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

knowablemagazine.org

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

#431

Post by elil17 »

moffkalast wrote: post #418
elil17 wrote: post #79

Earlier quoted context omitted.

If you have a resistance electric furnace, that is essentially true. With gas, you add the electric generation and distribution losses, which is a pretty big difference. It does cost more to run an appliance than to heat with gas.

It's always been funny to me that throughout engineering people chase like 1% efficiency improvements from like 20 to 21 or 35 to 36 and it's usually a big win when achieved... meanwhile resistive heating has an efficiency of 100% and it still manages to absolutely suck.

It only sucks because of generation and transmission losses. If those didn’t exist (not possible), electricity would be much cheaper and they would be on par with or better than natural gas furnaces

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

#432

Post by [deleted] »

riceart77 wrote: post #368
elil17 wrote: post #350

Earlier quoted context omitted.

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.

[deleted]

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

#433

Post by elil17 »

riceart77 wrote: post #368
elil17 wrote: post #350

Earlier quoted context omitted.

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.

Oops I meant to say it is wasteful - typo

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

#434

Post by pxmpxm »

PaulHoule wrote: post #283
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 doesn't get that cold in most places in Australia does it? Heat pumps need to be scaled for the maximum heating or cooling load, whichever is greater. The optimal situation is that the heating and cooling loads are similar, but in colder parts of the U.S. the heating load is much larger than the cooling load and the case for the heat pump is not so good as a place where the need for heating and cooling are more ba…

We have a brand new Daikin VRV system in new york and are currently working on retrofitting a nat gas heating solution - heat pumps aren't a good fit for anywhere north of Atlanta:

When it's really cold out (say 25F or below), the heat pump stops for around 10mins to defrost the exterior coils, which means no heat running at all in that period, and this pause happens more frequently the colder it's outside. The end result, our ~1400 sq place took more than 24hrs to heat up from 55F to 72F when we got back after christmas.

Also you don't save any money on operating it, even with the efficiency yade yada the cost of electricity will run you more than the equivalent in nat gas. So nothing but downside.

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

#435

Post by Zach_the_Lizard »

yaysyu wrote: post #290
PaulHoule wrote: post #283

Earlier quoted context omitted.

It doesn't get that cold in most places in Australia does it? Heat pumps need to be scaled for the maximum heating or cooling load, whichever is greater. The optimal situation is that the heating and cooling loads are similar, but in colder parts of the U.S. the heating load is much larger than the cooling load and the case for the heat pump is not so good as a place where the need for heating and cooling are more ba…

Depends on your frame of reference but in Melbourne it can get to around 1 degree Celcius in winter (33~F). Sometimes subzero but very rarely

In my part of Texas, it gets below freezing on 12 days a year on average, but within the last two years it's been as low as 7F / -14C.

I guess that's the value of having a big heat sink, the Pacific Ocean, at your doorstep: temperatures are more stable.

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

#436

Post by TruthShare »

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…

[flagged]

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

#437

Post by thedougd »

turtlebits wrote: post #381
hawaiianbrah wrote: post #358

Earlier quoted context omitted.

I’ve been eyeing https://mrcooldiy.com/ , even easier.

The problem with Mr. Cool is that their DIY claim is because you don't cut the lineset (I believe they give you 25 ft). Any excess length you're supposed to coil up and hide, which is not ideal- plus you'll lose efficiency.

I believe they now sell other size lines and extensions.

I got hung up on the excess line set idea and did a full DIY install of a non-DIY model mini-split. I bought, borrowed, and rented a lot of tools, spent a lot of time researching and learning. I really wish I went with the DIY model.

Despite that lesson, I may do it again when I finish my attic space, but this time I'll add copper line brazing to the list.

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

#438

Post by thedougd »

AOsborn wrote: post #249
teruakohatu wrote: post #110

Earlier quoted context omitted.

> Ducts are dead. Ducted heatpumps are a thing here in NZ and make sense to me, not that I have used one. The heatpump sits in the roof and air is pushed into three or so rooms through ducts. If building a new house I think ducts would be the way to go.

I thought this was absolutely the solution but backtracking a little now based on experience so far. We have a two-level, five bedroom new build in Auckland which came with a single-zone ducted system. So outputs are the bedrooms plus upstairs and downstairs lounges. The vents are tidy and unobtrusive - much less space than a wall unit in each location. We're having major issues balancing the temperature across the d…

Have checked the ducts for dampers? They're often installed where the duct branches. It's not unusual to find they're not balanced well or the locking screws have loosened allowing the dampers to move on their own.

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

#439

Post by thedougd »

SoftTalker wrote: post #188
ComputerGuru wrote: post #56

Earlier quoted context omitted.

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…

The moisture can promote mold in the ductwork though. We had our furnace replaced a few years ago and had the central humidifier removed. The interior of the ductwork was black with mold near the humidifier so that was also replaced.

I had a misting humidifier. I put my finger through the metal duct, completely rusted.

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

#440

Post by nemo44x »

Sytten wrote: post #334
nemo44x wrote: post #166

Earlier quoted context omitted.

It’s not always possible. For instance old wood double hung sash windows require a weight box to work. Those boxes can’t really be insulated. And there’s a good chance you don’t want to replace the old windows (or possibly can’t due to historic restrictions) because they are a massive part of the homes character. Also insulating an old home (pre-WW2) could begin to introduce moisture issues in the walls that weren’t…

On the contrary modern houses often rot because of the water barrier. Condensation gets trapped in the wall and it rots really fast. If you insulate your old house from the inside you wont have this issue. I spent the last 3 years remodelling at 1875 house and we opened all the walls to spray urethane foam. It sealed all the cracks between the wood beams but still leaves the exterior untouched to moisture can leave.

Yeah any house build in the 70’s, 80’s, or early 90’s might had issues with moisture. Water vapor in particular.

Im not sure I’d spend the money (or desire the inconvenience) on a job like that on my old home. I’m not sure I’d make the money back in savings during my time here. But during a gutting, makes sense.

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