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Heat pumps of the 1800s are becoming the technology of the future

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Re: Heat pumps of the 1800s are becoming the technology of the future

#51

Post by ComputerGuru »

AlanSE wrote: post #22
nickpeterson wrote: post #4

Why can’t my whole home participate in this technology? It would seem an ok fit for things like freezers, refrigerators, hot water heaters, etc. When it’s freezing cold outside, it seems crazy that I warm the air of my house and then use electricity to keep the fridge cooler than the air I just heated. Someone needs to make a standard for moving heat/cool through all appliances in a house…

The fridge isn't the biggest energy hog in the house, but I'm very sympathetic to the absurdity of heat levels in a house. I often see my HVAC cooling when the set-point temperature is actually _higher_ than the outside temperature. Logically, the house is a heat generator, it makes sense physically. The roof is black, etc. It would offer a good number of benefits if the system could outright open a duct to the outdo…

I've built/retrofitted and a prototype of mechanically operated louvres with push/pull fans for air exchange in an old school building, tied to the thermostat, ac, and a CO2 detector.

The idea of doing the same in my home has been taunting me for years now. Ideally you'd have two such louvres, one with a push fan in the upper floor and the other with a pull fan in the lower floor to simultaneously eject unwanted heat, bring in fresh air, and boost whole-house circulation. They'd be set up to interface with the thermostat/hvac and would operate when the outdoor temperature at intake is lower than the temperature at exhaust and both are above the set point on the ac.

The biggest problem is really one of convenience. You'd need a filter on the intake and a rather large and powerful fan to overcome that static pressure - ergo, a noisy one. And you'd probably have to fully dismantle the system in the winter to prevent the cold from getting in (the Midwest is cursed with both hot and humid summers and cold and dry winters). It just end up being the kind of thing where the devil really is in the details and you either do it right and it's a huge undertaking or you do it fast and sloppy and its drawbacks won't be worth it.

But I agree, nothing is more infuriating than seeing the AC on and the outdoor air temperature being lower than that of the home. And opening windows just doesn't make a difference since in most 20th century homes there's just poor airflow and no circulation.

Re: Heat pumps of the 1800s are becoming the technology of the future

#52

Post by Volundr »

jdmichal wrote: post #37
ballenf wrote: post #28

Earlier quoted context omitted.

I've often wondered if opening windows while AC is running and outside temp is below inside temp is less efficient than keeping them closed. My thought is I should keep them closed due to extra load on the AC to dehumidify the outside air. Or open windows and turn AC to fan-only mode to prevent stagnant air in rooms without windows.

Unless you have a very strange setup, centralized A/C does not have humidity sensors nor run just to dehumidify. Nor does removing humidity increase the load on the A/C system. Removing humidity is just a happy by-product of how centralized A/C works. So no, you would not be increasing load for that reason.

FWIW I had a new Lennox heat pump installed a couple years ago, and I can (but don't) configure it to "cool to dehumidify", and it tells me the humidity on the thermostat. I don't know if this is common in new units, or if I'm just special.

Re: Heat pumps of the 1800s are becoming the technology of the future

#53

Post by poutine »

jakedata wrote: post #19

In 2017 we installed a very efficient air-source heat pump and solar panels. My electrical utility offers 1:1 buyback of electricity so I am able to build up a credit in the summer and run the heat pump well into the fall and winter on that surplus. The system is sized for cooling the house which means that it is undersized for heating, but during cool fall and spring temperatures it operates satisfactorily as a heat…

Living in the PNW, I'm building a new house and I've chosen a dual fuel hybrid heat pump system as per https://www.bryantbing.com/products/hybrid-heat/

I'll also have solar + battery. Should be able to run the furnace & fan but not the heat pump (too many kW/h) during a power outage and thus heating with gas. It'll run off the heat pump for 90-95% of the year, only using gas on the coldest days, or during an outage. To go full heat pump for 100% of the year you need to seriously upsize the heat pump(s) and you wouldn't have performance during an outage.

Re: Heat pumps of the 1800s are becoming the technology of the future

#54

Post by rstupek »

soco wrote: post #39
ballenf wrote: post #28

Earlier quoted context omitted.

I've often wondered if opening windows while AC is running and outside temp is below inside temp is less efficient than keeping them closed. My thought is I should keep them closed due to extra load on the AC to dehumidify the outside air. Or open windows and turn AC to fan-only mode to prevent stagnant air in rooms without windows.

Is the AC dehumidifier an extra feature/task, so actively followed, or is it doing dehumidification just as a byproduct happening while cooling?

It's a byproduct of the process of cooling the air

Re: Heat pumps of the 1800s are becoming the technology of the future

#55

Post by PinguTS »

fasteddie31003 wrote: post #8

I had a similar idea when I was designing a heating system for a mountain house I was planning on building. I was planning on primarily heating with an oversized wood stove. The excess heat the wood stove would produce would be captured by a heat pump inside the house with its coils in a 500 gallon tank of water that was well insulated. When the house needed heat you could run the heat pump in reverse or make a syste…

I have about 1050 US gallons (4000 l) of water storage in my house. The very effective wooden carburettor heating system is heating up the water storage. Then you use the water storage for next days until you have to re-fire.

That is a standard package provided by many companies from Austria and Germany.

Re: Heat pumps of the 1800s are becoming the technology of the future

#56

Post by ComputerGuru »

TeMPOraL wrote: post #45
jdmichal wrote: post #37

Earlier quoted context omitted.

Unless you have a very strange setup, centralized A/C does not have humidity sensors nor run just to dehumidify. Nor does removing humidity increase the load on the A/C system. Removing humidity is just a happy by-product of how centralized A/C works. So no, you would not be increasing load for that reason.

Happy in some times, unhappy in others. There are days I'd love if the A/C would have a humidifier built-in, for those winter months when you might want to use A/C to warm the interior.

A good chunk of the United States (and a number of other countries) uses forced air natural gas heating. If you fall into that group, you can install a "whole-house humidifier" that injects steam into the hot air plenum, distributing it around the house. This makes the air less dry (obviously) but also has the side-effect of actually reducing the need for heating because air holding moisture feels warmer than air without (hence the oppressive heat in the humidity of summer), meaning you can lower the thermostat.

Unfortunately I have only seen commercial humidification units that boil water into steam with the use of natural gas. Without exception, everything for sale for home use uses electricity (you'll need 230V minimum, single phase will do just fine) to boil the water, which is costly (though this year natural gas prices have risen or even doubled, but even in states with cheap electricity it's probably still cheaper to use natural gas).

Re: Heat pumps of the 1800s are becoming the technology of the future

#57

Post by poutine »

rsynnott wrote: post #41
macinjosh wrote: post #30

Earlier quoted context omitted.

Still waiting for one of these people who rave about their heat pump system to actually rely on it full time without a backup. Most folks could barely afford to replace an existing furnace in a place that has all the fixtures installed, much less pay to install a second one based on different setup, and then pay for maintaining two systems on top of everything else. It is absurd to think that this is a plausible way…

> Still waiting for one of these people who rave about their heat pump system to actually rely on it full time without a backup. Eh? Most new houses in Ireland have them these days (it's more or less the only way to meet the efficiency requirements). There's never a backup. > Same thing for induction stoves. Eh? Again, these are pretty standard these days, and why would you need a backup?

Different geographies have different requirements. You're not likely to need to face a week or more of no power after an ice storm in -10'C in Ireland.

Re: Heat pumps of the 1800s are becoming the technology of the future

#58

Post by rainsford »

macinjosh wrote: post #27

Half way through the article the author is touting how these can work in cold climates like Norway, then their example homeowner immediately states they have this but also they still have a furnace for when it actually is cold. Why do journalists try to pull crap like this? Contradictory information in the same paragraph!? If you have to have a backup it is _not_ a replacement and it will not get us off of carbon. Mo…

A solution doesn't have to move us away from fossil fuels all by itself to be a useful piece of the puzzle. Even if heat pumps were only viable in places that don't regularly get super cold in the winter (which isn't true), that's a huge number of places covering a large portion of the population. A lot of the US, for example, gets hot enough in the summer that you want central air conditioning but also gets moderately cold in the winter. A heat pump system can cover you all year round with the same exact system. If you install a backup heat source, which can be electric by the way, that covers even more potential installation locations.

Re: Heat pumps of the 1800s are becoming the technology of the future

#59

Post by Volundr »

macinjosh wrote: post #30
jakedata wrote: post #19

In 2017 we installed a very efficient air-source heat pump and solar panels. My electrical utility offers 1:1 buyback of electricity so I am able to build up a credit in the summer and run the heat pump well into the fall and winter on that surplus. The system is sized for cooling the house which means that it is undersized for heating, but during cool fall and spring temperatures it operates satisfactorily as a heat…

Still waiting for one of these people who rave about their heat pump system to actually rely on it full time without a backup. Most folks could barely afford to replace an existing furnace in a place that has all the fixtures installed, much less pay to install a second one based on different setup, and then pay for maintaining two systems on top of everything else. It is absurd to think that this is a plausible way…

Define backup? I have a heat pump as my only source of cooling/heat, but it does have a single heat strip in it for the couple days a year it gets too cold for the heat pump alone. There no "second fixture" to maintain.

This is common for my area.

Re: Heat pumps of the 1800s are becoming the technology of the future

#60

Post by ars »

retrac wrote: post #2

> heat pumps: electrical devices Just to be pedantic, but not exactly. The typical design in a domestic heating unit, or refrigerator is mechanical. A fluid is pumped and cyclically compressed/expanded. While electric motors are usually used, they can be driven by any source of mechanical energy; driven directly by a combustion engine is not too unusual. There are also heat pump cycles that can be driven directly wit…

> There are also heat pump cycles that can be driven directly with heat.

They are called https://en.wikipedia.org/wiki/Absorption_heat_pump

But they are much less efficient that electrical ones, adding even a small amount of electricity to the cycle (even if the primary energy is heat) can dramatically improve efficiency.

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