Gonna be a cold winter in Minnesota unless they have auxiliary heat strips and $$$ if they do.
https://techxplore.com/news/2021-07-minnesota-energy-law.html
A lot of people in Minn. , especially rural, have wood burners or pellet stoves as supplemental/backup. Suburbanites too.
The fuel-switching issue is interesting. And the fact that they have units that work down to zero F. We're on the cusp of being able to use them for heat. Since it is not uncommon to go into the teens at night and rarely below 25 during the main part of the day, some people do get by with just the air-source heat pump, but when it's in the 20s, they run and run. The overall efficiency of the house is a big factor. The neighbor with a new SIP house has no trouble. The neighbor with an old house with very little insulation has it run non-stop for weeks at a time, sometimes with huge amounts of ice building up on it.
I've also been curious carbon and cost tradeoffs. I think the cost tradeoff would be less here because electricity is expensive in CA, though with the pricing going into effect this year, there will be summer and winter rates for us and the winter rates are a lot lower.
Tiered rates are a big disincentive. If changing to electric heat pushes me into a higher tier, it means those KWH are all at the most expensive rate. If I go into Tier 3, that's 41 cents per KWH. My lowest possible rate in the winter is 23 cents. Google says the average rate in MN is 11.5 cents. So if I went to electric heat, I would be almost 2X to 4X that, which cuts into the savings from a heat pump.
Insulate, insulate, insulate!
Quote from: buckworks on July 11, 2021, 06:39:53 PM
Insulate, insulate, insulate!
Exactly. This will serve anyone well, long into the future.
But, having been in the real estate development business, it's amazing to me how many home buyers pay so little attention to this. They want play area for their drooling spawn, home theatre room, snarfy kitchen, bathrooms big enough for bus loads of people and a three car garage but if you tell them the house is built to be "green" you get a Homer Simpson blank look.
>Insulate, insulate, insulate!
And, this makes just about any home built before 1970 functionally obsolete. I sure as hell wouldn't want to rip out the drywall or siding to insulate. ....And those windows are crap by today's standards. By the time you add it all up, the place is a tear-down.
QuoteTear down
In the UK the building regs don't always make a place better. Our place in Wales, in a windy (very windy) spot on the coast, has an extension. It has thick insulation in the roof and the walls and actually the floor. The problem is that the vent requirements mean that the wind that travels through the insulated cavity cool the wall down so much that the 1960s (or 1950s?) wall next to it is warmer.
Also, the venting in the windows means that on a windy day.... it's cold.
I am appalled.
UK:Low carbon heat pumps: Everything you need to know from cost to efficiency
https://www.telegraph.co.uk/news/2021/10/19/heat-pumps-explained-everything-need-know-cost-efficiency/
>UK
There is a similar scheme already running in Scotland, first come first served until the money runs out. Up to £10K interest free loan, and up to £7500 'cashback' when installing a heat pump. Cashback effectively being a grant. Subject to credit checks of course, and mandatory that your energy performance cert for the house doesn't recommend loft or cavity wall insulation.
Think the newly announced grant equates to about 50,000 installations so not a huge amount considering there's 20M households in the UK- but decent incentive for those who want to get on with it.
When you factor in RHI https://www.gov.uk/renewable-heat-incentive-calculator you can potentially make the money back within a few years.
What are you doing about all those stone wallS? R-value SUCKS.
R-Value | EGEE 102: Energy Conservation and Environmental Protection
https://www.e-education.psu.edu/egee102/node/2062
>stone wallS? R-value SUCKS.
For sure. At mine they're cold to the touch over the Winter months. Suspended floor also needs a look at as floor is also cold. Not any easier that older houses have to be 'in keeping' with the rest of the street so a new external facade tends to not be an option. Regulations...
Looked at internal wall insulation via the same routes as heat pumps (Home Energy Scotland). £10K loan available, £4K back. Quote arrived at £12K and that's not for the whole house, maybe 60% of it. Company that quoted me flat out said they ignore kitchens and bathrooms, too much hassle for them apparently. Doesn't take into account cornices or alcoves or generally any alteration near the outside corner walls. The local council run a means tested scheme where they will grant £7500 and that loan stuff can come afterwards. All seems like a gift but there's obviously some work required after it wrt the original look.
If UK gas prices stay where they're at may all end up the better economical choice.
Tempted by the idea of a GSHP but got a new gas boiler after moving in here a year ago. Seems like insulating is the priority.
>> venting
>> R-Value
I doubt I'll ever be able to find it again, but I read an interesting article by an engineer who specializes in home insulation. She pointed out that one small hole in a wall dramatically lowers the R-Value of the whole system. The point was that, for example, if you have a big window, it makes no sense to spend a lot of money on super-insulated walls.
Basically, what happens is that cold spot by its very nature cycles warm air past it and so even if it's .01% of the wall area, it might be 5% of the heat loss (I'm making those numbers up, of course). But the point was that you can never really insulate your way out of a leaky wall, even if the leaks are small.
By the same token, modern houses often have horrid indoor air quality and need mechanical systems to circulate the air because they are so tight. So there's that consideration too.
update: I can't find the original article, which had all the math and some good diagrams. This gives the rough idea
https://www.canadiancontractor.ca/canadian-contractor/road-nze-part-three-new-window-technology-delivers-big-r-value-gains/1003280773/
TL;DR
An R50 wall with 10% windows at R3 is not 50*.9 + 3*.1 = R45.3, which you might intuitively think. Instead, it's R15.
Long ago, I read that it takes about 6 meters of stone to equal 3.5 inches 9 cm of fiberglass insulation. AFAIK, there is currently no 'reasonable' interior sheeting material tech that will work adequately without one helluva lot of work (and some interior loss of space). Air-to-air heat pump output is cool-ish and slow to bring the room up to temp. It'll need to run much longer than your boilers. ...And we haven't even discussed old windows.
I foresee a great deal of wailing & chattering of teeth in uninsulated legacy construction.
> if you have a big window
Yeah, my house is 20-25% glass.
>> need to run much longer than your boilers
As a rough guide, if it's 40F out and an empty house is at 55F, count on 20 minutes to get up to temperature with my forced air furnace and two hours with a somewhat undersized heat pump.
>>chattering of teeth in uninsulated legacy construction
The old, poorly insulated house across the street is a second home, typically unoccupied. Even with the thermostat set low during long absences, when it drops below freezing, the heat pump would run non-stop. That resulted in condensation which froze into huge ice blocks which is how I noticed it was running non-stop. At a certain point the ice touches the fan blades and I can hear it running 24/7 from 100m away.
The new owners got rid of that heat pump and put in another one (it actually looks like a standard A/C unit, though, so I'm not sure). In any case, the original rather large heat pump is now gone.
Short version: they work well in a tight, well-insulated house. But even in our moderate climate where temps rarely go below 20 degrees, they are no match for an old, poorly-insulated house or, at the very least, they need to be sized way up to account for the rapid heat loss.
QuoteThat resulted in condensation which froze into huge ice blocks which is how I noticed it was running non-stop. At a certain point the ice touches the fan blades and I can hear it running 24/7 from 100m away.
The new one probably has a defrost cycle. Its raw heat to defrost, so is pretty inefficient. They work best where the water does not freeze. I cannot imagine why you would have one somewhere that cold, I suppose the rest of the time its cheaper to run than straight elec heating, but the cost of installation must be hard to recoup.
>straight elec heating
That's the dirty little secret of the great majority of air-to-air heat pumps ...they have big auxiliary straight elec heat strips in the interior ducts. These strips come on when conditions aren't ideal, or the start-up air is too cold. In many homes, the auxiliary strips run a lot.
I'm not trying to be negative about the prospects for northern/colder climes, but I get the general feeling that the government & media are glossing over the failings (in desperation?). Here,when our older legacy homes started switching to heap pumps in the 80-90s my friend in the hvac trade told me that he was busy UNinstalling new air-to-air units. He developed a policy of not installing for anyone over 65-70. "I'm just going to end up taking it out. Too cold & drafty."
Proceed with caution. There have been some advances and higher SEER, but I don't think the current tech is the final solution.
They can work in the UK, if in a location that is generally cool and damp, but rarely freezing.
we have one.... Expensive to install, but generally nice to have in the house. (Saves £1000 p.a on heating over the previous bottled gas, and I have had it a few years now)
>> I cannot imagine why you would have one somewhere that cold
We have a moderate climate here. Maybe 15 nights per year below 20 degrees Farenheit (-7C). The original article that started this thread was about MN. Northern MN must at least have 100 nights a year that cold. There are stretches of 10 days where it won't get above 0F/-20C. I've experienced days where the *high* for the day was -20F/-30C
So I wouldn't call us "that cold" in the grand scheme of things. If it can't work where we are, it can't work for much of the US and basically none of Canada.
UK: More from the Telegraph;
'However, in a hydrogen strategy unveiled last month, officials said the Government would also explore "enabling or requiring" new natural gas boilers to be "easily convertible to use hydrogen" by 2026. This could apply to new boilers fitted in existing homes.'
Gas boiler ban: a comprehensive guide to what you'll pay and when it comes into effect
https://www.telegraph.co.uk/money/consumer-affairs/gas-boiler-ban-uk-2035-replace-heat-pumps-guide-cost/
QuoteSo I wouldn't call us "that cold" in the grand scheme of things. If it can't work where we are, it can't work for much of the US and basically none of Canada.
And I think thats probably right, it wont.
https://flowingdata.com/2021/02/17/low-temperatures-map-of-the-united-states/
And no idea how accurate this is, but it reflects my experience:
https://www.estesair.com/blog/at-what-temperature-do-heat-pumps-become-ineffective/
TLTR... you need a back up heating.
I am sure there will be someone who has worked it out. Air source I would guess would be of marginal benefit anywhere it goes below zero for long. Just because it simply does not work. There is a point where you could potentially use more energy defrosting than you do for straight heating.
I would think ground source will still work, but that depends on how deep you can go. I was discussing this with my sister in law who lives just outside Granton on Spey in Scotland, and she thinks they can easily dig below the frost... It needs to be.
Therefore I would be surprised if many in Canada can get air source working well.
>she thinks they can easily dig below the frost... It needs to be.
...And, unless you are doing a closed loop -usually requiring multiple wells on the installations around here-- you have a helluva lot of discharge to get rid of. IIRC, it averages 3 US gallons per ton per minute of runtime --so my 5 ton unit is discharging 15 gallons a minute (a stream about as big as your wrist). Excessive discharge has caused many governments to outlaw discharging it into a ditch, storm sewer, or sewage system.
Quoteyou have a helluva lot of discharge to get rid of.
Interesting, the the ones I have come across here have been closed look, I assumed it was the law, it might well be in the UK.
come to think of it discharging anything into a water course is controlled.
>in desperation?
Heat pumps are practical and necessary | Letters | The Guardian
https://www.theguardian.com/environment/2021/oct/24/heat-pumps-are-practical-and-necessary
8% of EU population unable to keep home adequately warm: the largest share of people saying that they were unable to keep their home adequately warm were in Bulgaria (27%), followed by Lithuania (23%), Cyprus (21%), and Portugal and Greece (both with 17%).
https://old.reddit.com/r/europe/comments/qn59oo/8_of_eu_population_unable_to_keep_home_adequately/
This says 5.9% for UK in 2019
https://www.statista.com/chart/amp/16859/share-of-the-population-who-cannot-keep-their-home-adequately-warm/
Uh oh, The Telegram goes rogue on the UK message...
Six reasons not to buy a heat pump
https://www.telegraph.co.uk/money/consumer-affairs/should-buy-heat-pump-why-shouldnt-cons/
>> Six reasons
Here's a window mount in an apartment in Manhattan
https://www.youtube.com/watch?v=GuM2ePzSCQs
If you have slider windows, that will be a much bigger challenge
How flooded coal mines could heat homes
https://www.bbc.com/future/article/20210706-how-flooded-coal-mines-could-heat-homes
>mines
"Warmed by natural geological processes, the water they pumped to the surface was a pleasant 15C (59F)"
That's the temperature of the ground water here along the coast, considered to be perfect for geothermal heat pumps.
Charity bosses and poverty campaigners have written to Boris Johnson demanding home insulation and heat pumps for people on low incomes, and a windfall tax on fossil fuel companies to fund emergency support on energy bills for vulnerable people. | The Guardian
https://www.theguardian.com/money/2022/jan/14/fund-home-insulation-and-heat-pumps-for-people-on-low-incomes-pm-urged
Applies to Minnesota, too.
"Some have questioned whether heat pumps are appropriate for rural homes at all. Properties in the countryside tend to have poorer insulation than urban houses, making heat pumps less efficient. More than seven times the proportion of rural homes are rated F or G for energy efficiency, the lowest grades, than urban dwellings."
UK: Millions of rural homes forced into expensive eco upgrades
https://www.telegraph.co.uk/money/consumer-affairs/millions-rural-homes-forced-expensive-eco-upgrades/
UK: How much installing a heat pump will actually cost you
https://www.telegraph.co.uk/money/consumer-affairs/revealed-how-much-installing-heat-pump-will-actually-cost/
I just had my brother's hp replaced (existing ductwork), cost was $5900.