Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #430567 > unrolled thread

10 mega-watt hours

Back to article view | Back to sci.electronics.design

Contents

  10 mega-watt hours Winfield Hill <hill@rowland.harvard.edu> - 2016-10-07 11:16 -0700
    Re: 10 mega-watt hours Jon Elson <jmelson@wustl.edu> - 2016-10-07 14:13 -0500
      Re: 10 mega-watt hours Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2016-10-07 12:41 -0700
        Re: 10 mega-watt hours makolber@yahoo.com - 2016-10-07 13:08 -0700
          Re: 10 mega-watt hours Winfield Hill <hill@rowland.harvard.edu> - 2016-10-07 14:27 -0700
        Re: 10 mega-watt hours Winfield Hill <hill@rowland.harvard.edu> - 2016-10-07 14:09 -0700
          Re: 10 mega-watt hours Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2016-10-07 14:18 -0700
            Re: 10 mega-watt hours Ralph Barone <ralph@invalid.com> - 2016-10-07 22:40 +0000
              Re: 10 mega-watt hours Winfield Hill <hill@rowland.harvard.edu> - 2016-10-07 16:42 -0700
                Re: 10 mega-watt hours Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2016-10-07 17:35 -0700
                  Re: 10 mega-watt hours Jeff Liebermann <jeffl@cruzio.com> - 2016-10-08 09:09 -0700
                    Re: 10 mega-watt hours John Larkin <jjlarkin@highlandtechnology.com> - 2016-10-08 09:53 -0700
                      Re: 10 mega-watt hours Jeff Liebermann <jeffl@cruzio.com> - 2016-10-08 11:10 -0700
                    Re: 10 mega-watt hours Bob Engelhardt <BobEngelhardt@comcast.net> - 2016-10-09 12:30 -0400
                      Re: 10 mega-watt hours Jeff Liebermann <jeffl@cruzio.com> - 2016-10-09 10:26 -0700
                  Re: 10 mega-watt hours Ralph Barone <ralph@invalid.com> - 2016-10-08 23:38 +0000
                    Re: 10 mega-watt hours Jeff Liebermann <jeffl@cruzio.com> - 2016-10-08 18:13 -0700
                      Re: 10 mega-watt hours Ralph Barone <ralph@invalid.com> - 2016-10-09 05:02 +0000
                        Re: 10 mega-watt hours Jeff Liebermann <jeffl@cruzio.com> - 2016-10-08 23:29 -0700
            Re: 10 mega-watt hours Chris Jones <lugnut808@spam.yahoo.com> - 2016-10-09 11:42 +1100
    Re: 10 mega-watt hours Martin Riddle <martin_ridd@verizon.net> - 2016-10-07 17:30 -0400
      Re: 10 mega-watt hours Winfield Hill <hill@rowland.harvard.edu> - 2016-10-07 17:14 -0700
        Re: 10 mega-watt hours Jon Elson <elson@pico-systems.com> - 2016-10-11 10:28 -0500
          heatpump vs furnace Winfield Hill <hill@rowland.harvard.edu> - 2016-10-12 05:57 -0700
            Re: heatpump vs furnace bill.sloman@ieee.org - 2016-10-12 07:33 -0700
              Re: heatpump vs furnace "dcaster@krl.org" <dcaster@krl.org> - 2016-10-12 17:41 -0700
                Re: heatpump vs furnace bill.sloman@ieee.org - 2016-10-12 18:26 -0700
                  Re: heatpump vs furnace "dcaster@krl.org" <dcaster@krl.org> - 2016-10-13 06:45 -0700
                Re: heatpump vs furnace Winfield Hill <hill@rowland.harvard.edu> - 2016-10-12 18:57 -0700
                  Re: heatpump vs furnace bill.sloman@ieee.org - 2016-10-12 22:36 -0700
                    Re: heatpump vs furnace Winfield Hill <hill@rowland.harvard.edu> - 2016-10-13 03:57 -0700
            Re: heatpump vs furnace Ecnerwal <MyNameForward@ReplaceWithMyVices.Com.invalid> - 2016-10-12 10:33 -0400
              Re: heatpump vs furnace Winfield Hill <hill@rowland.harvard.edu> - 2016-10-12 09:46 -0700
                Re: heatpump vs furnace Ecnerwal <MyNameForward@ReplaceWithMyVices.Com.invalid> - 2016-10-12 14:39 -0400
            Re: heatpump vs furnace Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2016-10-12 08:10 -0700
              Re: heatpump vs furnace Winfield Hill <hill@rowland.harvard.edu> - 2016-10-12 09:39 -0700
            Re: heatpump vs furnace makolber@yahoo.com - 2016-10-12 13:02 -0700
              Re: heatpump vs furnace Winfield Hill <hill@rowland.harvard.edu> - 2016-10-13 06:10 -0700
            Re: heatpump vs furnace "David Eather" <eather@tpg.com.au> - 2016-10-15 14:47 +1000
              Re: heatpump vs furnace krw <krw@nowhere.com> - 2016-10-15 10:56 -0400
                Re: heatpump vs furnace "David Eather" <eather@tpg.com.au> - 2016-10-17 12:47 +1000
                  Re: heatpump vs furnace krw <krw@nowhere.com> - 2016-10-17 19:50 -0400
    Re: 10 mega-watt hours sean.c4s.vn@gmail.com - 2016-10-12 06:13 -0700
    Re: 10 mega-watt hours Yzordderrex <powersupplyguy@netzero.net> - 2016-10-13 07:52 -0700
      Re: 10 mega-watt hours Winfield Hill <hill@rowland.harvard.edu> - 2016-10-13 08:09 -0700
        Re: 10 mega-watt hours Yzordderrex <powersupplyguy@netzero.net> - 2016-10-14 03:05 -0700
          Re: 10 mega-watt hours Winfield Hill <hill@rowland.harvard.edu> - 2016-10-14 05:52 -0700

Page 2 of 3 — ← Prev page 1 [2] 3  Next page →

#430593

On 7 Oct 2016 11:16:22 -0700, Winfield Hill <hill@rowland.harvard.edu>
wrote:

> The production meter for our solar roof just
> ticked over past 10MWh.  That's a pretty
> serious amount of power to generate in the
> 9.5 months since switching on the system.
> https://enlighten.enphaseenergy.com/pv/public_systems/WAJT773668/overview

Do your power credits roll over to the next year? (anniversery date)
I think your allowed to change it once. And most recomend to place it
in April/May, so the winter bills can be offset.
You may find that your Jan/Feb bill are 'high'

Cheers

[toc] | [prev] | [next] | [standalone]

#430611

Martin Riddle wrote...
>
> Do your power credits roll over to the next year? (anniversery date)
> I think your allowed to change it once. And most recomend to place it
> in April/May, so the winter bills can be offset.
> You may find that your Jan/Feb bill are 'high'

 I don't know for sure, but my understanding is the
 credits do not expire.  However, if we make more
 than we consume, we don't get paid for any excess.
 But we can give it to someone else in our district.
 Like maybe our town's Senior Citizens Center.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#430873

Winfield Hill wrote:

> Martin Riddle wrote...
>>
>> Do your power credits roll over to the next year? (anniversery date)
>> I think your allowed to change it once. And most recomend to place it
>> in April/May, so the winter bills can be offset.
>> You may find that your Jan/Feb bill are 'high'
> 
>  I don't know for sure, but my understanding is the
>  credits do not expire.  However, if we make more
>  than we consume, we don't get paid for any excess.
>  But we can give it to someone else in our district.
>  Like maybe our town's Senior Citizens Center.
> 
> 
WOW!  They ALLOW you to give the utility energy for free!  What an 
incredibly generous deal!

Jon

[toc] | [prev] | [next] | [standalone]

#430979 — heatpump vs furnace

Jon Elson wrote...
> Winfield Hill wrote:
>> Martin Riddle wrote...
>>>
>>> Do your power credits roll over to the next year? (anniversery date)
>>> I think your allowed to change it once. And most recomend to place it
>>> in April/May, so the winter bills can be offset.
>>> You may find that your Jan/Feb bill are 'high'
>> 
>> I don't know for sure, but my understanding is the
>> credits do not expire.  However, if we make more
>> than we consume, we don't get paid for any excess.
>> But we can give it to someone else in our district.
>> Like maybe our town's Senior Citizens Center.
>> 
> WOW!  They ALLOW you to give the utility energy for
> free!  What an incredibly generous deal!

 We just replaced our entire HVAC-oil-furnace stack,
 and elected the heat-pump option instead of a simple
 AC compressor.  I've been taking some performance
 measurements, e.g. with Tout = 45 deg, it takes the
 heatpump about 1 hour to raise the house temp by 2
 degrees.  It consumes 5kW, so that's 2.5kWh/deg.
 Whoa, we'll be using far more electricity than our
 roof makes!  The default outside-temp breakpoint
 for switching to the oil burner is 40 degrees.
 I'm studying the thermostat manual's installation
 instructions to change to 50 degrees.  They claim
 heatpump heating is cheaper than oil, but I doubt
 it!  Anybody have experience with a hybrid system?


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#430985 — Re: heatpump vs furnace

On Wednesday, October 12, 2016 at 11:57:54 PM UTC+11, Winfield Hill wrote:
> Jon Elson wrote...
> > Winfield Hill wrote:
> >> Martin Riddle wrote...
> >>>
> >>> Do your power credits roll over to the next year? (anniversary date)
> >>> I think your allowed to change it once. And most recomend to place it
> >>> in April/May, so the winter bills can be offset.
> >>> You may find that your Jan/Feb bill are 'high'
> >> 
> >> I don't know for sure, but my understanding is the
> >> credits do not expire.  However, if we make more
> >> than we consume, we don't get paid for any excess.
> >> But we can give it to someone else in our district.
> >> Like maybe our town's Senior Citizens Center.
> >> 
> > WOW!  They ALLOW you to give the utility energy for
> > free!  What an incredibly generous deal!
> 
>  We just replaced our entire HVAC-oil-furnace stack,
>  and elected the heat-pump option instead of a simple
>  AC compressor.  I've been taking some performance
>  measurements, e.g. with Tout = 45 deg, it takes the
>  heatpump about 1 hour to raise the house temp by 2
>  degrees.  It consumes 5kW, so that's 2.5kWh/deg.
>  Whoa, we'll be using far more electricity than our
>  roof makes!  The default outside-temp breakpoint
>  for switching to the oil burner is 40 degrees.
>  I'm studying the thermostat manual's installation
>  instructions to change to 50 degrees.  They claim
>  heatpump heating is cheaper than oil, but I doubt
>  it! 

Heat-pump heating is cheaper than oil per kilowatt-hour delivered if the temperature difference between the inside of the house and the external radiator is small enough.

The real advantage obviously is that the heat pump can go both ways - to cool the house in summer and to heat the house in winter.

In Sydney it's a good deal. In the UK you needed a bigger heat pump to supply the heat you needed in the depths of winter, and the capital cost got a bit out of hand. I never did the sums myself, but I knew people who did.

If you could super-insulate your house to start with, the heat pump made more sense - the 150 Watt you generate all the time (alright 100 Watt when resting, about 150 Watt when doing stuff and anything up to 600 Watt when doing hard physical labour) started being a significant part of the heat you needed in the depths of winter.

Using a buried heat-exchanger coil also made sense - about 50cm of dirt is about six months of thermal lag, so some of the heat you pumped into the ground in summer could still be hanging around in winter when you needed to pump it back out - but it's even more capital investment.

-- 
Bill Sloman, Sydney

[toc] | [prev] | [next] | [standalone]

#431054 — Re: heatpump vs furnace

On Wednesday, October 12, 2016 at 10:33:10 AM UTC-4, bill....@ieee.org wrote:

> 
> Using a buried heat-exchanger coil also made sense - about 50cm of dirt is about six months of thermal lag, so some of the heat you pumped into the ground in summer could still be hanging around in winter when you needed to pump it back out - but it's even more capital investment.
> 
> -- 
> Bill Sloman, Sydney

All of the data I have seen on soil temperatures does not agree with your statement of 50 cm giving a six months thermal lag.

                                              Dan

[toc] | [prev] | [next] | [standalone]

#431063 — Re: heatpump vs furnace

On Thursday, October 13, 2016 at 11:41:33 AM UTC+11, dca...@krl.org wrote:
> On Wednesday, October 12, 2016 at 10:33:10 AM UTC-4, bill....@ieee.org wrote:
> 
> > 
> > Using a buried heat-exchanger coil also made sense - about 50cm of dirt is about six months of thermal lag, so some of the heat you pumped into the ground in summer could still be hanging around in winter when you needed to pump it back out - but it's even more capital investment.
> 
> All of the data I have seen on soil temperatures does not agree with your statement of 50 cm giving a six months thermal lag.

So post some of it. My figure is dredged out of memory. If you've got a better reference it wouldn't have to be all that good to be pretty convincing.

The more general point - that a buried heat-exchanger is a good idea - still stands. It's economic viability usually does seem to depend on somebody wanting to do a lot of earth-moving anyway.

-- 
Bill Sloman, Sydney

[toc] | [prev] | [next] | [standalone]

#431098 — Re: heatpump vs furnace

On Wednesday, October 12, 2016 at 9:26:22 PM UTC-4, bill....@ieee.org wrote:

> So post some of it. My figure is dredged out of memory. If you've got a better reference it wouldn't have to be all that good to be pretty convincing.
> 
> The more general point - that a buried heat-exchanger is a good idea - still stands. It's economic viability usually does seem to depend on somebody wanting to do a lot of earth-moving anyway.
> 
> -- 
> Bill Sloman, Sydney

I looked at a bunch of sites before I started insulating the basement walls.  But have not kept any links to the data.  So if you are interested you can find the information as easily as I can.   

A buried heat exchanger is a good idea.  But when they are used for heat pumps they generally either use a couple of wells or trenches at least 4 feet (  1.2 meters ) deep.

[toc] | [prev] | [next] | [standalone]

#431066 — Re: heatpump vs furnace

dcaster@krl.org wrote...
> Bill Sloman wrote
>> Using a buried heat-exchanger coil also made sense - about 50cm
>> of dirt is about six months of thermal lag, so some of the heat
>> you pumped into the ground in summer could still be hanging
>> around in winter when you needed to pump it back out - but
>> it's even more capital investment.
>
> All of the data I have seen on soil temperatures does not agree
> with your statement of 50 cm giving a six months thermal lag.

 Right, it's entirely a matter of the available water.
 Maybe a small well, tapping an underground aquifer.
 Slightly complicated if you don't have a well.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#431079 — Re: heatpump vs furnace

On Thursday, October 13, 2016 at 12:57:25 PM UTC+11, Winfield Hill wrote:
> dcaster@krl.org wrote...
> > Bill Sloman wrote
> >> Using a buried heat-exchanger coil also made sense - about 50cm
> >> of dirt is about six months of thermal lag, so some of the heat
> >> you pumped into the ground in summer could still be hanging
> >> around in winter when you needed to pump it back out - but
> >> it's even more capital investment.
> >
> > All of the data I have seen on soil temperatures does not agree
> > with your statement of 50 cm giving a six months thermal lag.
> 
>  Right, it's entirely a matter of the available water.
>  Maybe a small well, tapping an underground aquifer.
>  Slightly complicated if you don't have a well.

It isn't. You just bury a long enough loop pf closed pipe and circulate your water - other heat exchange fluid - through it. You need to be in contact with a much larger thermal mass than the heat capacity of your house. 

-- 
Bill Sloman, Sydney

[toc] | [prev] | [next] | [standalone]

#431086 — Re: heatpump vs furnace

bill.sloman@ieee.org wrote...
> Winfield Hill wrote:
>> dcaster@krl.org wrote...
>>> Bill Sloman wrote
>>>> Using a buried heat-exchanger coil also made sense - about 50cm
>>>> of dirt is about six months of thermal lag, so some of the heat
>>>> you pumped into the ground in summer could still be hanging
>>>> around in winter when you needed to pump it back out - but
>>>> it's even more capital investment.
>>>
>>> All of the data I have seen on soil temperatures does not agree
>>> with your statement of 50 cm giving a six months thermal lag.
>> 
>>  Right, it's entirely a matter of the available water.
>>  Maybe a small well, tapping an underground aquifer.
>>  Slightly complicated if you don't have a well.
>
> It isn't. You just bury a long enough loop pf closed pipe
> and circulate your water - other heat exchange fluid -
> through it. You need to be in contact with a much larger
> thermal mass than the heat capacity of your house. 

 Exactly, and for the time period in question.  Here the
 ground can freeze down nearly a foot in winter.  We get
 a situation where the ground below that is devoid of
 much water.  That's a problem that has cost us several
 valuable trees, because we didn't water them midwinter!

 I could solve that problem by running the pipe 100 feet
 down to a stream that runs through our back yard, and
 burying it deep there.  Maybe get a 45-degree return
 fluid temperature in winter.  The pipe would have to
 be insulated and buried the whole way, difficult with
 our yard's granite rock fill.  A geothermal heat sink
 would be good for more efficient AC in summer.  Might
 need our town's Conservation Commission permission.
 I've been thinking about it.  Guy who installed our
 system has a geothermal hot-water heater, using an
 existing well on his lot.  Research geothermal heat
 pumps.  Probably just too many issues to overcome.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#430986 — Re: heatpump vs furnace

In article <ntlc010ihl@drn.newsguy.com>,
 Winfield Hill <hill@rowland.harvard.edu> wrote:

>  instructions to change to 50 degrees.  They claim
>  heatpump heating is cheaper than oil, but I doubt
>  it!  Anybody have experience with a hybrid system?

That depends very much on the specifics of the heat pump (COP) and the 
price of the two fuels, and the efficiency of the oil burner. In many 
cases it's true, particularly with a proper cold-climate heat pump 
(which a 40 F switchover - does not sound like.)

The good cold-climate mini-splits will put out 3X the heat (COP of 3 or 
more) as the electricity put into them, and operate effectively down to 
sub-zero F temperatures. For whatever reason most whole house systems 
are still sucky southern-oriented things with lousy COP and poor cold 
performance.

It's been an included line on the Vermont Fuel Price Report for a couple 
of years now with some assumptions you can read about and prices that 
may vary from your own local prices. The VFPR is one of the clearer 
expositions of these trade-offs on the net - If Mass. makes anything 
like it they hide it well, but I bet they simply don't.

-- 
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.

[toc] | [prev] | [next] | [standalone]

#431014 — Re: heatpump vs furnace

Ecnerwal wrote...
>
>In article <ntlc010ihl@drn.newsguy.com>,
> Winfield Hill <hill@rowland.harvard.edu> wrote:
>
>> instructions to change to 50 degrees.  They claim
>> heatpump heating is cheaper than oil, but I doubt
>> it!  Anybody have experience with a hybrid system?
>
> That depends very much on the specifics of the heat pump 
> (COP) and the price of the two fuels, and the efficiency
> of the oil burner. In many cases it's true, particularly
> with a proper cold-climate heat pump (which a 40 F
> switchover - does not sound like.)
>
> The good cold-climate mini-splits will put out 3X the heat
> (COP of 3 or more) as the electricity put into them, and
> operate effectively down to sub-zero F temperatures.

 Whoa, 3x!  Is that at high outside temps?  Apparently
 my system will work fine to far below freezing (runs
 at 40-degrees with a modest duty cycle), even includes
 automatic defrost features.  Maybe the default 40-degree
 setting is considered an economic tradeoff point.  Our 
 installer says the electric heat-pump is cheaper down
 to 40 degrees; clearly I need to research the numbers.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#431024 — Re: heatpump vs furnace

In article <ntlpd0017fm@drn.newsguy.com>,
 Winfield Hill <hill@rowland.harvard.edu> wrote:
 
>  Whoa, 3x!  Is that at high outside temps?  Apparently
>  my system will work fine to far below freezing (runs
>  at 40-degrees with a modest duty cycle), even includes
>  automatic defrost features.  Maybe the default 40-degree
>  setting is considered an economic tradeoff point.  Our 
>  installer says the electric heat-pump is cheaper down
>  to 40 degrees; clearly I need to research the numbers.

It varies with the specific unit and the specific temperature. If you 
look at the October, 2015 VFPR they discuss it vaguely and have a vague 
diagram with an unlabeled temperature axis to go with their guesstimate 
of 2.4 (240%) for Vermont conditions (which of, course, are rather 
variable from one end of the state to the other, plus they are trying to 
get an average seasonal number.) Your conditions in Eastern MA may be 
somewhat more favorable. COPs around 3.5 at moderate (40's F) 
temperatures are not uncommon. 

At current Vermont prices and the 2.4 COP guesstimate, oil has a slight 
edge per the September, 2016 report. Having see twice the price on oil 
and pretty much the same price on electricity in the past few years, 
that is not a static situation, and it's also not static with outside 
temperature since the COP varies with that.

Ideally, you find a specific diagram (or table) that's specifically 
labelled for your particular unit, and then you can plug in price of 
electricity, price of oil (cost of what you have in the tank or 
replacement cost, as you prefer) and temperature to see which is 
cheaper, when. When oil is cheap and electricity isn't, that will be 
different than when oil is expensive and electricity still is kinda 
expensive. If you expect the election-year low-price-oil to last, 
history may have an opposing view. 

If you really want to be an efficient whacko, get a diesel generator and 
put your heating oil through that, recover the high quality waste heat 
directly, use the electricity generated to run your heat pump, and put 
the otherwise unrecoverable waste heat into the path of the heat pump's 
outside unit ;-) But then you'll have to pay sales tax on your heating 
oil...and it's a good deal of capital expense.

Having just done the replacement, your only economically sensible option 
is to try and get the data on what you got, and then figure out where 
the tradeoff temperature is as prices shift.

-- 
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.

[toc] | [prev] | [next] | [standalone]

#430996 — Re: heatpump vs furnace

On 12 Oct 2016 05:57:37 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>Jon Elson wrote...
>> Winfield Hill wrote:
>>> Martin Riddle wrote...
>>>>
>>>> Do your power credits roll over to the next year? (anniversery date)
>>>> I think your allowed to change it once. And most recomend to place it
>>>> in April/May, so the winter bills can be offset.
>>>> You may find that your Jan/Feb bill are 'high'
>>> 
>>> I don't know for sure, but my understanding is the
>>> credits do not expire.  However, if we make more
>>> than we consume, we don't get paid for any excess.
>>> But we can give it to someone else in our district.
>>> Like maybe our town's Senior Citizens Center.
>>> 
>> WOW!  They ALLOW you to give the utility energy for
>> free!  What an incredibly generous deal!
>
> We just replaced our entire HVAC-oil-furnace stack,
> and elected the heat-pump option instead of a simple
> AC compressor.  I've been taking some performance
> measurements, e.g. with Tout = 45 deg, it takes the
> heatpump about 1 hour to raise the house temp by 2
> degrees.  It consumes 5kW, so that's 2.5kWh/deg.
> Whoa, we'll be using far more electricity than our
> roof makes!  The default outside-temp breakpoint
> for switching to the oil burner is 40 degrees.
> I'm studying the thermostat manual's installation
> instructions to change to 50 degrees.  They claim
> heatpump heating is cheaper than oil, but I doubt
> it!  Anybody have experience with a hybrid system?

But it's green >:-}
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

                          In Memoriam...
                       James Ralph Thompson
                October 12, 1918 - November 7, 2008

[toc] | [prev] | [next] | [standalone]

#431013 — Re: heatpump vs furnace

Jim Thompson wrote...
>
>> instructions to change to 50 degrees.  They claim
>> heatpump heating is cheaper than oil, but I doubt
>> it!  Anybody have experience with a hybrid system?
>
> But it's green >:-}

 Gotta be a patriot and burn somma that Montana crude.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#431031 — Re: heatpump vs furnace

  They claim
>  heatpump heating is cheaper than oil, but I doubt
>  it!  Anybody have experience with a hybrid system?
> 
> 
> -- 
>  Thanks,
>     - Win

Yes,
I have a hybrid oil heat pump system.
My COP is about 3 and that makes oil at $2.00 per gallon
equivalent to about $0.18 per kWh of electricity.
So it depends on what YOU pay for each fuel.

And then there are those pesky intangible issues.
What is the wear and tear cost on an AC compressor vs
an oil burner?

How comfortable is your house when the vent is 
blowing 80 deg air from the heat pump vs 120 deg air from the 
the oil burner?

And the heat pump compressor 
includes a crankcase heater that runs 100 Watts 24/7 to keep
it warm so it can start anytime.  Freon will migrate to the coldest
part of a system when it is off and you don't want 
your compressor full of liquid Freon when it starts, so they keep
a heater running in it 24/7. 

And below about 32 the outside coils can freeze up and the 
system has to run in reverse defrost mode for a few minutes.

My bottom line is, once the temp is consistently below about 35, 
I turn off the heat pump, switch off its breaker to kill the heater,
 and keep it from coming on, and I stick with the oil.
I just hope oil stays around $2 per gallon.

In spring I turn the breaker back on a few days before I let it run so it 
warms enough to drive the liquid Freon out before I let it start.


mark

[toc] | [prev] | [next] | [standalone]

#431094 — Re: heatpump vs furnace

makolber@yahoo.com wrote...
>
>  They claim
>>  heatpump heating is cheaper than oil, but I doubt
>>  it!  Anybody have experience with a hybrid system?
>
> Yes, I have a hybrid oil heat pump system.
> My COP is about 3 and that makes oil at $2.00 per gallon
> equivalent to about $0.18 per kWh of electricity.
> So it depends on what YOU pay for each fuel.

 My Carrier 25HCC5 heatpump's COP is 3.88 with
 47 deg (+8C) air, dropping to 2.64 with cold
 17-deg (-8C) air.  For 40 to 50-deg settings,
 and our $0.20 elec, isn't that close to a wash?

> And the heat pump compressor includes a crankcase
> heater that runs 100 Watts 24/7 to keep it warm so
> it can start anytime.  Freon will migrate to the
> coldest part of a system when it is off and you
> don't want your compressor full of liquid Freon
> when it starts, so they keep a heater running in it 24/7. 

 Whoa!  100 watts 24-7 = $175/yr.  (Sadly I have
 2 to 3 times that already in wallworts, etc.)

> My bottom line is, once the temp is consistently
> below about 35, I turn off the heat pump, switch
> off its breaker to kill the heater, and keep it
> from coming on, and I stick with the oil.  I just
> hope oil stays around $2 per gallon.
>
> In spring I turn the breaker back on a few days
> before I let it run so it warms enough to drive
> the liquid Freon out before I let it start.

> And below about 32 the outside coils can freeze up and the 
> system has to run in reverse defrost mode for a few minutes.

 Yes, we have that aspect.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#431267 — Re: heatpump vs furnace

On Wed, 12 Oct 2016 22:57:37 +1000, Winfield Hill  
<hill@rowland.harvard.edu> wrote:

> Jon Elson wrote...
>> Winfield Hill wrote:
>>> Martin Riddle wrote...
>>>>
>>>> Do your power credits roll over to the next year? (anniversery date)
>>>> I think your allowed to change it once. And most recomend to place it
>>>> in April/May, so the winter bills can be offset.
>>>> You may find that your Jan/Feb bill are 'high'
>>>
>>> I don't know for sure, but my understanding is the
>>> credits do not expire.  However, if we make more
>>> than we consume, we don't get paid for any excess.
>>> But we can give it to someone else in our district.
>>> Like maybe our town's Senior Citizens Center.
>>>
>> WOW!  They ALLOW you to give the utility energy for
>> free!  What an incredibly generous deal!
>
>  We just replaced our entire HVAC-oil-furnace stack,
>  and elected the heat-pump option instead of a simple
>  AC compressor.  I've been taking some performance
>  measurements, e.g. with Tout = 45 deg, it takes the
>  heatpump about 1 hour to raise the house temp by 2
>  degrees.  It consumes 5kW, so that's 2.5kWh/deg.
>  Whoa, we'll be using far more electricity than our
>  roof makes!  The default outside-temp breakpoint
>  for switching to the oil burner is 40 degrees.
>  I'm studying the thermostat manual's installation
>  instructions to change to 50 degrees.  They claim
>  heatpump heating is cheaper than oil, but I doubt
>  it!  Anybody have experience with a hybrid system?
>
>

don't worry too much - the waste energy turn into heat too

[toc] | [prev] | [next] | [standalone]

#431299 — Re: heatpump vs furnace

On Sat, 15 Oct 2016 14:47:39 +1000, "David Eather" <eather@tpg.com.au>
wrote:

>On Wed, 12 Oct 2016 22:57:37 +1000, Winfield Hill  
><hill@rowland.harvard.edu> wrote:
>
>> Jon Elson wrote...
>>> Winfield Hill wrote:
>>>> Martin Riddle wrote...
>>>>>
>>>>> Do your power credits roll over to the next year? (anniversery date)
>>>>> I think your allowed to change it once. And most recomend to place it
>>>>> in April/May, so the winter bills can be offset.
>>>>> You may find that your Jan/Feb bill are 'high'
>>>>
>>>> I don't know for sure, but my understanding is the
>>>> credits do not expire.  However, if we make more
>>>> than we consume, we don't get paid for any excess.
>>>> But we can give it to someone else in our district.
>>>> Like maybe our town's Senior Citizens Center.
>>>>
>>> WOW!  They ALLOW you to give the utility energy for
>>> free!  What an incredibly generous deal!
>>
>>  We just replaced our entire HVAC-oil-furnace stack,
>>  and elected the heat-pump option instead of a simple
>>  AC compressor.  I've been taking some performance
>>  measurements, e.g. with Tout = 45 deg, it takes the
>>  heatpump about 1 hour to raise the house temp by 2
>>  degrees.  It consumes 5kW, so that's 2.5kWh/deg.
>>  Whoa, we'll be using far more electricity than our
>>  roof makes!  The default outside-temp breakpoint
>>  for switching to the oil burner is 40 degrees.
>>  I'm studying the thermostat manual's installation
>>  instructions to change to 50 degrees.  They claim
>>  heatpump heating is cheaper than oil, but I doubt
>>  it!  Anybody have experience with a hybrid system?
>>
>>
>
>don't worry too much - the waste energy turn into heat too

If your intention it to heat the great outdoors.

[toc] | [prev] | [next] | [standalone]

Page 2 of 3 — ← Prev page 1 [2] 3  Next page →

Back to top | Article view | sci.electronics.design

csiph-web