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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

#451

Post by turtlebits »

thedougd wrote: post #437
turtlebits wrote: post #381

Earlier quoted context omitted.

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.

As long as the unit is pre-charged, DIY installs aren't that bad. I've done 2 Pioneers at my home. I spent around $150 in tools.

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

#452

Post by MaKey »

fjfaase wrote: post #389

I have wondered whether using a small windmill (on the roof) to power the compressor directly could work. This to prevent the energy loss of converting mechanical energy to electrical and electrical to mechanical again. Combining this with a heat/cold storage which is filled there is a lot of wind to be used when there is less, seems to be good idea as well.

The energy those small windmills could generate on a typical house roof is in the double digit kWh territory per year, so I doubt you'd be able to power a compressor with one.

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

#453

Post by mrexroad »

nsxwolf wrote: post #446
operatingthetan wrote: post #176

Earlier quoted context omitted.

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?

Two multi-head units should work just fine.

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

#454

Post by mrexroad »

WestCoastJustin wrote: post #149
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.

On the west coasts of Canada (BC) we've had insane forest fires the past few years and you 100% want to filter the internal air when it's extremely unhealthy outside. We're talking air quality index in the 300+ range or off the charts at times [1]. Plus, we've had these heat domes were it's in the high 30+ and just gross inside, where you really want to open the windows, but you're letting in tons of pollution. Basic…

This. We live <50’ from an expressway, so after air sealing and replacing all of our ducts, I added a MERV 16 filter to our air handler. We had the windows open at night a few years back (no ac as well), and I woke up to smell of smoke from a forest fire after the winds changed direction. AQI2.5 was 200+ inside. Closed windows, ran the fan on high and after a couple minutes the AQI throughout the house was within healthy range (tested multiple locations). Unfortunately our furnace model leaves few realistic options for controlling it programmatically, so I still have to manually turn on the fan when AQI drops.

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

#455

Post by mrexroad »

fifteenforty wrote: post #306
mvnuweucxqokii wrote: post #292

Earlier quoted context omitted.

If it's pretty cold outside, then you're throwing all of the ostensible energy savings of a heat pump out the window the minute you open it to air out the house. Following the thread of conversation, it just didn't compute to me: >>>> Heat pumps are great for climate control >>> Yeah, ducts are dead >> What if you want to recirculate air in your house through your central air filter to eliminate smells? > Just open t…

For an existing dwelling, the best solution is probably mini splits (wall mounted) combined with decentralised heat recovery ventilation as required. Ducts running in an insulated space are sources of huge energy loss.

*uninsulated

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

#456

Post by mixmastamyk »

adgjlsfhk1 wrote: post #376
mixmastamyk wrote: post #117

Earlier quoted context omitted.

> But I agree, nothing is more infuriating than seeing the AC on and the outdoor air temperature being lower Won't cooler temps outside make the AC work more efficiently and get to the desired temp more quickly?

yes but it still will be a lot less efficient than a window

Windows help of course but often there’s not enough wind to make a difference.

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

#457

Post by fifteenforty »

pxmpxm wrote: post #434
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…

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 r…

In Melbourne’s climate where piped methane costs 1/3 per kWh that of electricity, but heat pumps are 300-500% efficient and you remove the duct loss, for most people their heating bill drops by 2/3. Add solar self consumption and you are way ahead.

My limited understanding of the defrost cycle is that it’s most a problem around 0c? If it’s a colder or warmer it doesn’t get triggered as often?

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

#458

Post by mrexroad »

metadat wrote: post #198
fifteenforty wrote: post #161

Earlier quoted context omitted.

I paid real money to have my ducts removed. They cause issues installing comprehensive insulation and caused hot/cold spots on the ceiling.

Honest question: Why would one care about cold or hot spots on the ceiling? I don't spend much time up there.

Because in the winter the thermal energy within your room will “flow” out of those “cold spots” at surprisingly high rates; in summer those spots act as space heaters. In both scenarios they will adversely affect the ambient temp of the room. In short, whatever method you use to heat/cool the room will have to work harder and will take longer. Here’s [0] a good overview of heat flow in this context, with some hints towards the math behind if you wish to go deeper.

[edit: add link]

[0] https://www.energyvanguard.com/blog/Flat-or-Lumpy-How-Would-...

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

#459

Post by phyzome »

xpe wrote: post #416
phyzome wrote: post #144

> owners of drafty homes may need to take on the added cost of insulation when installing a heat pump Installing good insulation is also really important even if you're not using heat pumps! With bad insulation, you're wasting energy no matter what technology you're using.

Sure, but don't overlook air sealing. Drafts are caused by air getting through. Most kinds of insulation won't solve this problem.

Yes, true. I kind of lump them together when I think about them, and I think they're often remedied together during retrofits, but they're different issues.

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

#460

Post by mrexroad »

Dylan16807 wrote: post #353
EricE wrote: post #338

Earlier quoted context omitted.

Less that 2% of insulation being out of place can waste something like 40% or some ridiculous amount of energy. It's quite nuts how even just a little break in insulation can have a significantly negative effect. A few years after I moved into my first home - a townhouse - I added some R-16 bats to the already existing R-12 insulation in the attic and it more than cut my heating bill in half. It was a three story nar…

Okay but that's not what I was asking. That much heat loss will affect the overall temperature.

He did answer what you asked, but I think you may be losing sight of the forest for the trees here. Maybe re-phrasing will help?
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