Cycling UK Forum

PedallingSquares wrote: ↑25 Oct 2022, 5:07pm

Paulatic wrote: ↑24 Oct 2022, 7:29pm Our house has been at 20C all day and while I’m moving around and going in and out it’s fine with my jumper on.
As soon as I sit down after eating though my hands go cold and my nose also. Fire lit and it’s now 25C I’ve taken my jumper off and I’m now warm and comfortable.
After a lifetime of arching my back against the cold working above 1000’ I really dread the cold.

If I have to wear a top and long trousers inside then,for me,it's too cold.Our house was built in 1969 and despite insulating the loft etc it's still a 'cold' house.My next step is to get rid of the tiled bit between the upstairs and downstairs windows.We had cavity walls done years ago but the front couldn't be done because of this.
22° is a good temp for through the night but if I'm home in the day I like it to be 25°.
It's cold on the shop floor at work, extremely cold in Winter,so we have the pulpit temp/fans set to 30° to warm us up It's strange.In Summer add 5-10° to the outside temperature and in Winter -5-to10 degrees what ever it is outside.Currently it's about 10°.

Nearholmer wrote: ↑20 Oct 2022, 5:06pm 24p day; 8p night.

There, I whispered it.

All that really adds to the discussion is nostalgia for the halcyon days of last September, when I found the tariff.

Nearholmer wrote: ↑19 Oct 2022, 6:23pm I won’t quote the prices for fear of provoking widespread jealousy - I struck very lucky.

ANTONISH wrote: ↑19 Oct 2022, 5:36pm My latest tarrif is 38.715p (day) , 23.15p (night) - I've never known the night tarrif to be one third of the day rate.

Jdsk wrote: ↑14 Oct 2022, 12:22pm Those attitudes towards behavioural change are only one of the components for achieving real change. Others are consistent national policies on a timescale much longer than the current farce, financial incentives both as carrots and sticks, perceived fairness, realistic timescales in expectations, and technological opportunities.

But those attitudes offer possibilities that wouldn't be there if, for example, there was widespread opposition to even the concept of change.

Jonathan

Nearholmer wrote: ↑5 Oct 2022, 5:26pm
I could swear that I never suggested metering in MJ. Is that a quote from within a quote or something? Or, am I cracking up (again)?

Nearholmer wrote: ↑4 Oct 2022, 3:26pm Having dredged my brain a bit, I think I can add more regarding the "extract heat from water by freezing it" idea.

As I said yesterday, a key question is the Coefficient of Performance that the heat pump is able to deliver (whether it be a GSHP, fridge, deep freezer, aircon unit, or whatever), and that is crucially dependant upon the difference between source temperature and output temperature required.

A GSHP operating optimally, pulling energy from cool (c10 - 15 degrees) ground and depositing it at say 40 degrees, can attain a CoP of between 3 and 4, so for every unit of energy used to drive the system, 3 to 4 units are extracted from the ground. Brilliant!

If the GSHP is required to do more work, to cross a greater temperature gradient, say to raise the output temperature to 60 degrees its CoP drops sharply, which is why a well-designed heating system run from a GSHP uses fairly low temperature, fairly big radiators (sometimes the entire floors of rooms are used as radiators).

The bad news is that a 'fridge bringing food down from ambient to about 2 degrees has a CoP of somewhere a bit either side of 2, and a deep freezer dragging things down to far lower temperatures might have a CoP of only 1. BUT, the cited CoP for cooling plant tells us something different from the cited CoP for heating plant, so the CoP for a freezer viewed as a heater will be different from the CoP of a freezer viewed as a cooler, IIRC from long ago learning, we need to add 1 to the CoP cited as a cooler to get to the equivalent viewing it as a heater.

Anyway, it looks to me as if the best bet here for Heath Robinson arrangements is to cool the water in a fridge, rather than freeze it in a freezer, but I will keep pondering and will correct the foregoing if I realise any mistakes.

Nearholmer wrote: ↑4 Oct 2022, 3:26pm A GSHP operating optimally, pulling energy from cool (c10 - 15 degrees) ground and depositing it at say 40 degrees, can attain a CoP of between 3 and 4, so for every unit of energy used to drive the system, 3 to 4 units are extracted from the ground. Brilliant!

Biospace wrote: ↑3 Oct 2022, 6:52pm

853 wrote: ↑3 Oct 2022, 6:23pm
I think that by the time I have designed and built something that will be worth doing, it might be ready for March to catch the equivalent spring heat. I take on the advice of all of my consultants, and so it all hinges on whether I can obtain a radiator free of charge. One of my neighbours is going to replace their elderly ones soon, so I may develop the idea further.

In the mean time, I have a better idea. Or at least I think it's a better idea, so I'd be grateful if those of you who know more will scrutinize it fully. Here goes:

Imagine filling 100 litres of tap water, (currently around 15 degrees C), into plastic containers and putting these into an empty freezer and freezing them to -15 degrees C. Then, once frozen, taking out the ice and discarding it in the garden and repeating this with 100 litres of 15 degrees C water again.

If I did this, the freezer could be used like a ground source heat pump - but with a very different initial cost outlay. Is this viable?

Any constructive advice/criticism/calculations gladly accepted

Very intriguing!

My initial thought is that it will work from a point of view of heat generated (although not so much heat), but economically not.

Unless you've a diesel generator running on free, waste plant oil to power the freezer. In which case you'd hook it up to a small electric heater.

Jdsk wrote: ↑3 Oct 2022, 6:26pm What's the objective?

Jdsk wrote: ↑3 Oct 2022, 6:26pm Where would the freezer be?

Thanks

Jonathan

Biospace wrote: ↑2 Oct 2022, 10:00pm

853 wrote: ↑1 Oct 2022, 6:31pm
Following advice from my consultant ( ), I am very happy to report success in experiment 2

I managed to find an old plastic cool-box, from about 30 years ago, so I used this with the acrylic sheet on top. Although it has been sunny here in the North Midlands, it has also been very windy with gusts of 30mph. I couldn't angle the cool box to the sun because of the wind, and I had to use two bricks on top of the acrylic sheet to keep it down. My thinking was that only the top brick would get any real heat, and this would only be if it was raised within the box. To my surprise, when I came back about 6 hours later I had four hot bricks which I carried inside the house within the cool box. I don't have measuring equipment to find out how hot they were, but they were definitely hot to touch and probably around 50 degrees C.

A good result. Time to work quickly if you want any free heat this year, there are only a few weeks left where the sun will significantly warm things up!

853 wrote: ↑30 Sep 2022, 6:23pm The forecast is for sun here tomorrow, so I will try the same arrangement as experiment 1 but try and stop the drafts. I'll let you know how I get on, as it will be a change from reading Woodburners Weekly

axel_knutt wrote: ↑1 Oct 2022, 1:27am

853 wrote: ↑26 Sep 2022, 6:30pmI am considering an insulated, south-facing, cold-frame to heat up bricks which could then be brought inside to dissipate their heat.

The specific heat of brick is ~800J/kg/K, so if you assume you can get a temperature of 40C (~20C above room temp), then to collect 5kWh of heat (not much more than a quids worth), you'll need over a ton of bricks. If you're willing to cart a ton of bricks in and out of the house for a quid you don't value your time very highly. Water has five times the specific heat of brick, which is why it's used for heating & cooling, and you can move it with a pipe instead of a wheelbarrow. You can also make simple DIY solar panels from central heating radiators sprayed matte black.

Biospace wrote: ↑29 Sep 2022, 5:37pm

853 wrote: ↑29 Sep 2022, 5:28pm I tried a first experiment yesterday, when it was nice and sunny here. The 'cold-frame' was a quick lash together of a transparent acrylic sheet resting on bricks, so drafty, uninsulated and without any reflectors. Heated the one brick I put inside slightly, but not significantly. Looking like the marginal end of 'marginal gains'

Draughty and uninsulated, mmm. Even the heaviest bricks painted mattest black, nestled in cotton wool, with hot sun pouring through triple glazing on to them will not warm so much if there's a draught.

On the other hand, a ~ 20'x4' wall built with some heavy older bricks painted black, facing south and in a properly insulated box will warm a room very comfortably, as described up-thread. A double row with a small air gap between even better. Eliminating draughts at the very minimum is essential, otherwise the heat gained will be lost through convection pretty effectively, especially if outside.

Think about how warm the interior of a car grows on a sunny day in October or March/April. Open the windows a little and it soon cools.