Geothermal vs Wood Boiler

[peakbagger]

What's the thinking on this? Feasible to store sufficient geo-thermal heat pump produced hot water during daytime electric production to make it through the night or cloudy period? Other ideas?

Probably not a good option to store geothermal produced hot warm water as geothermal heat is generally relatively low temperature, thus the storage needs to be huge. As long as net metering remains available it is the way to go but as non dispatchable renewables like solar increase as a proportion of the grid, I fear that it is going to be chipped away by the utilities. At some point real time pricing is going to appear which will shift a portion of the burden for high heating season power demand into the consumers laps and I expect even the folks will net metering will be clipped by that shift.

Ultimately the best investment is energy reduction. Spend the money to build a net zero energy house and on the rare times you do need heat, run a small woodstove. Unfortunately, most folks want to keep their current home so the net zero house is unlikely although deep retrofitting of a current house can substantially reduce usage.

Off gridders in northern climates have already worked out solutions to this and generally it entails wood heat, solar panels, a battery bank good for three days, a back up generator and a willingness to change their lifestyle to adjust to low energy use.

 

[moey]

We have a ground loop about 3200ft about 5 foot deep in the ground 5 ton system in mid maine ( colder then where you are ) about 2400sq ft house. This is our first winter it has done very well in the cold. Last month my kw usage was about 2600kw before the system it was around 900kw per month. So about 1700kw $238 per month for heat last month. Ping me if you have some questions Ive learned a lot since we got it.

I question any heating system adding value to a house it may sell a house faster but adding value in my opinion just isnt there but what do I know.

Ductwork isnt included in the 30% credit there was a recent IRS ruling 2 months ago excluding it.

 

[jebatty]

Energy reduction has been our focus and change in life style in addition to simple reduced usage is our direction. Looking at past electric bills, before our big effort to reduce usage, Nov and Dec electric usage for general service historically was about 600 kwh/mo. For Nov and Dec 2013 the usage was 350 kwh/mo. Beginning in Jan 2014 we switched our lighting to nearly all LED, so I expect a further reduction. The reductions so far have been no more radical than shutting things off when not being used or needed. Reductions beyond this likely will entail a change in lifestyle and the thinking has started as to what to change.

 

[Karl_northwind]

Over here geothermal is taking over the market. Not many people instal pellets/wood boiler. The market for the pellets boilers are like dead..
The newest heatpumps have a cop of 5. Good to have floorheat or big radiators as the cop gets lower when using higher tempetures to heat the house.

in Sweden this fall that is what I saw, and was told. There are some interesting problems that the utilities are encountering with large amounts of solar electric in the summer and large amounts of geo heat in the winter. My wife's cousin is an engineer with one of the utilities up north (Karlstad) That said, the geo units I saw in all sorts of places (including the old family homestead) were way more advanced looking than the clunky stuff I see around here. Compare looking at a european Mod-con versus an atmospheric gas boiler. that kind of comparison.

the availability of 3 phase power everywhere and low-carbon electricity (lots of hydro from Norway) makes that option a lot less ugly to me.

 

[Hansson]

Dont u have 3 phase power in the US?

 

[peakbagger]

Dont u have 3 phase power in the US?

Three phase is generally not available for residential homes and rural areas in the US and generally when it is available it is priced as a commercial account. Thus most folks have to live with single phase. This makes it difficult to run industrial equipment in residential area and there is market for converters that convert single phase to three phase. Inverter type motors generally can accept single phase input but the given the scarcity of three phase residential equipment is rarely offered as three phase. Generally commercial equipment can be had in either single or three phase in the smaller units and then switch to three phase for the larger units.

 

[Karl_northwind]

I need to get a convertor, we just got our first piece of 3-phase equipment, a food processor of all things!

 

[arbutus]

This is great advice here. I'd go with ASHP's over GSHP any day of the week. Similar efficiency. Less upfront cost (even once the 30% GSHP rebate is factored in). The only question is existing distribution system. If you have baseboard then maybe a biomass boiler (bulk-fed pellets or wood) would make sense.

The other question is A/C. The ASHP's will give you an A/C system and the biomass will not. The GSHP system will provide A/C as well, but only if you are using water to air units, not if you are using water to water and planning to run it through a radiant floor or something.

ASHP if you need air conditioning at all. Modern units appear to have good performance down into the teens.
Here in Michigan's UP we do not need AC, and spent a LOT of time last winter well below zero. I looked into GSHP and needed something like 22 gpm water in an open loop water to water system on a design day - No thanks!

 

[AK13]

Just to be clear they are not similar efficiency. Under average conditions, the ground source is about 2x as efficient. In very cold weather that grows to maybe times more efficient depending how cold your field gets.

I disagree. Although it could depend on your definition of similar. Modern ASHP's are providing AVERAGE annual COP's on the order of 2.5. Obviously this is ENTIRELY dependent on where you live. So my value is for the Northeast. Up in NB, perhaps this drops to 2.0 to 2.25 range. But the OP is in CT where the temps are warmer and he'll be seeing a COP of 2.5 easily. I do not believe GSHP's are producing COP's of 5.0 plus. And even if the mfr's are making that claim if you do an honest analysis and include all of the pump energy, etc you'll find that the true COP takes a significant hit. Last time I did a thorough analysis we determined that the GSHP's COP for our closed loop application was about 0.5 to 1.0 COP higher than for the ASHP's. And we calculated that the better investment was in PV panels to make up this difference.

Obviously, I'm not a big fan of GSHP's. They have their place, but they are costly, complicated and there are far more pitfalls to avoid. For example, one dirty little secret is that in a closed loop system the ground is not an infinite source of heat. Here in the northeast if you have a system that is used only in heating mode or very unbalanced with much more heat than cool you will actually cool the earth over several years. You need to "recharge" the ground in the summer by using A/C.

 

[Hansson]

U dont need to recharge the ground. Do you think that u can do that whit a A/C?

The swedish energy agency have done a real test in 20 houses. The SCOP in the newer instalions is around 3

https://translate.google.se/transla...varmepumpar-matningar-i-hus/?tab=2&edit-text=

 

[heaterman]

I haven't verified this but I was told just last Saturday that the largest Mitsubishi wholesaler in the state just dropped the line. From what the contractor was telling me they let it go because the inverter units did not perform as promised and Mits will not do anything about it. They have a LOT of unhappy customers.

I like ground source heat pumps for the way they perform but only in a closed loop vertical bore field. I heard of a couple people whose horizontal fields froze solid last winter. The system ran so much that it pulled frost right down to the elevation of the ground loops. At that point system performance plummeted and those poor fellas were running on electric backup.. $$$$$.$$

As Arbutus said the flow rate can get really high when we get temps like last winter. I quoted a house last year (McMansion) that had a max flow rate of 97GPM and the owner wanted to go pump n dump rather than closed loop. Didn't happen.

From what I have observed and heard from customers, the comfort level of the two systems is not comparable. Wood hands down.

 

[jebatty]

This comparison is one of apples and oranges: different systems with different considerations.

For me, with an ample supply of wood from our own property and the ability to harvest the wood for my gasifer and wood stove, plus being present between my wife and I to fuel each as needed, and not minding very minimal mess (grandchildren are messier than is the wood), wood wins over all alternative heat sources on comfort and cost. That said, a mini-split may be in the future for us if we can get an off-peak electric rate and where the mini-split can meet our heat demand down to about 20F or lower. That would eliminate much of the labor in C/S/S wood, which as I age becomes of more significance, and with our solar electric, the cost may be near $0 (although we would lose credits that otherwise would be convertible to cash). I doubt geothermal ever would be a consideration for us.

For a person who wants a fully automated system, who must pay high prices for wood, who cannot be around to fuel the wood appliance as needed, who will not accept minimal smoke and mess, and who is in a climate where a HP geothermal is in its sweet spot, I can fully understand the interest in geothermal.

This discussion is good, in large part because it leads to a more complete appreciation of the pros and cons of two types of heating system.

 

[goosegunner]

My cousin has a very elaborate and expensive horizontal loop Geo system. First year would not keep up. Added another field. It will heat down to about 15 degrees after that the house starts losing temp. For many weeks this past winter it would maintain his house from 55 to 60 degrees. He refused to use propane so he slept with many layers and stocking cap.

His heat emitters are all low temp in floor, gypcrete on the upper levels.


One of our new Fire station's has a geo pond loop. There is no back up system. You basically freeze your ass off a lot. Depth of winter the glycol loops coming back were 27 degrees.

I will stick to my wood boiler.

gg

 

[Karl_northwind]

Nothing makes heat like burnin' stuff.