New HVAC system bid

FlumoxedMay 2, 2012

We recently added another bedroom to our house by putting a floor/ceiling across a great room that previously was open the full two stories. We also have a space off the master bedroom that is over the garage that is always too hot in the summer.

We currently are on a single hp system and I was thinking of adding a mini split system that could handle multiple heads, placing one in the new room and one in the area over the garage.

I had several people out to quote on doing that, though they all said our current system was sized properly to handle the new room and thought some duct changes could be made to resolve the area over the garage.

I agreed to let them quote on multiple solutions, even considering replacing my entire current unit. (only about 6 years old) mainly because they all said that not only would my monthly bills increase if we went the mini route, but also the main unit would likely not run enough to remove the humidity from the rest of the house. (these two stmts seem incompatible to me though, if the main unit ran less, wouldnt the bill have a chance of being less?)

So I only have quotes from one of the vendors at the moment, but they came up with 4 different options with a price swing of $5,000 from the lowest to the highest. Half of that price jump seems to be coming from the change in the humidifiers.

Common to all options are:

EWC Zoning System BMPLUS3000 Zoning System w/2 FocusPro stats

2-3 zones

2 stage heat/ 2 stage cool

3 dampers, one by-pass

Option 1:

Amana ASZ16 w/o coil 5 ton

Amana AEPF VarSpeed AHU 5 ton R-22/R-410a

Aprilaire 600 Humidifier

Option 2:

Trane XL16i w/o coil 5 ton

Trane Hi Eff AHU Var Sp Comm (4TEE3C08A1000A)

Aprilaire 600A Humidifier w/outdoor temp sensor

Option 3:

York Affinity HP w/coil 5T, 16S (YZH-06011C)

ADP Coil AD-58P245UD1

TXV 1 TVM4F1

True Stream 12 gal humidifier w/ECO Pure EP 6130

Option 4:

Trane XL20i Heatpump w/o coil

Trane Hi Eff AHU Var Sp Comm (4TEE3C08A1000A)

True Stream 12 gal humidifier w/ECO Pure EP 6130

I'm not convinced I need a 5 ton, as when I asked they said they factored in enough to cover what is currently an unfinished basement.

I guess I'm asking for thoughts on the 4 base units and what other questions I should be asking. I should have competing offers in the next few days.

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ionized_gw

Cutting off part of the house could indeed make your current system oversized. Otherwise, I would say that mini splits could be a good solution, but you have to be careful. this is not an addition, but carving up.

Consider fixing your master bedroom space problem by adding better insulation there.

    Bookmark   May 2, 2012 at 9:15PM
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mike_home

What is your location and what size system do you currently have? Does the new bedroom have duct work?

I don't understand why you need to replace your 6 year old heat pump. I would first investigate if your issues can be corrected with modifying the current duct work.

I would be concerned about a contractor who suggests installling a 5 ton unit in order to cover an unfinished basement. Basements rarely have to be cooled, and the heating load is small. Most houses don't have the duct work to support a 5 ton system. You may be creating more problems if you take this route.

    Bookmark   May 3, 2012 at 8:49AM
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Flumoxed

I'm in Kansas City, MO. The new bedroom does not currently have duct work. This bid included adding two ducts as the bedroom also has a small bath. (Though not sure about a return?) The current system is a 5 ton, but it was put in misguided efforts to increase the airflow upstairs to the space over the garage.

I do believe that more insulation and the duct work would allow us to get more life out of our current unit, but my desire to have more control over the temperature upstairs vs downstairs as well as the size of our monthly bills lead to discussions of replacing it. (or mini splits) Most houses in our area have either a system for each floor or one with some kind of zoning. My electric bills in the summer are usually about twice that of my neighbors. We are all electric, so winters are equally bad.

I agree about the basement. It's normally pretty cool and I'd likely put in radiant for heat.

    Bookmark   May 3, 2012 at 9:19AM
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ionized_gw

15 months ago I abandoned my ducts and replaced the system with mini splits. I like the new way, but that is much different from cutting off part of your house from a properly-sized or over-sized system and adding even more capacity in mini splits.

If you were to down-size a central, ducted system and split off some areas and cool them with mini splits, it could work. I considered that with my home. There may be no real advantage to that in your house depending on the details of the construction and condition of your home and duct system.

    Bookmark   May 3, 2012 at 2:44PM
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Flumoxed

It has been confirmed that our duct work can support the 5 tons. Load tests will determine exactly, but several firms have put it in the 4-5 ton range.

Does anyone have any input on the equipment choices from my first post?

    Bookmark   May 4, 2012 at 12:10PM
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