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Old 04-15-2017, 11:58 AM
 
Location: Kailua
8,385 posts, read 10,310,496 times
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Quote:
Originally Posted by pj737 View Post
Who on earth has a "guest" house that runs their ac 24/7 365 days a year? A guest house that is used to house tenants would be the general conclusion from any rational person. Most people don't have guest houses occupied 365 days a year and most people won't run their ac constantly if nobody is actually living in it.

Bottom line is nobody on Oahu has 6 TONS of cooling capacity running 24/7 at 76 degrees in the heat of the summer and only an extra HECO bill of $120/mo to go along with it.
Let's try to explain this to you one more time.

1). The units are on 24/7 - you don't need a parka to enter the home. I seriously doubt the units are blowing out cold air more than a few hours a day, max. And even when you know the units are blowing cold air, which is hard to tell begin with - it isn't a wind tunnel blowing loose objects all over the place. This running "constantly " notion is rather silly.

2). I live across the street from the ocean. Keeping the home with low humidity and not having the salt air attack metal or high humidity impacting the rest of the interior is important to me for just a few dollars a day. I like a bug free home and prefer the lanai/backyard, ocean if I want to be outdoors rather than open windows.

I've shared my model numbers, the vendor/installer, pics - if someone has comparable models (energy efficiency split a/c in a SFH) and can share their data of before/after let's hear it.
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Old 04-16-2017, 12:53 PM
 
921 posts, read 1,448,378 times
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I totally believe whtviper1 here. I've got a split unit too, and they are super efficient. Mine is 11,000 BTU and 800W max (and something like 31 SEER). I can see running it on low constantly and not using that much energy, especially if the outside units have lots of ventilation and in the shade. Plus you guys are just making up excuses to jump on him: if I owned a rental unit, I'd take pictures of the inside and all appliances BEFORE then tenants moved in (and save them on my computer, with backup).

To answer the OP, I live on Kauai and I partly installed my own mini-split, but I didn't buy it here. Plus it was a special solar unit that I ordered on Oahu and had shipped to Kauai ($2100 including shipping, not that expensive, but needed a truck to pick up). First I hired a electrician to run the conduits for the outside unit. On my own, I drilled my cement pad to put in the 4 anchor bolts, wired up the outside unit, then installed the inside part (fairly easy with mounting bracket and 2 holes in the single wall for pipes) and ran the wires and pipes between the units, bending carefully to follow the wall. Then I called a local refrigeration company to check the connections, pull the vacuum and release the refrigerant (the unit is pre-charged). You have to be fairly handy and lifting the units isn't easy (outside unit onto the anchors, inside unit up on the wall), but there isn't anything technical. I found videos on YouTube that explained most of it.

The only thing I didn't have were rubber pads to put under the feet for damping, and the refrigeration guy had that (or you could buy and/or cut them yourself). I also need to buy the box-conduit to cover the pipes on the outside of the house, but after a year, I haven't gotten around to it yet--it's purely cosmetic.

What's special about this unit is that it can take DC input directly from 3 solar panels and not need to use AC (110V) when he sun is shining. It is connected to AC too, so it can run anytime. It is a heat pump as well, so we also use it on those few chilly winter nights (and still very efficient). For the solar, I bought the 3 full-size panels and mounting brackets from Inter-Island Solar in Puhi, and the elctrician (who works for a solar installer) helps me mount them on the lanai roof. He also installed the breaker boxes and shutoff switch for the DC wiring (it's not inverted or tied to the house 110 VAC). All that, panels, mounting hardware, cables, boxes, breakers, and electrician hours was probably 1500. But I could probably run my AC for $20-40 per month instead of $120, so that is around 18-24 months to payoff for the extra solar capability--and then tons of savings.

If you're interested, I ordered from Jerry S. at GreenPath technologies (GreenPath-tech.com) on Oahu.

Full disclosure: after 6 months of use, this unit had a leak and lost its refrigerant, so perhaps the guy I hired didn't do it right, not sure. Jerry came over from Oahu and replaced the coolant line connections, and it has worked since.
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Old 04-17-2017, 01:42 PM
 
Location: not sure, but there's a hell of a lot of water around here!
2,518 posts, read 5,871,295 times
Reputation: 3404
Quote:
Originally Posted by KauaiHiker View Post

Full disclosure: after 6 months of use, this unit had a leak and lost its refrigerant, so perhaps the guy I hired didn't do it right, not sure. Jerry came over from Oahu and replaced the coolant line connections, and it has worked since.
That's why I wondered how a company could install that many split systems in a half day. Four hours doesn't really leave adequate time for a full vacuum test on each unit, and, a unit with 400 psi in it doesn't need much of a leak to fail in a short order.
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Old 04-18-2017, 12:54 AM
 
1,317 posts, read 1,214,128 times
Reputation: 1457
Quote:
Originally Posted by whtviper1 View Post
Let's try to explain this to you one more time.

1). The units are on 24/7 - you don't need a parka to enter the home. I seriously doubt the units are blowing out cold air more than a few hours a day, max. And even when you know the units are blowing cold air, which is hard to tell begin with - it isn't a wind tunnel blowing loose objects all over the place. This running "constantly " notion is rather silly.

2). I live across the street from the ocean. Keeping the home with low humidity and not having the salt air attack metal or high humidity impacting the rest of the interior is important to me for just a few dollars a day. I like a bug free home and prefer the lanai/backyard, ocean if I want to be outdoors rather than open windows.

I've shared my model numbers, the vendor/installer, pics - if someone has comparable models (energy efficiency split a/c in a SFH) and can share their data of before/after let's hear it.
Give me a break. It is 100% impossible to reduce the interior temperature of 1,800 SF of typically built and typically insulated new home on inordinately humid Oahu by 10-12 degrees during the heat of the summer (average summer temp of 86-88 degrees vs 76 degrees thermostat set point) with 460 kilowatt-hours of electricity when you are running 55,000 BTU's of condensers with an efficiency of 16 SEER. It is 100% theoretically impossible unless your home is literally built like a freezer (as I mentioned in my first post on this thread).

You never bothered mentioning what the total bill for the house is. I can guarantee that you have no idea or understanding of the consumption of everything else (outside of AC) and that your AC system is using much more power than you think.

I have dozens of AC systems installed on dozens of rentals and I actually monitor (quarterly) the usage of their AC units. SURPRISE! I have PV on all my rentals; I installed CT's and monitoring equipment (by E-mon et al) on sub panels built exclusively for the AC unit disconnects. So I know exactly what each unit consumes. I've never had to charge tenants for ac use but I installed it just in case there is excessive abuse of the "free electricity".

I have Mitsubishi, Fujitsu and Daikin installed in the rentals and each vary from 16 SEER to 21 SEER. Sadly, your system is at the bottom of the efficiency list (16 SEER) so you overpaid for your system, sorry to say. Even those systems that have a 21 SEER rating still consume FAR MORE electricity than your system that is 25% LESS efficient.

Go on an HVAC forum (HVAC Talk is a good one) and tell them the technical details of your system/house and that you are only using 460kWh/mo. They'll have a frigging field day with you.
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Old 04-18-2017, 01:18 AM
 
1,317 posts, read 1,214,128 times
Reputation: 1457
Quote:
Originally Posted by KauaiHiker View Post
I totally believe whtviper1 here. I've got a split unit too, and they are super efficient. Mine is 11,000 BTU and 800W max (and something like 31 SEER). I can see running it on low constantly and not using that much energy, especially if the outside units have lots of ventilation and in the shade. Plus you guys are just making up excuses to jump on him: if I owned a rental unit, I'd take pictures of the inside and all appliances BEFORE then tenants moved in (and save them on my computer, with backup).

To answer the OP, I live on Kauai and I partly installed my own mini-split, but I didn't buy it here. Plus it was a special solar unit that I ordered on Oahu and had shipped to Kauai ($2100 including shipping, not that expensive, but needed a truck to pick up). First I hired a electrician to run the conduits for the outside unit. On my own, I drilled my cement pad to put in the 4 anchor bolts, wired up the outside unit, then installed the inside part (fairly easy with mounting bracket and 2 holes in the single wall for pipes) and ran the wires and pipes between the units, bending carefully to follow the wall. Then I called a local refrigeration company to check the connections, pull the vacuum and release the refrigerant (the unit is pre-charged). You have to be fairly handy and lifting the units isn't easy (outside unit onto the anchors, inside unit up on the wall), but there isn't anything technical. I found videos on YouTube that explained most of it.

The only thing I didn't have were rubber pads to put under the feet for damping, and the refrigeration guy had that (or you could buy and/or cut them yourself). I also need to buy the box-conduit to cover the pipes on the outside of the house, but after a year, I haven't gotten around to it yet--it's purely cosmetic.

What's special about this unit is that it can take DC input directly from 3 solar panels and not need to use AC (110V) when he sun is shining. It is connected to AC too, so it can run anytime. It is a heat pump as well, so we also use it on those few chilly winter nights (and still very efficient). For the solar, I bought the 3 full-size panels and mounting brackets from Inter-Island Solar in Puhi, and the elctrician (who works for a solar installer) helps me mount them on the lanai roof. He also installed the breaker boxes and shutoff switch for the DC wiring (it's not inverted or tied to the house 110 VAC). All that, panels, mounting hardware, cables, boxes, breakers, and electrician hours was probably 1500. But I could probably run my AC for $20-40 per month instead of $120, so that is around 18-24 months to payoff for the extra solar capability--and then tons of savings.

If you're interested, I ordered from Jerry S. at GreenPath technologies (GreenPath-tech.com) on Oahu.

Full disclosure: after 6 months of use, this unit had a leak and lost its refrigerant, so perhaps the guy I hired didn't do it right, not sure. Jerry came over from Oahu and replaced the coolant line connections, and it has worked since.

So let me try to make sense of your post. Viper installs 55,000 BTU of air conditioning capacity; you install 11,000 BTU of air conditioning capacity. Your system is 1/5 the size of Viper's. Viper's system is 5X larger than yours. I think we have a good understanding of that.

But then it gets bizarre...

You state that your 11,000 BTU ac system will consume the same amount of electricity ($120/mo) as Viper's 55,000 BTU ac system before you add in those 3 solar panels. So a system that is 5 TIMES larger than your system, which is on 24-7 during the heat of the summer will consume the same amount of electricity?

It gets even more bizarre... you then say after installing 3 solar panels you believe your ac unit will only consume $20-$40/mo... or that those 3 panels are saving you $80-$100 per month in electricity costs.

But in reality, a solar panels (assuming 300W each) will save a theoretical maximum of $30/mo in a high solar insolation area on Oahu and that's if every single watt-hour generated by the panels actually gets utilized. In order for you to get the same value of those panels, as let's say a grid-tied PV panel tied to a system approved by HECO's now defunct NEM program, the ac system MUST BE on ALL day, EVERY day, 365 days/year (when the sun is shining). And even assuming it was on full blast (i.e. compressor on 100%, fan on full blast, ac cranking away from 8 a.m. to 4 p.m. non-stop) you are only going to save $30/month - not $80-$100/mo. Clearly you have been fed some nonsense by the snake oil sales people that push that garbage product.
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Old 04-18-2017, 03:14 AM
 
Location: Kailua
8,385 posts, read 10,310,496 times
Reputation: 3800
Quote:
Originally Posted by pj737 View Post

You never bothered mentioning what the total bill for the house is. I can guarantee that you have no idea or understanding of the consumption of everything else (outside of AC) and that your AC system is using much more power than you think.
I hadn't bothered since nobody asked.

Summer runs about $220-$240/month - winter abou $180/month.

Before install bill ran about $120/month
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Old 04-18-2017, 08:00 AM
 
Location: not sure, but there's a hell of a lot of water around here!
2,518 posts, read 5,871,295 times
Reputation: 3404
Quote:
Originally Posted by pj737 View Post
So let me try to make sense of your post. Viper installs 55,000 BTU of air conditioning capacity; you install 11,000 BTU of air conditioning capacity. Your system is 1/5 the size of Viper's. Viper's system is 5X larger than yours. I think we have a good understanding of that.

But then it gets bizarre...

You state that your 11,000 BTU ac system will consume the same amount of electricity ($120/mo) as Viper's 55,000 BTU ac system before you add in those 3 solar panels. So a system that is 5 TIMES larger than your system, which is on 24-7 during the heat of the summer will consume the same amount of electricity?

It gets even more bizarre... you then say after installing 3 solar panels you believe your ac unit will only consume $20-$40/mo... or that those 3 panels are saving you $80-$100 per month in electricity costs.

But in reality, a solar panels (assuming 300W each) will save a theoretical maximum of $30/mo in a high solar insolation area on Oahu and that's if every single watt-hour generated by the panels actually gets utilized. In order for you to get the same value of those panels, as let's say a grid-tied PV panel tied to a system approved by HECO's now defunct NEM program, the ac system MUST BE on ALL day, EVERY day, 365 days/year (when the sun is shining). And even assuming it was on full blast (i.e. compressor on 100%, fan on full blast, ac cranking away from 8 a.m. to 4 p.m. non-stop) you are only going to save $30/month - not $80-$100/mo. Clearly you have been fed some nonsense by the snake oil sales people that push that garbage product.

That's not what he said. And, the idea behind solar, in my opinion, is that one 300 watt panel will replace one barrel of crude oil in about 4 years, given that the panel produces 1.5 KWH per day, 300 days a year, and a barrel of light, sweet, but oh so crude, is 1,700 KWH of potential energy.
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Old 04-18-2017, 10:26 AM
 
1,317 posts, read 1,214,128 times
Reputation: 1457
Quote:
Originally Posted by Jungjohann View Post
That's not what he said. And, the idea behind solar, in my opinion, is that one 300 watt panel will replace one barrel of crude oil in about 4 years, given that the panel produces 1.5 KWH per day, 300 days a year, and a barrel of light, sweet, but oh so crude, is 1,700 KWH of potential energy.
That's exactly what he said -

Quote:
Originally Posted by KauaiHiker View Post
But I could probably run my AC for $20-40 per month instead of $120, so that is around 18-24 months to payoff for the extra solar capability--and then tons of savings.
Agreed that solar panels are wonderful wonderful things. I have 30 of them on my own home. But I have a problem with companies misleading people into thinking that a solar panel attached to a stand-alone air conditioning system can have a payback that is 3 times better than solar panels attached to a home's electrical system when in truth the payback is far worse. Solar panels attached to a stand-alone ac system are only providing any value IF the AC system is on and on full blast. Otherwise the potential power generation of the panel is wasted.

Think of it this way, the AC unit will cool the interior of your home (i.e. turn on or off or provide variable cooling output) based on the thermostat setting inside the home - not the output of the solar panel. If a cloud passes by when the AC system cycles on (because the thermostat inside triggers the compressor to kick on) the power from the solar panel at that time is useless because it's insufficient to run the compressor. Then, should the cloud pass and sun come out and your AC system is cycled off (i.e. room met set point temp for comfort) the power generated by the solar panel is completely wasted. If the solar AC system was designed to cool based on the input of the solar panel, that would provide for a higher solar panel utilization rate... but we all know that would be a very uncomfortable home because the temperature inside would vary wildly and would not be consistent.

I've seen the solar AC products out there as I expressed some interest initially. It seems like a great idea on the surface. But all the companies pushing them are misleading customers into thinking they'll pay off in a period of time that is unrealistic.

Further, the actual solar powered AC units themselves (not the panels) are inferior compared to solid HVAC products sold by solid, reputable companies like Mitsubishi, Fujitsu, et al. Often times, the SEER rating is reported (by solar AC manufacturers) to be in excess of 30 but in reality, the AC units (when operating without solar input) are generally in the 14-16 SEER range, which is abysmal by today's standards for split units.

Outside of all the bogus marketing and poor technical attributes associated with those solar AC products, there are other concerns like what happens when the solar AC company (both installer or manufacturer) go out of business? Where do you get service? Where do you get parts? Sure anyone can recharge the systems a million times... but what if a part fails and needs replacement... and the company is gone? The actual AC systems themselves (condenser, evaporator, controls) are manufactured by no-name/limited history companies that have a high chance of disappearing before units reach the end of their traditional useful service life (~15 years). And these systems inherently have a higher chance of failure because they have more parts and more controls to accommodate the solar input. More complexity = higher chance of failure. Not rocket science here.

If someone wants AC and solar they should install a traditional AC system and a traditional solar PV system but one with a battery back up (since NEM is now gone). That way the solar panels can at least provide power to other electrical needs of a home and not just sit there on the roof doing nothing when the AC is off or not in cooling mode. That solar power can also be utilized in the evening. And being able to run a home in a power outage is a nice plus.
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Old 04-18-2017, 11:59 AM
 
168 posts, read 93,013 times
Reputation: 205
Quote:
Originally Posted by whtviper1 View Post
I hadn't bothered since nobody asked.

Summer runs about $220-$240/month - winter abou $180/month.

Before install bill ran about $120/month



Just out of curiosity and this being a guest house, how may days a year do you expect it to be occupied?


We have no A/C (don't really need it where we live) and a family of 2+/- (depending on grandkids, drop-ins, etc. ), our year round occupied home averages approximately $130/month in electrical costs. Averaging about 430 KwH/month.
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Old 04-18-2017, 03:12 PM
 
Location: Kailua
8,385 posts, read 10,310,496 times
Reputation: 3800
Quote:
Originally Posted by Rain Monkey View Post
Just out of curiosity and this being a guest house, how may days a year do you expect it to be occupied?


We have no A/C (don't really need it where we live) and a family of 2+/- (depending on grandkids, drop-ins, etc. ), our year round occupied home averages approximately $130/month in electrical costs. Averaging about 430 KwH/month.
It'll be occupied most of the time - mostly between very elderly in-laws who live in Mililani - or my not as elderly retired parents when they come in for extended stays - or other mainland friends,etc. If I pegged a number to it, I'd say 80% of the time over the course of the year.

The bill is kept lower by solar hot water and thus far no kids in the house.
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