Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-12-2015, 10:47   #76
Registered User

Join Date: Apr 2011
Posts: 2,243
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by kombivan View Post
and so is diesel hair shampoo petrol vasoline wd40 thinners paint sinkers everything around us has issues but I like a warm shower and I like clean dishes. I also don't drink hot water. But if you have to boil it to purify it for drinking I am sure the impurities will seperate.
The boiling point of DEHP is 385C, so all that boiling the water will do is RAISE the concentration, by boiling off some of the water as steam.
__________________

__________________
Bristol 31.1, SF Bay.
MarkSF is offline   Reply With Quote
Old 02-12-2015, 12:12   #77
Senior Cruiser
 
northwestsailor's Avatar

Cruisers Forum Supporter

Join Date: Nov 2009
Location: Kenai, AK
Boat: Meta Dalu 47
Posts: 277
Images: 10
Send a message via AIM to northwestsailor Send a message via Skype™ to northwestsailor
Re: Using an Electric Tea Kettle to Save Propane ?

We bought a cheap induction hot plate from China and wife loves it. Now wants a spare.
__________________

__________________
Victor Raymond
S/V Rajah Laut
1988 Meta Dalu 47

completion by Peter Smith
northwestsailor is offline   Reply With Quote
Old 02-12-2015, 15:40   #78
Registered User
 
zboss's Avatar

Join Date: Sep 2011
Location: On a boat
Boat: Cabo Rico 38
Posts: 3,426
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by northwestsailor View Post
We bought a cheap induction hot plate from China and wife loves it. Now wants a spare.
I've looked at those - 1500 watts. Do you find you run them at 1500 watts or a lot less? About how many Ah do you pull a day from using it?
__________________
zboss is offline   Reply With Quote
Old 02-12-2015, 16:00   #79
cat herder, extreme blacksheep
 
zeehag's Avatar

Cruisers Forum Supporter

Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 17,762
Images: 56
Send a message via Yahoo to zeehag Send a message via Skype™ to zeehag
Re: Using an Electric Tea Kettle to Save Propane ?

btw--has anyone said yet that propane is actually cheap fuel??
doesnt cost much.
"3rd world" runs on propane so availability is not problem.
zeehag is offline   Reply With Quote
Old 02-12-2015, 16:53   #80
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Using an Electric Tea Kettle to Save Propane ?

Propane has a heat rating of 21,600 btu's per pound of fuel (91,000 btu per gallon). It actually varies a bit from location to location. Butane is 21,300 btu per pound, which is pretty close to propane.

The typical galley stove burner is rated at 6500 or 7000 btuh. The energy required to heat one quart (~liter) of water from 45 degrees to 212 degrees is roughly 347 BTU's or 0.101 KWh.

The nitty gritty is a resistive immersion heating element will give you right near 100% eff. That is all the heat goes to the water. A kettle on the stove is probably only capturing 40% ( my WAG or wild a$$ guess of heat transfer efficiency) of the heat of the burner. It could be less then that, probably not much more. Most of it is going around the kettle, heating the stove top, etc.

So right off the top, the propane will need about 868 BTU's per quart (~liter), which with propane being $3.50 a gallon here would be roughly 3.48 cents of propane.

Electrical cost in California at 0.16 cents per kw would be 1.61 cents if your paying for electric use. Of course an electric stove would have similar efficiency's of a gas stove. So if your heating the kettle on an electric stove the cost rises to 13.8 cents (ouch).

But a kettle with an immersion heating coil would be very efficient.
__________________
sailorchic34 is online now   Reply With Quote
Old 02-12-2015, 17:29   #81
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: Using an Electric Tea Kettle to Save Propane ?

If your inverter is big enough, it can be done. Also at sea, on a less rolly day. Make sure you build a gimballed holder if you want to boil water at sea or in a rolly anchorage.

There are 12 / 24 Volt kettles too. (e.g. WAECO)

PS Mind the initial power of the kettle that can be way higher than its specs at the very start.

b.
__________________
barnakiel is offline   Reply With Quote
Old 02-12-2015, 20:38   #82
Senior Cruiser
 
northwestsailor's Avatar

Cruisers Forum Supporter

Join Date: Nov 2009
Location: Kenai, AK
Boat: Meta Dalu 47
Posts: 277
Images: 10
Send a message via AIM to northwestsailor Send a message via Skype™ to northwestsailor
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by zboss View Post
I've looked at those - 1500 watts. Do you find you run them at 1500 watts or a lot less? About how many Ah do you pull a day from using it?
Since my wife does most of the cooking, I would have to ask her for specifics but I don't think she runs it at full tilt, and if so not for long. We do have an electric kettle for boiling hot water which is great to have. But for all other cooking we use the induction stove.

I don't know how many Ah we use because we have a large 960 w solar panel array which keeps the batteries at full charge all day.
__________________
Victor Raymond
S/V Rajah Laut
1988 Meta Dalu 47

completion by Peter Smith
northwestsailor is offline   Reply With Quote
Old 02-12-2015, 22:07   #83
Senior Cruiser
 
northwestsailor's Avatar

Cruisers Forum Supporter

Join Date: Nov 2009
Location: Kenai, AK
Boat: Meta Dalu 47
Posts: 277
Images: 10
Send a message via AIM to northwestsailor Send a message via Skype™ to northwestsailor
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by zboss View Post
I've looked at those - 1500 watts. Do you find you run them at 1500 watts or a lot less? About how many Ah do you pull a day from using it?
Since my wife does most of the cooking, I would have to ask her for specifics but I don't think she runs it at full tilt, and if so not for long. We do have an electric kettle for boiling hot water which is great to have. But for all other cooking we use the induction stove.

I don't know how many Ah we use because we have a large 960 w solar panel array which keeps the batteries at full charge all day.
__________________
Victor Raymond
S/V Rajah Laut
1988 Meta Dalu 47

completion by Peter Smith
northwestsailor is offline   Reply With Quote
Old 03-12-2015, 09:56   #84
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: Using an Electric Tea Kettle to Save Propane ?

You will find Watts / degrees / time calculators online.

If I remember well, a 200W kettle boils 1 liter of water in about 30 minutes. Water 0 degs at the start 100 degs at boil. Scalable too.

Scale it up (you can) and a 2000W kettle will do this in 3 minutes. (Again from zero degs centg)

2000W will take out some 8 Ah out of a 12 Volt battery in same time. More if small battery (Peukhert)

Etc. Get the exact formulas from the web to make accurate calcs. The above very rough and from the top of the battered head.

Cheers,
b.
__________________
barnakiel is offline   Reply With Quote
Old 03-12-2015, 10:44   #85
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: Using an Electric Tea Kettle to Save Propane ?

OK.

I have right now boiled 0.5 liter of 25 degs cent water (to the boiling point at the water level, press 1024). 1 minute and 30 seconds.

5Ah out 12 Volt battery, 0.5 liter over 75 degs cent. Conversion losses included.

b.
__________________
barnakiel is offline   Reply With Quote
Old 03-12-2015, 12:08   #86
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,896
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by sailorchic34 View Post
Propane has a heat rating of 21,600 btu's per pound of fuel (91,000 btu per gallon). It actually varies a bit from location to location. Butane is 21,300 btu per pound, which is pretty close to propane.

The typical galley stove burner is rated at 6500 or 7000 btuh. The energy required to heat one quart (~liter) of water from 45 degrees to 212 degrees is roughly 347 BTU's or 0.101 KWh.

The nitty gritty is a resistive immersion heating element will give you right near 100% eff. That is all the heat goes to the water. A kettle on the stove is probably only capturing 40% ( my WAG or wild a$$ guess of heat transfer efficiency) of the heat of the burner. It could be less then that, probably not much more. Most of it is going around the kettle, heating the stove top, etc.

So right off the top, the propane will need about 868 BTU's per quart (~liter), which with propane being $3.50 a gallon here would be roughly 3.48 cents of propane.

Electrical cost in California at 0.16 cents per kw would be 1.61 cents if your paying for electric use. Of course an electric stove would have similar efficiency's of a gas stove. So if your heating the kettle on an electric stove the cost rises to 13.8 cents (ouch).

But a kettle with an immersion heating coil would be very efficient.
A thread elsewhere measured it empirically at something less than 40% Say about 35%.
__________________
hpeer is offline   Reply With Quote
Old 03-12-2015, 15:38   #87
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,707
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by barnakiel View Post
2000W will take out some 8 Ah out of a 12 Volt battery in same time. More if small battery (Peukhert)
<Pedant mode>
Strictly speaking, it will be the same Ah out regardless of battery size. But since you are drawing at a higher "discharge rate", the reduction of capacity remaining in the battery will be greater for the smaller battery because of the Peukert effect.
</Pedant mode>

But the result is the same, the smaller the battery the bigger the reduction in remaining capacity whichever way you look at it
__________________
StuM is offline   Reply With Quote
Old 03-12-2015, 15:41   #88
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,707
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by sailorchic34 View Post
Propane has a heat rating of 21,600 btu's per pound of fuel (91,000 btu per gallon). It actually varies a bit from location to location. Butane is 21,300 btu per pound, which is pretty close to propane.

The typical galley stove burner is rated at 6500 or 7000 btuh. The energy required to heat one quart (~liter) of water from 45 degrees to 212 degrees is roughly 347 BTU's or 0.101 KWh.

The nitty gritty is a resistive immersion heating element will give you right near 100% eff. That is all the heat goes to the water. A kettle on the stove is probably only capturing 40% ( my WAG or wild a$$ guess of heat transfer efficiency) of the heat of the burner. It could be less then that, probably not much more. Most of it is going around the kettle, heating the stove top, etc.

So right off the top, the propane will need about 868 BTU's per quart (~liter), which with propane being $3.50 a gallon here would be roughly 3.48 cents of propane.

Electrical cost in California at 0.16 cents per kw would be 1.61 cents if your paying for electric use. Of course an electric stove would have similar efficiency's of a gas stove. So if your heating the kettle on an electric stove the cost rises to 13.8 cents (ouch).

But a kettle with an immersion heating coil would be very efficient.

Absolutely spot on!
__________________
StuM is offline   Reply With Quote
Old 03-12-2015, 15:49   #89
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,707
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by barnakiel View Post
If your inverter is big enough, it can be done. Also at sea, on a less rolly day. Make sure you build a gimballed holder if you want to boil water at sea or in a rolly anchorage.

There are 12 / 24 Volt kettles too. (e.g. WAECO)

PS Mind the initial power of the kettle that can be way higher than its specs at the very start.

b.
But I'd stay away from those 12V "trucker" mug immersion heaters that you see on Ebay for a couple of bucks. Every review that I've seen of them is that they are a cr*p and take forever to heat a mug of water.


(As an aside, none of my cooking appliances are gimballed )
__________________
StuM is offline   Reply With Quote
Old 03-12-2015, 16:16   #90
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Using an Electric Tea Kettle to Save Propane ?

Quote:
Originally Posted by hpeer View Post
A thread elsewhere measured it empirically at something less than 40% Say about 35%.
That sounds like a nice number. I used 40% as a WAG just from experience with burner efficiency etc. Close enough. Of course, it will vary a bit depending on burner width,flame spread, o2 mix, pan support material and width and the shape of the kettle.

I suspect an inductive griddle on electric might get the efficiency up a bit. But an electric kettle with immersion element probably gives the best efficiency.

Of course, if one had to run the genny to boil water, then your loosing engine efficiency, generator efficiency before you even get to the stove or kettle. So that would factor into diesel or gas usage.

A pretty fun little question.
__________________

__________________
sailorchic34 is online now   Reply With Quote
Reply

Tags
electric, propane

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Getting Too Fat to Sail pillum General Sailing Forum 160 07-01-2016 12:15
Manual for a Winchmaster Electric Winch Handle uhatlevi Deck hardware: Rigging, Sails & Hoisting 2 31-08-2013 12:45
Australia - What a Beautiful Place to Cruise Lagoon4us Sailor Logs & Cruising Plans 90 15-12-2012 03:51
For Sale: Andersen 52 Electric Winch smith401 Classifieds Archive 2 12-06-2012 06:31
How to Control Pingbacks on CF Oceandrifter Forum Tech Support & Site Help 4 29-02-2012 14:48



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 14:27.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.