HVAC options - two installers, different approaches

11 years ago

We are looking at getting a new HVAC system. We currently have a 10 SEER Carrier system that is roughly 10 years old. Ever since we have lived in the house (6 years) we have lived with a problem of air flow on the third floor (three story townhouse). When it gets warm in the summer (90+ degrees) we can't get the third floor to 77 degrees, at that point the AC runs constantly during the day. We have lived with it in the past, but now have a 7.5 year old and really want to regulate the temperature better on the third floor. Really, though, none of our vents (even the one coming right off the current air handler) would blow your hair back.

Our home is not open concept, the top and bottom floors have about 4 rooms each, and the second floor has three. By exterior dimension the home is about 2300 hundred square feet. (a little over 700 per floor).

We have talked with two different HVAC companies about the issue. The first suggested a Carrier Infinity 15 SEER system with a 3 ton variable speed air handler. He also talked about installing some directors in the vents to see if we could get some better flow on the third floor.

The second company suggested a 17 SEER Lennox system (he has some rebates right now that make it he same price as a 15 SEER, and the price is the same as the first installer) but recommended a 3.5 ton variable speed air handler to see if we could get better air flow that way. He also recommended trying (with a piece of cardboard at first) blocking the return on the first floor to see if that would help pull more air out the third floor return and better flow (if that worked he recommended partially sealing part of the 2nd floor return so that the third floor return would pull in more air). He said he recommended the 3.5 ton because of the number of registers we had (20).

So we called the first company back to ask for a quote on a 3.5 ton air handler, and he told he wouldn't do it, because it would cause back flow to the compressor that would shorten its lifetime and was a bad idea.

So the question is what should we do? I am no HVAC expert but I'm not sure who to believe here and would like some other opinions.

Thanks!

Matt

Comments (6)

tigerdunes
11 years ago
Matt

What is your location?

This is a HP system?

What size is existing system?

Air handler is located in attic?

Where are vents located both supply vents and return vents? You have a return vent on each floor?

Ok, here are my thoughts and you probably won't like it. It is near impossible to balance air flow for a three story townhouse that operates off one system and does not have zoning controls. Oh you can make modest improvements but comfort will still be lacking.

You need a thorough review of your ductwork system-size, insulation properties,adequate return. Does it ave damper control on the trunk lines to each floor? If not, can they be added? How are the insulation properties of the attic? Good windows on the third floor?

I personally think very little of the suggestions from both dealers. Has anyone suggested a separate small system for the third floor?

Your problem is quite typical and unfortunately can be very difficult and sometimes expensive to solve.

Post back.

IMO
mike_home
11 years ago
I would be suspect of any HVAC contractor who tries to fix an air flow problem by blocking return vents.

In your situation the SEER rating has no bearing on the problem. Don't get hung up on 15 vs 17 SEER. If you have duct work problems you will not see any gain in efficiency even compared to your old system.
Related Discussions
Best HVAC option for a small duplex? One system or two?
Q
Comments (10)
for that size i would just buy 2 240V window shakers and put them in. the problem you run into when the control is in the other person's hands is it is never the right temp. 2 of our previous offices had the Tstat in another companies office and they always either froze us out or burnt us up. we literally kept the front door propped open 75% of the time! honestly you should have this duplex setup with seperate utilities per side. this way YOU don't get stuck for a monthly bill if someone skips out on you. my wife's grandmother rents out several trailers on the cheap. she has all the utilities in her name so they never have to wait to get turned on. problem is tha ta few times a year folks will up and move and never pay the high electric or water bill they owe. i know you are trying to get some good recurring income, but you need to protect yourself by spending a little up front so it don't cost you a lot later.
...See More
Extreme Price Difference on 'same' HVAC System
Q
Comments (12)
Thanks again. I feel we fall somewhere in the middle of your two descriptions. Our design was created with Southern exposure, solar gain, ample overhang, high efficiency, quality construction, etc. in mind. Architecture and aesthetics undoubtedly played a major role. I don't think we will be LEED certified but it is not your average house. That being said, we did not begin with our expected monthly utility bill as the basis for design. I think we have been reasonably responsible with our design choices thus far. Hence the Geo system. I, not knowing the trade inside and out, am just trying to get the most comfort (and pleasure) out of our system. I think that the higher end system will, without a doubt, provide the level I expect. What I am trying to glean is the sacrifices we would make if we spend less. I realize that the desuper heater and boiler will provide more consistent heat in the basement and that it will also be a more efficient back up/supplemental heat on the very cold days. The question becomes how much less comfortable will the basement be? How many days a year will we need the supplemental heat and is it worth the extra expense. How much better is an Infinity Carrier air handler than the Trane air handler? Will it be noticeably better? I need someone who knows to help me answer these questions. We are not against spending the money if the differences are going to be compromises we regret but we don't know how to figure that out before hand...
...See More
HVAC: House Design - HVAC input please
Q
Comments (6)
I suggest separate systems for the first and second floor. That is the best way to have even temperatures on each floor. It costs more up front, but you potentially have lower operating costs. You could zone the loft off the second floor system. However if you are going to be working 10 hours days with multiple pieces of equipment generating heat then spend the money on a mini split.
...See More
Have you switched from traditional HVAC to Geothermal HVAC?
Q
Comments (19)
I'm disappointed that what had at first seemed a very balanced comment was followed by what seems to be misinformation and misdirection. People buy ground source heat pump equipment because they want to and can afford it. Or decide they need to in their locations. They're hugely more expensive than alternatives, which is why they're still not very common. "When’s the payback on a Tesla? People still choose to buy them for reasons other than the ‘bottom line’." Not a comparable. A false analogy. "I would not choose natural gas or propane for reasons relating to the environment, safety, IAQ & paying for yet another utility hookup for an energy source that might not even be used for months on end during the year." What effect having a gas furnace has on indoor air quality. Another hookup? Most people prefer gas cooking appliances and besides, the OP is talking about an existing home, he either has gas service or he doesn't. "Rather than spending perhaps tens of thousands of dollars on a Solar Array, I would sooner invest that same money, hopefully less, in a ground loop for a Geothermal system." Sure you would, that's the business you're in. The ground source heat pump market is not growing as expected by those in the industry, which suggests that your opinion isn't widely held or easily sellable. In many parts of the country, solar panels can have a quick payback. Not so ground source heat pumps. "I often hear about Solar Panels when geothermal is mentioned, as an alternative way to save money by creating energy." In a place like Texas, where electricity is cheap (other than during cold weather crises as they just experienced) there's likely no payback from a solar panel installation. People do it as a personal statement, call it for environmental or other personal reasons. Like buying the Tesla, not a financial decision. An HVAC system blows warm air when it's cold, cool air when it's hot. It's one of those things people don't care about - either it works or it doesn't work. Spending extra money for an exotic system doesn't equate to extra payback when the home is sold. Neither owners, nor visitors, nor people passing by, nor anyone else, concern themselves with what's doing the work. It's equipment that doesn't produce an experience for someone in the house if it's working. In the US, there are vast areas where electricity is cheap. It will remain so for some time. People don't spend money today to potentially save money 10 years out when market conditions may or may be different. I suspect you could build a house with mahogany or teak framing. Or you could paint the framing bright colors. Why bother, you can spend less money and effort and get something else that will do the same job. "We almost never use setbacks at our home - even when going on vacation for weeks on end with no one home, our geothermal just runs." You're combining two different things to produce confusion. Thermostats that have a setback feature ALL are set up to provide lower overnight temperatures to have more comfortable sleeping conditions and then a recovery in the morning before wakeup time. As sleep specialists recommend. That in demand comfort features isn't possible with ground source heat pumps because the warm up period from a setback is too slow to be convenient to use, absent triggering a secondary heating source (like a furnace) to help. THAT'S why you don't "believe" in setbacks with a heat pump - they don't work. Turning down a thermostat during heating season when the home will be unoccupied is not a "setback" as that word is most commonly used. It's done to save money, why heat a vacant house? No setback thermostat is needed, even a dumb 50 year old analog thermostat can be turned down.
...See More
weedmeister
11 years ago
TD is correct. This is very typical of a townhouse.

Any chance you could put a small window unit in upstairs? Or a mini-split?
mattshwink
Original Author
11 years ago
I live in Alexandria, VA, just south of Washington DC.

The current system is a 10 SEER Carrier HP (3 ton) and the air handler is located in the utility room in the basement. There is a return on each floor (one in the bottom of the air handler, one in middle of the middle floor (hallway) and one at the top of the stairwell outside the master bedroom. No dampers on the lines, attic insulation is good, but probably could be improved.

No one has recommended window units.

How do I find someone who will do a ductwork review? I contacted four reputable (well reviewed companies) and none mentioned this. I did reach out to someone this morning and got a reply that they were looking at my inquiry, but nothing in 12 hours. It seems people that do duct reviews/analysis are few and far between.

If I went with a system on the 3rd floor, how would that work? I have approximately 730 sq feet of space, divided into a master on one side and two smaller bedrooms on the other (separated by a hallway with the split foyer stairwell in the middle. There is a bathroom in the master and in the hall by the other bedrooms.
mike_home
11 years ago
A good HVAC contractor will do a load calculation to size the equipment, and measure and inspect the duct work. If they are not doing that, then they are not very reputable in my opinion.

Do any of your neighbors have a similar townhouse? It would be interesting if they are facing the same issues and have tried to solve the problem.

Is there an internal chase which could be used to run a duct up to the third floor or attic? A duct could also be hidden inside a closet or you could make a chase in the corner of a room. If this is not viable, then adding a separate HVAC unit for the third floor is the only effective solution. You could install a unit in the attic with duct work to each room. I think a mini-split could work, but it may not be as effective for air flow movement throughout three rooms.
Johnquigs
11 years ago
Matt,

I was wondering if you ever found a solution to your HVAC problem. I also have a three story townhome in Alexandria and this past week has been brutal. My HVAC system runs non-stop throughout the day until halfway into the night. My first floor is cool, second floor mild, and third floor barely comfortable.

I have partially closed the vents on the first floor, got all new windows, and had insulation blown into the attic. My HOA will not let me put an attic fan in my unit which would probably alleviate at least some of the problem...

HVAC options - two installers, different approaches

Comments (6)

tigerdunes

mike_home

Related Discussions

weedmeister

mattshwink
Original Author

mike_home

Johnquigs

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

HVAC options - two installers, different approaches

Comments (6)

tigerdunes

mike_home

Related Discussions

weedmeister

mattshwinkOriginal Author

mike_home

Johnquigs

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

mattshwink
Original Author