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-   -   Ductless Heat Pumps for Heating & A/C ? (http://www.bikeforums.net/foo/946271-ductless-heat-pumps-heating-c.html)

Homebrew01 05-04-14 08:03 AM

Ductless Heat Pumps for Heating & A/C ?
 
Anyone in cold climates using these for heating & Cooling ?

Here's 1 example: Fujitsu General America

dstrong 05-04-14 11:08 AM

Same question but for hot climates?

I just started reading up on these. I'm wondering whether they're a legitimate replacement for the whole house a/c systems.

We had heat pumps in a previous house (all electric neighborhood) and I thought they were good. They didn't put out the dramatic heat that a furnace does, so I recall they ran for longer periods of time.

One reason I'm looking at them is that we have a difficult time getting our a/c and heat distributed evenly around the house. The ductless units basically put a unit/thermostat in each room so it can be better controlled.

skijor 05-04-14 01:58 PM

Wait, is that similar to geothermal? Cuz geothermal is the way to go if you're gonna be in your house for the long haul.

Gallo 05-04-14 03:18 PM

generally if you have gas available the cost for electric heat is more. They will have the same rating for heat as they do for cool. So a 1500 btu cooling will produce about 1500 btu for heat. In cold climate it needs to be big enough to meet the demand load. When you consider that AC needs to make up about 20-30 degrees max 100 degrees outside 70-80 inside. For heat we often have a bigger delta 10-20 degrees outside 70 inside now we a re talking a swing of 50-60 and more demand.

Reducing your load will be the best thing to do whether you use ductless minisplits or traditional ducted split systems. This is done through air sealing and insulation or weatherization for one word. windows have less effect than many would suspect but hey who does not want new windows? When air sealing it is important to consider that what your house once diluted through leaks is no longer available. A balanced air exchange or mechanical ventilation is almost a must or at least must be considered. testing combustion appliances for safety is also a must.

In a mild climate with little heating the minisplit should be purchased on efficient of the unit

In a cold climate it should be sized based on heating load which can be done with a calculation called Manuel J. Snow will have to be kept off the unit and it will need a defrost function (not sold on each unit)

There are always advantages and disadvantages

advantages

no ducting and therefore no duct leakage

110 and extremely efficient.

low installation cost.

slim profile

factory charged refrigerant

disadvantages

does not heat as well

often multiple units are needed for load increasing cost

they do not dehumidify as well as a traditional system which is critical in humid climates

A home that reduces load will be more comfortable in any climate. When looking at your house look at it as system, any changes you make how will that effect the system. Duct leakage is typically 30 percent or more in most homes through air sealing, insulation and duct sealing many homes will be more comfortable with their current systems.

overthehillmedi 05-04-14 04:29 PM

Just watched a episode of Ask This Old House where they sealed the duct work form the inside using an aerosol spray system. Reduced the leakage from almost 30% to under 3%. That might be something to consider.

Homebrew01 05-05-14 04:54 AM

Quote:

Originally Posted by skijor (Post 16727549)
Wait, is that similar to geothermal? Cuz geothermal is the way to go if you're gonna be in your house for the long haul.

No, geothermal has pipes into the ground to transfer heat back & forth with the earth.

Ductless heating/AC has a compressor outside the house and sends the heat or A/C into the house into a wall unit that has a fan & thermostat..

deeth82 05-05-14 07:05 AM

I haven't seen this used throughout an entire house in-person, but my folks had one wall unit installed in their F.R.O.G. when their house was being built, as its installation/upkeep was going to be cheaper than running more duct work. It's a Mitsubishi unit, and it does quite the admirable job of cooling/heating that room on-demand. For my next home I might even consider this a viable upgrade to whatever system we end up with.

Homebrew01 05-05-14 07:17 AM

We just got it installed for the whole house. I am worried that the bathrooms will get cold in the winter. We'll have to remember to leave certain doors open for air flow. We still have our old forced air oil furnace as a backup.

jsharr 05-05-14 09:34 AM

I want one of these for my sons room.

genec 05-05-14 10:10 AM

Seems to be a room to room solution... ducts, after all, are to move air from a central unit to all rooms... so ductless would only supply heat/cool to one room... or you install these things all around the house... which might make sense if you don't use certain rooms often.

Where I am in San Diego, our temps are very moderated by the ocean temp... only a couple of weeks out of the year are uncomfortable and we only use a couple of rooms a lot, so a couple of these would work far better than the current window AC we use.

Homebrew01 05-05-14 10:55 AM

Quote:

Originally Posted by genec (Post 16729853)
Seems to be a room to room solution... ducts, after all, are to move air from a central unit to all rooms... so ductless would only supply heat/cool to one room... or you install these things all around the house... which might make sense if you don't use certain rooms often.

Yes. We have 1 installed in each main room, and several can share the same outside compressor. According to the sales pitch, we should save big bucks on heating oil, with return on investment in 4-5 years. It also eliminated me having to install/uninstall window air conditioners twice a year.


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