11-01-11, 05:31 PM | #21 |
Lex Parsimoniae
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Our cooling is awesome. One unit cooled the whole house this past summer.
We did have a few hot spells. But, a few days in the 90s is nothing compared to AZ.. You can get older tech non-inverter units.. They are cheaper and less efficient. Low SEER, with fixed speed compressors. Nothing you want. Some modern hi SEER units can run in a 'Quiet' mode. Or in low fan.. That allows them to run very quietly.. Most of the time, you can't tell when the are on. Even the outdoor units are low noise.. Here's the only good pic of a remote I could find on-line.. Mine looks much better..(More buttons).. |
11-01-11, 06:14 PM | #22 |
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I was thinking the Sanyo 2 ton unit would be more than enough to cool the master bedroom & bath. Most likely I'll breakdown and get the software to do a heat load calculation. Maybe I'll get lucky and the mini splits will get even better.
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11-01-11, 08:58 PM | #23 |
Lex Parsimoniae
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If it's 35'x40' two tons should work..
Depending on the amount of insulation and glass. SEER makes a difference too.. |
11-02-11, 09:53 AM | #24 | |
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Quote:
But if you include the bathroom area, which is open to the master, then the larger unit might be needed. Have to do some measuring! Plus the bath has a glass block wall, which is pretty, that does a poor insulating job compared to a regular window. |
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11-02-11, 12:05 PM | #25 |
Lex Parsimoniae
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My large room is the Den, 18x16=288 sqft
http://i46.photobucket.com/albums/f1.../9784_9784.jpg So, a 7k BTUhs would likely do the cooling. Due the 100 sqft of glass (none of it southfacing), I think 12k-14k is needed for heating.. I wanted to buy a small 9-10k mini-split.. But my wife was okay with cleaning out the garage and using the old 24k in the den.. So, it's about twice what we need. The heating is super fast (when it's in the 30s) and I figure the cooling will be ultra-fast. We had a light layer of ice on the ODU coils this morning, so I did a manual defrost. Put both units into cooling mode for about 4 minutes. The IDU coils got down to the 20s real fast. They quickly sucked enough heat outdoors to completely clean up both units.. Switched them back to heat mode and watched them both start running more efficiently. I'm going to try to get a low temp/dew-point alarm system going. So, it can tell me when things are icing up. Otherwise I am going to need come video cams out there.. |
11-02-11, 08:04 PM | #26 |
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It seems there is some value to "over sizing" the mini split heat pump. How much "extra" does it cost to run an over sized, say 3 ton vs 1.5 ton unit. The enjoyment of faster temperature recovery cannot be directly measured, but does have significant value to those who are always too cold or too hot.
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11-02-11, 09:05 PM | #27 |
Lex Parsimoniae
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I'm not sure. I've only used a couple of 2 ton units.
One thing that I have noticed in the den, is a pretty short warming cycle, when it's mild out. Yesterday and this afternoon, I noticed the ODU fan only ran for 30-50 seconds before shutting down. On the TED power monitor, it shows 30-60 watts, then creeps up to 450-480 for 30-50 seconds and then back to 30-60 watts again.. The remote's heat sensor is enabled, and the remote only sends it's data once every 5 minutes. So, when it's mild, I guess the system must be using it's IDU heat sensor to keep it from over-heating the room. Or, maybe an increase in heat to the remote, will trigger it to send a data bust earlier than normal.?. When the ODU shuts down, the IDU fan stays on a while, since the coil is still warm. After the coil cools down some it switches to super-slow-flow. It uses super slow to slowly move air past the built in thermistor. It's also slowly filtering the air in the room. Sanyo#1 is heating a much larger space, and runs longer, when it comes on. Maybe 4 or 5 minutes on mild days. But it might stay off longer too. ~~ Anyways, the Sanyo can throttle WAY back and work like a little 4k BTU wall AC, but not use that much power..(300-480 watts). http://i46.photobucket.com/albums/f1...L/poweruse.jpg So, if you do get one too big, you should not end up using excessive power. You should look at the specs of the units.. I think there might be a low end, where you can't use any less power and still be pumping refrigerant. I'm amazed to see my both units cranking out some good heat in the morning, running at 900 watt total. Then it gets warm and they slow down.. 60watts total in idle mode.. (Heaters on the crankcases). |
12-31-11, 06:11 PM | #28 | |
Lex Parsimoniae
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Scraping the transistor for a 555 timer chip..
Quote:
After months of careful deliberations, I've decided to change my design. I will connect the current sensor to (pin2) trigger the 555 timer. Over-Current: The output (Pin 3) of the 555 (connected to the cathode of the SSR dc control) will go high, turning OFF the SSR for a controlled time period. I was thinking of selecting C1 & R1 for a 5 minute time delay. I want to make this change, in case there is a failure in the Sanyo controller, that causes it not to reset, but to go nuts drawing excessive power.. In that case, a timer would insure there was no relay chatter or Low frequency 230vac Buzzz! Which, could generate a lot of heat.. Defrost Speed Control: A 5 minute cooling off period, combined with the 5 minute delay built into the remote, might slow down a Defrost cycle, but should allow it to be done using less power. Comments?
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01-02-12, 04:34 AM | #29 |
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Xringer, the point of these is to stop the units from drawing excessive current during defrost or temp change calls from the thermostat right? What does Sanyo say about these spikes? Are they over the rated electrical consumption of the Minisplits? I feel like somewhere I've read that inverter driven units can run up to 120% as a "Boost" if need be, could that be what your units are doing, and thus totally normal/unharmful? Does this actually use more power than if it were to run at a normal load for a longer amount of time since it would achieve setpoint sooner and go into idle mode sooner?
Just trying to gain a little understanding because I find this interesting, Adam |
01-02-12, 08:41 AM | #30 |
Lex Parsimoniae
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Yeah, I'm limiting the current to around 10A (around 2.4 kW) since the spike
wants to run up over 3.5 kW. (about 15A). The last time I inquired, Sanyo USA didn't seem to know what do to. Their expert told me to have the charge pulled and weighed. They might even think it's okay to pull that kind of power.. Supposedly, there is already protection in the unit, to limit power to 5 kW.. (Why use 22.5A, when the max breaker they list is 20A)??? I obtained a 15A breaker, but the dang thing wouldn't trip.. I guess regular electromechanical breakers need a big overload to trip.?. They rate them, so they can take the huge Start current of the old tech HVAC systems.. That seems very odd, since the Compressor Locked Rotor is 17.5 amps. As you can see, the system is rated for a max of 13.5A and that's just a tad over 3 kW.. So, IMHO going over 3.5 kW isn't where it should be operating. Is it harmful? I'm not sure. But, I wouldn't want to try running my Ford Escape at 150 MPH for very long.. I suspect that very high pressure occurs in the R410A output line of the compressor, when power use exceeds 3.5 kW.. I also suspect that high pressure blew a hole in the output line, on my original ODU. http://ecorenovator.org/forum/geothe...html#post13279 I have a few theories about why this problem is occurring. #1 The control firmware is NG. Programming mistake. Maybe the marketing guys told the engineers to add a big boost of heat for the North American market, since Americans must have instant heat, or they won't buy a Sanyo.. So, it was hastily done. The Big Boost function wasn't fully tested. Maybe they only had 208VAC in their lab at the time?? Maybe their test unit didn't self-destruct? (Tested for 2 hours)? I've just learned to accept the system, warts and all. The work-around ,was to carefully watch power use and hit the off button, when power started shooting up to 3.5 kw.. Adding an automatic power limiter means I don't have to get up at 3AM to press the off button..
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