Green Building Forum - running freezer on Watson optiplug Tue, 19 Dec 2023 06:04:14 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202188#Comment_202188 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202188#Comment_202188 Sun, 18 May 2014 23:04:38 +0100 caspen
Do you know if we could use it to run an additional freezer? The freezer would be turning off whenever there was no electricity generated. But if we didn't open the freezer when it was off, eg in the evenings and at night, would the food inside be OK until the freezer turned on in the next generating cycle. It's likely to be the excess fruit and veg from the garden.

Many thanks for your experience / knowledge.]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202190#Comment_202190 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202190#Comment_202190 Sun, 18 May 2014 23:47:08 +0100 tony

some kind of bypass switch that would switch on at -16 would solve it and then use the one you are planning to use to run it at -20 that would save a reasonable amount of money.]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202191#Comment_202191 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202191#Comment_202191 Mon, 19 May 2014 00:01:25 +0100 markocosic
The problem you'll run into is complexity. A piece of shit G to A rated old freezer that's better off scrapped than running is easy to frig. (mechanical thermostat) Modern A+++ equipment that's worth having is hard to frig. (inverter driven digital thermostat and so forth)

You might get lucky and find an A+ or A++ that still has on/off contacts to decide when to run. Wattson runs a contactor to bypass the OE thermostat and force the freezer to run; fit a second thermostat to stop it by -30C* or so?

*ask a refrigeration guy for a sensible number.

Exporting the electricity and making jam from the fruit also works. :wink:]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202193#Comment_202193 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202193#Comment_202193 Mon, 19 May 2014 06:19:32 +0100 SteamyTea
I cut the energy use of my fridge by 30% by just adding some insulation to the sides.]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202196#Comment_202196 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202196#Comment_202196 Mon, 19 May 2014 09:05:57 +0100 Ed Davies Posted By: tonysome kind of bypass switch that would switch on at -16 would solve it and then use the one you are planning to use to run it at -20 that would save a reasonable amount of money.

Seems a good plan to me. Less temperature margin for power cuts, though.

Not overly convinced by A++++++ fridges. Seems to me that the extra PV to run a more moderate one (A+ or so) can be cheaper than the extra cost of the fridge, bearing in mind that the fridge usefully acts as a heating element throughout the heating season. In the summer your extra PV runs it anyway, though you lose the COâ‚‚ benefit of exporting the electricity.]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202198#Comment_202198 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202198#Comment_202198 Mon, 19 May 2014 09:14:49 +0100 fostertom Posted By: SteamyTeaI cut the energy use of my fridge by 30% by just adding some insulation to the sides.Would that work on
Posted By: markocosicA piece of shit G to A rated old chest freezer
]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202202#Comment_202202 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202202#Comment_202202 Mon, 19 May 2014 10:23:49 +0100 GarethC running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202214#Comment_202214 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202214#Comment_202214 Mon, 19 May 2014 14:35:09 +0100 SteamyTea Posted By: fostertomWould that work onNot sure if it would make it an A, but would help.
Part of the problem is that in my instance, the fridge energy use is pretty low anyway.
I seem to remember that our old friend Damon dug out seem info about how the rating system works, moving average I seem to remember.

Posted By: GarethCbut why don't fridges have drawers the way freezers do
Not the air you need to keep cool, its the goods inside. There is very little air in a fridge, which has a low SHC when compared to a few cans of beer. So probably not worth the inconvenience.]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202231#Comment_202231 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202231#Comment_202231 Mon, 19 May 2014 18:33:28 +0100 Ed Davies
Indeed, the effect of air getting into the fridge is not large but to the very limited extent it does matter the effect of condensation of water vapour (and freezing it in a freezer) is nearly as important as simple cooling.

Number sources can be found in this blog post: http://edavies.me.uk/2013/12/dehumifiers/ , particularly the table in the other place linked from there.

Room air at 20 °C, 60% RH would contain 9 g/kg of water vapour. Cooled to 5 °C, 100% RH it would contain 5 g/kg so 4 g/kg would need to be condensed out. At around room temperature water has a latent heat of vaporization of about 2.4 MJ/kg so 2.4 kJ/g or with 4 g/kg of water vapour 9.6 kJ/kg of air.

For comparison, the SHC of air is around 1 kJ/kg so cooling it from 20 °C to 5 °C needs 15 kJ/kg so a total of 24.6 kJ/kg. A litre of air has a mass of just under 1.3 g so it'd be about 30 J/l.

A heat pump with a cooling COP of 2 (equivalent to a heating COP of 3) consuming 150 watts would extract 300 W (or 300 J/s) so get rid of that in a tenth of a second.]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202242#Comment_202242 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202242#Comment_202242 Mon, 19 May 2014 20:31:05 +0100 markocosic
fostertom - not even close. If the fridge/freezer isn't A-rated weigh it in for scrap now as it's better for the environment than keeping it. We're talking £3000 in electricity to run it for 20 years vs £600 type money here!]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202321#Comment_202321 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202321#Comment_202321 Wed, 21 May 2014 00:36:24 +0100 caspen running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202375#Comment_202375 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202375#Comment_202375 Thu, 22 May 2014 06:51:10 +0100 Jonti Posted By: SteamyTea
I cut the energy use of my fridge by 30% by just adding some insulation to the sides.

ST,

did you just insulate the sides and door/front or did you also do the back?

Jonti]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202383#Comment_202383 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202383#Comment_202383 Thu, 22 May 2014 08:51:57 +0100 SteamyTea
http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=7998]]> running freezer on Watson optiplug http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202710#Comment_202710 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12104&Focus=202710#Comment_202710 Wed, 28 May 2014 17:05:27 +0100 rhamdu Posted By: GarethCwhy don't fridges have drawers

Ikea used to make a below-worktop fridge with drawers. Perhaps they still do. It was very expensive and I guess they never achieved economies of scale.

One other thought. If we are going to apply demand management to fridges, thermal mass becomes important. So don't drink all the beer.]]>