Alternative Air Conditioner -- Your Ingenuity Required

Re: Alternative Air Conditioner -- Your Ingenuity Required

Blackcherry04 wrote: »

Could you explain what " Rated " output is ?? Is that taking a 36,000 BTU unit and downgrading it to say 16,000 BTU's . Do you still use 50-55 BTU's per SQ foot in temperature zone 5 ?? Are some of these figures that are posted mixing Fahrenheit and Celsius??

No there is no derating all the way to 5F. The only thing that changes is the efficiency rating. The 12,000 BTU H2i's, though they will produce 12,000 BTU's at 5F (their rated capacity), will suffer losses in efficiency there and will not realize the COP ~4.3 at those temps. But they will in fact still produce 12,000 BTU's at 5F.

The 9,000 BTU model will operate at it's rated efficiency (COP 4.3) at 17F outdoor temp if the load is 6700 BTU or less.

I measured the heated air coming from my H2i while the outside air temp was 9F. It was 105F measured to the best of my $20 infrared thermometer's ability...according to the published mfg data condenser temp should be ~120F so close enough measuring the air with a cheapo tool.

Hope this helps.

Re: Alternative Air Conditioner -- Your Ingenuity Required

It's because AHRI only rates them to 17F. Mitsubishi does their own testing down lower. I needed to contact an Application Engineeer at Mitsu US in order to wade through the specs. The guy was great and I got right through. Maybe worth a call to them?

Re: Alternative Air Conditioner -- Your Ingenuity Required

Blackcherry04 wrote: »

Thats my problem, I have a bid to install a new Trane XL 20i in my house for $9,300. If I went with one of these Posters say I get 100% of the 36,000 BTU's down to 5 deg F or to some other below zero temperature . Then I go to the specifications and they only so 60% or so at 17 deg, much less at some below zero number.

It's 100% of something, I just need to figure out what. I could save a boat load of money installing a mini-split.

The Mitsubishi has a much higher btu capacity than the Trane at lower temps. The Mitsubishi was designed for low temp operation, the compressor and the inverter software allow the compressor to spin at 5000 + RPM at the lower temperatures to get the rated BTU output. Mitsubishi is producing the highest technology in heating and cooling units at this time.
check out this link http://www.ottawahomeservices.ca/uploads/2011_Zuba-Central_Brochure.pdf. Unfortunately the Zuba is not available in the US at this time, but it does use the same hyperheat condenser as the H2. Daikin also has something similar in the available in the US Altherma unit.
Don't expect to save a lot of money on the Mitsubishi H2 or the Daikin the technology is not cheap.

Re: Alternative Air Conditioner -- Your Ingenuity Required

Blackcherry04 wrote: »

I was digging some today, one would think the Mitsubishi would be much better than the Trane in low temperature output from whats been said about them, but according to their certificates on some units that is not the case.

Attachment not found.

When viewing AHRI data and certificates one has to remember that Their Glossary of terms do not include terms like Rated Capacity or Maximum Capacity, these are marketing terms made up the manufacturers. AHRI uses BTU output.

The Mitsu look far better than the Trane to me. Dont forget that those 17F ratings are at the stated efficiencies like I said above. The Mitsubishi is running at COP 4.3 there....how about the Trane?

Re: Alternative Air Conditioner -- Your Ingenuity Required

has anyone compared these units on a watt or ? per BTU of cooling to see what it costs to get each BTU of output?

Re: Alternative Air Conditioner -- Your Ingenuity Required

SteveK wrote: »

I see they chose to eliminate the advantage of the variable speed compressors in this test report selecting steady state instead of variable. I liken this to a single speed bicycle being compared to a 10 speed one with the deraileurs welded fixed. I did not bring the Trane up for comparison and would not consider one for our application, therefore, I do not know what the COP of the Trane is and no one has brought that data forth for the comparison...so the Trane sits unchallenged. The Trane could be a COP of 0.5 for all we know @ 17F to produce that 84.2% ratio. There is a number that the H2I would be comparing it to the Trane at 84.2% too. If we get the data we would know better......personally I'm done surfing specs on heating systems and am enjoying the performance of our new one's (yes even at 9F believe it or not).

However.

When the performance of H2i FE09 is being discussed it is truth that it will operate at advertised efficiencies, and that includes COP, at 17F when 6700 BTU is required. Like I said above... So, the system is sized to operate within this efficiency band by oversizing the system to allow it to fulfill the heating requirement of the space at it's sweet spot i.e. you install a 9000 BTU systeme in a space that will require 6700 BTU @ 17F in order to extract it's rated efficiency.

This so it acts like an inverter mini split..... not a steady state heat pump like that report does that you linked to.

Very good presentation of The Mitsubishi and I'll see if Trane folk's will give up the data they have. Then we can compare them side by side. The inverter should make the Mitsubishi more efficient. I'd like to see the data at much lower temperatures than 17 F , but I don't think they want to show it. They don't want to say a 9,000 BTU unit only put's out 4,000 BTU's at 5F and probably 2,000 BTU's at -15 F. Some of the posters on prove that with the posts they make, so I hope we'll get some real information.

Thank's for the discussion.

Since this has become about Mini-Splits I'll only post verifiable facts. I don't own one yet and I don't sell them or know anyone that does. There are 30+ Manufacturers making them in some rendition or another. If you have a favorite, that's fine. No one here knows all the variables that you have or your comfort level, your heat load or temperature differential.

All of the manufacturers subscribe to the AHRI ( Air-Conditioning, Heating, and Refrigeration Institute ) you can look up your Unit or anyone else's from their database. The data is in BTU output, not some made up term. In the heating mode they have two measurements 47 F and 17 F . I know you will have issues with them not going lower. If you look at the difference between 47F and 17 F it's 30 degrees. Based on Thermodynamic Cycles of Refrigeration you can bet if a unit falls 25%-35% in 30 degrees, it's output will fall another 25%-35% in the next 30 deg or more. It appears where you can find data that the difference between 47 F and -15 F is about 75% lower or 25% output of the 47 F temperature. So a 9,000 BTU unit would have a output of about 2200 BTU's @ -15 F, some units can be more efficient, some less, but your not going to find anything earth shaking. If you don't think this is true, find a engineer that knows R-410A and it's properties, I am not. Some of the claims of sub zero output to heat a home with are just not Theoretically possible.

Mitsubishi for instance has 5 F on their charts, but they leave blank the Rated Capacity. I guess they don't want to say a 9,000 BTU unit only output's 4,000 BTU's @ 5 F. Moving 3 shell's around with a pea under one with some Rated Capacity number doesn't make it so.

http://www.ahridirectory.org/ahridirectory/pages/vsmshp/defaultSearch.aspx

Something else they don't want to talk about is defrost cycles. A unit could require a Defrost cycle once a hour more or less to a day or two, depending on the humidity in your location and temperature and the sophistication of the controller. A defrost cycle requires your room air and or some form of auxiliary heat to accomplish. It could take 4-8 minutes or more to complete. That takes away from the BTU's delivered to your room and the heat taken from the room.

Where these Unit's really shine is the SEER and COP, they are a big bang for the buck in that department and the technology is amazing. It looks like they vary widely, it takes some study to sort them out. As in all things life there trade-off's, saving some power and being cold might be something you think about.

Re: Alternative Air Conditioner -- Your Ingenuity Required

The important specs. are the EER & HSPF #'s. The Mitsubishi is far more efficient than the trane.
ARI only rates HP's at 47 & 17 degrees at this time, they need to update their rating criteria to accommodate the new inverter equipment available.

Re: Alternative Air Conditioner -- Your Ingenuity Required

My issue is the Trane dealer is the only Company within 100 miles that has a competent Service department. If I lived in the city , it might be different. Even the companies that are willing to come out don't sound like they are all that swift in servicing Mini-Splits or the parts necessary to do so.

Here is something interesting for estimating the BTU output of a Unit. It will be easy for us to come up with some data here. Measure the of the temperature of the Return air ( Room Air ) measure the out going out air handler ( Supply Vent ) this gives you Temperature Change differential . The fan Air Flow you can find on the spec sheet of the unit.

To find system delivered Btu, simply multiply the fan airflow times the temperature change through the system times the sensible BTU constant of 1.08. The answer is the approximate BTU's the system is delivering into the room.

The problem of using one posters feelings about how a unit performs is the Variables, there 100 different variables in the way a unit will perform. To say it was 5F out and we were warm, is feeling of comfort. If you know the BTU's output that at least gives you a spot to put one foot in the sand.

If you know that the incoming air was 70F and the outgoing was 105F and the cfm's were 325 it's easy to say the BTU output was 12,285. that takes some of the variables out. Then knowing the outside temperature you have a good picture.

Re: Alternative Air Conditioner -- Your Ingenuity Required

LucMan wrote: »

Here is a great calculator to compare heating systems and fuels.
http://www.eia.doe.gov/neic/experts/heatcalc.xls

This calculator is coming up with what we expect to achieve going from coal to the H2i's. Around a 33% increase in heating costs. This will cost us an extra $200 per heating season over coal. The season will run around $800. Not dumping ashes and needing to stay close... priceless.