Posted by Johan on October 1, 2005, 12:00 am
Hello,
I'm about to make a big decision regarding installation of a ground
source heat pump (closed loop wells) and a traditional hydro air/boiler
oil-fire system. I'm looking for some advice/comments regarding the
assumptions/calcs. that I've made regarding cost savings. Here goes:
1. Southern New England temps.
2. heat loss calcs from me and others confirms about 85000 Btu/hr
3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
5. 175MBtu/year <---is this right? This is roughly based on my previous
experience with an oil system scaled up for difference in square
footage between the homes. I realize this is VERY inaccurate. What
more information do I REASONABLY need for a more accurate number? Is
there an equation/rule of thumb?
6. Therefore, for savings calcs, Oil heat costs $3300/year and GSHP
heat costs $1200/year
8. $25000 (quoted) additional cost of GSHP over Oil, 11 to 12 years
payback of investment.
Any comments/suggestions are greatly appreciated as this is a really
big decision.
Thanks
Posted by nicksanspam on October 1, 2005, 7:36 am
>I'm about to make a big decision regarding installation of a ground
>source heat pump (closed loop wells) and a traditional hydro air/boiler
>oil-fire system. I'm looking for some advice/comments regarding the
>assumptions/calcs. that I've made regarding cost savings. Here goes:
>1. Southern New England temps.
>2. heat loss calcs from me and others confirms about 85000 Btu/hr
On a very cold day, a 97.5 percentile winter temp?
>3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
>4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
>5. 175MBtu/year <---is this right?
About 1750 gallons of oil? Sounds like a lot.
>This is roughly based on my previous experience with an oil system scaled up
>for difference in square footage between the homes. I realize this is VERY
>inaccurate. What more information do I REASONABLY need for a more accurate
>number? Is there an equation/rule of thumb?
Your heat loss calc should lead to a thermal conductance from indoors to
outdoors, eg 400 Btu/h-F. Multiply that by 24 (hours) and the number of
heating degree days in your climate, eg 5641 in Boston. So, a 400 Btu/h-F
house in Boston would need 24x400x5641 = 54 million Btu of heat. Some of
that may come from indoor electrical usage and sun into windows. Then again,
you might forget all this heat pumping and solar heat the house, 100%, or
add a sunspace or some polycarbonate "solar siding" air heaters on the south
wall. Be sure to make the house extremely airtight, less than 0.2 ACH,
with a blower door test.
You might also consider cogeneration, eg a 6 kW water-cooled Honda.
Nick
Posted by pjm on October 1, 2005, 9:01 am
Do not cross-post this shit to alt.hvac
wrote:
>Hello,
>I'm about to make a big decision regarding installation of a ground
>source heat pump (closed loop wells) and a traditional hydro air/boiler
>oil-fire system. I'm looking for some advice/comments regarding the
>assumptions/calcs. that I've made regarding cost savings. Here goes:
>1. Southern New England temps.
>2. heat loss calcs from me and others confirms about 85000 Btu/hr
>3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
>4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
>5. 175MBtu/year <---is this right? This is roughly based on my previous
>experience with an oil system scaled up for difference in square
>footage between the homes. I realize this is VERY inaccurate. What
>more information do I REASONABLY need for a more accurate number? Is
>there an equation/rule of thumb?
>6. Therefore, for savings calcs, Oil heat costs $3300/year and GSHP
>heat costs $1200/year
>8. $25000 (quoted) additional cost of GSHP over Oil, 11 to 12 years
>payback of investment.
>Any comments/suggestions are greatly appreciated as this is a really
>big decision.
>Thanks
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Posted by Solar Flare on October 1, 2005, 10:26 am
Do not cross-post your shit to alt.energy.homepower
Do not cross-post this shit to alt.hvac
wrote:
>Hello,
>I'm about to make a big decision regarding installation of a ground
>source heat pump (closed loop wells) and a traditional hydro air/boiler
>oil-fire system. I'm looking for some advice/comments regarding the
>assumptions/calcs. that I've made regarding cost savings. Here goes:
>1. Southern New England temps.
>2. heat loss calcs from me and others confirms about 85000 Btu/hr
>3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
>4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
>5. 175MBtu/year <---is this right? This is roughly based on my previous
>experience with an oil system scaled up for difference in square
>footage between the homes. I realize this is VERY inaccurate. What
>more information do I REASONABLY need for a more accurate number? Is
>there an equation/rule of thumb?
>6. Therefore, for savings calcs, Oil heat costs $3300/year and GSHP
>heat costs $1200/year
>8. $25000 (quoted) additional cost of GSHP over Oil, 11 to 12 years
>payback of investment.
>Any comments/suggestions are greatly appreciated as this is a really
>big decision.
>Thanks
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Posted by nicksanspam on October 1, 2005, 10:37 am
>Do not cross-post this shit to alt.hvac
Sez who? :-)
Nick
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>source heat pump (closed loop wells) and a traditional hydro air/boiler
>oil-fire system. I'm looking for some advice/comments regarding the
>assumptions/calcs. that I've made regarding cost savings. Here goes:
>1. Southern New England temps.
>2. heat loss calcs from me and others confirms about 85000 Btu/hr