When if ever, will VRF manufactures give designers products that meet their true needs? 5,000 - 6,000 BTU concealed air-handlers 1.5 - 2.5 Ton multi splits which can power down to 2,000 BTU's or less We know manufactures hold back..... They can do it now, will it happen in your life time?

A Chiltrix HP plus buffer tank might be the closest to that.

Posted By jonr on 20 Jan 2016 08:33 AM
A Chiltrix HP plus buffer tank might be the closest to that.

A manufacture to only providing a 1 year warranty sounds like they don't have much faith in there product or want to take responsible for their own doings. Chiltrix would be a Unwise Investment!

Maybe, or maybe it will be like my refrigerator - 1 year warranty and working fine 20 years later. Maybe it's based on some special case concerns - like people who live right on the ocean.

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The Fujitsu -7RLF mini-duct cassette is about 8000 BTU/hr max, and can modulate down quite a bit, even if the multi-split compressor it is tied to can only dial back to 6000-7000 BTU/hr @ 47F. The fact that you can split the output to a handful of low-load rooms makes it pretty reasonable for by-floor zoning in high-R houses.

Even the smallest Fujitsu multisplit the 1.5 ton AOU18RLXFZH 2- zone unit only modulates down to 6800 BTU/hr @ +47F, but so do the bigger ones. Most code-min homes would have a heat load at +47F higher than 6800 BTU/hr. The market for even lower modulation on multi-splits is vanishingly small, but may rise as California's Net Zero code requirements kick in by 2020.

The Mitsubishi -FH09NA wall-coil type head can modulate down to ~1700 BTU/hr @ 47F, and still delivers ~10K @ 0F. Makiing a comparable mini-ducted version would not be a stretch of enginerring , but most homes have heat loads 2-5x the 0F out put of the FH09. They're not really holding back, there's just no market yet.

Mini-splits are FAR more capable of right sizing for low-load homes than the typical condensing gas furnaces & boilers. The HTP UTF-80 boiler only modulates down to ~7500 BTU/hr out, and I'm not aware of gas-burners that go lower than that. The minimum output of the multi-splits are about an order of magnitude smaller than the firing rates of the smallest heating-oil burners out there.

MITSUBISHI Cooling Capacity of outdoor units

Multi Split

• MXZ-2C20NAHZ - 12,600 - 20,000 Btu/h (3.7 - 5.9 kW) - Throttle Down 37%
• MXZ-3C24NAHZ - 12,600 - 23,600 Btu/h (3.7 - 6.9 kW) - Throttle Down 47%
• MXZ-3C30NAHZ - 12,600 - 28,400 Btu/h (3.7 - 8.3 kW) - Throttle Down 56%
• MXZ-4C36NAHZ - 6,000 - 36,000 Btu/h (1.8 - 10.5 kW) - Throttle Down 83%
• MXZ-5C42NAHZ - 6,000 - 42,000 Btu/h (1.8 - 12.3 kW) - Throttle Down 86%
• MXZ-8C20NAHZ - 6,000 - 48,000 Btu/h (1.8 - 14.1 kW) - Throttle Down 87%

Mini Splits

• MSZ-FE09NA-8 - 2,800 - 9,000 BTU/h (0.8 - 2.6 kW) - Throttle Down 69%
• MSZ-FE12NA-8 - 2,800 - 12,000 Btu/h (0.8 - 3.5 kW) - Throttle Down 77%
• MSZ-FE09NA-8 - 8,200 - 25,200 Btu/h (2.4 - 7.4 kW) - Throttle Down 67%

It is obvious Mitsubishi is holding back the modulation percentage on the MXZ-2C20NAHZ, MXZ-3C24NAHZ and MXZ-3C30NAHZ. I'm going to speculate that they are doing it through the firmware. Would love to hack / dig into the firmware on the controller boards and adjust the config files to throttle the units down to the same levels, or lower as the MSZ-FE09NA-8 or MSZ-FE12NA-8

For example, I'm going to say you could take the MXZ-3C30NAHZ - 12,600 - 28,400 Btu/h (3.7 - 8.3 kW) - unit modify the firmware and hit these numbers MXZ-3C30NAHZ - 2,800 - 28,400 Btu/h (0.8 - 8.3 kW) -Throttle Down 90%

So that's it Guys..... You could leap frog product release cycles by adjusting the Modulation in the firmware yourself :)

I would have bought a much smaller mini for our bedroom if I could have found one. We have a Mits 9K, and it's way overkill. We normally just use the bigger 12K for the whole house (1400 sq ft ICF), but run the BR one when it's in the single digits outside. For our master suite, a 3K would be plenty.

Why are you looking at the FE Mitsubishis, a nearly 10 year old design? ( When if ever are YOU going to start looking at the most recent models? :-) )

The FH series has been out for a bit over two years now. The FH09 has an 11:1 turn down ratio, throttling back to 1600 BTU/hr out @ 47F, wiht 18K of capacity at that temp:

http://news.mehvac.com/Bulletins/FH_Product_Guide.pdf

The Fujitsu RLS3s all throttle back to 3100 BTU/hr, independent of size:

http://www.fujitsugeneral.com/PDF_06/9-12-15RLS3%20Sell%20Sheet.pdf

That's also true of thei RLFCD slim-duct series:

http://www.btureps.com/fujitsu/fujitsu-literature/2014-rlfcd-rlfcc-brochure.pdf

Posted By jdebree on 21 Jan 2016 07:26 AM
I would have bought a much smaller mini for our bedroom if I could have found one. We have a Mits 9K, and it's way overkill. We normally just use the bigger 12K for the whole house (1400 sq ft ICF), but run the BR one when it's in the single digits outside. For our master suite, a 3K would be plenty.

I'm glad you mentioned your problem jdebree because its not just you its most everyone...... This is a VERY important option that needs to be offered by VRF manufactures, and they could if they wanted to. My design layout for our bedrooms, bath and closet as one zone (700 sf) is optimized for a concealed unit and I only need 2k to 4k to heat and cool the bedroom zone depending on the season in the Atlanta Ga area. I know its not just a problem for me and you, it's a problem for anyone trying to optimize a new home layout for maximum efficiency. Would like to get my hands on the firmware files for the multi splits and concealed air handlers to see how much time it would take to modify the firmware.

My assumption would be that they had good reason for not making it throttle back that far. For example, lubrication needs with certain compressors.

Posted By Dana1 on 21 Jan 2016 07:40 AM
Why are you looking at the FE Mitsubishis, a nearly 10 year old design? ( When if ever are YOU going to start looking at the most recent models? :-) )

The FH series has been out for a bit over two years now.

I'm Proving a Point :) ....... there hasn't been any improvements in Efficiency over the past 10 years. But through modifying the firmware on the outdoor unit and air handlers you can lower the operating speeds for improved efficiency and get closer to matching the actual BTU needs for each zone.

I need the Firmware files ..... Anyone?

"...there hasn't been any improvements in Efficiency over the past 10 years."

Really?

The FE12 heating efficiency was what, HSPF 10.6?

https://younits-iviloinc.netdna-ssl.com/media/wysiwyg/Literature_PDF/Mitsubishi/MSZ-FE12NA-8-MUZ-FE12NA1_Submittal.pdf

The FH12 tests at HSPF 12.5:

http://richairductless.com/wp-content/uploads/2015/09/MSZ-FH12NA_MUZ-FH12NA_Submittal.pdf

SURE they're not making efficiency gains?

It must be the new arithmetic: 12,500 BTU/kwh = 10,600 BTU/kwh (But who knew? :-) )

By old-school arithmetic that's an efficiency improvement of about 18%.

The venerable Fujitsu RLS2 series have all been soundly beaten on efficiency by their RLS3 series equivalents too.

It's interesting living in a very energy-efficient home. Our power bill, for an all-electric home is significantly less than our cell phone bill! With a tight home and efficient mini-splits, HVAC has shrunk to a fairly small percentage of our power usage; less than 20%. I really need to address that old-school electric water heater.

Posted By Dana1 on 27 Jan 2016 05:13 PM
"...there hasn't been any improvements in Efficiency over the past 10 years."

Really?

The FE12 heating efficiency was what, HSPF 10.6?

https://younits-iviloinc.netdna-ssl.com/media/wysiwyg/Literature_PDF/Mitsubishi/MSZ-FE12NA-8-MUZ-FE12NA1_Submittal.pdf

The FH12 tests at HSPF 12.5:

http://richairductless.com/wp-content/uploads/2015/09/MSZ-FH12NA_MUZ-FH12NA_Submittal.pdf

SURE they're not making efficiency gains?

It must be the new arithmetic: 12,500 BTU/kwh = 10,600 BTU/kwh (But who knew? :-) )

By old-school arithmetic that's an efficiency improvement of about 18%.

The venerable Fujitsu RLS2 series have all been soundly beaten on efficiency by their RLS3 series equivalents too.

Apparently a discussion on firmware is beyond your scope ....... but as usual you always have to throw in some arrogant remarks. I would rather you not respond to any of my post JERK!

Posted By ricky_005 on 02 Feb 2016 03:57 PM

Posted By Dana1 on 27 Jan 2016 05:13 PM
"...there hasn't been any improvements in Efficiency over the past 10 years."

Really?

The FE12 heating efficiency was what, HSPF 10.6?

https://younits-iviloinc.netdna-ssl.com/media/wysiwyg/Literature_PDF/Mitsubishi/MSZ-FE12NA-8-MUZ-FE12NA1_Submittal.pdf

The FH12 tests at HSPF 12.5:

http://richairductless.com/wp-content/uploads/2015/09/MSZ-FH12NA_MUZ-FH12NA_Submittal.pdf

SURE they're not making efficiency gains?

It must be the new arithmetic: 12,500 BTU/kwh = 10,600 BTU/kwh (But who knew? :-) )

By old-school arithmetic that's an efficiency improvement of about 18%.

The venerable Fujitsu RLS2 series have all been soundly beaten on efficiency by their RLS3 series equivalents too.

Apparently a discussion on firmware is beyond your scope ....... but as usual you always have to throw in some arrogant remarks. I would rather you not respond to any of my post JERK!

Arrogant? Hey, I hung some emoticons on it- WTF ?!!

If you're going to complain about vendors not meeting the needs of the market or that efficiencies aren't improving it behooves you to refer to their latest-greatest (and not 10 year old) designs.

The market keeps moving, and it's simply not accurate to assert that the vendors aren't moving along with it. I'm not anti-firmware discussion- I am anti-BS. To have room for intelligent discussion about it requires working within the tested & measured facts.