Do ducted split units perform??? + contractor recs
We are about to get started renovating a small (1800 sq ft) hundred year-old colonial-style house with 2 floors plus a finished attic. The house has hot water heat with radiators and no a/c.
Our current plan is to replace the radiators on the 1st floor with in-floor radiant heat and to install a whole-house a/c system. After reading this forum for a while, I'm leaning heavily toward installing a split a/c system -- either standard-split or VRV -- using Daikin or Mitsubishi equipment.
I'm wondering if I can get advice on 2 issues:
1. My architect thinks ductless interior units are ugly. Is there a disadvantage to using the ducted or recessed units rather than ductless ones? I've scoured the forum posts but haven't found much discussion about this so I would REALLY appreciate professional opinions on the subject.
2. Could someone recommend a contractor who really knows their stuff and has substantial experience designing and installing this kind of system? We are in Westchester County.
Thanks in advance ...
FWIW, if there's a good company and a physical way to put in a central system, your future life will be less complex and repairs if/when needed will be more straight forward. However, if a mini-split system is the way to go (there are also mini-ducted systems too) then it still needs to begin with proper load analysis of the home.
Originally Posted by overhear
Good questions. I was trying to spare the reader the gory details, but I guess that's not so helpful...
We are doing quite a bit of work on the house, but not quite "gutting" it. We are keeping the original footprint and floor plan in place and will be preserving most of the plaster walls. But we are doing a lot of interior work -- replacing some of the floors and ceilings, installing a new roof, as well as renovating the kitchen and baths.
We are doing enough work to justify installing ducts, but we're leaning toward a split system because we work full-time and don't want to cool the whole house while we're all holed up in one room as we usually are (either sleeping or eating).
I don't mind the look of the indoor ductless units so much, but given that we're making an effort to preserve the historic look of the 1905 house, it would be preferable not to see the units. That's why I'm trying to understand if the ducted or ceiling-recessed units work well. (I thought I read a blog post in which an HVAC contractor implied that recessed units were less efficient, but haven't been able to dig it up again.)
Please correct me if I'm bungling the terminology: I understood that a "mini-split" system used multiple outdoor units whereas "standard-split" and VRF/VRV systems used a single outdoor unit and multiple indoor units. Am I wrong on that?
I don't know which type of split system would be best for our needs. We have a smallish house that's fairly divided up (meaning, not an open plan), so I am guessing that a single outdoor condensing unit would suffice, but I know what I don't know and that's a lot! Aw, now you know I'm female -- what guy would say that??? :-)
LOL. Okay, now I know but I never would have suspected. Anyway, no foul as far as terminology is concerned but it might help you in your discussions regarding your project. So...
A split system, as opposed to a packaged unit, is any system where the indoor and outdoor components are physically separated. Packaged units have all components for processing the air within the 'box' and only the distribution system is external. Packaged units are what you would see as large 'boxes' on commercial and industrial rooftops, should you venture there!
So splits come in 7 different "unitary" sizes, from 1.5-tons (18,000 Btu's) to 5.0-tons (60,000 Btu's). There are 12,000 Btu's in 1-ton of cooling or heat pump capacity. (A heat pump in the vernacular is a "reverse cycle cooling unit", which is a fancy way of saying that in the summer, heat is absorbed by refrigerant indoors and rejected to the atmosphere outdoors, while in winter the heat is absorbed outdoors and rejected indoors. Thus the same unit that cools in the summer can also heat in the winter.
When it comes to wall hung/ceiling/drop-in or similar split systems, they're called mini-split systems due to their normally smaller Btu capacity. When there is more than one indoor unit for only one outdoor unit, it's referred to as a "multi-zone mini-split system". There are many manufacturers of mini-splits just as there are for conventional splits. Mitsubishi with the Mr. Slim line has the lion's share of the market, while Sanyo, Fujitsu, Daikan and a few other names share the rest. Most have similar product options. We represent the Mr. Slim line and they are capable of handling from one to 8 zones on a single outdoor unit, the limitation being total system capacity in Btu's.
So how will you shop? I've attached some documents to help you wade through the multiple opportunities to be disappointed with a system and hopefully to find a well qualified company to assist you with your choices. Since you have an excellent opportunity to have a really good system installed, whether it's a mini or a maxi, careful shopping with some basic knowledge should give a good result. You'll pay for a good company for sure but I think in the long run it will be well worth the investment. If you do a ducted system, consider that a properly done system, absent changes in the home, will last 100-years. If done improperly it'll still last 100-years but whoever occupies the home will the uncomfortable.
Very helpful post, Skippedover. Thanks! I am receiving an error "you do not have permission to access this page" when I try to view the attachments. I have Acrobat installed so it's likely an account setting that's the problem. Looking forward to reading the docs when I get access ...
Originally Posted by overhear
I have an 1889 home that I installed a Daikin VRV split system a couple of years ago. While it can have up to eight (8) indoor units connected to the single 4 ton outdoor unit I have four indoor ducted units. These are the physically small indoor units not the larger units that are similar in size to the indoor units of conventional air conditioners, heat pumps, and forced air gas furnaces.
Based on the Daikin documentation the ducted units are not quite as efficient as the ductless units. It is due to the type of blower that is used between the two. I suspect operating in the real world you would be hard pressed to see any difference. My ducted units do a good job with the two second floor units located in the small attic over the oldest part of the home and the two first floor units installed in a utility closet on the first floor.
One issue with the ductless units is they do not do a very good job of conditioning any room but the one room they are installed.
If you have have any specific questions I would be glad to answer then for you.
Pay a third party engineer to design the system for you, then submit that spec to all the different companies.
Originally Posted by overhear
This way everyone will be bidding the same thing. Otherwise 20 different contractors will come up with 20 different designs and equipment specs, and you'll only get more confused.
Originally Posted by heatingman
Or, since you are in NY you might start with an energy audit.
Here's the application for the free/reduced cost audit. Go to the link in my signature or search "get energy smart" to find someone near you.
Which makes more sense to you?
- turning your thermostat back and being uncomfortable. Maybe saving 5-10%
- leaving your thermostat where everyone is comfortable. Saving 30-70%
DO THE NUMBERS! Step on a HOMESCALE.
What is comfort? Well, it AIN'T just TEMPERATURE!
Energy Obese? An audit is the next step - go to BPI.org
, or RESNET
, and find an auditor near you.
I've just installed a ducted Mitsubishi and am impressed with the system.
The amount of duct work the system can work with is limited so a careful designs is important.
As tedkidd noted the energy audit route is a good way to go, there are some good HVAC companies participating in Westchester NY
Some of the ducted units outside of the VRV/VRF lines do have a limited ability to withstand the resistance to the air flow of a duct system as measured by ESP. Most all of the ducted units for the Daikin and Mitsu VRV/VRF systems have higher ESP capabilities and should not pose any big challenges to duct design. Mine certainly didn't.
Originally Posted by tlj000
Yes, Westchester County, NY.
I've been reading Skippedover's references. They make clear that we will need for someone to do an energy audit, and eventually the full assessment.
That brings up the issue of staging: According to "How a Pro Designs" the Manual J load calculations take into account some features of the house that will be impacted by our renovation (we will be adding some windows, enclosing a screen porch, adding a bathroom, and changing some ceiling heights).
I'd appreciate suggestions about when in the renovation process to have the calculations done. Right now we are just finalizing the building plans, so the house is still in "original" condition, and our plans are just on paper.
Manual 'J' load calculation that can take from about 4S-minutes to several hours,
depending on the size and complexity of your home. What is needed are the dimensions
of all rooms (LxWxH) and windows in each room, the orientation of the home, the
number of fireplaces, number of occupants, significant appliances (heat sources),
construction materials, insulation factors, window and door materials to name the basics.