Bill Neukranz
Veteran Member
Posts:1103
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| 10 Nov 2013 07:52 AM |
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Yesterday I attended a meeting with a Dallas area builder ( http://www.ferriercustomhomes.com ) that specializes in building ultra efficient residential structures.
Many of the concepts he talked about make sense and align with generally accepted concepts.
Of interest for posting here is what he's doing for heating and cooling these structures that require so little to do so.
Not surprisingly, he's moved to mini-splits. Generally he puts an appropriately sized unit in every key room. I don't know if he's doing this via one condenser unit outside, or a one-for-one setup.
He said that he can get efficiencies at or better than high performance air-to-air heat pumps, and at a lower cost per BTU. The mini-splits go down to fractional ton units such that the appropriate size can be implemented per room.
He also said that geo HP is out due to too expensive. This aligns with comments here from time to time that as you get down to smaller amounts of heating and cooling needed, it's increasingly hard to amortize geo's drilling cost needs.
He commented that they were using Daikin units, but no more. Too many failures, too many repair needs, and to much difficulty on parts. He's moved to Mitsubishi.
Just FYI, primarily on reliability of mini-splits as seen from a local Dallas area builder.
Best regards,
Bill |
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Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
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engineer
Veteran Member
Posts:2749
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| 10 Nov 2013 08:38 AM |
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Several points:
1) The smallest standalone mini I'm aware of is 3/4 ton, with about a 4:1 turndown
2) The smallest mini "air handler" is 1/2 ton. Use of that size requires multi-split condenser
3) (My) cost per head is about the same, mini or multi.
4) Some standalone Minis (chiefly 3/4 and 1 ton) have SEER >25, but efficiency falls away into the teens with multi-splits and ducted variants, as well as larger units
5) the 4:1 turndown rule applies to multi-splits, so a two ton multi feeding a 1/2 ton head will have to run that head at its full capacity if that head is sole calling zone. Since many smaller rooms have loads of 1/10 ton or less, short cycling can still occur.
6) Each head has its very own drainline to clog.
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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SkyHeating
Basic Member
Posts:203
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| 12 Nov 2013 10:11 PM |
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My qualm with the ductless systems is what happens when R410a is gone and repairs happen? I am a bit scared for homeowners who are putting in 4 port systems and all the lines are ran through walls. As equipment changes I see this as a big issue. Look back to when R22 was the only way to go, now imagine that each home had 2-8 indoor coils and 2-8 linesets ALL hidden in walls. Fast forward to 2013 and you go out for a leak check and repair. How the hell are you going to find a leak and you can't find a matching coil for that R22 unit so you have to replace the whole thing. Because you don't know where the leak is you can't flush and reuse the linesets, or lets say its an acide burnout and you can't reuse the lineset. I can see 1:1 systems and 2:1 systems but three or more wall heads seems scary. I think to many people are not thinking long term if they think R410a is here to stay and that we won't have another R12 or R22 scenario in 5-15 years.
Also going to maintenance costs, which I think we all agree any system should receive yearly maintenance, what are your maintenance costs if you have 2 outdoor heat pumps with 2 or 3 wall heads each? Outdoor units take lets say 45 minutes each, then indoor wall heads take another 20 minutes each to move the ladder to each one and remove the filters, check the coil and fan and put filters back in after cleaning so another 120 minutes and now you're 210 minutes into a maintenance that normally takes 120 minutes at best for a furnace and AC if done at the same time. So how much are you saving with maintenance and multiple filter cleanings and such. I like Keep It Simple Stupid and mini splits do not meet this philosophy.
Note: My company installs close to 100 mini split per year so its not that I don't like them, because I do go where the market goes, I just would not put them in my own home as a primary heating system and can not recommend a builder to do it either because they are meant to be a supplementary system not a primary system.
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Visit my Youtube channel for product reviews and customer testimonials http://www.youtube.com/user/skyheating1
http://www.welserver.com/WEL0626/
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Bill Neukranz
Veteran Member
Posts:1103
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| 12 Nov 2013 10:18 PM |
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(Sky Heating) Fascinating market comments. Thanks! Bill |
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Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
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Lbear
Veteran Member
Posts:2740
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| 12 Nov 2013 10:35 PM |
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Mini splits are the primary heating & cooling source for many buildings throughout the world. With Europe and Asia being huge consumers of mini split units.
Yes, it would be a pain to replace a mini split unit if they needed to have the lines pulled. How plausible is that? What is the likelihood that R410a will be obsolete within the next 20 years?
The other question is what is the alternative? Installing inefficient duct work?
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joe.ami
Veteran Member
Posts:4377
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| 13 Nov 2013 09:41 AM |
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There is a good chance R410 will be obselete soon. In our rush to find something less ozone depleting we adopted something with a higher global warming potential. Doesn't matter where your polotics are on this, it will change again. |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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jonr
Senior Member
Posts:5341
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| 13 Nov 2013 01:06 PM |
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Maybe they will realize that refrigerants like R-600a/R290/R32 can be safely used in mini-splits. |
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mtrentw
Basic Member
Posts:128
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| 13 Nov 2013 01:29 PM |
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Propane (R-290) is a great refrigerant in many applications. EPA had a good white paper on taking a new look at flammable refrigerants.
http://www.epa.gov/greenchill/downloads/ul_whitepaper_flammablerefrigerants.pdf
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ICFHybrid
Veteran Member
Posts:3039
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| 13 Nov 2013 02:33 PM |
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they are meant to be a supplementary system not a primary system. I don't understand your rationale there. They are going in all over here as a primary system when the original heat plant is outmoded or fails. The houses then have both heat and for the first time, AC as well. If I was designing cost-effective new homes, I'd design for mini splits. They are primary systems in homes all over Europe and Asia. |
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Dana1
Senior Member
Posts:6991
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| 13 Nov 2013 04:56 PM |
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The notion that they're supplementary only is clearly a cultural bias. They were invented in Japan, where nearly all heating & cooling is point-source, not ducted (but where there are far fewer McMansions :-) ), and resident tolerance for room to room temperature differences is high.
The more performance you put into the building envelope, the smaller those room deltas become, and the less tolerant you NEED to be to live with point-source heating/cooling. Most Net Zero Energy homes in New England are heated by one, sometimes two ductless heads. A 2- story PassiveHouse 5 crow-miles from my place is also heated with one head per floor.
As I understand it, replacing R22 with another refrigerant is primarily a lubricant compatibility issue with "lubricant contaminated" linesets and coils, and it needs a higher operating pressure than R22 or propane. The scroll compressors used in mini-splits don't have quite the same lubrication requirements as reciprocating compressors, but that may or may not be enough to make re-charging an existing system with a different refrigerant any easier/harder.
HFC32 is already being used in some Asian mini-splits (including Daikin) , but at at 650x C02 it's hardly "low" GWP, even if it's only about a third that of R410A. Propane is a lot lower GWP (but also a lot more flammable.) IIRC, HFC32 is a sub-component comprising about half the weight or volume of R410A, and combined with something else (HFC125 ?), in part to lower/prevent the fire hazard presented by the HFC32.
Bottom line, I'm doubtful that moving from R410A to a lower GWP refrigerant won't be nearly as painful as the R22 phase out was. But I'd be happier if there were more residential scale CO2 refrigerant heat pump technology on the horizon. CO2 requires much higher pressures and 2-stage compressors, but it's only 1x CO2 for GWP, and is fireproof. With the phase-out of HFC134a as an automotive AC refrigerant in Europe CO2 has become preferred alternative in Germany, but a car-cooler is a far cry from a space heating/cooling heat pump. Sanyo had rolled out a decent hydronic-output CO2 space heating heat system pump shortly before they sold out to Matsushita (Panasonic), but that product line disappeared after the buy-out (though the compressors are still sold as components.) |
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mtrentw
Basic Member
Posts:128
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| 14 Nov 2013 11:26 AM |
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CO2 is rapidly gaining share in vending machine sector. I've yet to see a larger scale CO2 application. |
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SkyHeating
Basic Member
Posts:203
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| 20 Nov 2013 12:47 PM |
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Posted By ICFHybrid on 13 Nov 2013 02:33 PM
they are meant to be a supplementary system not a primary system. I don't understand your rationale there. They are going in all over here as a primary system when the original heat plant is outmoded or fails. The houses then have both heat and for the first time, AC as well.
If I was designing cost-effective new homes, I'd design for mini splits. They are primary systems in homes all over Europe and Asia.
If you ask any utility in my area they call them a "supplementary system" as they are not the full source of heat since they can not be properly sized and sized for full load heating on the coldest design day. If they had backup electric heat strips i would say they are a full system. Also with current wall heads and the way they are designing systems in my area it is not a full heat scenario. In my area, many smaller two story homes/townhomes are getting one wall head downstairs and one wall head in the master upstairs so the bedrooms and bathrooms have cadet/baseboard heaters. Yes I understand you could have a wall head in each room but A. that is not cost effective and B. it is not proper sizing, because either you are oversizing your cooling so you can meet your highest heat load day or, vastly oversizing in heating to meet your cooling load. I understand they are variable capacity but that does not solve all issues. Even a dump truck has a variable capacity gas pedal, but in the end its capacity is to much for me 99% of the time so I don't drive one. |
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Visit my Youtube channel for product reviews and customer testimonials http://www.youtube.com/user/skyheating1
http://www.welserver.com/WEL0626/
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Dana1
Senior Member
Posts:6991
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| 20 Nov 2013 01:52 PM |
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There are whole developments in my area (US climate zone 5) where mini-splits are the sole heating appliances- typically one head per floor, w/high- performance building envelopes. A deep energy retrofit on an 1890 home in zone 5 I was involved with last year has only mini-splits for heating, with a very modest amount of heat transfer via the active ventilation scheme. No backups installed or necessary- three conditioned floors, 1 head per floor (none in the fully insulated basement.) I have two sets of relatives in YOUR area (marine zone 4) heating solely with mini-splits (and not stupid & expensive 1- head per room kinds of installations.) Very open floor plans help, but these homes are not even at current code-min R (though both have better than code windows, and low glazing fractions.) Doesn't much matter to them if the units are oversized for cooling, the cooling season being so short & shallow. It's not as if you have much in the way of latent load that would require longer run times to be comfortable in that climate. Code a code min McMansion with a code-max glazing fraction isn't usually going to cut it for ductless-only heating in your area, but that's not the only type of house out there, eh? The utility companies don't exactly get to dictate how people use them, or define what they are "..meant to be..." nor does code require backup (in my area, anyway). The manufacturer "meant them to be" point source heating or cooling. If the heating & cooling needs can be met with just a mini-split (or other point-source heating), it's a legitimate option. Some local codes require a duct or other heat emitter in every room, but those can be ignored, or waivers granted where the modeling shows that all rooms can be heated passively from the adjacent space (which usually requires very low loads for the doored off rooms.) Some lenders might balk though (but what the hell do bankers really know?  ) Bottom line, they're supplemental heat only if applied as such. They're fully capable of handling the loads of well designed houses even in fairly cold areas (much colder than yours.) |
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jonr
Senior Member
Posts:5341
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| 20 Nov 2013 02:24 PM |
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I wonder if any of them have "hours ratings". At least in theory, it would be possible for some to be built to last longer under heavier use. |
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ICFHybrid
Veteran Member
Posts:3039
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| 20 Nov 2013 08:49 PM |
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since they can not be properly sized and sized for full load heating on the coldest design day. I have a Daikin 4 port multi rated at 22kBTU for outdoor temp of 17F. It heated my entire 7,000 sf home during last winter, even with multiple holes in the envelope. Most people I know who are replacing a bad oil furnace or propane or resistance heat in 70-100 year old farmhouses are doing it with ductless minis. Usually two heads, sometimes three or four. They are very comfortable and provide AC where there was none previously. Since design days are relatively rare, it is very cost-effective to provide a cold room or corner with a wall heater as supplementary heat and I'm a big fan of radiant mat floors in bathrooms for a low cost approach to radiant where it counts. |
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Lbear
Veteran Member
Posts:2740
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| 20 Nov 2013 09:34 PM |
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Posted By SkyHeating on 20 Nov 2013 12:47 PM
If you ask any utility in my area they call them a "supplementary system" as they are not the full source of heat since they can not be properly sized and sized for full load heating on the coldest design day.
Utility companies don't set code or standards. Utility companies don't care about energy efficiency, the bigger and more inefficient system you put in, the happier they are because they get $$$ each month from your high utility bill. Mini splits are used as the primary heat and cooling source in thousands of homes without any issues. |
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ICFHybrid
Veteran Member
Posts:3039
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| 21 Nov 2013 07:15 AM |
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Utility companies don't care about energy efficiency, the bigger and more inefficient system you put in, the happier they are because they get $$$ each month from your high utility bill. They actually do care as the cost of building new generating capacity is higher than that of utilizing existing. That's why you see so many promotions involving energy efficiency and most of them originate with the utility company. |
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Bill Neukranz
Veteran Member
Posts:1103
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| 21 Nov 2013 09:47 AM |
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"Utility companies don't care about energy efficiency, the bigger and more inefficient system you put in, the happier they are because they get $$$ each month from your high utility bill."
This is hugely untrue for the Dallas area, and pretty much Texas overall.
For example, the utility for Dallas just announced yesterday putting $11.5M on the table for 2014 as incentives for reducing peak demand (kW) and energy consumption (kWh), focused on commercial reduction efforts, including lighting and HVAC. This will be the fourth year for the program.
Over the last 3 years the incentive programs in aggregate have caused energy users to implement lighting and HVAC measures that have reduced down their demand by 838 MW. Noting that the average MW capacity of a gas fired generating plant is about 196 MW, that's about 4 gas plants avoided so far, that otherwise would have to be built.
It's a 'no-brainer.' For the money that the utility is paying out in incentives, the return to the utility is substantial.
Down here, electricity usage is increasing amongst the population and businesses, while at the same time utilities can't afford to build new generating plants. Thus, reserve generating capacity is getting squeezed more and more. Actually, the utilities here have no choice but to offer the incentives, and plea for less usage from everyone. The incentives are a small amount compared to what they otherwise would have to pay to build more generating capacity.
Best regards,
Bill
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Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
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joe.ami
Veteran Member
Posts:4377
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| 21 Nov 2013 09:51 AM |
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Utility companies are legally obliged to promote energy efficiency and in my AO with aged grids they like reduced consumption to get more years out of 50 year old infrastructure. |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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jonr
Senior Member
Posts:5341
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| 21 Nov 2013 09:53 AM |
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Flattening the demand curve makes lots of sense for increasing profitability (for the grid owner). Make more by selling less depends on the situation and is often just PR or required by regulators. |
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