Does anyone have an air to air heat pump... and how is it coping with the cold temps...

[richardc1983]

I have air to air heat pump that heats my flat... its -5C out and not having any problems maintaining the indoor temp of 22-23C. Defrost cycles have been approx 1 every 3 hours of constant running however the unit is happily ticking away and not working that hard.

When temps drop below 0C it doesnt have an electrical strip heater of any sort, it keeps on going down to -15C however output does start to drop off the colder it gets upto -15C.

Were very happy with it... its an LG system...

Heres some videos...

 

[richardc1983]

Vid 2

Vid 2

 

[richardc1983]

forgot to mention....

The system is purposely oversized so as to allow for these cold conditions so we have the extra kick if we need it!

 

[penguinsoup]

interesting question...

At my last house I had a heat pump, and it had some similar issues. At one point I had to kick on the emergency heat part of the system, but that later went out.
I know generally that is how they seem to function, not putting out the warmest of air in very cold temperatures, but after the e-heat went out, it was found that a circuit board or something similar went out.
My friends who also had a heat pump had the same issues with theirs, with the exception of the part going out. I have been told that is generally the nature of the beast.
I know I'm not really being of any help here, but more sharing my own heat pump experience.
Best of luck,
P

 

[supersurgilator]

My grandparents have a Janitrol packaged heat pump in their moble home. The previous owners would go to Florida in the winter so never used the heat. My grandparents soon found out that when the temps got below 40 it would just kick off all of the heat. After a couple of service calls, they found out that the strip heat which is supposed to kick in once the heat pump shuts off at 40 degrees had never been hooked up. But the heat the strip produces is still pretty lethargic because as my grandpa said, the house wiring in the circuit breaker didn't have enough power to hook both of the heat strips up, only one. I'm so glad we live in an area where we have natural gas and can have furnaces.

 

[richardc1983]

The technology is only for inverter systems, these have a compressor that ramps up and down based on load requirements.

Fixed speed systems would not heat below perhaps 0C so needed backup heat.

The modern split systems are fanstastic...

In New Zealand they have the same systems optimized for condtions there.

At -25 they say it will still deliver full heat output which is fantastic really...

REad this for info on the technology that is available now... I dont think there is a market for the split systems in America so they still use central systems which have the old technology.

http://www.bdt.co.nz/hypercore/technology.aspx

 

[appnut]

I have a Trane, the 2nd one for my house, purchased March 2002 and is TOL. My previous one was a bilder's grade RUUD. I've been pleased with both. My heat strips do kick in when it gets close to freezing and when it gets 25 degrees F (I don't know what C is), it starts to struggle and the strips kick in. But it has managed to keep me comfortable even when it's 5 degrees outside and I keep my indoor temp at around 68 degres F.

 

[toggleswitch2]

The heat-pump I'm familiar with (Carrier brand) works until about 10*F (-12*C), at which point the resistance electic heat coils need to be energized.

 

[hydralique]

Split sytems are actually the most common form of HVAC in American homes. So long as the condensing unit is outside and the evaporator is inside it is considered a split system, regardless of whether or not it uses a heat pump, resistance heat, or a gas/oil furnace. Package units are used mostly in commercial rooftop installations, or mobile homes as noted above.

 

[toggleswitch2]

I believe this is what is meant by a spilt-sytem overseas.

We'd call that a split-ductless system as opposed to a split central / ducted system.

http://www.mehvac.com/products/category.asp?ProductCategoryID=24

 

[brisnat81]

Steve, thats correct.

We call that a Split System.

A ducted split system is purely known as a Ducted or Central AC system.

We've got two split systems in our place and between the two of them they do an admirable job of dealing with the 35degC 85% humidity days in summer and the Mild 5degC winter nights.

 

[toggleswitch2]

There is a market here for spilt-ductless sysems, that is small but ever-growing. Our style of double-hung sash windows allows for window air-conditioner affectionatelt called "Winodw-rattlers", ostesnsibly because they are quite noisy!

We are slowly learning how quiet, efficent, effective and versatile (they are heat-pumos as well) the split-ductless units are. They are woefully expensieve to have installed at this time.

I'm seeing them more and more in finished (inhabitable) basements which typically don't have enough or large-enough windows to "support" /allow for a window unit.

http://www.bestbuy.com/site/Air-Conditioners/Window-Air-Conditioners/abcat0907005.c?id=abcat0907005

 

[toggleswitch2]

Please pardon my editing skills. UGH!

 

[tolivac]

Not using my Lennox Ac-Heat pump at this time-its a BOL model-The heat pump function is rather inefficient and inadequite.Use electric space heaters instead.The Lennox unit works great as an AC in the spring and summer.But it is a poor "heater".

 

[toggleswitch2]

Actually doesn't a heat-pump use 1/3 of the energy to do the same job as electric resistance coils?

Dont let the cooler air-outflow temperatures(oftern no higer than body temperature) fool you.

Are any potential saving perhaps from heating fewer spaces and to a lesser degree?

 

[tolivac]

My saving from the portable heater is considerable!!I am not trying to heat the whole house.If I use the Heat pump I have it would cost around $200 per mo.The heater its less than $150.If I had a BETTER heat pump would use it-In one house I lived in the place had a Trane system-best HVAC system I had ever used.Worked great as an AC in the summer and an excellent heat system in the winter.That Trane worked even when there was 2 Ft of snow around it!Had to shovel the snow from the outside unit.The resistence back up heat hardly came on.The power bill was under $200 per mo.Would like to have a Trane in the place I have now--but it would cost about $6000.

 

[richardc1983]

Yes thats correct, they are 300% more efficient than electrical space heaters or coils... some of them are 400% more efficient.

An electric heater is 100% efficient, the air blown out of them is cooler than would be blown from an electric heater but they are much cheaper.

 

[dj-gabriele]

At my parents' we have split air conditioners in all the bedrooms, with a single outside unit, changing from the previous three separate machines with the 3 separates condenser outside units.

The EER for cooling isn't high, stated as 3,62Wcooling/Welectric (A class enegy) and COP for heating 4,16Wheatuing/Wectric, also A class energy but not so high. The machines, Panasonic, are made to be able to continue heating up to -10°C but since we never had temperatures so low in our town, we never had problems. It's stated that at -7°C the output is 75% than total at 7°C. But, I must say that I never had problems even on coldest cold that was -2 in our town Plus we have hot water central fired heating with aluminum radiators, so heat is never a problem, except in summer when the old A/C halted because of internal overheating with temperatures of 45°C in the shades...

 

[richardc1983]

dJ-gabriele what you have is a multisplit system, the disadvanatage of that is that you cant run each room in separate modes they all either have to be heating or cooling.

Not good if you have one side of the house that requires cooling due to sunlight and the other side heating.

I have multi system installed.. purely on space outside that was lacking.

 

[toggleswitch2]

~Not good if you have one side of the house that requires cooling due to sunlight and the other side heating.

In that case one can put a fan on the floor in the hallway to push the heat from the hot room/side to the cold rooms/side.

Low-tech solution to a low-tech problem and much less energy/electricity used.

 

[sudsmaster]

You can actually get portable AC units that have heat pumps. So they can be used for room cooling in the summer, and room heating in the winter, for far less cost in energy than a room electric resistance space heater. The ones I've seen have dual vent pipes (look like flex plastic dryer exhaust hoses) and run about $500.

Out in this area, the temps rarely get below freezing, and then just for a few nights each year. So it's probably ideal for air-air heat exchangers. Except at least in the older cities and older suburbs they are relatively rare. Most homes have gas furnaces of some sort, and no central AC. I guess historically natural gas has been plentiful and cheaper than even heat exchangers running on electricity. For a while there, natural gas was getting pretty dear, but in the past year the prices have dropped dramatically, and there's talk of vast new fields being tapped with advanced horizontal drilling techniques. So prices will probably stay relatively low for some time yet.

I got a couple of 5500 BTU "window rattlers" a couple years ago. They are small enough to fit into the horizontal sliding windows here - made some plexiglas spacers to fill in the missing window pane above them. It all works, but this past summer I didn't bother to drag them out of storage and install them. The natural AC of the area sufficed, coupled with lots of attic insulation and judicious intake of cool air at night via multiple fans, and shuttering of the house during the heat of the day.

 

[hydralique]

It is possible to have one system that can accommodate different exposures by using an electronic damper system. I recently did a major, down-to-the studs remodel and addition to a house which has four very different exposures. Finding room for four different systems would have been exceedingly difficult, so the house was equipped with two systems, one of which has a three zone damper.

The living room and kitchen are on the simple system without the damper, so these rooms are either both heated or cooled according to the demands of the thermostat. The second system has three thermosats and three zones, with the zones being a rec room, the master suite, and two secondary bedrooms with their bathroom. The master suite tends to be the hottest zone, with large south facing windows, while the rec room is built into a hillside and thus the coolest. With the damper, if the rec room needs heat in the morning but the master suite thermostat sends a call for cooling, the system will keep the furnace on until the rec room is satisfied but it will shunt all the heat into that room. Once it is hot enough, the furnace will turn off and blow ambient air through the ducts to exhaust the heat. Then the dampers will switch the air handler's output to the master suite and start the air conditioning cycle, which will continue until that room's thermostat is satisfied. If the secondary bedrooms need heating or cooling they can share in either cycle, or if all rooms need heating or cooling at the same time they can all share the cycle. The system has a variable speed compressor and fans to deal with the varying loads. It works very well if designed and sized correctly and only adds a few thousand to the price of the system, much less than having lots of separate systems.

 

[dj-gabriele]

richardc1983:

Oh no Richard, that system is the best thing after air conditioning itself! Each room can work on it's own, the compressor is only one but it's of the inverter type and power output varies from 4000 to 28000 btu, so each room can have separate cooling. I know one room can't use cooling while the other uses heating but it never happened to have a room at -10 and another at 40 (well, not even 20° vs 30°)
Each room has a 9000 BTU split, and they can run really independent, as an example my parents can't bear no less than 28°C and stick with that, my sister likes the same and I use 26°C all the time, the compressor never switches off but it modulates power to cope with the inside units requirements. Same goes for heating.
Also, compared to our single split units, it's also much more efficient! Some average saving of 30€ per month in summer!

 

[toggleswitch2]

3 inches = 7.62 cm

Actually I think they are called "Ductless mini-splits" to differenciate them from a standard central cooling/ heat-pump system.

 

[jaxsunst]

My upstairs has a heat pump. The coldest it has been here has been in the 20'sF.

It will let the house get really cold before it kicks itself over to "Aux Heat", so I usually do it manually. This year, the first time I flipped it, it tossed the breaker. I switched it back to auto and no problems so far. This is the unit's 2nd winter, I hope it doesn't cause any more problems.

 

[richardc1983]

|YOu can also get mini split VRF systems that use heat recovery so taking heat from rooms that require cooling and put the heat that would normally thrown outdoors into the rooms that require heating:

 

[dj-gabriele]

richardc1983

Do you really have the need to cool a room while heating another? It feels like another planet to me! What temeperatures there are in your home? Even on the most extreme, the coldest room and the hottest room are no more than 5° difference!

 

[iheartmaytag]

They are offering a hybrid system here. You have an electric high efficiency A/C and Heat Pump and a gas aux system. The electronics are supposed to monitor when the heat pump is no longer heating efficiently and automatically switches to the gas back up.

People I have talked to said the only way you know the system has switched is teh first time the gas system fires up the dust burning off the heat exchanger will give off a smell for a few minutes. Otherwise it is a very efficient system.

My boss has a well sourced system where there is no outside unit. Everything is contained in his basement. Combined with his woodburner he says his highest electric bill was about $55.

 

[DADoES]

 
Jackson, something is probably adjusted wrong on your system if the house gets "really cold" before the auxiliary triggers. It's the indoor thermostat that does the switchover, normally triggers if the room temp drops more than ~2°F below the setpoint (which means the heat pump alone isn't adequately handling the load) ... UNLESS it works in conjunction with an outside temp sensor that locks-out the auxiliary until the outdoor temp drops to a specific point. Your thermostat itself either has too wide a differential for triggering the auxiliary, or your auxiliary lock-out is set too low.

 

[richardc1983]

DJ Gabriele...

I am speaking on larger scale like office buildings etc but also in my flat nearer the spring/summer time there is a large bedroom that has large windows and sun shines through these windows bedroom temp can increase to nearlly 30C even when its only 10C outside.

THe lounge may require heating as its cold in there but the bedroom is very hot.