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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

#131

Post by broken-kebab »

Tostino wrote: post #117
broken-kebab wrote: post #111

Earlier quoted context omitted.

Can you elaborate on the statement in the first para? Is it a guess, calculation, or there are real-world data?

A heat pump can be well over 100% efficient based on the energy input for equivalent resistive / chemical heating. E.g. your heat pump could use 100w of electricity to move 400w worth of heat (if generated resistively) from the outside to inside. There have been multiple studies done that show that current generation heat pumps are quite a bit more efficient for a given volume of gas to burn it in an electrical gener…

I see, but it's still mostly a theory unless we count in all small nuances. Like for a place where winters are really frosty heat-pump usually can't help enough (my own experience), and it seems they come with resistive heating built-in nowadays. Which may change the picture. Also, I'm not a specialist, but my guess is that delivery (or how they call it in the industry) of electricity can be priced in potentially wide range.

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

#132

Post by bumby »

tguvot wrote: post #26
bumby wrote: post #23

Earlier quoted context omitted.

You can energy model it if you have the time.

if you do fresh manual J calculation, with updated design temperature (which in reference manual is still incorrect) and blower door test, than maybe. And it still very theoretical but realistically, very few people do it when they update hvac system. in fact, most (all?) of hvac installers simply refuse to do it.

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 go to the level of blower door testing. They generally take design information (materials, orientation, etc.)

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

#133

Post by widdershins »

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.

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

#134

Post by Tostino »

broken-kebab wrote: post #131
Tostino wrote: post #117

Earlier quoted context omitted.

A heat pump can be well over 100% efficient based on the energy input for equivalent resistive / chemical heating. E.g. your heat pump could use 100w of electricity to move 400w worth of heat (if generated resistively) from the outside to inside. There have been multiple studies done that show that current generation heat pumps are quite a bit more efficient for a given volume of gas to burn it in an electrical gener…

I see, but it's still mostly a theory unless we count in all small nuances. Like for a place where winters are really frosty heat-pump usually can't help enough (my own experience), and it seems they come with resistive heating built-in nowadays. Which may change the picture. Also, I'm not a specialist, but my guess is that delivery (or how they call it in the industry) of electricity can be priced in potentially wid…

Yup, that was all accounted for in what I read (well over a year ago, can't find the link...sorry). It was also for a northern climate country (possibly the UK, maybe Norway, memory is failing me here), so it was not "best case" for heat pumps. They took into account losses from generation, transmission, number of days so cold that it is acting as close to a resistive heater (100-120% efficiency), etc. It was pretty comprehensive.

It was from a "what is the best way to lower our use of fossil fuels" perspective, and acknowledged that switching out all boiler systems for heat pumps would be a high cost, but it wasn't really a study on the economics of it. Just a resource usage perspective.

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

#135

Post by sct202 »

Amorbellum wrote: post #115

I'm in Kitchener Ontario Canada, I'm a licensed gas and refrigeration tech I've pulled my gas meter off my house and I'm exclusively heat pump now. I'm saving money, absolutely. Canada has cold ambient temps and cheap natural gas, and I'm still saving money, so I don't know how you aren't I'm paying 10 cent pretty kwh electricity, gas here is 15 cents per cubic meter

The author didn't pull all gas usage. We did the math on our home, and it really only makes sense right now if we eliminate all gas usage, since 65%+ of our gas spend is fixed connection fee related.

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

#136

Post by tguvot »

bumby wrote: post #132
tguvot wrote: post #26

Earlier quoted context omitted.

if you do fresh manual J calculation, with updated design temperature (which in reference manual is still incorrect) and blower door test, than maybe. And it still very theoretical but realistically, very few people do it when they update hvac system. in fact, most (all?) of hvac installers simply refuse to do it.

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 :)

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

#137

Post by NotAnOtter »

buo wrote: post #90
NotAnOtter wrote: post #75

Earlier quoted context omitted.

>the point of switching to electricity is to be able to use renewables That argument won't work in practice though. You have to make it make financial sense to each and every individual to encourage them to switch, "Do it because it's the right thing to do" is a tall order when people are already on a tight budget. I'm sure the new US president will assist in this matter.

> to each and every individual Not to each one. I'm willing to pay more (within my means and within reason) if it pollutes less and/or produces less CO2.

Given you're surfing this forum, you probably work in tech and have expendable income, most people don't. Also there are many ways you could (and maybe already are) spend money to reduce CO2 impact. Electric car, buying solar, etc.

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

#138

Post by sagarm »

beepboopboop wrote: post #128
Amorbellum wrote: post #115

I'm in Kitchener Ontario Canada, I'm a licensed gas and refrigeration tech I've pulled my gas meter off my house and I'm exclusively heat pump now. I'm saving money, absolutely. Canada has cold ambient temps and cheap natural gas, and I'm still saving money, so I don't know how you aren't I'm paying 10 cent pretty kwh electricity, gas here is 15 cents per cubic meter

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.

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

#139

Post by sagarm »

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.

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

#140

Post by itsdrewmiller »

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…

The information you are looking for can be found in the article.
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