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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

#361

Post by Mandatum »

EricE wrote: post #335
fifteenforty wrote: post #269

Earlier quoted context omitted.

The no 1 reason I bought the Daikin model referenced over the comparable Mitsubishi Electric is that it has the ‘MOULD PROOF’ function. It runs the fan automatically after you have had it in cooling mode, to evaporate the moisture build up from the interior condenser coil, thereby removing the moisture required for the growth of bacteria and mould. So far, it seems to be working! Better than relying on everyone to ma…

If you live in any kind of area with high humidity you just shifted the mold from the AC unit to the rest of your house. Hell even here in the desert I'm not sure I'd want to use that "feature".

It only becomes mold by sitting and growing. If the A/C dries it after use, it doesn't have any time to grow.

Yes, over time - any amount of moisture will produce some mold. But it will be negligible.

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

#362

Post by operatingthetan »

fifteenforty wrote: post #359
throwawayacc3 wrote: post #346

Earlier quoted context omitted.

Except it's incorrect. The best system is a "ducted ductless" system that circulates and filters air throughout the house.

I've seen that terminology used on US websites, it took me a while to get my head around. In Australia it would just be called ducted reverse cycle. In the vast majority of cases it would be "ducted ductless" I guess: outside unit connects via refrigerant lines to a heat exchanger and fan in the roof cavity, when then distributes the heated/cooled air to rooms via conventional ducting.

Nobody calls it that (ducted ductless), it would just be called a ducted heat pump. The refrigerant lines just run to a central air handler where the ducts start in the house, instead of the air handlers that mount on the walls.

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

#363

Post by Dylan16807 »

elil17 wrote: post #316
Dylan16807 wrote: post #245

Earlier quoted context omitted.

Thermal infrared doesn't go through glass. You only lose a negligible amount of visible light. It's still 100% efficient as an integer percent.

I assume by “thermal infrared” you mean the IR produced by approximately room temperature objects. Incandescent bulbs produce much higher energy infrared because the filament reaches about 2000 Celsius. Those higher energy waves can go through glass.

Right, that's true, I was thinking about it wrong.

Still, not much is going to hit a window on average. So maybe 90% efficient.

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

#364

Post by westurner »

jwcooper wrote: post #148
kccqzy wrote: post #132

Earlier quoted context omitted.

Not being snarky but why don't you just open the window for that? I have a CO2 detector that I believe is a reasonable proxy for stale air. When it goes above 1000 I simply open the windows. By the time I remember to close the windows the reading is almost always below 500.

Where I live, it can get very cold. Not always very efficient to open windows for 5 months out of the year. A great option for keeping CO2 levels down in a house is with an HRV (or ERV) [1] that will heat the fresh air coming in to cycle it throughout the house. [1] https://en.wikipedia.org/wiki/Heat_recovery_ventilation

From the ERV/HRV (Energy Recovery Ventilation / Heat Recovery Ventilation) wikipedia page: https://en.wikipedia.org/wiki/Energy_recovery_ventilation#Ty... :

> During the warmer seasons, an ERV system pre-cools and dehumidifies; During cooler seasons the system humidifies and pre-heats.[1] An ERV system helps HVAC design meet ventilation and energy standards (e.g., ASHRAE), improves indoor air quality and reduces total HVAC equipment capacity, thereby reducing energy consumption.

> ERV systems enable an HVAC system to maintain a 40-50% indoor relative humidity, essentially in all conditions. ERV's must use power for a blower to overcome the pressure drop in the system, hence incurring a slight energy demand.

In Jan 2023, the ERV wikipedia article has a 'Table of Energy recovery devices by Types of transfer supported': Total and Sensible :

> [ Total & Sensible transfer: Rotary enthalpy wheel, Fixed Plate ]

> [ Sensible transfer only: Heat pipe, Run around coil, Thermosiphon, Twin Towers ]

Latent heat: https://en.wikipedia.org/wiki/Latent_heat :

> In contrast to latent heat, sensible heat is energy transferred as heat, with a resultant temperature change in a body.

Sensible heat: https://en.wikipedia.org/wiki/Sensible_heat

There's a broader Category:Energy_recovery page which includes heat pumps. https://en.wikipedia.org/wiki/Category:Energy_recovery

Are heat pumps more efficient than ERVs? Do heat pumps handle relative humidify in the same way as ERVs?:

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

#365

Post by [deleted] »

throwawayacc3 wrote: post #346
operatingthetan wrote: post #176

Earlier quoted context omitted.

Good callout. Some people have the strangest reasons to hate high-efficiency ductless systems.

Except it's incorrect. The best system is a "ducted ductless" system that circulates and filters air throughout the house.

[deleted]

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

#366

Post by ace2358 »

fifteenforty wrote: post #109

In a house I own in Melbourne, Australia, I just replaced an old gas central heating system with 3 new top of the line Daikin mini split heat pumps. The new units can heat the entire house for the same amount of electrical energy that was used to run the FAN in the old gas unit. They are crazy efficient. Ducts are dead. The Daikin Alira X is the gold-plated option and cost $8k AUD for 2x2.5kw and 1x7.1kw units includ…

It’s going to take a lot of work to get Melbourne homes up to modern standards for heating cooling and insulation!

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

#367

Post by riceart77 »

batiudrami wrote: post #258
jimmaswell wrote: post #238

Earlier quoted context omitted.

That thing's an eyesore compared to a duct to me.

Much like solar panels on the roof (which I have also heard Americans describe as an eyesore), once they are common enough your eyes just slide over them and you don’t notice.

> your eyes just slide over them and you don’t notice.

Nah.

There have been minisplits in the US for years, they are just not very common. Moreover they have been commonplace in Asia for decades now. They are noticeable. I personally think they look like ass. They are huge and you are blind if you don't notice them. There is a reason why ducted or recessed models are available internationally for luxury homes. It has nothing to do with Americans.

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

#368

Post by riceart77 »

elil17 wrote: post #350
sidewndr46 wrote: post #327

Earlier quoted context omitted.

But if we're going with the "heatpumps are more than 100% efficient" that everyone brings out, then running my computer to work & heat my room is far above 200% efficiency. If I'm running my computer to use it & it keeps me warm, there is no way turning on a natural gas heater is going to reduce my costs.

Heatpumps are more than 100% efficient refers to a technical specification measure called efficiency, which is watts of heating per watt of energy input. For space heaters, electric furnaces, and your computer (/many other appliances), it’s always 100%. For modern gas furnaces it can be 90%ish (but the difference in electricity and gas prices mean that gas furnaces are still cheaper). For heat pumps it’s typically be…

> So, yeah, it’s not wasteful to vent your computer exhaust outside in the winter, but no one’s doing that.

Uh, come again? If I am using my computer anyway - why would I exhaust the waste heat outside if I have to heat the indoors anyway? That is wasteful.

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

#369

Post by Schweigi »

fifteenforty wrote: post #159
jimmaswell wrote: post #151

Earlier quoted context omitted.

> Ducts are dead. How do you move the heated/cooled air into/around the house without ducts?

It’s a ‘mini split’ in US lingo. There are thin, highly insulated refrigerant lines going between the outside unit and the inside unit. The inside unit exchanges heat with the air. https://www.daikin.com.au/our-product-range/split-system-air...

Though mini split heads can be ducted too. There are several choices, wall heads, ceiling heads, ducted heads etc. The wall head is just the cheapest solution since it’s very easy to install.

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

#370

Post by riceart77 »

abakker wrote: post #173
kwhitefoot wrote: post #122

Earlier quoted context omitted.

How do they affect the air quality indoors? Don't modern (less than fifty years old) gas boilers have balanced flues so that they take in air from the outside and exhaust the combustion products outside too? Surely properly installed gas boilers always did that even without balanced flues too.

My experience (sample of one) is that they don't. They're supposed to, but VOCs are definitely higher all winter running heat than all summer running air conditioning. Natural gas combustion is at best _mostly_ exhausted.

> My experience (sample of one) is that they don't.

There is something very very wrong with your equipment (or you're measuring something else not having anything to do with the heating equipment - more likely). A high efficiency furnace has a sealed combustion chamber, the entire thing runs in a circuit vented to the outside - combustion air comes from the outside and it is vented to the outside. If it is not airtight sealed from the indoors, it is broken. Even a mid-efficiency furnace with a non-sealed system will vent 100% of the flue gas outside.

> Natural gas combustion is at best _mostly_ exhausted.

Bullshit for any modern equipment (ie installed in the last 50 years).

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