Ductless mini-splits: Fujitsu now rivaling (or equal to) Mitsubishi?

[ignorant1]

I just looked at the new products on the Fujitsu website; their systems have great specifications, plus their multi-unit condensers can handle 4 indoor units versus Mitsu’s 3-unit design.

Any opinions as to the reliability or build quality of Fujitsu versus Mitsubishi?

[heatingairman]

I personally prefer the Fujitsu. They allow longer linset lengths and install easier than the Mits.

[udarrell]

What bothers me most about the split systems is many have very low airflow per ton of cooling. Many appear to be below the minimum 350-cfm per ton of cooling.

Which brands have the highest airflow per ton of cooling, - any at 400-cfm per ton? - udarrell

[heatingairman]

None that I'm aware of. I guess you get really,really, really good dehumidification!

[stafford]

We've installed both Fuji's and Mitsu's. Can't say one is really better than the other, they're just different and the Fuji's are significantly less expensive. Both seem very reliable, I think the Mitsu remote is easier to use/understand.

[ignorant1]

Thanks Guys...

Now I'm curious to know where the Fujitsu units are made.

The last Mitsubishi "Mr. Slim" I had was actually made in Japan. For whatever prejudiced (justified/unjustified?) reason, I would be even more comfortable going with Fujitsu if they were also made in Japan, and NOT made in China like so many other ductless units.

P.S. I don't WANT to send my money out of the US, but if I am going to do so, I want to get the best build quality available.

[udarrell]

Using a search, - I found a duct-less mini-split system with what I consider adequate design rated airflow.
It is SOLEUSAir: http://www.expairco.com/soleus5.jpg

I want equipment that is mfg'ered to deliver the nominal required 350 to 450 CFM/Per Ton of cooling and nothing less. Mfg'ers have a responsibility to meet the required airflow per ton of cooling standards! - udarrell

[pstu]

Udarrell, you clearly feel pretty strongly about airflow being in the range of 350-450 cfm/ton. What bad things do you say would happen if airflow were less?

Thanks for you ideas -- Pstu

[ignorant1]

Udarrell:

From what I know (probably very little) the usual airflow requirements you mention are for traditional forced air systems, with design considerations for a typical evap configuration.

Physics? The speed / efficiency of heat-energy transfer from/to any surface is dependant upon the difference in temperature between the air & the surface, PLUS:
1.) the VOLUME of airflow
2.) the surface AREA that any given volume of air interacts with, and
3.) the TIME that any given unit of air is in contact with the surface

Perhaps the minisplits don’t use as much VOLUME of airflow because the indoor evap unit is designed so that factors 2 & 3 allow for adequate heat transfer, thus reducing the need for volume (and thus quieter operation).

Just a theory…

[udarrell]

Originally posted by pstu
Udarrell, you clearly feel pretty strongly about airflow being in the range of 350-450 cfm/ton. What bad things do you say would happen if airflow were less?
Thanks for you ideas -- Pstu

First, I will admit that I do not have experience with using duct-less mini-split A/C & heat pump units, therefore, you tell me how they make that amount of airflow work with entirely different application requirements.

A 2-ton system operating on high speed with only 536-CFM of airflow is a mere 268-cfm/per ton of cooling.

1) I suppose that will provide what they consider is enough throw for the size room that they state that the 2-ton is designed for.

2) I suppose the Indoor Unit is design-engineered & will be charged to work with 268-cfm per ton of cooling, and might put a marginal load on the E-Coil.

However, what if it is a dry climate with a tight home & you want more sensible Btuh along with more throw across or through one or more rooms, - I will take the unit that can deliver 350 to 450-cfm per ton of cooling.

3) Most of those indoor units are engineered with three speeds, therefore why not have those speeds cover the normal nominal 350 to 450-CFM per ton of cooling standards?

4) Like my little 6,000 half-ton window unit, - by using a floor type fan to increase airflow throw & circulation, as well as more airflow through the E-Coil, even at 112-F Heat Indices with high humidities, - it cools in an old 1937 home over 900-sq. ft., three rooms & a hallway down to 75 to 76-F 50 to 55% RH.

5) Ignorant1, your list of factors were not posted when I initially responded. You are Right on Target, & you are NO amateur!

Yes, those listed factors influence the Btuh delivery, however, there is much more to cooling differing areas when there is a need for more airflow volume & throw.

Most Half Ton window units do not have nearly enough airflow throw, & will therefore begin to recirculate the colder conditioned air & not deliver with better throw & circulation of the air from more distant areas.

Why not have four speeds & use a minimum of 300-cfm per ton on the quietest lowest speed? Note what my Half-Ton Delivers!
- udarrell

[Edited by udarrell on 10-31-2006 at 09:40 PM]

[thehumid1]

I'm biased I have FJ laptop but now being the redifinition of energy star's definition of a central a/c FJ"s high (17 seer) mini splits can get many local utility rebates as well as Fed tax credit

[udarrell]

Originally posted by thehumid1
I'm biased, I have FJ laptop but now being the redefinition of energy star's definition of a central a/c FJ"s high (17 seer) mini splits can get many local utility rebates as well as Fed tax credit
I like the adaptability of mini-splits, being able to utilize four indoor unit locations would cover a lot of varied applications.

Dealing with situations where the duct system is undersized & duct retro too costly to meet the heat/gain calc, I would size the A/C equipment to the duct capacity & add whatever would be needed to supplement it.

In some climates there would probably be a large percentage of the run-time when one or the other system could handle the load thus resulting in very efficient SEER performance levels.

I was merely stating my personal preferences based on window A/C performance experiences, which may or may not be applicable to mini-splits.

Most of them probably do the job okay, and I would prefer them over having numerous window shakers!
http://www.udarrell.com/airconditioner_current_temperature_btuh_charting.h tml

The four indoor units would have worked perfectly for my brothers home. With my home's oil heating system I would prefer mini-splits; I would need three upstairs' units & one or two downstairs' units. - udarrell

[ignorant1]

Regarding Daikin:

I had a chance to look at the Daikin products & download the installation guides for them. They look & spec out very nicely and have great design flexibility. Daikin also has a lot of other very nice systems & control options. Obviously a company that has their “stuff” together.

The only downside on the Daikin products are the need for seperate 220v circuitsto each indoor unit (or am I wrong?). It appears that Fujitsu uses the wiring coming from the outdoor unit to power the indoor units, making installation a lot cleaner & easier.

Are there any downsides to Fujitsu’s way of wiring? (It’d be great if Daikin did it the same way.)


[Edited by ignorant1 on 11-02-2006 at 11:38 AM]

[udarrell]

Any indoor unit setup would have to comply with the prevailing electric code concerning, conductor insulation, amperage ratings, & breaker protection.

I do not understand why there would be any difference between the Brands. (?) udarrell

[ignorant1]

If an indoor unit is 110v it is possible (depending upon local code) to tie into an existing circuit. Both Fujitsu & Daikin indoor units are 220v, but (I believe) that the Daikin’s require a separate 220v branch circuit to each indoor unit.

With Fujitsu’s setup, you have a single 220v source to the outdoor unit, and then each indoor unit is powered from the outdoor unit. This can greatly simplify installation – reducing the need to run a bunch of branch circuits back to the breaker panel (PLUS not to mention that if there are not enough open slots left, you would need to install a subpanel)

I haven’t checked the Mitsubishi installation docs yet, so I’m not sure how they are wired…

[rclaoac]

Originally posted by thehumid1
I'm biased I have FJ laptop but now being the redifinition of energy star's definition of a central a/c FJ"s high (17 seer) mini splits can get many local utility rebates as well as Fed tax credit

I have been installing Fujitsu's for the last 2 years and so far, I've been happy with them. I recently tried to submit for a rebate from a local utility and found out the 16.5 SEER 2 ton unit I installed was not elgible because it did not meet the EER requirement. I understand SEER is derived from EER at different conditions, but why is the EER so much lower than the SEER for this unit?