Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

knowablemagazine.org

Post reply on HN
Print view View original

441–450 of 494 posts

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

#441

Post by nemo44x »

2rsf wrote: post #427
nemo44x wrote: post #171

Earlier quoted context omitted.

Why not install heated floors? That would be my choice in a new build.

Why? heated floor are a little more efficient in heating and for some are a little more comfortable, but from my experience they are also slow to react so it's harder to control the temperature when the weather changes daily for example in the spring or automn.

They’re much more efficient (and comfortable imo) than other systems. You’ll see pretty big costs savings. But yes, you need to be in a climate that sees long, cold winters to get the best of them I guess. Or if your home has lots of tile/stone/concrete flooring.

You’re right though, they take awhile to heat up and if you’re in a place where you may need heat at night and AC in the day, they won’t be ideal.

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

#442

Post by iso1631 »

jahewson wrote: post #189
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.

I used to have a bathroom without an extractor and in the winter with the window open the cold air would just cool the walls and cause more condensation there than I’d get with it closed.

I have a bathroom without an extractor. If I don't open the window the mirror fogs up in seconds of turning the shower on, and over time I get mould. If I do open the window it stays clear the entire time. By the time I'm out and dry the moist air has left and I close the window.

This morning it was -5C, so not cold by continental standards, but certainly cold enough.

In the UK recirculating air is very rare. In cases that bathrooms don't have a window (or indeed in new houses where they do) there's an extractor fan, but that just vents the air directly outside.

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

#443

Post by JustSomeNobody »

jdmichal wrote: post #247
JustSomeNobody wrote: post #61

Earlier quoted context omitted.

My thermostat allows me to set the humidity level at which it will turn on the A/C to deswampify my southern home.

Interesting. But I assume it's not a separate function from cooling, right? It might just over-cool the house in order to meet the humidity target?

Right. It takes into account both temp and humidity and either can trigger the cooling. It is a two stage system, so usually on the first stage is enough to get the humidity low enough to feel better.

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

#444

Post by refurb »

fifteenforty wrote: post #269
darken wrote: post #266

Earlier quoted context omitted.

I love our Daikin mini-splits (came with the house), but as you allude to I've had to become an mini expert on deep cleaning them. They've can get GROSS with mold when used for cooling, and the cursory filter only does so much. That being said, now they stay clean for a few years after a deep cleaning -- though my first few attempt before I refined the process did not stay clean nearly as long. (Proper water pressure…

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…

That definitely helps and I used to do that in my car where the A/C got smelly pretty quickly. Just run the "fan" for a few minutes after you turn off the A/C and it doesn't get gross.

But one problem is the dust in the house. It will collect on the unit and hold moisture and give a great substrate for mold to grow. But regular cleaning usually takes care of that.

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

#445

Post by 2rsf »

nemo44x wrote: post #441
2rsf wrote: post #427

Earlier quoted context omitted.

Why? heated floor are a little more efficient in heating and for some are a little more comfortable, but from my experience they are also slow to react so it's harder to control the temperature when the weather changes daily for example in the spring or automn.

They’re much more efficient (and comfortable imo) than other systems. You’ll see pretty big costs savings. But yes, you need to be in a climate that sees long, cold winters to get the best of them I guess. Or if your home has lots of tile/stone/concrete flooring. You’re right though, they take awhile to heat up and if you’re in a place where you may need heat at night and AC in the day, they won’t be ideal.

Pretty big costs savings compared to what? if you compare radiators to floor heating, both connected to the same heat pump system than the savings are not significant

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

#446

Post by nsxwolf »

operatingthetan wrote: post #176
fifteenforty wrote: post #167

Earlier quoted context omitted.

A recirculating central heating system doesn't do that. As mentioned below you either need exhaust only ventilation, balanced ventilation or ideally ERV/HRV. All of the above are available in both ducted and ductless forms.

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

How do you go ductless in a 6000 sq ft home?

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

#447

Post by red-iron-pine »

tomcam wrote: post #274
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…

> Ducts are dead Great. You just eliminated approximately 15% of lazy screenwriter tropes for thrillers and action movies. Now they are forced to rely on replacing live surveillance camera feeds with a loop.

No one is crawling through house ducting

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

#448

Post by bumby »

fooqux wrote: post #352
bumby wrote: post #243

Earlier quoted context omitted.

> And mistakes by installers will cost even more. I once looked at a house with a new GSHP horizontal loop installed in the desert southwest US. I talked to the installer and they said the loop was only 12” deep. There’s no way the ground maintains steady temp at that depth, meaning you’re losing efficiency in the hot months when you need it most. Not to mention thermal pollution which will exacerbate the problem and…

Twelve inches ? If that's true it seems like it would get ruined quickly by roots, animals, vehicles, lawn mowers, and basically everything else.

Yeah, I know it seems more likely that was a typo, but that's what they told me :) Tbf, roots, animals, and mowers probably aren't that big of an issue because it was mostly xeriscaped desert.

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

#449

Post by sidewndr46 »

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…

Sure but why limit ourselves to "which is watts of heating per watt of energy input." Wouldn't "amount of useful work per watts of energy input" be OK? So if I am putting in 100 watts constantly to my PC I am getting 100 watts of heating & 1 unit of computing. Which is more than 100%

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

#450

Post by BostonEnginerd »

hoseja wrote: post #393
Mandatum wrote: post #361

Earlier quoted context omitted.

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.

Where does mold even get the energy to grow, it really seems to spring up from nothing but water.

The fins in the heat exchanger will get covered in dust and dandruff over time. This provides a reasonable media for the mold to grow on.
Post reply on HN