Solar Assisted A/C

[tipsrfine]

I can't access that thread, anything of use in there to me?

I'd really like to find anyone else that has/had one of these things and find out what they did to resolve their issues with the manufacturer.

Also, I really wished I had looked "under the hood" to realize I was paying extra to blow up compressors and void warranties.

Actually, you are the only person I've been able to find. I've been looking all over the internet for reviews or third party testing/verification=-nothing. I did find one BBB review that gave them a C. The C was due to a complaint and also because the BBB had requested info on how the system works and the company never complied. So far I would say it is looking like the others here may be right. I have sent an e-mail to the company and am going to try and phone them to see if they can provide any additional info.

[Bobberly]

If the condensing unit is a standard item - how does it reject all the solar added heat?

Why does the condensing of refrigerant start at the beginning of the condenser?

Where is this working unit on display?

In our Miami Distribution Center our display unit a 12,000 Btu (split model) is cooling a 15x20 (300 sq feet) room with a 90° ambient outside temperature it is drawing 2.71 total running amps (the inside air temperature drawn in is 75°F and the out flow air temperature is 46°F)…a 29°F difference!

I had to reverse engineer some numbers out of my CurrentCost unit since I didn't have a clamp meter on the compressor, but these are my own observations of power usage with no collector.

36,000 btu split
1150 sq ft house (also factor in 4 desktop computers and 2 servers running 24/7)
90-95 ambient outside
~75 at the return/thermostat
~55 at nearest register
Base power draw of the house = 1400 watts
State 1 cooling + air handler = 2800 watts ( 1400 watts / 5.8 amps estimated)
Stage 2 cooling + air handler = 3900 watts ( 2500 watts / 10.4 amps)

Again, those numbers are with the air handler and no collector. I'm working on extracting my numbers from earlier in the year when the collector was still attached.

[Shophound]

Actually, you are the only person I've been able to find. I've been looking all over the internet for reviews or third party testing/verification=-nothing. I did find one BBB review that gave them a C. The C was due to a complaint and also because the BBB had requested info on how the system works and the company never complied. So far I would say it is looking like the others here may be right. I have sent an e-mail to the company and am going to try and phone them to see if they can provide any additional info.

Here's a fallback position for you to consider the next time you come across something like this that on the surface seems novel and promising, but in reality is smoke and mirrors:

Ask yourself why no established OEM has already thought of it and brought it to market. Most, if not all major HVAC manufacturers certainly have the R&D capital and know-how to do so.

One might say, "They're just too conservative; only renegade innovators come out with something like this solar powered a/c."

Lennox did come out with a solar powered a/c. They just happened to leave the refrigeration circuit out of it and go with PV powering the condenser fan.

"Well, they're just playing it safe, then. Why not use the sun to do the work of the the compressor?" Because the sun in this case isn't compressing anything.

This is one reason among many why those of us in this HVAC trade really need to understand refrigeration theory. If you know your theory in all aspects (not just refrigeration) of HVAC, you'll smell a rat a mile away.

[tipsrfine]

Hey Shophound, I'm not completely understanding you on this. This sedna thing seems to be basically based on an absorption chiller, and the only major difference is that it is using solar heat to replace the flame heat. Can you explain what your major point is a little clearer for me? It almost seems you are saying an absorption chiller system is bogus, which I know you are not.

[stonewallred]

Here's a fallback position for you to consider the next time you come across something like this that on the surface seems novel and promising, but in reality is smoke and mirrors:

Ask yourself why no established OEM has already thought of it and brought it to market. Most, if not all major HVAC manufacturers certainly have the R&D capital and know-how to do so.

One might say, "They're just too conservative; only renegade innovators come out with something like this solar powered a/c."

Lennox did come out with a solar powered a/c. They just happened to leave the refrigeration circuit out of it and go with PV powering the condenser fan.

"Well, they're just playing it safe, then. Why not use the sun to do the work of the the compressor?" Because the sun in this case isn't compressing anything.

This is one reason among many why those of us in this HVAC trade really need to understand refrigeration theory. If you know your theory in all aspects (not just refrigeration) of HVAC, you'll smell a rat a mile away.

Just as as thought, what does a compressor do? It changes a low temp, low pressure gas into a high temp, high pressure gas, IIRC.

Now since the sun adds a heat source, which heats the refrigerant, and due to pressure equaling temperature in refrigerant, shouldn't enough heat from the sun cause a low temp, low pressure gas to become a high temp, high pressure gas?

The pumping part I ain't getting right now, as I can't see how the gas doesn't flow in both directions, and even a check valve wouldn't work as the hot side is always going to have more pressure than the cold side.

[Shophound]

Hey Shophound, I'm not completely understanding you on this. This sedna thing seems to be basically based on an absorption chiller, and the only major difference is that it is using solar heat to replace the flame heat. Can you explain what your major point is a little clearer for me? It almost seems you are saying an absorption chiller system is bogus, which I know you are not.

It's not an absorption system. Absorption chillers use lithium bromide as a refrigerant. Sedna is claiming they use R407C, an HFC refrigerant with a notable temperature glide. Check out the bubble and dew points of that refrigerant vs. R-410A or R-22.

Vapor compression refrigeration, which Sedna is claiming to enhance with their solar component, depends on two points of pressure separation to function correctly. You need a metering device and a compressor. The metering device separates high pressure from low pressure. The compressor takes low pressure and makes it become high pressure. It also simultaneously maintains a barrier between low and high pressure.

If you bypass the compressor and use the solar device alone, you don't have that wall of separation the compressor provides anymore. Refrigerant heated by the sun will pressurize the entire system until some measure of equilibrium is established. True, with an indoor blower and outdoor blower running there may be some convective flow, but I'm doubtful it's of sufficient mass flow to provide adequate refrigeration.

The compressor's advantage is that it provides a fixed pumping capacity, 24/7. While it's not always pumping at nominal capacity, it is always pumping steadily. The solar device claims to do this by having its tubes surrounded by soybean oil as thermal storage. I'm doubtful. I'm not sold the solar device can even move the refrigerant in enough quantity to get the work done.

Until I see operating system pressures on one of these things in operation with just the solar device providing motion to the refrigerant (compressor off), we're missing a huge chunk of essential data to judge this thing as worthy.

[Shophound]

Just as as thought, what does a compressor do? It changes a low temp, low pressure gas into a high temp, high pressure gas, IIRC. That's right.

Now since the sun adds a heat source, which heats the refrigerant, and due to pressure equaling temperature in refrigerant, shouldn't enough heat from the sun cause a low temp, low pressure gas to become a high temp, high pressure gas? You'd think it would. But, as I note in my reply to Tips, how does this arrangement prevent the high pressure, high temperature gas from backfeeding all the way into the evaporator?

The pumping part I ain't getting right now, as I can't see how the gas doesn't flow in both directions, and even a check valve wouldn't work as the hot side is always going to have more pressure than the cold side. The gas will flow in both directions. That's the problem. A compressor does not let this happen. That's why a recip compressor has valves and scrolls have check valves. A centrifugal compressor is an exception, but when reverse flow happens through a centrifugal, it's not pretty. It's called surging and it can tear a centrifugal compressor apart. But I digress.

I think you're seeing what I'm seeing, here.

[Poodle Head Mikey]

Was anyone awake though their entire Thermodynamics Class? If so; whatever you managed to retain from it is now apparently useless:

"The basic Sedna thermodynamic process is not a conventional thermodynamic cooling process based on Charles Law. Instead, it is based on evaporation, carrying heat, in the form of fast-moving (hot) molecules from one material to another material that preferentially absorbs hot molecules."

Apparently down an alternate reality hallway was the Sedna Thermodynamics Class which this guy attended.

I guess we should have all chosen our course load just A Little More Carefully, eh?

PHM
-------

I can't access that thread, anything of use in there to me?

I'd really like to find anyone else that has/had one of these things and find out what they did to resolve their issues with the manufacturer.

Also, I really wished I had looked "under the hood" to realize I was paying extra to blow up compressors and void warranties.

[Shophound]

Was anyone awake though their entire Thermodynamics Class? If so; whatever you managed to retain from it is now apparently useless:

"The basic Sedna thermodynamic process is not a conventional thermodynamic cooling process based on Charles Law. Instead, it is based on evaporation, carrying heat, in the form of fast-moving (hot) molecules from one material to another material that preferentially absorbs hot molecules."

Apparently down an alternate reality hallway was the Sedna Thermodynamics Class which this guy attended.

I guess we should have all chosen our course load just A Little More Carefully, eh?

PHM
-------

Yep, that line about "hot molecules" is one of the bigger loads of horse hockey I've smelled lately.

Molecular motion is not "hot" or "cold". Molecular motion itself is what temperature is measuring.

From a note I made to myself when working my way through the RSES Technical Institute Training Manual #1, Lesson 4, Gas Laws (Part 1):

"Charles' law: if the volume of a gas remains constant, the absolute pressure of a gas varies as the absolute temperature varies (change in pressure occurs at same rate as change in temp)."

Show me why Sedna is exempt from a dead scientist's law.

[tipsrfine]

I've invited the inventor of the system to come here and answer some of our questions, so he has his opportunity to explain. If he chooses not to do so, I will conclude this system is just a bogus situation. That's a shame, 'cause I was really liking the concept.

[Shophound]

[QUOTE=tipsrfine;10997672]I've invited the inventor of the system to come here and answer some of our questions, so he has his opportunity to explain. If he chooses not to do so, I will conclude this system is just a bogus situation. That's a shame, 'cause I was really liking the concept.[/QUOTE]

Sometimes you gotta go Vulcan on stuff like this. Try to become a bit dispassionate and analyze your way through the thing thorougly. Once you reach your conclusion you can then cancel Vulcan mode and either become the biggest advocate or debunker, based on what you find out. But becoming attached to something before thoroughly investigating it can lead you to miss crucial aspects you need to be looking out for.

[Fabrk8r]

New and Improved!!!

Snake Oil now available in GREEN!

[Bobberly]

New and Improved!!!
Snake Oil now available in GREEN!

(emphasis removed)

This ^^ doesn't help the thread. I know the manufacturer has been made aware of this discussion and is probably following.

I asked in my first message about pressures to fittings (which no one has responded to) and try and make sense of where things went wrong. Prior to this I had been a happy customer enjoying an electrical drop of 15% based on when I had my Goodman 13 SEER 2.5 unit.

The theory now is that the lineset under my slab has been compromised. Without a chisel, there isn't a way for me to verify this, so my next solution is to replace the system with a non-solar model and run new copper.

While I've asked the dealer to take the system back I may end up with this stuff sitting in my garage. Again, anyone in Central Florida with time to experiment to sway the vote would be great. We may even be able to get the manufacturer to sanction the tests.