Call me crazy … again with the ideas!
Just a thought i had while using alot of hot water in my shower,
and i couldn’t find any info on the google …
It is about mini-splits …yes again i know i know …
Well they are mini, and also installed in split units !!!
But that is not the point,
i was wondering, what if one would be to use some kind of ” shelter ” on the exterior unit
let’s say an opened ( probably bottom and near top ) shelter of a certain size,
that would feature a glass window toward south side.
The point would be to help raise the temperature during daytime when sun hits the shelter,
when in heating mode … to finally help raise the COP.
With good design, it would also protect the unit from weather,
and direct hot sun during cooling season ( with the use of overhang/angles flat roof )
I can see how a -20c unit would start working if the air it has access to would be somewhat heated by a clear sky cold day sun , or simply raise the temp of the box a few degrees during daytime use,
and shelter from super cold wind during nighttime.
Stupid idea ?? missing something again ?
Let’s all build small houses for our mini-splits so it can feel at home while on duty.
:p
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Replies
Jin,
Do the math. Your idea won't work.
Your outdoor unit needs access to very large amounts of outdoor air so that it can extract the heat from that air. That's why the outdoor unit has such a powerful fan. The volumes of air involved are very large.
If you build a greenhouse around the outdoor unit, it will very quickly lower the temperature of the air inside the greenhouse, and the air will be so cold that the efficiency of the unit will drop. Soon it will stop working.
Free access to outdoor air is good. The outdoor air has heat -- and you want the unit to have access to that heat. Building a box around the unit interferes with air flow.
Ok Martin, i thought it would be evident that i never meant for a "closed" box ... neway
Let's assume the following conditions :
- exhaust air from the unit is isolated and outputs without mixing with intake air
- intake air has sufficient volume/size of port so the proper quantity of air is moved through
- intake air is preheated by the sun before reaching the intake point
may use something similar to what is suggested by NRCAN for high air change rate industries :
http://www.matrixenergy.ca/solar-air-heating/matrixair-system.html
etc. ..
Jin,
In his latest blog, Allison Bailes addresses your idea: Does a Heat Pump Condenser Need to Go Outdoors?
Yup- when the crayon-on-napkin math fails get out your lipstick and do the calculations on the mirror. Air source heat pumps need access to their source, the outdoor air, and LOTS of it. It takes a VERY large greenhouse to become a low-temp solar collector for feeding a mini-split.
But mini-splits DO need shelter from falling ice and drifting snow. The number of ground-mounted mini-splits I see in snow country, parked directly under the cornice-fall paths at the eaves are more numerous than I'd like. I suspect it's something slow to sink in for those more accustomed to installing air conditioners, that aren't likely to be called into service when there's a deep snowpack. It's far better to bracket-mount them on the walls above the historical snowpack depths, and put a shed roof over them if they're not sufficiently protected by overhanging eaves, that way the don't get clobbered by roof avalanches or iced up with drifting snow as easily.
I understand that large sum or air are required....but please let's put that simple fact aside..it is very easy to design the "enclosure" to let through the required amount of air for efficient operation .
Let's assume a cold climate situation
south wall location
south wall has a dark colored finish with air space under it of required size, that let the heated up air during day time to be collected by the intake of the HP unit
exhaust side of HP doesn't mix with intake side
if this would raise the air temperature ( i assume it could do it fairly easily if i use the numbers i've found around for air solar thermal setup )
It would result in increaed COP or have the HP working during super cold days ... ??
BTW :
""Imagination is more important than knowledge"" Albert Einstein
:p