Mini split install

[MN Renovator]

Thanks to both Xringer and st2288 along with everyone else involved including those on Ecomodder who discussed this and linked me to Xringers thread here.

I have been considering putting in a Fujitsu unit upstairs in my house. My upstairs square footage is about 430sq feet which includes two bedrooms and the master bath. In the winter I'm mostly between the main level for the kitchen and stay upstairs to watch TV and I've realized that I'm heating the entire house when I really only need a smaller area heated and the rest could be 45 degrees(which is the setting when nobody is home) and I wouldn't mind going into a cooler kitchen for a short period of time here and there.

I'm on the fence over a decision to supplement the current system in my house with a heat pump. I've been looking at the Fujitsu Halcyon Inverter ASU12RLS / AOU12RLS. Cooling 12,000BTU, heating 15,000BTU. The 25 SEER and 12 HSPF blow me away.

I was about to post my current equipment and if you'd like to I will but I don't want to make my first post here off topic but to put it simply, I'm heating with a 1983 oversized(in my opinion) natural gas furnace and have an air conditioner which is a little newer but still from the 80's.

I love the efficiency of these ductless units and have my eyes on the Fujitsu units and am thinking that using one of these to cool the upstairs and heat when the temperatures aren't too cold for it to work would bring my energy bills down quite a bit. The non-summer electric rate if I take out the flat $8.50 'basic service charge' and $2.50 'city fee' and take the full electric price paid including taxes and everything else and dividing by kwh is $00.1093/kwh. Roughly a cent more in the summer which includes the rate reduction that comes with having the electric companies switch that cycles the A/C on/off 15 minutes at a time when utility demand is high.

Would this be a bad idea to use something like this for most of the cooling and then use the old stuff as a backup for when the capacity is exceeded on one of these or its too cold outside for this to work well? I'm not sure where you are, but how cold does it get where you live? In Minnesota I figure if I start the unit during the warmest period of the coldest days combined with as much solar gain as I can get, I could manage to still have a cheaper result than using the gas equipment or at least enough supplement to really help.

Awesome setup. Which Fujitsu unit do you have? I can't wait to read more about its heating performance at very cold temperatures. I've been reading about how inverter heat pumps manage to perform so much better at lower temperatures that standard non-inverter forced-air type units couldn't dream of running in.

[Xringer]

Average climate in Minneapolis, Minnesota

Average climate in Woburn, Massachusetts


Wow! Beantown is in the sunbelt?? I can see Dec & Jan are gonna be a problem.
Unless it's a nice sunny day and the air temp is up above 12 degrees!
Yeah running it at 12 or 14 degrees does use more power, but it on average, it's way better than buying oil..

Minneapolis average is Dec-Jan is still above 12F.
My Sanyo works okay at 12F. But starts to struggle a bit in single digits.


My wife and I are getting old, so we have been using the heat for at least a couple of months this season.
And, I've stopped turning it down to 66 at night. 68 is working okay for me.
And, it's still 1/4 the cost of heating oil..
Right now, it's using 450 watts when it comes on.. Oops, just dropped down to 40w..

~~

One of the best, and most used fuel price performances, I've seen,
is when it's about 40F outdoors, and I need it to be 30F degrees warmer indoors.

When stepping up 1 deg C, it will slowly peak up to about 1500w, slow back
down to the 460w-500w range for a while. When things get stable or the sun
starts coming in the windows, it will drop down to the 40w stay-warm range.
(On my model, there is a small heating coil, wrapped around the base of the compressor).

It's kind strange to think my 42" Plasma TV uses almost the same wattage,
it takes to heat my home. (260w to 350w~ $1.63 per 24hr day).

If I left the big TV on all day, it would cost me about the same as the Sanyo
costs to heat the house on these cool fall days!

If only that Plasma would put out more BTUhs..

[MN Renovator]

The biggest issue that I see is that I don't know what the exact fuel costs for me will be using natural gas. This house was owned by a family with children before I bought it and this is the first winter I'll be living in it.

I obtained the records from the gas company of the amount and costs from last winter.
167 therms for January was $151
Problem is, not too sure what the temperatures were during that period both inside and outside the house. I have a feeling with kids they may have heated the house to 72 or so, I've been okay with 55 degrees during the day and 50 degrees when I'm sleeping using a mattress pad heater. In contrast I had a 7 therm gas bill of $15.10 last month since I didn't use the furnace and let the house get as cold as 45 degrees a couple of times. I'll let it get to 45 degrees when I'm at work but will need to have somewhere between 55 and 60. I did some load math, very crude with lots of possibly false assumptions, but using their previous most expensive month(Jan) of 167 therms compared to the 75,000 input BTU and therm factor led me to determining a rough run time of 6.55 hours per day if averaged amongst the 34 day billing period. The furnace has a 57,000 BTU output so the 10,100 at 17 degree F from a 12,000BTU Fujitsu wouldn't cut it for the same heat levels for the whole house. I would need about 15,573BTU as a constant average for the month. So this should work for the 430sq ft (roughly 30% of currently heated airspace) in the rated temperatures for the unit though but I'd have to airseal the house probably to keep the heat from circulating. ...I think, right? I think with the heating costs from last year I need 40-60 bags of insulation added to the current 8-12 inches up there now along with sealing air leaks. I just pulled the trim off of a bedroom window and there was a solid 1/4" gap all around. Plenty of room for improvement in this 80's house. I'm not sure how to do the math between therms and kwh for using a heat pump. Would I take the 10,100BTU 17f output and the rated load amps under full power? I'm more considering it for the air conditioning but am not sure if heating makes it cheaper as I think our natural gas is fairly cheap at least until the 3rd tier comes up right past 110 therms which I might stay inside that range but I won't know until the season has gone by.

How many posts do I need before the average temperature links show up for me?

[RobertSmalls]

Originally Posted by MN Renovator

How many posts do I need before the average temperature links show up for me?

100 was insufficient for me.

Edit: Remote host disabled loading of images from remote pages.




Chances are, your furnace is grossly oversized. It was probably oversized for the leaky, underinsulated house it was installed in, and once you seal it up, you may find it's more than twice as oversized as it was before.

The USCS system is bursting at the seams with bad math and bad handling of units. When most folks say "BTU", they don't mean "BTU", but "BTU/hr" (except when they do mean BTU). There's 3400BTU/hr to the kW.

I wouldn't mind living in a house heated by a HP that meets my heating needs 96% of the year, and is supplemented by strategically placed resistance heaters for the coldest two weeks of the year.

[Xringer]

For me, the proof is in the real time data. If I'm getting great heating from
a very low amount of kwh used (compared to simple space heaters),
that's good enough for me.

It's working great, exactly how 'great'? Not something that keeps me up at night.

Since my primary heat & hot-water is from oil, I'm prone to make the price comparisons.
Looking back at pre-Sanyo electrical use, is very informative. I know that I'll be hitting
the break-even point pretty fast. That's great, but why should I care?

It's a fact the Sanyo ASHP is a good low cost way to heat & cool a home.
Since nothing but an expensive GSHP comes close, it's practically a no-brainer.

I'll bet the cost of an installed GSHP is pretty close to the price of a ASHP,
plus the installed PV to run it during the daylight hours..

(If I had 500watts of GTI PV running right now, I would be heating for free).

[st2288]

My primary heat and hot-water is also from Oil.. which I really hate.. With the heat pump/AC.. I know I will save a bundle..especially with my 7.99kw + 600w (should be installed soon). My goal is 100% free in Heating/cooling and electricity.. hopefully I can add more panels next yr

[Xringer]

It's been almost a year, I wonder how much those two systems cut your heating and cooling bills.?.

Did you get to see the performance of both units on cold days? (15F being cold to me)..

Cheers,
Rich