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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

#81

Post by mmaurizi »

ComputerGuru wrote: post #56
TeMPOraL wrote: post #45

Earlier quoted context omitted.

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 wit…

We run our steam humidifier just fine on 120v, but we have a relatively small townhome at 1400sqft

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

#82

Post by elil17 »

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…

That exists, it's called an air-side economizer. It's used a lot on big buildings.

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

#83

Post by cypherpunks01 »

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…

You are exactly describing a HVAC "Economizer" as they are called. I believe they are almost solely used in commercial HVAC installs, probably due to price/additional install complexity? They are very neat though, and do save significant energy in shoulder seasons, or at night in the summer as you mention.

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

#84

Post by landemva »

ComputerGuru wrote: post #51
AlanSE wrote: post #22

Earlier quoted context omitted.

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…

Whole house fans are often used in summer at dusk to rapidly cool house. Air is sucked through house into attic, which also cools the attic.

https://www.thespruce.com/whole-house-fan-vs-attic-fan-diffe...

Crack open a window downstairs before switching it on.

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

#85

Post by elil17 »

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.

The above comment is incorrect, even for systems without integrated dehumidifiers. AC systems absolutely do have a higher load with higher humidity because ambient water will condense on the evaporator coils if the dewpoint is higher than the evaporator temperature (which it typically is).

That said, it still may be more efficient to open your windows, depending on the humidity.

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

#86

Post by fnordpiglet »

the_other wrote: post #6
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…

> Finding a high-efficiency thermoelectric material that works at normal temperatures and pressures is nearly as much of a Holy Grail as finding a high temperature superconductor. Are they two sides of the same problem?

No, TECs operates on a quirk related to semiconductor properties and are using electricity to move heat from one side to another but necessarily have resistance. Superconductors however are seeking zero electrical resistance. Current TECs produce 5x heat vs heat moved, and have a limited range of operation and a small range (30c) for the delta in heat between the two sides. I’ve been fascinated by TECs for years and I aspire to freeze CO2 with them, but it’s actually been really difficult to get cryogenic temperatures. You need to build a pyramid that has increasingly powerful TECs drawing heat away faster than it can accumulate. Even then I’m hitting walls in the -30c range because efficiency falls off a wall at both ends as you exceed the optimal ranges for the semiconductor materials.

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

#87

Post by landemva »

ComputerGuru wrote: post #56
TeMPOraL wrote: post #45

Earlier quoted context omitted.

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 wit…

I had one that dripped water through a pad in air flow, and had a small drain pipe. Maybe not as good as steam, though much simpler.

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

#88

Post by wffurr »

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…

You are looking for a ventilation system like a HRV.

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

#89

Post by elil17 »

azdle wrote: post #29
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…

It is technically possible. I had the same thought as you and looked into it some time ago. The only references I ever found to it actually being implemented were in cases of giant walk-in (even warehouse sized) refrigerators/freezers in places where district cooling exists. For something the size of a home fridge the costs would be immense compared to the energy savings. You're far far better off spending that money…

Here's a research paper detailing a design for your idea: https://www.sciencedirect.com/science/article/abs/pii/S03605...

It was never pursued further for reasons I discussed in another comment on this thread.

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

#90

Post by cbrozefsky »

BooneJS wrote: post #3

When will air source heat pumps be ready for service in cold weather climates without gas backup?

They are now.

In Vermont, we are in our first year with heat pumps. Have a wood stove as backup and supplement when we want to go pantsless mode. The original oil burner is currently turned off, out of commission waiting on some parts. We could go without the wood stove, and have done so for stretches.

We installed Mistubishi Hyperheats, 3 external units, 5 heads. Zero interest financing by installer, for about 21k all in including electrical work. Earlier this year we also did air source hot water heater, for about 4k all in.

We were spoiled by the whole house air conditioning over the summer, and the heating has been performing just fine. It about doubled our electric consumption, but that bill is still less than my oil bill was, before the price of oil nearly doubled.

We're motivated primarily by a desire to minimize fossil fuel consumption, and then to mitigate volatility in fossil fuel markets. With this install we completed electrifying all utilities in the house , and have a rooftop solar array that previously offset the entirety of our consumption, but will not at current levels.

The heat pumps will just about pay for the cost difference between them and a new oil burner before their parts warranty is up. Add in the cooling, and the increased control and comfort we have, and it's a pretty sound investment, IMO.

As an anecdote, the conversation at the local bar in Rutland, VT the other night was all about people planning to get heat pumps, or promoting them after having them installed. Not wealthy tech enthusiasts, but bartenders, small business owners, and working class families. With the IRA inventives, and the price of heating oil -- it's becoming a normal thing, not an exception.

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