HVAC System Design

Not a problem getting equipment to the roof. It’s done all the time by crane assembled on site. That’s where mine is – and lots of neighbors I can see. I would never put heating equipment on the roof. The last thing you want in the middle of winter is have heat equipemnt failure that needs service and have the equipment on the roof buried under snow or open to cold rain or just cold/wind.

snowman2

in Heating and Cooling 9 years and 3 months ago

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petec | 9 years and 3 months ago

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Looking for people’s advice on the following situation. I have a 2 family (2 duplexes, plus basement) in Clinton Hill. Currently have central air split systems for each unit. Both compressors are in the backyard. The furnaces and blowers are in closets in each unit. The systems are from 2006/7 and although they get the job done, they are an off-brand, very loud, and poorly designed (one of blowers leaks water when cooling, one of the drainage lines is ductaped to the sewer line, air intake locations are terrible and make it very difficult to use intake filter properly, etc etc). Our backyard is very small (20×16), so I would like to move the compressors to the roof. I would also like to explore getting the furnaces out of our living spaces. One option would be to put the furnace for the lower unit in the basement, and then install a hybrid gas pack system for the upper unit on the roof. Anyone think this is a poor idea for any reason? Any systems I should look at specifically? Another potential option would be to install a mini split system, but given that the ductwork is already installed, I’m not sure what the advantages are here, except that the compressors are a lot smaller. I could also just move the compressors to the roof while keeping the furnace locations in the closets, though I would prefer to free up some space. Thanks for your input, auggieb

petec | 9 years and 3 months ago

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I should also add: i am inclined to replace the old equipment with a completely new system; i would be getting rid of the old units.

randolph | 9 years and 3 months ago

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replace the whole thing with a newer Mitsubishi split system that can do heating and cooling, then no need for the gas furnaces. take a look at this recent thread http://brownstoner.staging.wpengine.com/forums/topic/mitsubishi-h2i-heat-pump-does-the-job-in-brooklyn/

petec | 9 years and 3 months ago

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Using a Mitsubishi system is one idea. I do not want to mount anything on the walls, so I would have to place all the units in closets and hook them up to the exiting duct work. Is that possible (using this system with pre-existing duct work?) I am also unconvinced that the mitsubishi is going to cut it for heat. That post leads with the owner saying his new system is like getting into a lukewarm bath, and we hanvt had any really cold days yet. My house is not particularly well insulated; it’s over 100 years old.

randolph | 9 years and 3 months ago

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i don’t know about existing ductwork, but regarding if they can cut it or not sounds to me like insulation is the key- if your house is drafty you may have issues.

kenzdesigns | 9 years and 3 months ago

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Mitsubishi is my vote. You can replace your furnaces and air handlers with a mitsubishi closet unit that feeds right into your existing ductwork, it’s slightly less efficient than unsightly wall units but not that big of a deal. Equipment (indoor and outdoor) is almost silent compared to a regular AC system. Getting enough heat is just a matter of having big enough units to meet your heat loss needs, a mechanical engineer should be able to help you estimate how many BTUs you’ll need to size for.

brucef | 9 years and 3 months ago

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On the topic of roof mounting. New ironwork would need to span from noncombustible (masonry) walls. Flat roofs can sometimes bridge a corner on diagonal, but oftentimes steel beams must cross entire width of building. getting these beams up oftentimes takes a crane. Also condensers often are too big to carry up stairs. Just sayin.