[Greenbuilding] Sustainable Home Heating Systems: Mini-split ductless heat pumps

[Keith Winston]

I spec ductless heat pumps (also called mini-split heat pumps) all the 
time. The units I like most, still, are the Fujitsu 3/4 & 1 ton models. 
They've just added a couple more versions, but the specs diminish as the 
size increases. They already have another 10-12 models -- I just tend to 
stay focussed on the two that are 21 SEER:

9RLQ: 3/4 Ton (9000 Btu), 21 SEER, 11 HSPF (all units have higher 
heating Btu ratings than cooling)
12RLQ: 1 Ton (12,000 Btu), 21 SEER, 11 HSPF

These also have very respectable specs:
15RLQ: 1+ Ton (15,000 Btu), 20 SEER, 10 HSPF
18RLQ: 1.5 Ton (18,000 Btu), 19 SEER, 10 HSPF
24RLQ: 2 Ton (24,000 Btu), 18 SEER, 10 HSPF

You can find details on all this here:

http://www.fujitsugeneral.com/PDF_06/halcyon06_brochure.pdf

As you'll see, they have ceiling units, and multi-zone systems that 
allow multiple internal heads on a single outside compressor. But then 
you have to settle for efficiencies like 16 SEER (gasp! Still better 
than almost anything you can wheedle your local HVAC co. to install).

In case you didn't notice, these are INCREDIBLE specs! I am hoping to do 
an analysis soon to try to figure out if geothermal can be competitive. 
It looks to me like Fujitsu has been so clever in engineering these 
systems that they might have overtaken geothermal... Also, as someone 
was asking about coolth: they are much like a window unit, except hung 
on a wall. So they don't really work so well with many different rooms. 
You sort of need one per major space... Sorta like heating with a wood 
stove...

Your local RE Michels can order them for your local HVAC contractor 
(they are a wholesale-only house).

IMO they SHOULD be able to be installed for about $2500-$3000 in my 
opinion, in straightforward installs, but bids around here often come in 
at $5000. I think that's just unfamiliarity, they are very easy to put 
in. In many states you could (legally) put one in yourself, and hire an 
HVAC contractor to hook up the lines, evacuate it and commission it, 
though if they mark up the unit when they get it for you, you're doomed. 
You have to be able to run refrigerant lines without kinking them, and a 
drain line without forgetting that water runs... is it downhill or 
uphill? I always forget... There are profound limits, and BIG fines, 
regarding what ordinary people can do around refrigerants and AC 
systems. These units come pre-charged. They are very very quiet, and 
will run in heat-pump mode down to 5F! They have no resistive back up 
heating coils, so they can't provide back up heat below 5F (call it 10F 
to be safe). Around here it doesn't get that cold.

I figure if you can reduce heat and cooling load with insulation, air 
tightness, ERV/HRV, and proper attention to windows, then you can use a 
smaller unit and distribution is less important because you don't have 
the enormous and uneven heat gains throughout the day. But recognize 
that it can be hard to meet traditional HVAC design expectations with 
these small, central systems. And it can get expensive to install one in 
every room, plus not everyone likes the aesthetics. On the positive 
side, you get very precise zoning tossed into the equation...

Keith


wmdorsett at sbcglobal.net wrote:
> Paul, this is a system I'm not familiar with.  Heat through baseboard 
> radiators is fairly easy to understand but how does a ductless heat pump 
> distribute coolth? individual room fan coils? And are there particular 
> brands you recommend? Thanks for your thoughts.
>
> Bill Dorsett
> Sunwrights
> Manhattan, KS
>
>
>   
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-- 
Keith Winston
Earth Sun Energy Systems
Hyattsville, MD 20781
301-980-6325
send me mail at 
keith at the company below
www.EarthSunEnergy.com