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Good video. I've been thinking about heat pumps a lot lately, namely, is it possible to make geothermal ground loops cheap and not disruptive? I wrote a bit abo

Good video. I've been thinking about heat pumps a lot lately, namely, is it possible to make geothermal ground loops cheap and not disruptive? I wrote a bit about it here: https://www.greennewdealio.com/heating/robot-mole/ https://www.greennewdealio.com/heating/robot-mole/ Air source heat pumps really are great and it seems everyone in mild climates should be moving towards them. In fact, what I'm working on right now is trying to figure out the maximum ground loop "budget", beyond which it would be cheaper to run inefficient heat sources (COP of 1) for the small periods of time where air sourced pumps no longer work.

deckiedan 5y ago
Would it be possible to do multiple vertical shaft tubes, straight down rather than a huge flat thing? I feel like in 100 years time we'll have all these loopy pipe arrays all over the place being a pain to clean up...
- c22 5y ago
  Yes, this is usually how it's done when a large field doesn't happen to be available. Vertical boreholes are much more expensive to make than shallow trenches, though.
  - bradknowles 5y ago
    Depends on what your ground looks like. If it's bedrock at the surface and you'd have to dynamite to clear a large patch, then drilling a small hole will be much less expensive and much more efficient. If it is just plain brown dirt for miles down, then digging some trenches might be a better solution. If it's a few feet of sand until you hit the water table, then I have no idea what the best solution is.
sokoloff 5y ago
I looked into air-to-water heat pumps (hard) as I’m planning to replace my boiler this summer. Even with large cast iron rads, I need 130°F water temp when it’s below about 25°F outside and the air-to-water heat pumps struggle to hit 125°F output water temp there and fall even lower when it gets colder.
- chrislund 5y ago
  They aren’t in all markets but there are heat pumps that use CO2 as the refrigerant that can make quite-high output water temps. They’re often used for domestic hot water. I haven’t looked too deeply in to them but IIRC they have COPs around 3–4. Sanden is one manufacturer, Mitsubishi and their Ecodan line is another.
beamatronic 5y ago
The Bay Area has a mild climate but I’ve never seen a heat pump here.
- Tagbert 5y ago
  Probably because in a mild climate even conventional heating systems don’t cost much. There isn’t a lot of pressure to invest more in the system initially just to save only a small amount per month.
  - bradknowles 5y ago
    The heat pump has more to do with getting off gas and oil and other hydrocarbons that are burned at the house, and switching all your energy usage over to electricity, which can either be efficiently generated elsewhere, or allow you to go completely off the grid. Don't do it today to save money today. Do it to save the planet and help ensure that you're not beholden to $9000/hour bills because the people selling you the precious hydrocarbons have you backed into a corner that you cannot possibly dig yourself out of. You know, so like you can't be screwed by the like of ERCOT when they tell Texans "oh, that sure is a nice grid you've got there. It would be a real shame if it were to be shut down simply because some of the electrical generating plants haven't been properly weatherized. Hmm, I wonder how many of these plants we should take offline on the coldest day of the year????"

deckiedan 5y ago

Would it be possible to do multiple vertical shaft tubes, straight down rather than a huge flat thing? I feel like in 100 years time we'll have all these loopy pipe arrays all over the place being a pain to clean up...

c22 5y ago
Yes, this is usually how it's done when a large field doesn't happen to be available. Vertical boreholes are much more expensive to make than shallow trenches, though.
- bradknowles 5y ago
  Depends on what your ground looks like. If it's bedrock at the surface and you'd have to dynamite to clear a large patch, then drilling a small hole will be much less expensive and much more efficient. If it is just plain brown dirt for miles down, then digging some trenches might be a better solution. If it's a few feet of sand until you hit the water table, then I have no idea what the best solution is.

sokoloff 5y ago

I looked into air-to-water heat pumps (hard) as I’m planning to replace my boiler this summer. Even with large cast iron rads, I need 130°F water temp when it’s below about 25°F outside and the air-to-water heat pumps struggle to hit 125°F output water temp there and fall even lower when it gets colder.

chrislund 5y ago
They aren’t in all markets but there are heat pumps that use CO2 as the refrigerant that can make quite-high output water temps. They’re often used for domestic hot water. I haven’t looked too deeply in to them but IIRC they have COPs around 3–4. Sanden is one manufacturer, Mitsubishi and their Ecodan line is another.

beamatronic 5y ago

The Bay Area has a mild climate but I’ve never seen a heat pump here.

Tagbert 5y ago
Probably because in a mild climate even conventional heating systems don’t cost much. There isn’t a lot of pressure to invest more in the system initially just to save only a small amount per month.
- bradknowles 5y ago
  The heat pump has more to do with getting off gas and oil and other hydrocarbons that are burned at the house, and switching all your energy usage over to electricity, which can either be efficiently generated elsewhere, or allow you to go completely off the grid. Don't do it today to save money today. Do it to save the planet and help ensure that you're not beholden to $9000/hour bills because the people selling you the precious hydrocarbons have you backed into a corner that you cannot possibly dig yourself out of. You know, so like you can't be screwed by the like of ERCOT when they tell Texans "oh, that sure is a nice grid you've got there. It would be a real shame if it were to be shut down simply because some of the electrical generating plants haven't been properly weatherized. Hmm, I wonder how many of these plants we should take offline on the coldest day of the year????"