Octopus saving sessions coming 1st Nov

[Joeboy]

I forget about the stream for a while then I remember, just brilliant! A little bit on BBC news saying that this is the coldest snap in a decade. I am currently pulling 20kW from the grid with 5.5kW of that going to the EV. I am very glad of the extra storage capacity on the wall, it gives me more options, flexibility and less stress.

I had another problem yesterday and that was the pressure washer has packed up, might just be a frozen hosepipe I don't know. But I needed it to wash off the silt on the GSHP heat exchanger coils. So what do I do ?, old skool, fill a few buckets of water and throw them down the hole.

Absolutely brilliant, is there a temperature of water where its not worth it to run or is is good to run all year as long as the insulating silt is cleared?

[Fintray]

Nowty's heat pump will be pulling heat from that water which is at a greater temperature than the cold air we currently have in which the air source heat pumps are still able to extract heat from. As long as the water is flowing heat can be extracted from it.

[Oldgreybeard]

Very noticeable how much heat is in naturally flowing water. I walked into the village first thing (our stream runs right alongside the lane most of the way) and there was masses of "steam" rising off the water. The stream is fed from some springs further up the valley, and is probably at the same temperature as the water we pull up from our well (comes from the same aquifer I think). Our well water sits at around 8°C all year round, so there's a fair bit of of useful heat there to extract. My guess is that Nowty's stream may well be around the same temperature, so a really useful energy source in cold weather like this.

[nowty]

Absolutely brilliant, is there a temperature of water where its not worth it to run or is is good to run all year as long as the insulating silt is cleared?

No its good all year, the coldest the stream water gets to is about 7 degrees in February. That is the non operating temperature, so it gets a few degrees colder when the HP is running if the stream flow rate is low.

The main problem is the silt which acts as an insulator, so sometimes, I get this, the HP is pumping a fluid at -5 degrees into the stream heat exchanger and returning to the HP at a little over zero degrees, and the HP will trip out if the returning fluid to the HP falls below 0 degrees.


Just checked now and the flow is just above 0 degrees and the return to HP temp is 4 degrees. The fluid does a round trip in about 40 seconds and spends about 20 seconds in the stream warming up.

I re-wrote the project up in the thread below as the original one was shredded at St Elsewhere.
https://camelot-forum.co.uk/phpBB3/view ... f=17&t=487

[Joeboy]

Just excellent, a beautiful thing indeed.

[Oldgreybeard]

Just had thought, please bear with me, this might sound mad at first.

When we had problems with lift on wings suddenly decreasing at critical angles of attack, one fix was to add vortex generators, or more recently on high performance gliders, turbulators. These force the air to become turbulent and thus remain attached to the surface of the wing better, so there is no sudden lift drop off with a small increase in AoA (useful, stops aeroplanes falling out of the sky suddenly if they pitch up at low speed). You may have seen vortex generators, they typically look like this on the top of the wing (with apologies for those here that know this stuff already)s:

Vortex generators.jpg (42.93 KiB) Viewed 3459 times

The same sort of thing exists inside our noses, partly to keep the air clean that goes down to out lungs and partly to help warm and humidify air in cold weather. These turbinates throw some of the particulates that we breathe in to the sides of our airways, where mucous can trap them and then gradually be got rid of be being moved by the action of cilia, where we end up swallowing the nasty stuff and getting rid of it that way.

To get to the point. I wonder if some way of increasing the turbulence over the pipes might help? My guess is that when the stream is flowing fast there is enough natural turbulence to shift the silt away and keep the pipes clean, but when the flow velocity drops it may become laminar over the pipes, and that then results in silt dropping out and remaining attached to them.

The challenge would be to come up with some sort of vortex generator that could be retrofitted to create a lot of turbulence around the pipes during periods when the flow rate is low. Might be an awkward bit of bodgineering, but if it saves needing to clean the pipes then it might be worth doing.

On the other hand all the above could just be the ramblings of an old mad scientist that's best ignored!

[SimonSays]

What about a (couple of large) aquarium airstones fed from a beefy-ish air pump? Or just a length of airline which is weighted on the end in the stream? That could stop the silt from settling, no?

[nowty]

I've tried a number of things but in the end a pressure washer and a 2 meter lance once a week for 10 to 20 seconds is enough. Only problem at the moment the pressure washer is frozen up, hence I used a bucket of water thrown down a couple of days ago.

[Oldgreybeard]

I've tried a number of things but in the end a pressure washer and a 2 meter lance once a week for 10 to 20 seconds is enough. Only problem at the moment the pressure washer is frozen up, hence I used a bucket of water thrown down a couple of days ago.

I killed my pressure washer a few years ago from the cold. Like an idiot I'd left it in the car port at our old place, the weather turned very cold and the ice cracked the pump housing. I make a point of keeping it in the shed, next to the batteries and inverter, now, to avoid a repeat performance. Can't complain though, the one that cracked was a cheap one from Machine Mart that I'd bought from an ad in Exchange and Mart sometime around 1990, and it only packed up about 5 years ago, so I think I had my money's worth out of it. I still have it, as the motor is fine, and it may come in handy for something else one day.

[dlw]

Well it looked like it worked, now I will fully charge my battery on the next one