mini-split vs hydronic vs gas stove

[billconner]

I'm converting attached garage to a studio. Will be very well insulated though above average windows.

Cold here - days of below zero is possible and weeks below 10F is expected. Gives me doubts about mini-split. Have oil boiler and pretty sure it has capacity for another zone. Ideally located for minimal piping. I'd use Runtal radiators. Or I have a new gas stove I never installed in previous house, so it's nearly free - some flue pipe and a new propane tank and line in. Could combine mini-split with stove as back-up.

And personally I like the quiet, even, and dust free operation of hydronic.

I appreciate any thoughts shared.

 

[pcmeiners]

The newest low temperature heat pump have no issue heating well below 10 degrees. Also the newest/highest efficency units are twice as efficient as the heat pump cost in the heat cost spreadsheet linked below . Have a Fujitsu low temp unit running at less than $8.50/million BTUs

Home heating fuel comparisons.....

https://www.maine.gov/energy/sites/maine.gov.energy/files/inline-files/Home-Heating-Calculator.xls

Using oil it will cost almost 4 times as much as heating with a high efficency heat pump.

https://www.goodlifehvac.ca/images/Fujitsu_LZ_Series.pdf

 

[zak77]

That's an interesting calculator. Based on that, it'd cost me 10% more to heat with a heat pump vs oil.

 

[pcmeiners]

You need to read before posting..... the heat pump information is for inefficient units, as stated, so is the oil price at $2.00. For present heat costs you need to replace the past prices in the spreadsheet with present costs.

With Massachusetts price of oil (@$3.51/gal), it costs you almost 4 times as much to heat with oil than a very efficient heat pump. Enjoy your oil heat Zak.

 

[zak77]

I actually did update the price of oil today, some places less than $3 per gallon, and the current rate i pay for electricity. And talking to many people in my area who have heated in the winter with heat pumps, they were shocked to see their electric bill the first winter they ran them. I was talking to a building inspector and he was saying he just came back from a conference put on by the state regarding energy efficient heating methods and the person putting on the talk told about his own recent experience of his gas furnace crapping out. He replaced the gas furnace instead of going to heat pumps due to the overall cost and operating expenses.

I'm just going by the chart you posted and real world experiences in my area. Plus, i dont actually heat with oil, i just have it as a backup that i never use.

 

[ipgenie]

I've got hydronic heat in my house, a gas fireplace and a minisplit rated to heat down to - 22F.

I like the comfort of the warm tile from the hydronic heat but this past winter it was cheaper per BTU to use the minisplit so I only ran the hydronic enough to keep the tile from getting cold and kind of kept the floor just slightly warmish.

The minisplit is almost as silent as the floor heat, it just purrs along on low. We had a stretch of below zero days and even at -20 it was putting out plenty of heat. I have a second one in my small office that is only used for cooling and it's so quiet that it can't be heard by a caller or during a Zoom meeting. I'm building a new office space in the shop so my wife can have a piano room in the house. I'm going to heat and cool it with a minisplit.

The fireplace is also pretty quiet if the fan is off but it's the least efficient. It's occasionally used for the look but we installed it so we can have heat during a power outage since it can operate without it.

 

[billconner]

I'll try to open spread sheet later - can't on phone.

I'm not sure it factors in initial cost which is a significant factor. This is only a 460 sf addition. Own the gas stove, so very low initial cost. Have the oil boiler, just add a zone and radiators, so moderate cost. The mini-split would be all new and I'm wondering if the the small, inexpensive diy mini-splits are the ones that work at -15°F. (And my wife would only use AC for a few weeks each summer, me not at all.) How many years to pay back much higher initial cost.

 

[theoldwizard1]

In floor heating is the most COMFORTABLE form of heat. If your feet are warm you are warm.

The best of both is a mini-split for A/C and quick heat, but the mini-split needs feed a heat exchanger to heat the floor.

 

[Jackfre]

Mini-splits are terrific products. They are the only source of heat taht we have that can allow you to off-set the energy cost to run them. You can’t make your own gas, well most of us and for limited times perhaps, and you aren’t going to refine your own oil. You can add a solar system to your home and make your own electricity which can offset the cost of operation of the mini-splits. I zeroed my electric bill by self installing my own solar system. It was very gratifying. Now, having downsized I am analyzing the new property for the same treatment. Step by step!

 

[billconner]

Starting from scratch, assuming heat pumps will work in your climate, I don't question it's the way to go.

Changing over, like from oil boiler and radiant baseboard to heat pumps, will take a very long time to pay back, if it ever will within lifespan of heat pumps.

Our boiler is from 1994. A pretty plain boiler - probably in the 80% efficiency range. I asked service company about replacing it with a more efficient unit and they didn't hesitate to say it would never pay back. (Not even considering our age would need a quicknpayback.) They can service existing forever they claim, and are certain the newer - computerized - high efficiency ones will not last 20 years. What are the chances a new car today can work in 100 years, like a 100 year old car can today?

Still, if starting from scratch, I'm sure I go heat pumps if at all possible, respite electric baseboard with wood boilers and/or stoves seem popular here. Even those are getting complicated, making a big market for used older ones.

 

[fitter30]

If what your going to be working on minis don't like dirt. The fins are enhanced have little splits in them that get blocked. Filters on minis are not very good. Minis are a pain to clean. If your not heating the garage all the time hot water will catch up a lot quicker.