many iQuestions about zoning the iQDrive....
I'm doing a major remodel (gutting the house) and will be replacing the HVAC systems including ducts. The iQDrive seems like it would handle a wide range of zone sizes well. But, does anyone have any actual experience (or at least a genuinely knowledgeable opinion about) zoning with this system?
I would like to zone down to very small zones, preferably single rooms (house is a well insulated 5,300sf total with individual rooms ranging from approx 200sf/9' ceiling to 850sf/14' ceiling - I know that is skimpy info but it gives the basic situation).
How intelligent is the system? When a small room calls for cooling does the air handle and compressor "know" - and adjust for the fact - that this room needs less air flow & compressor energy than when a very large room calls for cooling?
I was thinking I might need two 4 ton units to service the whole house. But, since the system can only drop down to 25%(right?) of maximum rating, a 4 ton unit would probably be oversized when serving a single small room zone. Can the system dump air into some of the rest of the house to improve efficiency and reduce short cycling? Does it look at the conditions in each room and use that info along with it's knowledge of room sizes, etc. to recognize which other zones would make good dumps to minimize over-conditioning of the spaces not calling? Does it use modulating dampers to make this process more controllable?
Speaking of modulating dampers, are they used - perhaps along with varying blower speed - to make transitions in zone demands without causing abrupt changes in air flow as rooms call for conditioning and are satisfied? If not, how does the system minimize air noise from this process?
Can you undersize the whole house tonnage and still have good temperature & humidity control by having the system condition individual zones sequentially rather than simultaneously?
Can a thermostat (or other controller) control more than one zone using remote temp sensors or does each zone need a separate thermostat for control?
Thanks in advance for your help.
Unless something changed since my training class, Nordyne said DO NOT zone the IQ.
Originally Posted by EverettsHVAC
Same here. although they said it's on the way. Trust me on this one, unless you have a zone system specificly made for the variable speed, don't do it!!! I've never tried, but somehow I always bat Cleanup.
The IQ Drive system is based on inverter technology that has been used by top Japanese manufactures for years (since the mid `80's for Daikin). The technology is now being embraced here because of rising energy costs. Check out the VRV and VRF systems from Daikin, Sanyo and Mitsubishi.
I believe the IQ is not suited for zoning as we typically know it here in the US. The VRV/VRF systems use multiple indoor units, whether ducted or ductless, with one outdoor unit. Up to nine indoor units can be connected to one outdoor. Each indoor unit is a zone and is fully variable in its output just as the outdoor unit is. I think Mitsu has a ducted indoor unit rated as low as 6,000 BTU.
While you may not be able to zone an area as small as you are thinking, they can get fairly small. With these systems excess air flow is not an issue that has to be dealt with.
There is one central controller (even if you have more than one outdoor unit is used) connecting all the indoor units. Each zone has a small sensor that is tied in to the central controller or its own controller that can be set by the user of that space/zone.
These are top of the line comfort systems that are designed specifically for what you are trying to achieve.
The IQ drive system cannot currently be zoned. Since it is a communicating system, you couldn't even do a work around with a 3rd party zoning product.
Next year there is supposed to be zoning available for it. No idea how small of zones it will be able to handle. The current system will range between 40% and 118% of nominal capacity.
I'd be interested in seeing a variable capacity residential system with something like a Copeland Digital scroll compressor. Those can go down as low as 10% of nominal capacity, so in theory you could run some really small zones.
If more government is the answer, then it's a really stupid question.
I'm very surprised a very high end, very expensive system like the iQDrive isn't zone compatible right out of the gate. I would think that variable speed blower & compressor would make it a great match for zoning.
I had read about the Daikin/Sanyo/Mitsubishi systems while researching this site (which is great source of info and much appreciated). But I know less about them than forced air which means I basically know nothing.
One practical issue I have with Daikin is that there are only two dealers within a 2 hour radius and that makes me bit nervous. Sanyo is a bit better with a couple of dealers here in town. Mitsubishi has about a dozen dealers here and I like that degree of availability and alternatives.
Does anyone have a preference between the Sanyo and Mitsubishi systems? I want ducted both for aesthetics and noise and we have plenty of attic space for that.
Thanks again for the information.
Originally Posted by gcunnin
In terms of market share Daikin is the leader, then, I believe, Mitsu and finally Sanyo. Daikin is known for strong support to the field techs and often will be on site when the system is commissioned. Can't say about the other two, but I doubt they could exist at the levels that they do without similar levels of support.
In terms of operating efficiency it is Sanyo, then Daikin, and Mitsu. Daikin does have a new version (VRVIII-S), which will see an improvement in operating efficiency, but they have not made public when it will be released. Sanyo is the only one to have a 5 ton unit while two have 3 and 4 tons. All three manufactures are known for high quality systems.
If you are going to be getting more serious about one of these systems, have a detailed load calc done so that you can understand the diversity within the building. This is to see how different zones are impacted by changing ambient conditions during a day. For example, while the east side of the building may have the same load as the west, the load won't necessarily be at the same time of the day or night. Same with upper and lower floors. With many smaller zones the system will better meet the building diversity and potentially allow for a smaller total capacity. Size the total system for the higher of the heat load or cooling load - within reason.
Hmmmm...There are a dozen Mitsubishi dealers just counting those right here in town but only 2 Daikin dealers for entire region (and the closest is about 2 hours away). Not sure why this is, but whatever the reason, the lack of local competition and the distance give me pause in considering this brand.
Originally Posted by mchild
Anyway, regarding these multi-split systems: My impression is that they are heat pumps rather than furnaces. Our heating needs are not extreme but I do want the house comfortable on those days when temps drop into the teens. (Avg Low temp in Jan is 25^ but we get many days of 10-20^)(also, fyi, heating degree days=3,672 & cooling degree days=1,918). Does anyone forsee any problem?
Also, I would appreciate excellent dehumidification. [annual climate data: max daily RH 92%, min daily RH 47%, avg daily RH 71%, avg daily dew point 50^ (28^ in Jan, 71^ in Jul)].
And, very quiet operation (inside) is essential.
If I understand correctly, the Mitsubishi is a 2 speed blower and not variable speed. I found where the "Mr. Slim" units offer ramp up/down but I couldn't find anything regarding the ducted (VFRZ) system.
Presuming it doesn't ramp up/down, are there abrupt air noise changes when the air handler kicks on/off? And, if it is true that standard central AC systems with variable speed blowers in general offer the potential for better humidity control, and if it is also true that the multi-split system is only a 2 speed, then does the limited blower control hinder optimal humidity control?
Do the systems offer separate humidity control (other than just that which occurs incidental to cooling) and can the system optimize itself for dehumidification versus cooling when conditions warrant?
Finally, am I correct that an indoor unit can feed independently controlled "sub-zones" with damper controls so that 10 zones would not necessarily require 10 indoor units?
I know my questions are overly simplistic and of course I will discuss technical details with the dealers but I just like to get some education first so that I'm not completely clueless. I appreciate everyone's help with this.
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