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Old 11-13-14, 09:27 AM   #201
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Quote:
Originally Posted by theoldwizard1;41673...I still think any one north of the 40th parallel can not rely on an air-sourced heat pump as their [U
primary[/U] heat source 12 months a year. Either it has to be ground-sourced or have an alternative heat source for 3-4 months of the year.
I'm a total GSHP advocate and I am grudgingly using a mini-split while my GSHP project creeps forward. But...

With all due respect Old Wizard, your statement could be out of date.

I think your estimate if Mini-Split performance is still based on performance of 1st Gen ASHP.

The Asians have done their homework. There has been a quantum leap.

These things can deliver useful heat down to 5 F.

There have been extensive discussions on EcoRenovator over the last 4 or 5 years on the topic of Mini-Splits, with performance reports from users all over the country.

Backup heat is always a good idea, but mini-splits are quite amazing, and more capable than you might think.

Also, if you do a bit of research, you will find, as I did, that there is a drop-off in performance of multi-head units. The more heads, the lower the COP.

Better to go with discrete units, if efficiency is a concern.

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Old 11-13-14, 07:41 PM   #202
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Originally Posted by theoldwizard1 View Post
Mini-splits are CLEARLY the wave of the future for most parts of the US ! With 3 or 4 heads and between room air flow it should easily handle a 1500 sq ft home.

I still think any one north of the 40th parallel can not rely on an air-sourced heat pump as their primary heat source 12 months a year. Either it has to be ground-sourced or have an alternative heat source for 3-4 months of the year.
From someone near the 40th parallel, I can kinda agree with you, but there are exceptions to everything.

The big issue is winter time defrost drain freezing up. The only fix is a drain pan heater which knocks the efficiency numbers down quite a bit.

However, with enough units and well sealed/insulated home, you can get by. My unit never stopped working last winter, even down to -20 outdoors, but it did go into defrost mode quite a bit at that temp. Backup electric heat units or panels are very cheap hardware to makeup for those extreme temps.

Price wise it depends on your electric costs, and where natural gas pricing hovers if you have access. I'm in a high nuclear and wind area so my electricity costs less than dirt, currently 2.2cents per Kwh. Right now many have access to cheap natural gas that a mini split has a hard time competing with in the dead of winter, and the near instant 'hot' heat of natural gas furnaces can be a benefit. There is no way to leave a a mini split heater off during the day to save money and jump the thermostat when you get home, as it will take quite some time to come back up, similar to in-floor hydronic heating.

Not many people with real winters go it alone with a mini-split, so there are some extremes that most don't report, like say the noise issues with the indoor coil expansion/contraction as it shifts from defrost to heat constantly during brutal cold spells or the drain pain freezing, or the chill of long defrost modes if you have no other heat source going during cold spells.
It has been quite an experiment here in my 900 sq ft home.
The financial savings are the only thing making it bearable. The A/C and dehumidification aspect are wonderful and super cost efficient.

I also miss the central hvac based humidifier for winter time. Now I'm back to a manual fill the bucket every day model. I would like to have the central hvac filter system back too as it seems to do a more thorough job than a standalone unit I now resort too. I definitely don't miss the hvac maintenance.
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Old 11-13-14, 08:05 PM   #203
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It really does seem like my climate is much better suited for a Mini split. People in FL and lower TX must love them because they do so well in AC mode.
I would say 98% on the time they do really well here. We have natural gas backup heat.
We are home all the time I work from home so no need to turn up/down AC or heat here.

this gives us the ability to use our solar power for heat a big win for us.
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Old 11-13-14, 08:08 PM   #204
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Originally Posted by ctgottapee View Post
From someone near the 40th parallel, I can kinda agree with you, but there are exceptions to everything.

The big issue is winter time defrost drain freezing up. The only fix is a drain pan heater which knocks the efficiency numbers down quite a bit.

However, with enough units and well sealed/insulated home, you can get by. My unit never stopped working last winter, even down to -20 outdoors, but it did go into defrost mode quite a bit at that temp. Backup electric heat units or panels are very cheap hardware to makeup for those extreme temps.

Price wise it depends on your electric costs, and where natural gas pricing hovers if you have access. I'm in a high nuclear and wind area so my electricity costs less than dirt, currently 2.2cents per Kwh. Right now many have access to cheap natural gas that a mini split has a hard time competing with in the dead of winter, and the near instant 'hot' heat of natural gas furnaces can be a benefit. There is no way to leave a a mini split heater off during the day to save money and jump the thermostat when you get home, as it will take quite some time to come back up, similar to in-floor hydronic heating.

Not many people with real winters go it alone with a mini-split, so there are some extremes that most don't report, like say the noise issues with the indoor coil expansion/contraction as it shifts from defrost to heat constantly during brutal cold spells or the drain pain freezing, or the chill of long defrost modes if you have no other heat source going during cold spells.
It has been quite an experiment here in my 900 sq ft home.
The financial savings are the only thing making it bearable. The A/C and dehumidification aspect are wonderful and super cost efficient.

I also miss the central hvac based humidifier for winter time. Now I'm back to a manual fill the bucket every day model. I would like to have the central hvac filter system back too as it seems to do a more thorough job than a standalone unit I now resort too. I definitely don't miss the hvac maintenance.
Take a look at the new PTAC units and mini-split units that have come out recently. I believe these are a 4th or 5th generation, heat pump centered set of units. Many of the issues with energy wasting, whooshing sounds, ticking, clicking, being impossible to program, low ambient suffering,and such have been dealt with quite well. A decent portion of these units have electric expansion valves and big outdoor heat exchangers in them.

Lots of them have separate functions for different needs/goals. COP in heating between 3 and 5 down to 20 degrees F. Cold-buster hyper-heat turbo-blast function that spins inverter at 120% rpms and bypass pulses the evap coil with hot fog for more mass flow. Blow lots of 80 degree air at high efficiency. Don't blow air until the hx is above 90 degrees to avoid 80 degree airblow. Control it from your iphone at will. These units have come a long way in a short time.

That being said, expecting full capacity out of any ashp unit below about 25F is going to cost you energy. Either the electric meter runs faster or the heat doesn't come in very warm. The only way around that is a ground source that stays not cold all year long.

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Old 11-13-14, 10:27 PM   #205
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Quote:
Originally Posted by jeff5may View Post
Take a look at the new PTAC units and mini-split units that have come out recently. I believe these are a 4th or 5th generation, heat pump centered set of units. Many of the issues with energy wasting, whooshing sounds, ticking, clicking, being impossible to program, low ambient suffering,and such have been dealt with quite well. A decent portion of these units have electric expansion valves and big outdoor heat exchangers in them.

Lots of them have separate functions for different needs/goals. COP in heating between 3 and 5 down to 20 degrees F. Cold-buster hyper-heat turbo-blast function that spins inverter at 120% rpms and bypass pulses the evap coil with hot fog for more mass flow. Blow lots of 80 degree air at high efficiency. Don't blow air until the hx is above 90 degrees to avoid 80 degree airblow. Control it from your iphone at will. These units have come a long way in a short time.

That being said, expecting full capacity out of any ashp unit below about 25F is going to cost you energy. Either the electric meter runs faster or the heat doesn't come in very warm. The only way around that is a ground source that stays not cold all year long.
I'm using the latest gen Fujitsu model which has all of those features.

It doesn't blow until the heat exchanger warms up, but you still get a cool breeze during defrost (the fan runs at low speed) and no hot air which during a -2 degree outside temp and a long defrost of 5 minutes, you feel it. In fact the fan always runs at low speed.

The pop and crackle of the metal exchanger is typical of most systems, and it's no better or worse. BIg ol radiators and resistive electric wall mounts are not as common in serious winter areas so the noise is something new to get use to.
The issue is the typical wall unit is a large plastic case snapped together. In mild heating needs it's probably not that bad, but during deeper cold spells the dramatic swings in heat output back to long defrost and such really makes the thing crackle. You can simulate it by just holding the unit (when not installed) and twisting it with your hands.
This is a problem for very few, so it's not likely to see effort.
Personally I have doctored my unit in various attempts to quite it, adding buffer velvet to certain rubbing spots, etc.

The energy wasting I was mentioning comes with the outdoor pan heating element at the bottom of the unit. Defrost water collects and freezes there, and plugs the drain holes rather quickly. There is no 'smart' system of detecting such and only defrosting during that time, so the outdoor pan heater runs constantly at temps below 30 degrees, at 120watts which can be all day and night for a couple months during most real winters.
I've tried doctoring my own defrost strip using only 30watts, that runs on a timer, and i only plug it in when I start to see constant under 20degree temps.

There is a cold buster powerful mode, and it does work, but it throws the unit that much more quickly into defrost mode in deep cold so it has it's drawback too, unlike the powerful mode for cooling which you can keep pressing and runs continuously. Plus it sucks the watts obviously.


I think it's darn impressive that it can suck heat out of a 18 degree night like right now, and especially a -15 degree night. The reality is while they have been designed to work down to those extreme temps, they are not designed to operate long in them, so for cost efficiency will lack some necessary functions.
A simple resistive heating element strip that came on during startup or defrost cycles would help with the chills. The pan needs a smart rapid defrost.
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Old 11-14-14, 07:57 AM   #206
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The new zoneline unit I looked at has those functions. The thing only works in heat pump mode down to 26degF, though. I believe it has multiple options for strip heat sizes.
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Old 12-11-14, 10:22 AM   #207
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A couple months ago I installed two Gree 9,000 BTU 27 SEER Terra systems. Now I have three of these systems. They really work well we are very happy with these units. These units work really well in the small bedrooms.

When it is real cold outside the whole house does not seem as cold we don’t have the creeping cold from the bedrooms anymore.

My kids like them but I am still educating them on using them. The other day my boy had the room to hot the heat was turned up to high. He turned it down but then decided to turn on the AC to cool off the room.

It is Dec 11 and we have used no natural gas backup heat so far this winter.
I am sure we keep our house hotter that almost everybody on here. But they have been able to handle it so far.

It is still amazing to me how much heat a heat pump can put out even when the outside temp is 28 out.

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Old 12-11-14, 10:30 AM   #208
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Good to hear things are working well for you. I'll bet the kids love being able to control their own heat..

We are using more power than normal lately. Not very much sun at all.
Days of over-cast, followed by days of rain (basement is flooding now),
followed by snow.. There it is now!
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Old 12-11-14, 10:49 AM   #209
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Sorry about the flooding summer flooding is bad but winter flooding would be really bad.

My boy that likes his room really cold is the summer likes very warm in the winter.
My other son just keeps it set to 68 all the time. I make them both set them to 68 during the day when they are not here. They love their Mini splits and the ability to control their own temps. They keep their doors shut all the time now.

I thought these units might be too big but with inverter compressors there are no issues at all.

The different temp zones is such a nice feature we all like a little different temp and now we all can have it that way.

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Old 12-12-14, 10:01 AM   #210
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.


I'm looking at buying 3 of these and would like to know. Have you ever measured the actual amount of amps drawn by these units ?




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