Anyone added mini split heat pumps for supplemental heat? Did they save $$$?

Jamie Hall

So about 16 cents per BTUh capacity for geothermal wells? Interesting. Very interesting. At that cost, I could drill enough wells for Cedric for only about $70,000? humm... then replumb for hot water instead of steam? And get some heat pumps which would last 15 years?

pecmsg

Jamie Hall said:

So about 16 cents per BTUh capacity for geothermal wells? Interesting. Very interesting. At that cost, I could drill enough wells for Cedric for only about $70,000? humm... then replumb for hot water instead of steam? And get some heat pumps which would last 15 years?

When are you starting? 

wmgeorge

Jamie Hall said:

So about 16 cents per BTUh capacity for geothermal wells? Interesting. Very interesting. At that cost, I could drill enough wells for Cedric for only about $70,000? humm... then replumb for hot water instead of steam? And get some heat pumps which would last 15 years?

I do not get your point? The wells and loops are a one time expense, they do not wear out. Geothermal HP are 20 - 25 year service life? Its a sealed system water is pumped down into well loops and back out. One circulating pump less that 1/3 Hp.

pecmsg

wmgeorge said:

So about 16 cents per BTUh capacity for geothermal wells? Interesting. Very interesting. At that cost, I could drill enough wells for Cedric for only about $70,000? humm... then replumb for hot water instead of steam? And get some heat pumps which would last 15 years?

I do not get your point? The wells and loops are a one time expense, they do not wear out. Geothermal HP are 20 - 25 year service life? Its a sealed system water is pumped down into well loops and back out. One circulating pump less that 1/3 Hp.

Please show me the documents showing 20 years. Most of my heat exchangers are 10 -15 years. 

Jamie Hall

Do the math. The cost for the wells is 10 years of fuel. The boiler lasts 20 years -- more if it's taken care if, The lost opportunity cost (which no one ever seems to think about) for the overall conversion would be more than the existing system costs to run, counting in depreciation.

I'm not suggesting that, sooner or later, we may all have to go to electricity as our power source. We may. What I am saying is that there is no way that you can make an economic case for doing so, either as individuals or as a society. The sooner folks wake up to this, and are able to make an informed decision that this is going to cost a LOT of money but it needs to be done, and the money needs to be found, the better the discussion will go.

wmgeorge

Yes we will all be using electricity one way or the other for heating and cooling. The only way to go is nuclear power, the French are doing it. Solar is fine, wind generation is fine but it will not charge all those electric cars!

I am assuming your using your 78% steam boiler to also cool using an Absorption chiller like Carrier or some other? Geothermal heats and cools both with a COP of 4 or even 5. I had engineers I work with do the math, geothermal sells and works.

Hot_water_fan

A simple cost analysis showed the ASHP to be more afford- able than the GSHP based on performance and initial capital costs. 

@wmgeorge from the article you linked - the three ton single speed GSHP in Canada was $20k more than the variable speed cold climate heat pump and was hardly more efficient. There might be a payback some places for some houses, but almost always an ASHP seems to win out. The drillers need to move to Canada, if they can make money at $2k/ton, they’ll be kings up there . 

pecmsg

Again post the documents supporting these claims.  COP of 4 or 5?

Hot_water_fan

What I am saying is that there is no way that you can make an economic case for doing so, either as individuals or as a society. 

If the utilities do it right ( big if) it will be extremely easy to shift the vast majority of heating to electric. For forced air (majority of US homes and it’s not close), the three technologies are: hybrid furnace/heat pump, cold climate heat pump or heat pump plus resistance. We can pick from these three and get there very cheaply. Then it’s a matter of increasing electric system utilization (bringing down costs without adding capacity - easy to do if a grid is built for summer load). It would have more expensive for me, both upfront and over time, to install a furnace + AC vs a heat pump. 

ratio

But, what if the grid was built for a summer load c. 1952, and not c. 2022? I myself remember the time when AC was unheard of, at least in the kind of neighborhoods I lived in. It suuuure looks, admittedly to a layperson like myself, that we're already overextended.

& I still have trouble seeing how adding another conversion in the process is going to increase efficiency.

Hot_water_fan

Well the grid is obviously not the same size as it was pre AC, yet we managed to survive. It grows incrementally and will continue to. If it doubled over the next 20 years, no one would break a sweat. The conversion part is simple: new combined cycles (no one is installing 2001 vintage) are ~50% efficient, some even higher. Even with line loses, remarkably easy for a heat pump to surpass a gas furnace/boiler. 

wmgeorge

You folks can argue all you want and frankly I do not care. The market place picks the winners. Right now the winners are high efficiency air source heat pumps and geothermal, plus high efficiency HW boilers and gas furnaces. Added, the wells are generally unlined but some will need lined and 200 ft or so deep. Loops are 200 -300 ft or so long under 4 or 5 feet of dirt.

https://www.energy.gov/energysaver/geothermal-heat-pumps

and one more.... https://igshpa.org/geothermal

Jamie Hall

It is very easy to generalize from specific instances -- or regions -- and assume that everywhere is like what one knows. In fact, we all do it, whether we mean to or not, and it takes great effort to not do so. This is true of all kinds of things -- I could get quite philosophical about it -- but I won't. But for the purposes of this discussion, what @Hot_water_fan says is quite true -- in some places. The grid in those places is capable of handling the summer AC load, and the summer AC load is greater than the winter heating load. But... that isn't true everywhere, such as my corner of New England. The grid in our area has almost no summer AC load -- no one needs it except the very wealthy -- but it is already marginal for the winter heating load; all that needs to happen is one generating station to go off line and we have rolling blackouts. What happens when one dumps the entire load now taken by oil and gas onto that grid? It won't be pretty.

My point is this: like everything else in a country as large as this, with such wide variations from place to place, even within single States (consider just New York State for instance -- what looks wonderful in White Plains may not be quite so good in Gouverneur, for instance), it is essential that the "solutions" be tailored to the people and the regions. One trick ponies just won't do.

That's all I'm asking or suggesting.