Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread Darryl Thayer 
I had 3 customers that were my data source. unfortunately, I had trouble
monitoring the thermal systems and they got tired of me coming over daily
to see the runtimes ect one gave up on solar thermal when a leak occurred,
The other two I stopped monitoring because of expenses in the monitoring of
the solar thermal.

On Thu, Mar 15, 2018 at 12:35 PM, cwarfel 
wrote:

> That would be a good analysis to share. I can see how it could be possible
> with lower module costs, but I haven't seen any studies on this comparison.
> Chris
>
> On 3/15/2018 1:17 PM, Darryl Thayer wrote:
>
> When I did my study of solar water heating I found that PV water heating
> gave more hot water at a lower cost than solar thermal.  the Heatpump water
> heater was the big winner.
>
> On Thu, Mar 15, 2018 at 12:00 PM, Drake  redwoodalliance.org> wrote:
>
>> This discussion has been a great help. The house is built and the
>> plumbing is in, but could be modified. Wood stoves are not a likely
>> solution. I think we need a different water heating strategy.
>>
>> Thank you all!
>>
>> Drake
>>
>>
>>
>> At 09:21 AM 3/15/2018, you wrote:
>>
>> Content-Type: multipart/alternative;
>>  boundary="EE4E9806B711DEF636076840"
>> Content-Language: en-US
>>
>> This is what I came up with:
>>
>> The calculation is Q = mcp delta T
>>
>> Water Temp out =Â  120
>>
>> Water Temp in = ground source Temperature @ 50F?
>>
>> delta T = 70F
>>
>> m =  mass flow rate.  ASHRAE is the source for this. 20gals per person
>> per day = 20 gallons x 8.34 lbs/gallon =Â  167lbs/day/person
>>
>> cp =Â  1 BTU/lb-degree F
>>
>> Q = 167 x 1 x 70 = 11,676 BTU/day/person
>>
>> Divide this by the efficiency of the water heating system (I'll assume =
>> .86)Â  =11,676/.86 = 13, 577 BTU/person/day
>>
>> convert to kWh if necessarym 13,577/3412 = ~4 kWh/person/day, 120
>> kWh/month
>>
>> I checked this against one month and it seems reasonable.
>>
>> Website assuming ~3.5 family size comes up with @ 400kWh per month. They
>> approached it another way with assuming run times.
>>
>> https://www.google.com/search?safe=active=hp=Z3KqW
>> vXiNsGb5wKJ2Kf4DA=electric+water+heater+use+annual+
>> consumption=electric+water+heater+use+annually_l=psy-
>> ab.1.2.33i22i29i30k1l3.279.9222.0.12475.35.19.0.7.7.0.
>> 451.2360.0j6j4j0j1.11.00...1c.1.64.psy-ab..18.16.1952.0.
>> .0j0i67k1j0i131k1j0i22i30k1.0.CiU8wYZigpI
>>
>>
>> Chris
>>
>>
>>
>>
>> On 3/15/2018 8:09 AM, Mike Kocsmiersky wrote:
>>
>> Barton makes a good point with regards to the incoming ground water
>> temperature and the amount of heat required to bring it up to shower temp.
>> Â My recollection is that ASHRAE states 20gal/person/day for the first 2
>> people, then 15gpd or 12gpd thereafter.  However those rates vary wildly
>> with consumers, from those that never bathe to the high schooler that needs
>> 3 showers a day.  In the northeast water heating can be up to 19% of the
>> total household energy load for the year.  Also, I would recommend the air
>> source heat pump water heaters if you have significant humidity or an on
>> demand unit.  Water tanks are typically under insulated and can lose
>> 2kWh/day in standby losses.
>> Â
>> Mike Kocsmiersky
>> Principal
>> Spirit Solar Inc.
>> (413) 734-1456
>> Â
>> Â
>> Â
>> *From:* Barton Churchill [mailto:bar...@solarips.com
>> ]
>> *Sent:* Wednesday, March 14, 2018 7:31 PM
>> *To:* RE-wrenches
>> *Subject:* Re: [RE-wrenches] Electric Water kWh/ person
>> Â
>> You first need to know your ground temperature. Then figure a delta to
>> 100 or so degrees. Most but not all showerheads flow 2.5gpm and showers are
>> typically 10 minutes. You can then find a calculator online to calculate
>> how many Btus are required to raise water temp for your delta per gallon.
>> Convert to kWh, add some contingency and you should be good.Â
>>
>> On Wednesday, March 14, 2018, < drake.chamber...@redwoodalliance.org>
>> wrote:
>> Hello Wrenches,
>>
>> Is there a good way to estimate the power that will be consumed for
>> electric water per person per day? We are estimating the amount of power
>> that will be used by an all electric duplex, and the water heater amount
>> seems high. The current model we have claims 3493 kWh/ year per 26 gallon
>> tank will be consumed. With the two units, that would add up to 6986 kWh /
>> year for hot water, pushing the system size to humongous for a 1300 ft sq
>> building.
>>
>> Does that seem high? There will be a maximum of 2 people per unit.
>>
>> The owner is considering going to 115 V units with a 15 gallon tanks. I
>> think the smaller tank would help, but it would seem that the amount of hot
>> water consumed would be the main issue.
>>
>> How can we get a good estimate for a per person energy usage for electric
>> hot water? Any other suggestions are welcome.
>>
>> Thank you,
>>
>> Drake
>>
>>
>>
>> --
>> --Â
>> Barton Churchill
>> 406.587.5295

Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread cwarfel 
That would be a good analysis to share. I can see how it could be 
possible with lower module costs, but I haven't seen any studies on this 
comparison. Chris



On 3/15/2018 1:17 PM, Darryl Thayer wrote:
When I did my study of solar water heating I found that PV water 
heating gave more hot water at a lower cost than solar thermal.  the 
Heatpump water heater was the big winner.


On Thu, Mar 15, 2018 at 12:00 PM, Drake 
> wrote:


This discussion has been a great help. The house is built and the
plumbing is in, but could be modified. Wood stoves are not a
likely solution. I think we need a different water heating strategy.

Thank you all!

Drake



At 09:21 AM 3/15/2018, you wrote:

Content-Type: multipart/alternative;
 boundary="EE4E9806B711DEF636076840"
Content-Language: en-US

This is what I came up with:

The calculation is Q = mcp delta T

Water Temp out =  120

Water Temp in = ground source Temperature @ 50F?

delta T = 70F

m =  mass flow rate. ASHRAE is the source for this. 20gals per
person per day = 20 gallons x 8.34 lbs/gallon =  167lbs/day/person

cp =  1 BTU/lb-degree F

Q = 167 x 1 x 70 = 11,676 BTU/day/person

Divide this by the efficiency of the water heating system (I'll
assume = .86)  =11,676/.86 = 13, 577 BTU/person/day

convert to kWh if necessarym 13,577/3412 = ~4 kWh/person/day, 120
kWh/month

I checked this against one month and it seems reasonable.

Website assuming ~3.5 family size comes up with @ 400kWh per
month. They approached it another way with assuming run times.


https://www.google.com/search?safe=active=hp=Z3KqWvXiNsGb5wKJ2Kf4DA=electric+water+heater+use+annual+consumption=electric+water+heater+use+annually_l=psy-ab.1.2.33i22i29i30k1l3.279.9222.0.12475.35.19.0.7.7.0.451.2360.0j6j4j0j1.11.00...1c.1.64.psy-ab..18.16.1952.0..0j0i67k1j0i131k1j0i22i30k1.0.CiU8wYZigpI





Chris




On 3/15/2018 8:09 AM, Mike Kocsmiersky wrote:

Barton makes a good point with regards to the incoming ground
water temperature and the amount of heat required to bring it up
to shower temp. Â My recollection is that ASHRAE states
20gal/person/day for the first 2 people, then 15gpd or 12gpd
thereafter.  However those rates vary wildly with consumers,
from those that never bathe to the high schooler that needs 3
showers a day.  In the northeast water heating can be up to 19%
of the total household energy load for the year.  Also, I would
recommend the air source heat pump water heaters if you have
significant humidity or an on demand unit.  Water tanks are
typically under insulated and can lose 2kWh/day in standby losses.
Â
Mike Kocsmiersky
Principal
Spirit Solar Inc.
(413) 734-1456 
Â
Â
Â
*From:* Barton Churchill [mailto:bar...@solarips.com]
*Sent:* Wednesday, March 14, 2018 7:31 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Electric Water kWh/ person
Â
You first need to know your ground temperature. Then figure a
delta to 100 or so degrees. Most but not all showerheads flow
2.5gpm and showers are typically 10 minutes. You can then find a
calculator online to calculate how many Btus are required to
raise water temp for your delta per gallon. Convert to kWh, add
some contingency and you should be good.Â

On Wednesday, March 14, 2018,
> wrote:
Hello Wrenches,

Is there a good way to estimate the power that will be consumed
for electric water per person per day? We are estimating the
amount of power that will be used by an all electric duplex, and
the water heater amount seems high. The current model we have
claims 3493 kWh/ year per 26 gallon tank will be consumed. With
the two units, that would add up to 6986 kWh / year for hot
water, pushing the system size to humongous for a 1300 ft sq
building.

Does that seem high? There will be a maximum of 2 people per unit.

The owner is considering going to 115 V units with a 15 gallon
tanks. I think the smaller tank would help, but it would seem
that the amount of hot water consumed would be the main issue.

How can we get a good estimate for a per person energy usage for
electric hot water? Any other suggestions are welcome.

Thank you,

Drake



-- 
--Â

Barton Churchill
406.587.5295

Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread Darryl Thayer 
When I did my study of solar water heating I found that PV water heating
gave more hot water at a lower cost than solar thermal.  the Heatpump water
heater was the big winner.

On Thu, Mar 15, 2018 at 12:00 PM, Drake <
drake.chamber...@redwoodalliance.org> wrote:

> This discussion has been a great help. The house is built and the plumbing
> is in, but could be modified. Wood stoves are not a likely solution. I
> think we need a different water heating strategy.
>
> Thank you all!
>
> Drake
>
>
>
> At 09:21 AM 3/15/2018, you wrote:
>
> Content-Type: multipart/alternative;
>  boundary="EE4E9806B711DEF636076840"
> Content-Language: en-US
>
> This is what I came up with:
>
> The calculation is Q = mcp delta T
>
> Water Temp out =Â  120
>
> Water Temp in = ground source Temperature @ 50F?
>
> delta T = 70F
>
> m =  mass flow rate.  ASHRAE is the source for this. 20gals per person
> per day = 20 gallons x 8.34 lbs/gallon =Â  167lbs/day/person
>
> cp =Â  1 BTU/lb-degree F
>
> Q = 167 x 1 x 70 = 11,676 BTU/day/person
>
> Divide this by the efficiency of the water heating system (I'll assume =
> .86)Â  =11,676/.86 = 13, 577 BTU/person/day
>
> convert to kWh if necessarym 13,577/3412 = ~4 kWh/person/day, 120 kWh/month
>
> I checked this against one month and it seems reasonable.
>
> Website assuming ~3.5 family size comes up with @ 400kWh per month. They
> approached it another way with assuming run times.
>
> https://www.google.com/search?safe=active=hp=
> Z3KqWvXiNsGb5wKJ2Kf4DA=electric+water+heater+use+annual+consumption=
> electric+water+heater+use+annually_l=psy-ab.1.2.
> 33i22i29i30k1l3.279.9222.0.12475.35.19.0.7.7.0.451.2360.
> 0j6j4j0j1.11.00...1c.1.64.psy-ab..18.16.1952.0..
> 0j0i67k1j0i131k1j0i22i30k1.0.CiU8wYZigpI
>
>
> Chris
>
>
>
>
> On 3/15/2018 8:09 AM, Mike Kocsmiersky wrote:
>
> Barton makes a good point with regards to the incoming ground water
> temperature and the amount of heat required to bring it up to shower temp.
> Â My recollection is that ASHRAE states 20gal/person/day for the first 2
> people, then 15gpd or 12gpd thereafter.  However those rates vary wildly
> with consumers, from those that never bathe to the high schooler that needs
> 3 showers a day.  In the northeast water heating can be up to 19% of the
> total household energy load for the year.  Also, I would recommend the air
> source heat pump water heaters if you have significant humidity or an on
> demand unit.  Water tanks are typically under insulated and can lose
> 2kWh/day in standby losses.
> Â
> Mike Kocsmiersky
> Principal
> Spirit Solar Inc.
> (413) 734-1456
> Â
> Â
> Â
> *From:* Barton Churchill [mailto:bar...@solarips.com ]
>
> *Sent:* Wednesday, March 14, 2018 7:31 PM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] Electric Water kWh/ person
> Â
> You first need to know your ground temperature. Then figure a delta to 100
> or so degrees. Most but not all showerheads flow 2.5gpm and showers are
> typically 10 minutes. You can then find a calculator online to calculate
> how many Btus are required to raise water temp for your delta per gallon.
> Convert to kWh, add some contingency and you should be good.Â
>
> On Wednesday, March 14, 2018, < drake.chamber...@redwoodalliance.org>
> wrote:
> Hello Wrenches,
>
> Is there a good way to estimate the power that will be consumed for
> electric water per person per day? We are estimating the amount of power
> that will be used by an all electric duplex, and the water heater amount
> seems high. The current model we have claims 3493 kWh/ year per 26 gallon
> tank will be consumed. With the two units, that would add up to 6986 kWh /
> year for hot water, pushing the system size to humongous for a 1300 ft sq
> building.
>
> Does that seem high? There will be a maximum of 2 people per unit.
>
> The owner is considering going to 115 V units with a 15 gallon tanks. I
> think the smaller tank would help, but it would seem that the amount of hot
> water consumed would be the main issue.
>
> How can we get a good estimate for a per person energy usage for electric
> hot water? Any other suggestions are welcome.
>
> Thank you,
>
> Drake
>
>
>
> --
> --Â
> Barton Churchill
> 406.587.5295 <(406)%20587-5295> Â
> 2430 North 7th Bozeman, MT 59715
> www.solarips.com
> [image: Image removed by sender.]
> Â
>
>
>
> ___
> List sponsored by Redwood Alliance
>
> List Address:
> RE-wrenches@lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
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>
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>
> Check out or update participant bios:
> www.members.re-wrenches.org
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>
> --
>
> Â Â Â Â Â Â Â Â  Christopher Warfel, PE
> Â Â Â Â Â Â  ENTECH Engineering, Inc.
> PO Box 871, Block Island, RI 02807
> Â Â Â Â Â Â Â Â Â Â Â Â

Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread Drake 
This discussion has been a great help. The house 
is built and the plumbing is in, but could be 
modified. Wood stoves are not a likely solution. 
I think we need a different water heating strategy.


Thank you all!

Drake



At 09:21 AM 3/15/2018, you wrote:

Content-Type: multipart/alternative;
 boundary="EE4E9806B711DEF636076840"
Content-Language: en-US

This is what I came up with:

The calculation is Q = mcp delta T

Water Temp out =Â  120

Water Temp in = ground source Temperature @ 50F?

delta T = 70F

m =  mass flow rate.  ASHRAE is the source for 
this. 20gals per person per day = 20 gallons x 
8.34 lbs/gallon =Â  167lbs/day/person


cp =Â  1 BTU/lb-degree F

Q = 167 x 1 x 70 = 11,676 BTU/day/person

Divide this by the efficiency of the water 
heating system (I'll assume = .86)Â  =11,676/.86 = 13, 577 BTU/person/day


convert to kWh if necessarym 13,577/3412 = ~4 kWh/person/day, 120 kWh/month

I checked this against one month and it seems reasonable.

Website assuming ~3.5 family size comes up with 
@ 400kWh per month. They approached it another way with assuming run times.


https://www.google.com/search?safe=active=hp=Z3KqWvXiNsGb5wKJ2Kf4DA=electric+water+heater+use+annual+consumption=electric+water+heater+use+annually_l=psy-ab.1.2.33i22i29i30k1l3.279.9222.0.12475.35.19.0.7.7.0.451.2360.0j6j4j0j1.11.00...1c.1.64.psy-ab..18.16.1952.0..0j0i67k1j0i131k1j0i22i30k1.0.CiU8wYZigpI


Chris




On 3/15/2018 8:09 AM, Mike Kocsmiersky wrote:
Barton makes a good point with regards to the 
incoming ground water temperature and the 
amount of heat required to bring it up to 
shower temp. Â My recollection is that ASHRAE 
states 20gal/person/day for the first 2 people, 
then 15gpd or 12gpd thereafter.  However those 
rates vary wildly with consumers, from those 
that never bathe to the high schooler that 
needs 3 showers a day.  In the northeast water 
heating can be up to 19% of the total household 
energy load for the year.  Also, I would 
recommend the air source heat pump water 
heaters if you have significant humidity or an 
on demand unit.  Water tanks are typically 
under insulated and can lose 2kWh/day in standby losses.

Â
Mike Kocsmiersky
Principal
Spirit Solar Inc.
(413) 734-1456
Â
Â
Â
From: Barton Churchill 
[mailto:bar...@solarips.com]

Sent: Wednesday, March 14, 2018 7:31 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Electric Water kWh/ person
Â
You first need to know your ground temperature. 
Then figure a delta to 100 or so degrees. Most 
but not all showerheads flow 2.5gpm and showers 
are typically 10 minutes. You can then find a 
calculator online to calculate how many Btus 
are required to raise water temp for your delta 
per gallon. Convert to kWh, add some contingency and you should be good.Â


On Wednesday, March 14, 2018, 
<drake.chamber...@redwoodalliance.org> 
wrote:

Hello Wrenches,

Is there a good way to estimate the power that 
will be consumed for electric water per person 
per day? We are estimating the amount of power 
that will be used by an all electric duplex, 
and the water heater amount seems high. The 
current model we have claims 3493 kWh/ year per 
26 gallon tank will be consumed. With the two 
units, that would add up to 6986 kWh / year for 
hot water, pushing the system size to humongous for a 1300 ft sq building.


Does that seem high? There will be a maximum of 2 people per unit.

The owner is considering going to 115 V units 
with a 15 gallon tanks. I think the smaller 
tank would help, but it would seem that the 
amount of hot water consumed would be the main issue.


How can we get a good estimate for a per person 
energy usage for electric hot water? Any other suggestions are welcome.


Thank you,

Drake



--
--Â
Barton Churchill
406.587.5295 Â
2430 North 7th Bozeman, MT 59715
www.solarips.com
Image removed by sender.

Â



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Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread Darryl Thayer 
Sorry I could not find much data but here is what I found

Here is some of my data, take with a grain of sault.

Well pump ½ hp drawdown 60 feet, start surge 1500 Watts running watts 500
watts runtime 25 seconds 40-gallon bladder tank.  40 to 60 PSI.

Two people in the house about 60 years old, One shower the pump ran 4 or
sometimes 5 cycles of the water pump about 30 seconds on and 30 off.  This
means they ran water for about 4 or 5 minutes per shower.  When no one was
home the electric water 50-gallon energy star cycled about 4 times per day,
at 4500 watts for about 10 min,  just the non use water heater used 2.5
kWh/day when it was not in use.


Another example Family of three, heat pump water heater, energy conscious,
3 showers per day energy use was 1500 Watt hr/day.  If HP had COP of 4 then
equivalent to 6,000 Wh/d if it had been electric.  This means the family
was using 40 gallons /day for 3 people or about 13.5 gallons per person per
day.



Garage door opener 700 watts running very small surge, 2 car garage door,
typically 4 cycles per day, run time 12 seconds open and 12 seconds close.

 Refrigerator energy star about 50% duty cycle 100 watts on,  or 1200 Wh/d
Family of two 60-year-olds.


I have much more data but I could not find.


On Thu, Mar 15, 2018 at 8:42 AM, frenergy  wrote:

> Drake,
>
> It would help to knowis this duplex already built? and
> considering where you live, is a woodstove being considered for space heat?
>
> Bill
>
> Feather River Solar Electric
> Bill Battagin, Owner
> 4291 Nelson St.
> Taylorsville, CA 95983530.284.7849 <(530)%20284-7849>
> CA Lic 874049www.frenergy.net
>
> On 3/14/2018 4:19 PM, drake.chamber...@redwoodalliance.org wrote:
>
> Hello Wrenches,
>
> Is there a good way to estimate the power that will be consumed for
> electric water per person per day? We are estimating the amount of power
> that will be used by an all electric duplex, and the water heater amount
> seems high. The current model we have claims 3493 kWh/ year per 26 gallon
> tank will be consumed. With the two units, that would add up to 6986 kWh /
> year for hot water, pushing the system size to humongous for a 1300 ft sq
> building.
>
> Does that seem high? There will be a maximum of 2 people per unit.
>
> The owner is considering going to 115 V units with a 15 gallon tanks. I
> think the smaller tank would help, but it would seem that the amount of hot
> water consumed would be the main issue.
>
> How can we get a good estimate for a per person energy usage for electric
> hot water? Any other suggestions are welcome.
>
> Thank you,
>
> Drake
>
>
>
>
> ___
> List sponsored by Redwood Alliance
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Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread frenergy 

Drake,

            It would help to knowis this duplex already built? and 
considering where you live, is a woodstove being considered for space heat?


Bill

Feather River Solar Electric
Bill Battagin, Owner
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849
CA Lic 874049
www.frenergy.net

On 3/14/2018 4:19 PM, drake.chamber...@redwoodalliance.org wrote:

Hello Wrenches,

Is there a good way to estimate the power that will be consumed for 
electric water per person per day? We are estimating the amount of 
power that will be used by an all electric duplex, and the water 
heater amount seems high. The current model we have claims 3493 kWh/ 
year per 26 gallon tank will be consumed. With the two units, that 
would add up to 6986 kWh / year for hot water, pushing the system size 
to humongous for a 1300 ft sq building.


Does that seem high? There will be a maximum of 2 people per unit.

The owner is considering going to 115 V units with a 15 gallon tanks. 
I think the smaller tank would help, but it would seem that the amount 
of hot water consumed would be the main issue.


How can we get a good estimate for a per person energy usage for 
electric hot water? Any other suggestions are welcome.


Thank you,

Drake




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Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread cwarfel 

This is what I came up with:

The calculation is Q = mcp delta T

Water Temp out =  120

Water Temp in = ground source Temperature @ 50F?

delta T = 70F

m = mass flow rate.  ASHRAE is the source for this. 20gals per person 
per day = 20 gallons x 8.34 lbs/gallon =  167lbs/day/person


cp =  1 BTU/lb-degree F

Q = 167 x 1 x 70 = 11,676 BTU/day/person

Divide this by the efficiency of the water heating system (I'll assume = 
.86)  =11,676/.86 = 13, 577 BTU/person/day


convert to kWh if necessarym 13,577/3412 = ~4 kWh/person/day, 120 kWh/month

I checked this against one monthand it seems reasonable.

Website assuming ~3.5 family size comes up with @ 400kWh per month. They 
approached it another way with assuming run times.


https://www.google.com/search?safe=active=hp=Z3KqWvXiNsGb5wKJ2Kf4DA=electric+water+heater+use+annual+consumption=electric+water+heater+use+annually_l=psy-ab.1.2.33i22i29i30k1l3.279.9222.0.12475.35.19.0.7.7.0.451.2360.0j6j4j0j1.11.00...1c.1.64.psy-ab..18.16.1952.0..0j0i67k1j0i131k1j0i22i30k1.0.CiU8wYZigpI


Chris




On 3/15/2018 8:09 AM, Mike Kocsmiersky wrote:


Barton makes a good point with regards to the incoming ground water 
temperature and the amount of heat required to bring it up to shower 
temp.  My recollection is that ASHRAE states 20gal/person/day for the 
first 2 people, then 15gpd or 12gpd thereafter.  However those rates 
vary wildly with consumers, from those that never bathe to the high 
schooler that needs 3 showers a day.  In the northeast water heating 
can be up to 19% of the total household energy load for the year.  
Also, I would recommend the air source heat pump water heaters if you 
have significant humidity or an on demand unit. Water tanks are 
typically under insulated and can lose 2kWh/day in standby losses.


Mike Kocsmiersky

Principal

Spirit Solar Inc.

(413) 734-1456

*From:*Barton Churchill [mailto:bar...@solarips.com]
*Sent:* Wednesday, March 14, 2018 7:31 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Electric Water kWh/ person

You first need to know your ground temperature. Then figure a delta to 
100 or so degrees. Most but not all showerheads flow 2.5gpm and 
showers are typically 10 minutes. You can then find a calculator 
online to calculate how many Btus are required to raise water temp for 
your delta per gallon. Convert to kWh, add some contingency and you 
should be good.


On Wednesday, March 14, 2018, > wrote:


Hello Wrenches,

Is there a good way to estimate the power that will be consumed for 
electric water per person per day? We are estimating the amount of 
power that will be used by an all electric duplex, and the water 
heater amount seems high. The current model we have claims 3493 kWh/ 
year per 26 gallon tank will be consumed. With the two units, that 
would add up to 6986 kWh / year for hot water, pushing the system size 
to humongous for a 1300 ft sq building.


Does that seem high? There will be a maximum of 2 people per unit.

The owner is considering going to 115 V units with a 15 gallon tanks. 
I think the smaller tank would help, but it would seem that the amount 
of hot water consumed would be the main issue.


How can we get a good estimate for a per person energy usage for 
electric hot water? Any other suggestions are welcome.


Thank you,

Drake



--

--

Barton Churchill
406.587.5295
2430 North 7th Bozeman, MT 59715
www.solarips.com 

Image removed by sender.



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--

 Christopher Warfel, PE
   ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
   (401)466-8978

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Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread Bill Hennessy 
Drake--
The kWh numbers are reasonable. A few years ago, I metered our hot water heater 
for a family of three and we were using an average of 10kWh/day--about 
one-third of our electric bill. A heat-pump water heater will reduce the kWhs, 
but they cost more and are louder. A better insulated water heater, insulated 
supply lines, low flow fixtures and better consumption awareness would also 
help reduce energy use.

regards, bill Bill Hennessy
Berks Solar, LLC
371 Centennial Rd
Mertztown, PA 19539

o 610 682 4300
c 484 560 4666
NABCEP certified installer
PA contractor #44411
www.berkssolar.com

  From: "drake.chamber...@redwoodalliance.org" 

 To: RE-wrenches  
 Sent: Wednesday, March 14, 2018 7:19 PM
 Subject: [RE-wrenches] Electric Water kWh/ person
   
Hello Wrenches,

Is there a good way to estimate the power that will be consumed for electric 
water per person per day? We are estimating the amount of power that will be 
used by an all electric duplex, and the water heater amount seems high. The 
current model we have claims 3493 kWh/ year per 26 gallon tank will be 
consumed. With the two units, that would add up to 6986 kWh / year for hot 
water, pushing the system size to humongous for a 1300 ft sq building. 

Does that seem high? There will be a maximum of 2 people per unit. 

The owner is considering going to 115 V units with a 15 gallon tanks. I think 
the smaller tank would help, but it would seem that the amount of hot water 
consumed would be the main issue. 

How can we get a good estimate for a per person energy usage for electric hot 
water? Any other suggestions are welcome.

Thank you,

Drake


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Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread Mike Kocsmiersky 
Barton makes a good point with regards to the incoming ground water temperature 
and the amount of heat required to bring it up to shower temp.  My recollection 
is that ASHRAE states 20gal/person/day for the first 2 people, then 15gpd or 
12gpd thereafter.  However those rates vary wildly with consumers, from those 
that never bathe to the high schooler that needs 3 showers a day.  In the 
northeast water heating can be up to 19% of the total household energy load for 
the year.  Also, I would recommend the air source heat pump water heaters if 
you have significant humidity or an on demand unit.  Water tanks are typically 
under insulated and can lose 2kWh/day in standby losses.

 

Mike Kocsmiersky

Principal

Spirit Solar Inc.

(413) 734-1456

 

 

 

From: Barton Churchill [mailto:bar...@solarips.com] 
Sent: Wednesday, March 14, 2018 7:31 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Electric Water kWh/ person

 

You first need to know your ground temperature. Then figure a delta to 100 or 
so degrees. Most but not all showerheads flow 2.5gpm and showers are typically 
10 minutes. You can then find a calculator online to calculate how many Btus 
are required to raise water temp for your delta per gallon. Convert to kWh, add 
some contingency and you should be good. 

On Wednesday, March 14, 2018,  wrote:

Hello Wrenches,

Is there a good way to estimate the power that will be consumed for electric 
water per person per day? We are estimating the amount of power that will be 
used by an all electric duplex, and the water heater amount seems high. The 
current model we have claims 3493 kWh/ year per 26 gallon tank will be 
consumed. With the two units, that would add up to 6986 kWh / year for hot 
water, pushing the system size to humongous for a 1300 ft sq building. 

Does that seem high? There will be a maximum of 2 people per unit. 

The owner is considering going to 115 V units with a 15 gallon tanks. I think 
the smaller tank would help, but it would seem that the amount of hot water 
consumed would be the main issue. 

How can we get a good estimate for a per person energy usage for electric hot 
water? Any other suggestions are welcome.

Thank you,

Drake





-- 

-- 

Barton Churchill
406.587.5295  
2430 North 7th Bozeman, MT 59715
  www.solarips.com

Image removed by sender.

 

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Re: [RE-wrenches] Electric Water kWh/ person

2018-03-15 Thread jerrysgarage01 


DrakeWe have used 40 to 80 gallon water heaters mainly the Rheem Marathon 
electric units, we used 15 minutes per person twice a day on the timer, we did 
use 7 day timers to have different start times on the weekends. We had great 
success with that as a base line.Jerry


Sent from my Verizon, Samsung Galaxy smartphone

 Original message 
From: Darryl Thayer  
Date: 3/14/18  4:14 PM  (GMT-10:00) 
To: RE-wrenches  
Subject: Re: [RE-wrenches] Electric Water kWh/ person 

Sorry to say nothing, but a few years ago I did a study on off grid and on grid 
houses and some had electric resistance water heaters and one with a Heat pump 
water heater.  If I can find the data I will send.  However, it varied a lot 
most the families were for 2 or 3 people  The variation made it seem like my 
study was of little value.  except for the family with a heat pump water heater 
used about 1/4 the electricity of the other.    
On Wed, Mar 14, 2018 at 6:19 PM,   wrote:
Hello Wrenches,

Is there a good way to estimate the power that will be consumed for electric 
water per person per day? We are estimating the amount of power that will be 
used by an all electric duplex, and the water heater amount seems high. The 
current model we have claims 3493 kWh/ year per 26 gallon tank will be 
consumed. With the two units, that would add up to 6986 kWh / year for hot 
water, pushing the system size to humongous for a 1300 ft sq building. 

Does that seem high? There will be a maximum of 2 people per unit. 

The owner is considering going to 115 V units with a 15 gallon tanks. I think 
the smaller tank would help, but it would seem that the amount of hot water 
consumed would be the main issue. 

How can we get a good estimate for a per person energy usage for electric hot 
water? Any other suggestions are welcome.

Thank you,

Drake




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