Heat pumps

[stev'o]

Is anyone using, or considered using a heat pump?
My understanding is, they not only provide heat in the winter, but also provide cool air in the summer.
I live in on the eastern end of Lake Erie, so we get some fairly cold, and hot summers, but what I've read, leaves to me understand that, in the real cold months, that I may need to consider "supplemental" heat. So not sure if this is how I want to go.
As far as what I'm heating, I have a 18 X 36 shop I am framing in, inside of a 36 x 54 Pole barn. The 18x36 will have insulation at R11. I have used a Tyvec style wrap around the perimeter, so the insulation is over that.
I will not have gas feed out there, so the heat will have to be electric.
There is plenty of room between the outside walls, and the framing, so I would have no problems running ducts if I went with something like a heat pump.
Thoughts?

 

[OccupantRJ]

I am installing a heat pump in my workshop. Unit is 75% installed. My house has a heat pump. It was 20 degrees this morning, and all was comfy. It has reached 20 here several times this year, and so far, we are comfortable, with no aux heat. The thermostat is at 73 now. You can get split systems as well as package systems. Hope this helps.

 

[Olyar15]

I have a Carrier "Greenspeed" heat pump in my home. It is supposed to be one of the most efficient heat pumps on the market. I believe it is able to maintain 100% heating efficiency down to about 17F, when supplemental electric heating kicks in. Like you, I don't have natural gas access in my house, but I do have a large propane tank. That might be another option you might consider.

Now, I live in a pretty mild climate, similar to the PacNW (Washington and Oregon). The summer highs are usually around high 20s-low to mid 30s C (upper 80s-low 90s F) and winter lows are usually around the freezing mark, so it almost never needs to use the supplementary heater.

The nice thing about the Carrier Greenspeed unit is that it has a variable inverter motor, so it doesn't have to run at full speed if it is not needed. It is also amazingly quiet, especially compared to my neighbour's heat pump. While I am sure that it would work well for your shop (assuming it is properly insulated), you might also consider a mini-split heat pump so you can do away with the ductwork.

 

[Jackfre]

Fujitsu and Mitsubishi both make mini split heat pumps that operate down to -15*f. You have to be very careful when picking any heat pump. Their specs are improving, but as an example Fujitsu also makes hp's that will heat to 32f as well as 5f. Check the specs!

 

[theoldwizard1]

Is anyone using, or considered using a heat pump?
My understanding is, they not only provide heat in the winter, but also provide cool air in the summer.

100% accurate !

I live in on the eastern end of Lake Erie, so we get some fairly cold, and hot summers, but what I've read, leaves to me understand that, in the real cold months, that I may need to consider "supplemental" heat.

That is the "old" style heat pump ! Newer models are much more efficient.

As far as what I'm heating, I have a 18 X 36 shop I am framing in, inside of a 36 x 54 Pole barn. The 18x36 will have insulation at R11.

More insulation is always better. "You pay for insulation once. You pay for heating and cooling every month."

Fujitsu and Mitsubishi both make mini split heat pumps that operate down to -15*f. You have to be very careful when picking any heat pump. Their specs are improving, but as an example Fujitsu also makes hp's that will heat to 32f as well as 5f. Check the specs!

Jack is correct. Sounds like a perfect application for a mini-split heat pump.

These systems are still somewhat new, so hire an experienced, knowledgeable HVAC company and ask LOTS OF QUESTIONS !

If your 18x36 room is not divided, you will likely only need one outlet in the room.

 

[James-W]

Heat pumps are wonderful if you live in an area that doesn't get real cold. I live in southeastern Wisconsin and the company I worked for sold heat pumps for awhile, but then we quit doing it. We didn't sell very many and the people that bought the heat pumps were not overly thrilled with them. I imagine the newer heat pumps of today are much better than what they were back then. But the thing is, even though heat pumps will work in real cold weather, the colder it gets outside the harder it is for the heat pump to heat the building.

A heat pump would work really good in the Spring and the Fall when you need a little heat to get rid of the chill, and it will work great in the Summer for cooling. The down side of the heat pump is, in the Winter months you will most likely need some supplemental heat for the real cold days.

A lot of people go with electric heat for their supplemental heat. Electric heat is good if you don't need it a lot, but if you have a real cold Winter and you run it quite a bit, you may have some pretty sizable electric bills.

 

[tomroblee]

The best HVAC system for your needs depends on what you are trying to do and how much you are willing to spend.

A heat pump is the only system that will both heat and cool. A heat pump is basically an air conditioner that will also "work in reverse" to provide heating as well as cooling. One of the issues with heat pumps is the sizing. You will rarely want to cool the air more than about 30 degrees (from 100 degrees outside to 70 degrees inside) but you may want to heat the air 80 degrees (from minus 10 degrees outside to 70 degrees inside.) A unit that is properly sized for cooling may be undersized for heating. This means that you will need supplemental heat in very cold weather---or when you are trying to increase the temperature rapidly.

If you are using a regular split system heat pump (with an air handler and ductwork), your supplemental heat will probably be an electric resistance heater element that is installed in the air handler. Some people have suggested a mini split system. Very few of these have any back-up resistance heat built in, so you would need something like baseboard heat for the supplemental heat. They also make heat pumps in units that look like window air conditioners and packaged units like what are used in motels. These would obviously need to be installed on an outside wall of the pole barn in some fashion. They are cheaper than a split system, but also more noisy.

A heat pump is best for heating when you are trying to maintain a fairly constant temperature 24 hours a day. If you only want to heat your shop when you are using it, you will find that most of the heating is being done by the supplemental resistance heat.

If you shop is going to be heated and cooled for a substantial portion of the time, I would certainly want more than R11 insulation.

 

[RKA]

I use a mini split in my garage. Tomroblee hit the nail on the head. For my unit (2011 Fujitsu unit), 20F is about the point where supplemental heat is nice to have when raising the temp of a cold garage. When maintaining temps I haven't found the limit, but we don't see below 10F here. You will want to build some kind of shelter to keep snow away from your condenser unit as that will impact performance (but don't block airflow). On the whole, it's very efficient and I would do it again. But for your environment I would plan on some kind of supplemental heat.

 

[theoldwizard1]

Heat pumps are wonderful if you live in an area that doesn't get real cold. ...

Some people have suggested a mini split system. Very few of these have any back-up resistance heat built in, so you would need something like baseboard heat for the supplemental heat. ...

I use a mini split in my garage. Tomroblee hit the nail on the head. For my unit (2011 Fujitsu unit), 20F is about the point where supplemental heat is nice to have when raising the temp of a cold garage. ...

You guys are living in the past !

The Mitsubishi mini split inverter heat pumps can provide heat down to below zero F !! Yes, the efficiency drops off, but unless you frequently get below zero temps, I would not even think about any type of auxiliary heat.

Mitsubishi catalog

The base model only can only do one zone. The more expensive ones can do multiple zone, each with their own thermostat.

 

[TomT]

I live in Virginia so perhaps my experience is not the best to go by. But, we do get pretty cold as it's been 26 degrees the past 2 nights.

To me, good insulation and venting of the heated space are key. I have a "take out" 2.5 ton (?) heat pump I got for free and I've been using it in my 26x30x20' tall (to the peak) shop for 4 years now. Once thing I've learned, especially when you are running AC, is to be properly vented or you will build up mold - some kind of louvered vent system would work perfect as you can open and close it needed ....

Since electric is more money than gas around here (or at least in my usage) and I have run a natural gas line to my detached garage, I may install a vented gas heater on one wall just to get the place warmed up, then shut it down and let the heat pump maintain it. Heat pumps work efficiently in 4-6 degree swings in temp as I've been told. So, if I go to my garage and it's 42 degrees in there like it's been and I usually like it around 52-56 degrees working temp, that heat pump has to work pretty hard to get to the 56 degree temperature. Consequently I pay way more in electric. Having say a propane or natural gas vented or ventless wall mount 30K btu heater to warm things up quick and then shut it off to let the heat pump take over is a win-win to me. I get warm quick and I maximize my heating dollars.

BTW, my detached garage is 26x30x22 ft tall to the peak ....

 

[RKA]

You guys are living in the past !

The Mitsubishi mini split inverter heat pumps can provide heat down to below zero F !! Yes, the efficiency drops off, but unless you frequently get below zero temps, I would not even think about any type of auxiliary heat.

Mitsubishi catalog

The base model only can only do one zone. The more expensive ones can do multiple zone, each with their own thermostat.

Forget the min temp range at which they work. You have to look at the actual heat output as the temps drop. Most of the manufacturers intentionally omit those details (or at the very least obscure them). At 47F outside, I get close to 29K BTU output out of my unit. At 17F, I get 17K BTU (according to an AHRI cert). My experience/observations is consistent with those numbers, but that's a side of the barn estimation FWIW. When you're trying to raise the temp of a cold garage and it's below 20F outside, it takes time and 17K BTU isn't that much. If you're trying to maintain temps in a well insulated garage, it's fine. And when you're heating a cold garage and outside temps are over 30F, it heats up damn quick!

Now, I haven't used the current model Mitsu's, so maybe there is some new black magic there. Show me some heat output numbers or a graph as ambient temps fall and I'll be more persuaded.

 

[Highbeam]

It's not just that the units become less efficient at low temps, but that they are not capable of making as much heat. The rated output drops at low temps. Modern units don't drop as much but you need to design for this somehow either with auxilliary heat or with an oversized unit.

 

[pseudorealityx]

Forget the min temp range at which they work. You have to look at the actual heat output as the temps drop. Most of the manufacturers intentionally omit those details (or at the very least obscure them). At 47F outside, I get close to 29K BTU output out of my unit. At 17F, I get 17K BTU (according to an AHRI cert). My experience/observations is consistent with those numbers, but that's a side of the barn estimation FWIW. When you're trying to raise the temp of a cold garage and it's below 20F outside, it takes time and 17K BTU isn't that much. If you're trying to maintain temps in a well insulated garage, it's fine. And when you're heating a cold garage and outside temps are over 30F, it heats up damn quick!

Now, I haven't used the current model Mitsu's, so maybe there is some new black magic there. Show me some heat output numbers or a graph as ambient temps fall and I'll be more persuaded.

I don't think their small residential style units do this, but some of Mitsubishi's commercial level stuff is now basically running the compressor 'too fast' to build heat via friction at very cold temperatures. That's how they avoid going into a defrost mode like traditional heat pump units. It's certainly an interesting way to do things.

 

[tylernt]

I love my Amana heat pump. I only have 350sqft to heat/cool, so I have a small window unit, but it works great. It's advertised to work down to 40°F in heat pump mode, but I've used mine at 35°F and it still provided plenty of heat without kicking on the aux heat (verified by my meter).

Even though I live in a cold climate that a heat pump is not "ideal" for, I don't care to mess around with kerosene or propane (a hassle and $$) nor running nat gas to my shop ($$$). So while I might be spending more when the aux heat kicks in on really cold days, I still save a bunch over pure electric heat most days, and I didn't have to buy a separate air conditioner for summer.

For a 650sqft space, you can get a 18K BTU/h window unit (that can also be installed in a wall, which is what I did, and recommend). Stepping up from there, a PTAC (Personal Terminal Air Conditioner) like you see in many motel rooms, costs a bit more -- but is quieter, more efficient, and has features like "freeze prevention" (even when turned "off", it will still turn itself on just enough to keep temperatures above 35°F).

Both window and PTAC have built-in auxiliary heat, so no separate backup system is required.

From there you have the ductless systems, but from what I understand those usually need to be installed by an HVAC contractor since the lines have to be purged and charged with refrigerant? The window and PTAC units just require a hole in the wall and a 240V outlet, so a DIY install can be feasible (cheaper).

 

[theoldwizard1]

Forget the min temp range at which they work. You have to look at the actual heat output as the temps drop. Most of the manufacturers intentionally omit those details (or at the very least obscure them). At 47F outside, I get close to 29K BTU output out of my unit. At 17F, I get 17K BTU (according to an AHRI cert).

According to their specs, the Mitsubishi MUZ-FE18NA is rated at 29K BTU above 47°F. At 5°F, the spec says 21.6K BTU.

When you're trying to raise the temp of a cold garage and it's below 20F outside, it takes time and 17K BTU isn't that much. If you're trying to maintain temps in a well insulated garage, it's fine.

Likely true even with 21.6K BTU.

Recommendation: Use lots of insulation and never let the inside temp go below 55-60°F.

 

[tomroblee]

The quoted specs seemed amazing. I Googled the model number and found a service manual online at:


http://www.mitsubishipro.com/media/214712/muz-fe09-18na_service_obh543a_9-10.pdf

The heating capacities are shown on page 9.


It shows the heating capacity with a 47 degree outside temperature and a 70 degree inside temperature at 22,200 Btu. With a 5 degree outside temperature and a 70 degree inside temperature the heating capacity is 10,300 Btu

This sounds like a great system for a 600 sq. ft shop that is heated 24/7. I tried to find a price for this equipment. The only figures that I found were about $3000 for the equipment. I have no idea whether this is full "suggested retail price" or not. I have no idea about installation costs.

As a cheaper alternative, you could get the same 10,000 Btu heating capacity from a 3000 watt resistance heater that should cost around $200 for a decent quality unit.

 

[pseudorealityx]

The quoted specs seemed amazing. I Googled the model number and found a service manual online at:


http://www.mitsubishipro.com/media/214712/muz-fe09-18na_service_obh543a_9-10.pdf

The heating capacities are shown on page 9.


It shows the heating capacity with a 47 degree outside temperature and a 70 degree inside temperature at 22,200 Btu. With a 5 degree outside temperature and a 70 degree inside temperature the heating capacity is 10,300 Btu

This sounds like a great system for a 600 sq. ft shop that is heated 24/7. I tried to find a price for this equipment. The only figures that I found were about $3000 for the equipment. I have no idea whether this is full "suggested retail price" or not. I have no idea about installation costs.

As a cheaper alternative, you could get the same 10,000 Btu heating capacity from a 3000 watt resistance heater that should cost around $200 for a decent quality unit.

First cost vs. lifetime cost.

Even at 5 degrees, the COP of the heat pump is probably ~1.4. So it's 40% more efficient than the strip heater. At 17 degrees, it's over 200% more efficient. At 47 degrees, it's over 400% more efficient than the strip heater.

There's also the benefit that the system provides cooling/dehumidification, although those aren't likely huge benefits that far north.

If it's worth it to the [owner] is up to them.

 

[RKA]

The quoted specs seemed amazing. I Googled the model number and found a service manual online at:


http://www.mitsubishipro.com/media/214712/muz-fe09-18na_service_obh543a_9-10.pdf

The heating capacities are shown on page 9.


It shows the heating capacity with a 47 degree outside temperature and a 70 degree inside temperature at 22,200 Btu. With a 5 degree outside temperature and a 70 degree inside temperature the heating capacity is 10,300 Btu

This sounds like a great system for a 600 sq. ft shop that is heated 24/7. I tried to find a price for this equipment. The only figures that I found were about $3000 for the equipment. I have no idea whether this is full "suggested retail price" or not. I have no idea about installation costs.

As a cheaper alternative, you could get the same 10,000 Btu heating capacity from a 3000 watt resistance heater that should cost around $200 for a decent quality unit.

One important distinction I found between Mitsu and Fujitsu is that Mitsu stops at the 18K BTU unit (for the FE series units)...next model up was 30K BTU and came with a much bigger price tag. Fujitsu had a 24K BTU model. The prices online are about $2000 give or take a few hundred for the 18-24K BTU units from both manufacturers. The difference in cost from 18 to 24 was negligible. You lose a little overall efficiency going with the larger unit, but gain the additional heating capacity obviously.

 

[pseudorealityx]

One important distinction I found between Mitsu and Fujitsu is that Mitsu stops at the 18K BTU unit (for the FE series units)...next model up was 30K BTU and came with a much bigger price tag. Fujitsu had a 24K BTU model. The prices online are about $2000 give or take a few hundred for the 18-24K BTU units from both manufacturers. The difference in cost from 18 to 24 was negligible. You lose a little overall efficiency going with the larger unit, but gain the additional heating capacity obviously.

http://www.mehvac.com/UploadedFiles/Resource/MrSlim_catalog.pdf

Mitsubishi has a 24k model. It has a "GE" suffix on it, because it's an iteration above the "FE".

 

[theoldwizard1]

This sounds like a great system for a 600 sq. ft shop that is heated 24/7. I tried to find a price for this equipment. The only figures that I found were about $3000 for the equipment. I have no idea whether this is full "suggested retail price" or not. I have no idea about installation costs.

As a cheaper alternative, you could get the same 10,000 Btu heating capacity from a 3000 watt resistance heater that should cost around $200 for a decent quality unit.

So the real question is, consuming 3KW/Hr how many hours of heat can you buy with $2800 ?

 

[fstbusa]

Fujitsu and Mitsubishi both make mini split heat pumps that operate down to -15*f. You have to be very careful when picking any heat pump. Their specs are improving, but as an example Fujitsu also makes hp's that will heat to 32f as well as 5f. Check the specs!

You are correct but please still use aux heat. At temps below 10F there is very little heat for the heat pump to wring out of the air so you will likely need some extra heat.

Source: I'm an HVAC engineer and spec this stuff all the time.

 

[Mike in Indiana]

Northeast Indiana winter temps. usually well below freezing with weeks in the teens with days below zero on occasion.
I have a 40x60x14 steel building well insulated sidewalls and roof. I started with a Reznor 100,000 btu propane radiant tube unit which I ran for 2 winters and kept my temp. steady at 55 all winter. Dec. Jan. Feb. March. ran me about $450 in propane a month.
In 2011 I had installed a 4ton Goodman heat pump to get the moisture out of my building during the spring and summer months. I use it for the primary heat source all winter. Keep set at 62 and it runs longer and more often than the radiant tube did. Costs me about $200 a month during winter season, about less than 50 in the summer. In very cold temps. (14 and below) my radiant will kick in and run for a few minutes to help keep the temp. I have not had to fill my propane tank in two years and I still have 80% on a 250 gallon tank.
I still like my heat pump set up. No complaints. Just set the temp and forget it. Do not cycle it up and down.
Mike

 

[whatuusay1]

I love my mini split heat pump I put it in about a year and a half ago and it has been amazing. It cools and heats like you wouldn't believe. I run it at 60 in the winter (lowest it goes) and usually bring it up to 65-70 when im out there. I've had no problems with it at below 32 degrees (we have had many days below 20 degrees). Some of the older mini split/heat pumps have issues when it gets cold - make sure and read the specs. Mine has no supplementary heat (no concerns).

Mines an LG unit I picked up for around 1600 bucks. I installed it - with the exception of the lineset, I paid a HVAC guy to connect it ($130).

LSN240HSV / LSU240HSV - LG 24,000 BTU 18.9 SEER Heat Pump

I'll have a mini split in every garage I own now - I have been very impressed.

My wife loves having a warm car each morning too - that's a bonus

 

[Dick in Wisconsin]

I love my mini split heat pump I put it in about a year and a half ago and it has been amazing.

Where do you live?

 

[Dick in Wisconsin]

A couple of observations ...

First ... Because the (air to air) heat pump gets its "heat" from the outside air (when in heating mode) and dumps the waste heat into the outside air (when in cooling mode) there is a point as you go north where they just don't make economic sense (especially if you have access to natural gas or propane at a reasonable price). Where that "geographical point" is depends on the local temp range of course, but probably just as importantly what are going to be your heating and cooling demands, especially at the temperature extremes.

Second ... Where does this put the debate over infloor radiant heat?

Third ... Have any of you considered a ground water heat pump? My Dad put a GWHP in the family's funeral home in Shawano (WI) in 1947 and in his house in 1955. The funeral home system was decommissioned in the 80's or 90's (family no longer involved) and the system in the house "quit working" (compressor sprung a leak) in 2001. These system were "home made" by a local refrigeration mechanic using compressors from the 1930's, 40's and early 50's. Both the FH and the house had 480 three phase service; the compressors were powered by 6 to 7.5hp 480v/3ph motors and the blowers and well pumps were 3 phase (240v I presume). The house how has a Water Furnace brand GWHP which I'm very happy with.

The economics of pulling heat from 52 degree water in the winter vs the outside air temperature at the time and trying push waste heat into outside air in the high 80's or 90's or even 100 degree temps in the vs 52 degree water in the summer has to be pretty dramatic.

If you have a source of water (like a well) and a place to get ride of it (pond, stream, river, or large lot or field) consider the GWHP.

 

[fstbusa]

****, using ground water is one if the best if not THE best for efficiency. You just need to make sure you have an adequate water supply.

It's exceptionally great for cooling as great for heating. It is expensive up front if you need to drill a well to get the water.

Around my area we design systems that use 1000gal/min to heat/cool 150k sf buildings!

 

[pseudorealityx]

I have full on 4ton units in each of my two car garages complete with ducting. One intake and three exhausts. Both units are tranes.

It is the best thing I have EVER bought for a garage. Cost me $3500 or so with ducting. My units sit on the roof so I do not have a 'footprint' problem is the prime realestate next to my garage wall.

I did not use the split systems becasue they couldn't begin to change the temp as fast I need it changed. During a 120 degree summer the thermostat is set at 90, I change it to 76, go in get a drink, pee, get ready, change shirts and the temp is falling quickly.
Same with winter. 50 outside, 60 degree thermostat, I crank it up, 10 minutes later I'm comfortable.

The house we just bought for some damnably stupid reason has a propane heater and an a/c unit. It will be replaced this summer with a heat pump and the propane and a/c unit will be moved to the Behemoth garage for now just because I'd rather use than scrap it.

We have four heat pumps headed for our fifth and shortly [a few years after] our sixth.
If the split systems would do the job, I'd own the split systems.

That being said; Due to the unbeleivable heat in Havasu we are indeed contemplating a split system as an auxillary to my wifes sewing room. It's on the far side of the house, catches hell from the sun and the duct fan boost unit isn't really helping. In a small room I think we'll love it. The splits maintain a temp more than MAKE a temp.

I just read of your r value. In fairness I'm at about r36 in the ceiling and a good 23 in the walls.

I also read of heatpumps maybe not working so well on a zero degree day. I hate paying for the damn propane but I will rethink the heat pump at the behemoth.

There's a difference between a standard 'split system', and a Mini-split, which is what most people are talking about here. A split system and a packaged unit of the same capacity will change temperatures at the same speed if you're talking comparable units. 1 BTU = 1 BTU.

For some odd reason, the West seems to really like using packaged units for residential buildings, while the East seems to prefer "standard" split systems. Each has their own ups and downs, but if you're used to seeing one, then seeing the other will throw you for a minute.

 

[whatuusay1]

Mine is a 2ton mini split unit - and has zero problems cooling my 3 car garage down in a hurry (or heating it up).

I'm in the KC area - we just have 2 major snow storms (10" each roughly) and i've got a toasty garage

 

[fstbusa]

Snowstorms really aren't a gauge of temperature. It usually snows alot when it's in the mid to upper 20s. That's usually not a problem for a mini split.

When you get down to 10F and lower you will have issues without aux heat.

 

[pseudorealityx]

Does anyone know if any of the residential style Mini-splits use the trick of running the compressor at very high capacity to create friction heat for use at very low temps? That way, you don't have to depend solely on the refrigeration cycle.

 

[tylernt]

Does anyone know if any of the residential style Mini-splits use the trick of running the compressor at very high capacity to create friction heat for use at very low temps? That way, you don't have to depend solely on the refrigeration cycle.

Help me out here, I'm having a hard time seeing how friction heat via an 80% efficient spinning motor could be more efficient than 99% efficient resistive heat strips?

 

[theoldwizard1]

Does anyone know if any of the residential style Mini-splits use the trick of running the compressor at very high capacity to create friction heat for use at very low temps? That way, you don't have to depend solely on the refrigeration cycle.

No. They do use a "modern" "working fluid" (the stuff in the pipe).

The real real improvement in efficiency comes from "inverter technology" which allows the motor to run a different speeds depending on what is required. (As I understand it, the 240V 60Hz AC power is converted to DC and then immediately converted to variable frequency AC. I'm certain I just oversimplified the whole process, but this is the only way I know how to make a variable speed, high torque AC motor)

 

[theoldwizard1]

A couple of observations ...

First ... Because the (air to air) heat pump gets its "heat" from the outside air (when in heating mode) and dumps the waste heat into the outside air (when in cooling mode) there is a point as you go north where they just don't make economic sense (especially if you have access to natural gas or propane at a reasonable price). Where that "geographical point" is depends on the local temp range of course, but probably just as importantly what are going to be your heating and cooling demands, especially at the temperature extremes.

Good question. Almost impossible to answer. Add in electrical outage from a snow storm and you could be in a life or death situation if you were an invalid. Bottom line, if you live in an area were the outside temp drops below freezing for more than 24-48 continuous hours, I would want a backup (propane, wood), or at least the ability to let the building and its contents freeze.

Second ... Where does this put the debate over infloor radiant heat?

Another god question ! True "mini" split systems are ignoring this option. The commercial Mitsubishi do address it. These unit have multiple indoor units and one of the many options is a heat exchanger for radiant heat ! These are complex, expensive systems, but in general I think the multiple zone idea will catch on !

Third ... Have any of you considered a ground water heat pump?

Yes, GWHP are great ! But the cost of installing a well and the extra pumps can kill you. The new high efficiency split system, especially those that have multiple zones, are direct competition. If a GWHP was my only source of heat and I lived in an area where the temp goes below zero for 24-48 hours continuous, I would have a generator that would be capable of running the heat pump and auxiliary pumps.

The other big advantage of multiple zone split system is in new construction. No duct work is required and the piping can be run similar to PEX in a 2x4 wall. Plus you get individual zone controls.

 

[theoldwizard1]

For some odd reason, the West seems to really like using packaged units for residential buildings, while the East seems to prefer "standard" split systems. Each has their own ups and downs, but if you're used to seeing one, then seeing the other will throw you for a minute.

Mitsubishi is going away from "packaged" systems and toward mix and match. They now have residential systems that can handle up to 8 zones. The inside units include the typical high wall as well as floor units. Ceiling and ducted (?). I'm not certain their "commercial" radiant heat exchanger will work with their residential system, but I don't know why not.

If I were building new, either a home or a garage, I would seriously look into these systems. Because I live in an area where the temps can be below freezing for days on end, I would also have a backup system such as a simple gas fireplace.

 

[pseudorealityx]

No. They do use a "modern" "working fluid" (the stuff in the pipe).

The real real improvement in efficiency comes from "inverter technology" which allows the motor to run a different speeds depending on what is required. (As I understand it, the 240V 60Hz AC power is converted to DC and then immediately converted to variable frequency AC. I'm certain I just oversimplified the whole process, but this is the only way I know how to make a variable speed, high torque AC motor)

The commercial air cooled City-Multi stuff DOES use the "technology" I mentioned. I'm wondering if any of the residential stuff also uses it. Personally, the only projects I've done in cold climates (Buffalo) used Mitsubishi's water cooled condensors, so they don't have to be concerned with cold ambient temps as much since they can bypass the cooling tower, and likely even add auxiliary heat via a condensing boiler.

<--- HVAC P.E.

 

[pseudorealityx]

Help me out here, I'm having a hard time seeing how friction heat via an 80% efficient spinning motor could be more efficient than 99% efficient resistive heat strips?

The compressor adds heat to the refrigerant, and therefore, allows it to continue to use a refrigeration cycle. At extremely low temperatures, it's not likely much more efficient than a strip heater, but as ambient temperatures increase, the COP will just keep rising until it's much more efficient.

A strip heater's max COP is 1. Normal refrigeration cycles are 3+.

 

[tylernt]

What is the name of this technology? I tried Googling "heat pump friction" but the hits seem to be about reducing friction in the refrigerant lines.

I did find Mitsubishi's Flash Injection technology, but that has nothing to do with friction.

 

[pseudorealityx]

What is the name of this technology? I tried Googling "heat pump friction" but the hits seem to be about reducing friction in the refrigerant lines.

I did find Mitsubishi's Flash Injection technology, but that has nothing to do with friction.

Let me see if I can find an article or something...

 

[pseudorealityx]

Let me see if I can find an article or something...

Here's an older brochure from 2008: http://www.mehvac.com/UploadedFiles/Resource/H2i_brochure.pdf

H2i "Hyper Heat" is their name for it. Looks like it's only available on the big commercial stuff right now, and it's currently proprietary to Mitsu.

The newest engineering guide I have states 100% capacity at 0 degrees F and 84% capacity at -13 degrees F. I got this from Mitsu this year, so it should be pretty current.

 

[tylernt]

H2i "Hyper Heat" is their name for it. Looks like it's only available on the big commercial stuff right now, and it's currently proprietary to Mitsu.

Looks like H2i is the more advanced form of the Flash Injection they had earlier, which is unrelated to friction. The brochure you linked to says:

The Hyper-Heating INVERTER outdoor unit uses flash technology which re-collects heat energy that is normally wasted in the flash process at the outdoor coil. This process helps the H2i systems overcome issues commonly associated with conventional heat pumps such as decreases in low-side pressure, refrigerant mass flow rate and operational capacity.

The patent pending flash process cools the compressor allowing higher speeds at a lower outdoor temperature without overheating. This also allows increase in mass flow rate in the system providing phenomenal heating performance at low temperatures.

I see higher compressor speeds mentioned, but nothing about friction.

Just to be clear, I'm not debating the COP/efficiency gains of such technologies, and I understand how the refrigeration cycle can have a COP > 1 since it's just moving heat that's already there. I just don't think a COP => 1 is possible with friction, since friction needs motion and no electric motor producing said motion is 100% efficient.