Aboutjohn t. borgman Expertise I work days, so I can only answer early in the day or later in the evening, I live in Oregon. I have been so good at all the other area's of hvac, I am probably the only hvac guy that does not know oil. ( lol ) I am very well versed in gas, electric and heat pumps and will only answer residential applications. I have been known the past decade or so, by my employers as the guy you send when no one can figure it out. Trouble shooting is my special. I understand the physics behind air flow, refrigerants and electricity. I understand programmable t-stats, zone controls, economizers, fossil fuel kits and the engineering thought process in the wiring and construction of residential equipment
Experience I was lucky enough to start in this field over 25 years ago as an installer, for a company that installed the best duct systems I have ever seen, even to this day. The best ,as far as understanding the way air really flows through a duct system, from the return air to the very last supply register . They also had great pride and the duct work was put in, not only to last 50 years, but to look exceptional. Then as I started doing service work, I was again fortunate that I found a 3 year engineering class being put on be a man that was the educational director for the Entire united states for a society called " the Refrigeration Service Engineering Society " And for the next 3 years I schooled at night and practiced what I learned during the day, a great advantage over schooling and then trying to remember it years later.. Versed in duct design manual J heat gain/loss calculations. Also experience in wine rooms and indoor swimming pool hvac & humidity controls
Publications I have 2 inventions that have gone through the process and been recorded at the National Institute of Standards and Technology from start to finish and thus been invited to national innovation workshops by the dept. of Commerce and the dept. of Energy. They are waste heat recovery devices that N.I.S.T approved as valid and am currently looking for marketing partners to get this product into the hands of consumers and make a BIG difference in Energy savings for every Household and Eatery and take a big bite in the the peak hours power consumption that face our Utilities companies.
Education/Credentials factory training in Lennox ,Rheem, Ruud ,Trane, Tempstar ,Carrier, Day&Night, Payne, Bryant, Coleman, Intertherm, Ultra boilers, Unico, Mitsubishi,Sanyo, Taylor, Nicewonger, . Associates degree in Refrigeration Engineering. Certified with Energy Department, Check-me Program, have N.A.T.E. certifications in gas, a/c & heat pump. Teach and apprentice at every company I work at.
Question QUESTION: I'm replacing my 15 yr old 4 ton heat pump system. My current system has the air-handler in the attic and all the vents (29 of them) running from the attic throughout my two story 2,500 sqft home with a vaulted ceiling in my large living room. I do have one of the two returns in the crawl space. I've had problems with heating/cooling parts of my home probably due to too many ducts for this size system and one thermostat on the main floor. I live in central Virginia where it gets very humid and I've also had problems with humidity & mold (which I've mostly remediated) in my crawl space. I also have a musty smell sometimes in my house.
A company has proposed replacing this system with two heat pump systems (2&1/2 ton & 2 ton). They want to put one of the systems completely in my crawl space, air-handler, return, & vents. I'm hesitant to put a system in the crawl space, what do you think? Is it necessary to have vents in the floor (1st floor) to properly balance the HVAC in a two story house? I like the plan for two units, but could it work with most of the existing vents in the ceiling of the 1st floor? Also is ~$13K reasonable for this work?
ANSWER: Dean,
I have never encountered a duct system like that. The 1600 cfm from the air handler doesn't go far with 29? vents. That's like 50 cfm per...wow that's low. Two is the way to go, but if at all possible ( both for the equipment and for the techs in the future ) I would take that space where the return goes down to the crawl for my lower air handler and separate all the lower supply vents into one and use them as multiple returns, tied into the top of a down flow air handler and then yes, a duct system under the home.
Now,...All the money in the world in equipment is wasted if the duct system is not correct. So, do yourself a favor and put a few dollars more into this. Every room in your home has a mathematical number that equates to bth/per hour heat gain/loss. This is figured by manual J, something you should have done first. Then the duct system is installed in such a way as to supply the exact amount of cfm to each room to match the btu heat/loss.
The supply should be one continuous trunk line that goes in a straight line down the middle 3/4 of the length of the home, with branches coming off, for each vent and very important, 18 to 24 inches past that, the trunk line reduces by the exact amount of square inches of that run. This gives you a self balancing system with proper air flow to each room. The size of run is figured by the cfm required to match the gain/loss at .1 static pressure
If the company you are working with cannot do this, the local power company should know who can, and insist on a drawing showing the runs, compared to the requirements and you will have the type of duct system that should be in every home ( both floors ).
The Manual J will be a cost, but minimal. And the duct system put in this way wont cost any more than what they were going to do in the first place, except in the attic they will have to remove most of the main line and redo it. This arrangement will better control both temperature and humidity.
As far as the total, it also depends on if you are buying some of the last R22 units ( phased out in 1/1/2010 ) or the new R410a with much higher efficiencies
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QUESTION: Just curious what you think of trying to keep both of the air-handlers in the attic verses putting one in the crawl space? I'm very leery of putting anything in the crawl space. Does it make a lot of difference in the heating & cooling efficiencies if all vents on 1st floor are in the ceiling instead of the floor? As explained by the company, seems logical that the downstairs unit would do most of the heating in winter & upstairs unit would do most of the cooling in the summer and having vents in the downstairs floor does it most efficiently.
Answer Sorry if I didn't make myself clear Dean, I said to put the one air handler in the space in the house that the duct is going down to the crawl, not in the crawl. And then the lower unit would add a duct system in the floor and you would use the existing ceiling vents on the first floor as multiple returns all coming together at the top of the first floor air handler which is in the space on the first or second floor where the return duct goes down now for your existing return. That would give you a great system.
The ultimate system has a return and supply in every room, but no one wants to spend that kind of money. That way when doors are closed the room still gets full air flow.
