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balders118
Original Poster
3,215 posts
37 months
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I was cooking dinner tonight, and poored the boiling water from the kettle onto my frozen peas and wondered a question that I have, if I'm honest, wondered before... Obviously it takes longer to boil a large quantity of water than it does a smaller qunatity. However, when adding already boiling water to peas would using a larger volume and therefore a smaller overall cooling effect from the frozen peas be beneficial compared to using a smaller volume which would not take as long to boil if peas were not involved? I would have thought that the answer would be that the optimum volume would be a midway point, but then given a very small amount of peas (say 5) and a lot of boling water (say two litres) the cooling affect would be so small, that it should be able to re-boil fairly quickly, but then at the other end again with 5 peas, adding just enough water to cover the peas would not take long to boil in the first place. Anyone know for sure? Obviously this is very crucial infomation as this day and age, saving on energy costs os very important and the less gas used bring peas to the boil, the more money in my pocket 
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Eggman
1,253 posts
80 months
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Heating water requires a lot of energy, so you don't want to be heating more of it than you need.
The peas are going to need a set amount of energy to raise their temperature, and this can come either from the kettle element or the hob.
Kettles are very efficient ways of heating water, but hobs much less so because a lot of heat is lost to the room. The first site I turned up on Google appeared to suggest that a hob is only about 30% efficient. However, gas appears to be about a third the price of electricity per kWh so I reckon that'll pretty much balance out and the costs will be similar.
I reckon the cheapest method is to heat just enough water to cover the peas in the kettle and supply the rest of the energy using the hob.
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ruff'n'smov
641 posts
18 months
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Micro. 2 to 4 minutes depending on amount of peas ..pinch of salt little sugar...job done ..no water FFS
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LordFlathead
7,933 posts
127 months
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Off topic and dumbest of all comments relating to peas.. Why don't they explode when you boil them. They contain air and are sealed.  - Something I have thought about for years
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balders118
Original Poster
3,215 posts
37 months
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Eggman said: Heating water requires a lot of energy, so you don't want to be heating more of it than you need.
The peas are going to need a set amount of energy to raise their temperature, and this can come either from the kettle element or the hob.
Kettles are very efficient ways of heating water, but hobs much less so because a lot of heat is lost to the room. The first site I turned up on Google appeared to suggest that a hob is only about 30% efficient. However, gas appears to be about a third the price of electricity per kWh so I reckon that'll pretty much balance out and the costs will be similar.
I reckon the cheapest method is to heat just enough water to cover the peas in the kettle and supply the rest of the energy using the hob. I expect you're right for total energy consumption but my question really is ignoring the energy used to boil the water in the first place. Simply, which way around will allow the water to boil first, more or less water. My last comment about cost was rather tounge in cheek, but did kind of distract from the actual question.
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balders118
Original Poster
3,215 posts
37 months
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LordFlathead said: Off topic and dumbest of all comments relating to peas.. Why don't they explode when you boil them. They contain air and are sealed. - Something I have thought about for years The outer skin of the pea will be porus 
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Mr Sparkle
1,725 posts
39 months
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In both instances the peas will 'subtract' the same amount of heat from the water so you are even up to this point. Which means you want the smallest quantity of water you can as this will radiate the least heat.
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Eggman
1,253 posts
80 months
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balders118 said: Simply, which way around will allow the water to boil first, more or less water. I suspect that as long as the quantity of water is large in relation to the volume of peas it won't make much difference. I reckon 'large' in this context means that there's enough water that water and peas would quickly end up at a uniform temperature, thereby excluding scenarios like adding a drop of hot water to a cubic metre of peas. Once you've got that. the peas will take X joules of energy out of the (boiling) water whether it's half a pint or a gallon and the hob will have to supply X joules to get it boiling again, plus whatever escapes to heat the room. As the hob isn't that efficient, if the article I looked at earlier is right it'll have to supply about 3X joules to heat it up.
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Zumbruk
4,567 posts
129 months
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Put the peas in the kettle.
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xr287
819 posts
49 months
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Zumbruk said: Put the peas in the kettle. We have a winner. That sir is the kind of out of the box thinking I read ph for.
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LordFlathead
7,933 posts
127 months
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When I was at Uni, we used to boil eggs in the kettle 
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russ_a
1,386 posts
80 months
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Post removed as I posted utter tripe that hot water took longer to boil than cold.
When im fact I meant that hot water freezes faster than cold water
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balders118
Original Poster
3,215 posts
37 months
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russ_a said: .
When im fact I meant that hot water freezes faster than cold water
Well, thats not actually true now is it.
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Brite spark
1,158 posts
70 months
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xr287 said: Zumbruk said: Put the peas in the kettle. We have a winner. That sir is the kind of out of the box thinking I read ph for. Sounds familiar to another ph thread, kettle, peas and a hotel room. (well not peas But you get the idea)
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Zumbruk
4,567 posts
129 months
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Brite spark said: Sounds familiar to another ph thread, kettle, peas and a hotel room. (well not peas But you get the idea) Confucius he say "Man who cooks potatoes and peas in same pot unsanitary."
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Famous Graham
26,537 posts
94 months
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balders118 said: russ_a said: .
When im fact I meant that hot water freezes faster than cold water
Well, thats not actually true now is it. Sometimes.
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balders118
Original Poster
3,215 posts
37 months
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Famous Graham said: balders118 said: russ_a said: .
When im fact I meant that hot water freezes faster than cold water
Well, thats not actually true now is it. Sometimes. Yeah but to say "hot water freezes faster than cool" is false. In certain conditions, different waters can freeze differently i.e. the only regulalry reproduced study showed hot,, distilled water to freeze quicker than cool tap water. Using the same water has never produced reproducable results (AFAIK).
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kev b
607 posts
35 months
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If your main concern is saving energy then the best course of action is to take the peas from the freezer earlier and let them thaw using room heat before boiling them.
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Famous Graham
26,537 posts
94 months
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balders118 said: Famous Graham said: balders118 said: russ_a said: .
When im fact I meant that hot water freezes faster than cold water
Well, thats not actually true now is it. Sometimes. Yeah but to say "hot water freezes faster than cool" is false. In certain conditions, different waters can freeze differently i.e. the only regulalry reproduced study showed hot,, distilled water to freeze quicker than cool tap water. Using the same water has never produced reproducable results (AFAIK). Aye, fair enough. I thought hot water froze faster than lukewarm water though (all other things being equal)?
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balders118
Original Poster
3,215 posts
37 months
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Famous Graham said: Aye, fair enough. I thought hot water froze faster than lukewarm water though (all other things being equal)? Pretty sure thats not the case, i.e. all other things being equal cooler water will always freeze faster that warmer water
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