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

[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.

 

[toggleswitch2]

Jackson:

The electric resistance coils (or whatever your backup "emergency" heat is) should be energized during the defrost cycle/period in that defrost is nothing more than the system funcitning as an air-conditioner moving heat from inside the home to the outside unit, except that the outside unit's fan is "OFF". This can rapidly chill a home in winter if the backup heater does not run concurrently with a defrost cycle.

As a matter of fact the electric backup heat is so fast and effective that frequently a defrost cycle stops midway because the home/indoor thermostat becomes satisfied. Upon the next call for heat, it (the defrost cycle) then continues!

So one wants to make sure that an outside sensor does NOT cut off the electric-coil heat during defrosts, and that the electric-resistance heating coil runs during a defrost cycle.

BTW, if your home thermosat is an older model that has mercury in tubes within, please ensure that it is level, or temperature fluctions will result.

 

[richardc1983]

The defrost cycle in the uk involves the indoor fan being off so as not to cool the home down and experience cold draughts and the outdoor fan runs unless the temp is below 0C in which case it is turned off.

 

[whirlaway]

Gas Boiler

I love my old hot water gas boiler,keeps the house nice and warm and not dry,I can put a little Vics vapo rub in a pot of water by my bed and sleep if I feel the sniffles coming on,the radiator is so good for that.