Adding Forced Air Heat to NYC Condo with Central Air

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Kris Koeller
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Adding Forced Air Heat to NYC Condo with Central Air

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Kris KoellerOriginal Author

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