List price for the 3-ton 5 series was $8735 without any options, the 7-series was 13,395 an increase of $4,660.


The cost to Waterfurnace for the VFD itself is probably less than $300.  There is probably about a $50 printed circuit board in there to control compressor speed with a PID algorithm, and those are padded estimates.  Considering typical manufacturing markup on purchase cost (I am sure they source those things from Asia) of 100% to 200%, then worst case (for the customer) price gouge for this "new" technology is $3600 ($4660 - $1050) or so, neglecting if there is a cost premium on the compressor end of this thing ( lubrication system redesign) or if it is using some kind of fancy expansion valve.

In the meantime, cars and boats have been operating variable speed compressor systems for years, though designed for a different use and not near as much of it, any compressor design issues revolving around the variable speed aspect are certainly well known at this point.

I am a big fan of variable speed refrigeration systems, but that degree of mark up is scandalous considering that they were probably able to decrease the size of their heat exchangers and other system components and still get those high EER numbers at part load conditions.

Of course, you are quoting list prices, so real world prices might look considerably better.  Obviously, competition is desperately needed in this market.

You are forgetting the need to amortize product development costs, everyhting from manufacturing changes to tech pubs not to mention training for all concerned.

The compressor is by Danfoss, a departure from Copland. There is a an electronic expansion valve, as well.

Relative to air source equipment, unit sales volume is less than a tenth, so the cost burden per sale is much higher.

As with everything else, prices will drop as as these systems become mainstream.

The argument is being made that minisplits are an increasingly viable option in ever-colder climates. Carrier's Greenspeed split systems claim greatly improved cold weather performance over conventional air source heat pumps, so the competition you crave is definitely in the offing

Posted By engineer on 28 Jul 2012 08:15 AM
That said, an 038 in Y1 beats an 026 in Y2 for efficiency.

Why is that?

Larger heat exchangers moving similar amounts of heat.

Ahri Data shows an 026 able to reject 26 kbtuh into 86*F water at EER 16.0. using 8 GPM. An 038 rejects 28 kBtuh under similar conditions at EER 20.1. CFM is a bit higher for the 038, but that alone does not cause the 25% EER increase.

Also in play is the "up to" syndrome: Manufacturers claim "up to" X SEER, Y COP, Z EER for a given line of equipment. Quite often, it is the 3 ton system within a model line that is the steller performer. Other models come close, but the 3T is tops. WF claims 30 EER and 5 COP ffor the Envision line, but the 3T is the best of the bunch by a good bit. This same phenomenon plays out in the air source world, too.

Efficiency seems to really tail off in the higher tonnages, 5 and 6. I assume that is because to maintain "up to" values in the higher tonnages would require larger coils and heat exchangers than is cost feasible, or the cabinets wouldn't fit where often installed.

You are forgetting the need to amortize product development costs, everyhting from manufacturing changes to tech pubs not to mention training for all concerned.

Those are real costs, and it is part of the additional mark up, but if there were real competition in this market, that cost would be a couple of hundred dollars, not thousands.  Potentially, a VFD driven compressor could lead to lower cost components in the remainder of the system, but still offer greater efficiency.

A lot of the development cost has already been borne by the compressor manufacturer, and Danfoss already has tons of experience in both the industrial VFD market and in variable speed/capacity refrigeration systems.

In the meantime, I wonder if you couldn't achieve the same energy performance at a drastically reduced price through a combination of older, simpler technologies.

It's too bad none of the Asian manufacturers have gotten serious about pairing their VFD compressor units with traditional US style central air handlers.  Daikin has some offerings, but they don't seem to be serious about it, at least not in deep AC country down here.

Do you know if anyone other than AAON is implementing any version of the Copeland Digital Scroll?

If geo enjoyed half the sales (rather than a tiny percentage) of air source equipment then we could expect the cost premium for true variable capacity systems to be hundreds, rather than thousands of dollars

The premium for Carrier's GreenSpeed systems over their second best SEER 19 offerrings is much lower than WF's differential, but I expect Carrier will move many times WF's volume.

Posted By tigerfan6 on 29 Jul 2012 05:34 PM

1) In the meantime, I wonder if you couldn't achieve the same energy performance at a drastically reduced price through a combination of older, simpler technologies.

It's too bad none of the Asian manufacturers have gotten serious about pairing their VFD compressor units with traditional US style central air handlers.  Daikin has some offerings, but they don't seem to be serious about it, at least not in deep AC country down here.

Do you know if anyone other than AAON is implementing any version of the Copeland Digital Scroll?

1) One can raise COP by raising EWT. A significant jump however might require hundreds of feet of loop adding thousands to the cost so I don't know about the "drastically reduced cost".

2) Daiken is very serious about their offerings, large units however cost a ton of money. One could buy a decent furnace and air package for the cost of their 3 ton 19 SEER split.

1) One can raise COP by raising EWT. A significant jump however might require hundreds of feet of loop adding thousands to the cost so I don't know about the "drastically reduced cost".

It's an off the cuff remark.  I live in AC country and my perspective is AC performance, not heat pump performance, but I suspect that a combination of technologies such as desiccant dehumidification with waste heat recovery to regenerate the desiccant, downsizing AC unit due to reduced latent loads, evaporative subcooling (or even ground loop subcooling), and, of course, building envelope improvements to lessen load in the first place could produce a similar building energy usage for less money, but, it's not really an apples to apples comparison, more of a dollars to dollars one.

2) Daiken is very serious about their offerings, large units however cost a ton of money. One could buy a decent furnace and air package for the cost of their 3 ton 19 SEER split.

They are virtually unheard of down here on the Alabama Gulf Coast.

VFD's are absolutely the key to a high performing vapor compression air conditioner to meet widely varying load demands, but the cost premium, to me, is excessive for what amounts to $300 of throw away power electronics, neglecting the cost of that PWM expansion valve.  You can't repair most modern printed circuit boards and the power electronics are almost certainly non-servicable in residential size equipment, so it's not like there's got to be all this training to service the VFD, it's a throwaway component.  Plus, in addition to the real cost of that VFD being small, the manufacturer is also able to use a less expensive and more robust (i.e., lower warranty cost) three phase motor, plus could probably get away with decreasing the size of the heat exchangers to meet a given SEER performance, both of which should reduce the cost premium.

All that doesn't mean I don't want one, or that I wouldn't pay up to get one, just that I think the cost is ridiculous for technology that was ready to go 10 - 15 years ago.

By the way, does anyone have any idea of the amount of  performance increase in these units is due to the PWM expansion valve?  It would seem like a significant opportunity to conserve energy could be realized by adjusting the expansion valve output based on present sensible and latent loads, i.e., warmer coils and more air flow when sensible loads are higher, cooler coils and less air flow when latent loads are higher.

A problem with desiccants is that the temperatures needed to dry them are well above those found in rejected waste heat. As efficiency increases, waste heat is rejected at progressively lower temperatures, often less than 10* above ambient outdoors.

Servicing the variable capacity components isn't the main issue - a combination of throwaway components and on-board diagnostics will direct the tech as to what part likely needs changing. The challenge is getting the equipment sized, installed, ducted, and configured properly in the course of intial installation. Installers rank below service techs at many HVAC companies.

Past attempts at higher efficiency systems have foundered on poor contractor uptake. Many run-of-the-mill contractors scorn the higher end systems and / or fail to install them properly.

I think you have the tail wagging the dog with regard to metering devices. Higher efficiency is garnered by having as little area as possible of the evaporator coil devoted to superheating the refrigerant. Some superheat is needed to prevent the compressor ingesting liquid refrigerant, but improvements in metering devices clamp down on wasteful superheat.

A humidity-aware thermostat that modulates a variable speed ECM blower so as to provide maximum CFM per ton consistent with humidity control maximizes efficiency. Coil temperature follows CFM per ton and thermostat setpoint. The expansion valve tracks the coil temperature occasioned by thermostat setpoint and humidistat-driven CFM / ton adjustments, adding no more superheat than necessary.

PWM expansion valve

The one I'm familiar with is a stepper motor controlled valve. But in either case, they should be ~$100, not thousands.

Posted By tigerfan6 on 30 Jul 2012 11:05 AM
1) One can raise COP by raising EWT. A significant jump however might require hundreds of feet of loop adding thousands to the cost so I don't know about the "drastically reduced cost".

It's an off the cuff remark.  I live in AC country and my perspective is AC performance, not heat pump performance, but I suspect that a combination of technologies such as desiccant dehumidification with waste heat recovery to regenerate the desiccant, downsizing AC unit due to reduced latent loads, evaporative subcooling (or even ground loop subcooling), and, of course, building envelope improvements to lessen load in the first place could produce a similar building energy usage for less money, but, it's not really an apples to apples comparison, more of a dollars to dollars one.

Okay well for AC country, one can raise EER by lowering EWT.........

I am not an HVAC professional, so I don't know all the design constraints of the equipment, but....

I was thinking the Asian style electronic expansion valves were a Pulse Width Modulating design. I can easily see how a stepper design would have some limitations in the rate at which adjustments could be made.

I think you have the tail wagging the dog with regard to metering devices. Higher efficiency is garnered by having as little area as possible of the evaporator coil devoted to superheating the refrigerant. Some superheat is needed to prevent the compressor ingesting liquid refrigerant, but improvements in metering devices clamp down on wasteful superheat.

It sounds like I am adding a degree of freedom to conventional evaporator design processes. I remember the thermodynamics of the vapor compression cycle very well, but we never really got into the mechanical execution of the design, or the control systems.

Posted By engineer on 29 Jul 2012 08:08 AM
Larger heat exchangers moving similar amounts of heat.

Ahri Data shows an 026 able to reject 26 kbtuh into 86*F water at EER 16.0. using 8 GPM. An 038 rejects 28 kBtuh under similar conditions at EER 20.1. CFM is a bit higher for the 038, but that alone does not cause the 25% EER increase.

.

You might be comparing apples and oranges here. I would argue that AHRI Y1 and Y2 data are based on a different EWT, which itself can account for the difference in EER and COP. However, in real life, the loop and therefore the EWT does not drop 9F degrees (heating mode) just because the unit goes into second stage. The only thing which changes is the leaving water temp. In real life, EER and COP does not change much just because the unit goes into second stage. I agree that in general the 3 ton units are the most efficient ones, but the difference is not 25%, but around 7% between 2, 3 and 4 ton units, with the 2 and 4 tons usually pretty equal.

Interesting data coming from the sizing front with the new 7 series. If the Waterfurnace design software is correct, the 7 series requires a bit longer loop (which makes sense since it runs more efficient) but also can carries a much higher load. I just modeled a 51,800 btu/h heating load, where the 4 ton 5 series was the better choice, but the 3-ton 7 series in comparison was able to carry the whole house without only $11 in supplement heat, whereas the same size 3-ton 5 series was at $181 supplement heat. If true, it appears that one could reduce the heatpump size by about a 1 ton using the variable speed 7 series compared to the dual stage heatpumps, which than puts the overall premium price into a new perspective. But again, loopfield size increases, but operational costs came down by $260/annually.

I'll let you know when we have the first 7 Series on the WEL.

Posted By docjenser on 01 Aug 2012 07:10 PM
I'll let you know when we have the first 7 Series on the WEL.

I'll look forward to seeing the interesting data.

Meanwhile, in spite of the blistering hot weather we go through at this time every year here in Dallas, my now 5 year old Envision 3 ton unit continues to hum along just fine at about 27 - 30 KBTU/hr (depending on inside RH%), and my 5 year old Envision 5 ton unit runs at 51 - 53 KBTU/hr, both running first stage only ( see http://www.welserver.com/perl/plot/...UperHr.png .)

Best regards,

Bill

The biggest advantage to the new variable speed units is the ability to zone up to 6 zones on one unit. This is a big game changer where previously we would have to install multiple units to obtain that level of zoning.

One VS unit is a lot less than 2 2-stage units, in respect to equipment cost, and installation.

G.O. Joe