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I got a heat pump and my energy bill went up

heatpumped.org

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Re: I got a heat pump and my energy bill went up

#141

Post by bumby »

tguvot wrote: post #136
bumby wrote: post #132

Earlier quoted context omitted.

Like I think you are alluding to in your own response, manual J is just a design load calculation. It won't give you the annual energy usage so it probably isn't suitable for estimating annual energy costs. You want something that gives you (ideally) hourly load calculations. Like with all models, it depends on how accurate you need to get. Very few energy models (mainly TRNSYS or eQUEST) that I've been involved with…

you can't get hvac installers to do even manual j. i had to retain third party to do it when I wanted to replace hvac. if there are more progressive models, they are most definitely out of question for home owners :)

100% agree that HVAC techs are not going to do energy modeling. That's not really their role and I'd expect you to have to contract it to someone else. It's like asking a transport pilot to sign FAA certification paperwork. Design load calculations are more a part of the A/E design process than an installer task.

>they are most definitely out of question for home owners

Maybe the general home owner, but my comment was geared towards the HN crowd. I think running an energy model is within the grasp of most tech-savvy people if they have the inclination. Again, it depends on the accuracy you want. Even Excel can be used for a bin energy model approach (and is even advocated for in some commercial energy auditing texts as a suitable approach for of ASHRAE Level II audits). For example, eQUEST is free from the DoE and there are plenty of tutorials out there.

Edit: for anyone interested, this link gives an example of spreadsheet load calculations for residential applications (scroll to "ResLoad22")

https://geokiss.com/free-design-software/

Re: I got a heat pump and my energy bill went up

#142

Post by scoofy »

Spivak wrote: post #116
scoofy wrote: post #100

Earlier quoted context omitted.

Yes... that's because we're talking about externalities that an electorate wants to go away, but doesn't want to actually pay for. The entire problem is that we aren't paying the actual cost of what we are consuming, and the cost of a product without these externalities is slightly more, but without making people pay for the externalities, it's not marketable. This is the tragedy of the commons, and it's only a conun…

I see this argument a lot that "if only they priced in externalities the numbers would come out in favor of electricity" but I haven't seen a calculation of those externalities that isn't effectively just making up a number. Like I just picked one from a .edu https://scarab.bates.edu/cgi/viewcontent.cgi and it's just comical with 980% externalities. A number that can be turned into actual policy seems impossible to r…

Climate change is real. The economic impacts are well documented.

https://en.wikipedia.org/wiki/Economic_analysis_of_climate_c...

Re: I got a heat pump and my energy bill went up

#143

Post by tguvot »

bumby wrote: post #141
tguvot wrote: post #136

Earlier quoted context omitted.

you can't get hvac installers to do even manual j. i had to retain third party to do it when I wanted to replace hvac. if there are more progressive models, they are most definitely out of question for home owners :)

100% agree that HVAC techs are not going to do energy modeling. That's not really their role and I'd expect you to have to contract it to someone else. It's like asking a transport pilot to sign FAA certification paperwork. Design load calculations are more a part of the A/E design process than an installer task. > they are most definitely out of question for home owners Maybe the general home owner, but my comment w…

looked at spreadsheet. strong vibes of manual j :)

curious, does it take into consideration heat gain/loss by walls and insulation through the day ? or is there any model that does it ?

Re: I got a heat pump and my energy bill went up

#144

Post by physicsguy »

oliwarner wrote: post #106
chippiewill wrote: post #78

Earlier quoted context omitted.

> Here in the UK, natural gas is used to provide electricity[1], so switching to a heat pump right now isn't likely to help with the environment Efficiency of a typical combi boiler is 90%. The notional efficiency of a heat pump in UK climate will be around 300-400% (or rather 3-4 COP). Even accounting for transmission losses etc. a heat pump powered from gas turbines is better for the environment than a combi boiler…

But the efficiency of a gas power plant is only 20-60%. I'm all for electrification but unless my sums are wonky, a percentage of gas that was used to create electricity for heat pumps would have been better off burnt in a boiler. Over half the UKs power came from gas this last week. We need to turn back to nuclear until we've figured out grid level storage.

Why not just stay with nuclear, realistically?

Don’t need to reengineer the entire grid then…

Re: I got a heat pump and my energy bill went up

#145

Post by physicsguy »

widdershins wrote: post #133
rayiner wrote: post #10

I don’t know where this person is, but electricity is wildly expensive in many places. On a cold day, a good heat pump might give you say a COP of 2. So with 5 kW, you get out 10 kW of heat, or 35,000 BTU/hour. In say MA, at $0.25 per kWh retail, that’s $1.25/hour. In Boston, natural gas costs $1.5/therm, which is 100,000 BTUs. With a 96% efficient condensing boiler, you’re looking at $0.55/hour for the same 35,000 B…

That's on a very cold day. Depending where you are they may be more common or not. But in the UK, they're pretty uncommon. COP of ~4 is much more common.

https://www.pv-magazine.com/2023/03/17/field-data-on-heat-pu...

Some data from a U.K. funded study suggested the median was 2.44 here in winter and 2.8 not in winter.

Re: I got a heat pump and my energy bill went up

#146

Post by ssuds »

vfclists wrote: post #129

Should it require that much numeracy and time researching price options to benefit from a heat pump? Can't it be much simpler? Not all people have the brains AND assuming that they do, the time to go through these hoops to make their heat pump investment pay off.

You hit the nail on the head. I’ve spent the last couple years working full time on heat pumps, and even I forgot to switch to the right rate plan.

Most people will shut down and just stick with their gas furnace because it’s the path of least resistance. We need a blend of technology, policy and education to make this dead simple.

Re: I got a heat pump and my energy bill went up

#147

Post by 8fingerlouie »

nottorp wrote: post #99
Suppafly wrote: post #92

Earlier quoted context omitted.

It's still the same concept though. One is a bill you pay and other is free money you receive. There are all sorts of reasons for the bill you pay to be different based upon different criteria, that's not the same as getting free money directly.

Excise taxes on end-user energy don't tend to have exceptions...

They do in Denmark (and probably more of the EU).

If you have electric heating (resistive or heat pump, doesn't matter), you will pay €0.01 / kWh in energy tax for all electricity consumed above 4000 kWh per year.

The 4000 kWh is the "expected average" consumption for a household for a year, and of those you pay the full energy tax, which is currently DKK 0.9 / kWh including 25% VAT.

If you drive an EV, you can also get a refund for the energy tax of the electricity used to charge your car, provided you have an approved EV charger with a supported energy meter, which is most of the common chargers. You will need to enter into an agreement with a "charging company" to apply for the refund, so no individual refunds.

This of course doesn't apply if you have reduced energy tax, as you're not paying energy tax in the first place (except the first 4000 kWh)

Why €0.01 ? It's the minimum energy tax allowed by the EU, and i assume it's to avoid some spreadsheet breaking somewhere if it was 0.

Re: I got a heat pump and my energy bill went up

#148

Post by metalman »

sagarm wrote: post #139
metalman wrote: post #126

Something ignored in the article is that the old gas furnace was of an early and eceptionaly inefficient type, proven by its rotten flue pipe, newer gas furnaces are of the condensing type, and exract so much energy from the exhaust, that it condenses water, and the flue pipes are made of plastic, as the exhaust is barely warm.Older furnaces have hot caustic flue gasses, that will rot and corode the pipes. Total effi…

Even at a COP of 2, a heat pump powered by a 60% efficient gas power plant will use less gas at the power plant than gas heat.

60%? is a very optimistic number, and even if granted, does nit address the horrible reliabilty problems with heat pumps, which change the economics considerably. Heat pumps are noisy, and physicaly intrusive uggly wall lumps inside, and create a clutter outside. Well built passive solar creates a living environment that needs no heat source, is orders of magnitude more reliable in all conditions, while bieng invisible to all but the most observant.An added benifit is that a passive solar house is also acousticaly insulated, and therefor much nicer in a noisy, urban environment, near roads, etc. Financialy, the costs of building a passive house are not excessive, and once established, represent transferable value, while .... :)....insulating you from energy market fluctuations.

Re: I got a heat pump and my energy bill went up

#149

Post by bumby »

tguvot wrote: post #143
bumby wrote: post #141

Earlier quoted context omitted.

100% agree that HVAC techs are not going to do energy modeling. That's not really their role and I'd expect you to have to contract it to someone else. It's like asking a transport pilot to sign FAA certification paperwork. Design load calculations are more a part of the A/E design process than an installer task. > they are most definitely out of question for home owners Maybe the general home owner, but my comment w…

looked at spreadsheet. strong vibes of manual j :) curious, does it take into consideration heat gain/loss by walls and insulation through the day ? or is there any model that does it ?

>strong vibes of manual j

In the simplest terms, they're all derived from the heat transfer equation of Q=U*A*deltaT so all load calculation models will seem similar to an extent. It ultimately comes down to how nuanced you want the model to be.

>does it take into consideration heat gain/loss by walls and insulation through the day

Yes, it has factors like heat gain coefficient that are used in conjunction with U-factors, weather, and the orientation of the structure. Most of the more widely used models include those aspects.

Re: I got a heat pump and my energy bill went up

#150

Post by dizhn »

sagarm wrote: post #138
beepboopboop wrote: post #128

Earlier quoted context omitted.

How does your heat pump do on cold days like today? Do you still use an AC in the summer?

You realize that heat pumps also cool, right? They're just ACs that can also work in reverse.

It's really interesting. Around these parts you practically cannot buy an AC that is cooling only. All of them also heat.
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