This is the first post on this subject so there are no results yet so I hope you can bare with me.
While Bob was building my pond he talked about a heat box, where you wind a small bore pipe round and round and run a small watt pump so the flow is very slow. The idea sat with me for a while and now after getting more advice from Bob a small model has been made.
First I lined a clear plastic tub with tin foil, then drilled 2 holes in the lid for the airline, I placed the airline inside and closed it all up. I have a small aquarium pump and managed to get a piece of airline attached, I then used a 4mm Hozelock control flow so I can control the speed of the water. I then connected the pump and turned the switch to the minus sign to reduce the flow from the pump, I have put the pump in the moving bed filter and placed the box on top of the vortex so as to get as much heat as possible. The water is in the pipework for about 1 minute before it then returns to the pond. At the moment it is going to be a lot of trial and error and I know the size will have to increase to get the full benefit, but I though with the temps being what they are at the moment it is worth gving it a go. I know the box feels hot already so hopefully when I manage to get it it set up properly I will be getting some cheap heat for the pond
Looks a good prototype Kim, be interested to see if it can raise the temperature. Can you measure the increase? Perhaps put the return pipe into a small container before it overflows back into the pond, then you'll be able to measure the temperature of the returning water.
I thought exactly the same, it didn't go in until after 1pm today so I will do readings every hour tomorrow (as long as the sun shines) this will give a better idea of how things are going and if any adjustment are needed.
I know it is only small but I thought I would give it a try first and see how it goes
Great minds and all that bob, I have done My complete filter house roof as a heat panel. I will get some pics over weekend. I had some old top coat(black) So I glassed the roof and as you can imagine that gets plenty of heat. Anyway I fitted 75 meters of hose across the roof then fitted two salvaged pains of glass in a frame around it all. Gezzzzz if you dont turn it on until lunch time you can not keep your hand under the water until it has done a complete cycle.
So what I do now is have it on a timer comes on at 10 o`clock goes off at 8 o`clock in the evening, but this weekend will decrease the time it is on for as it is heating up to much!!! As the pond went up from 14 degrees to 24 dgrees within 3 days. I checked what temp the water was coming back to the pond yesterday and it was 28 degrees . So I have now increased the flow a little and today was at 26degrees. I know this will be no good in the winter months and will go back to a normel temperature control method. I just wanted to get up to a steady 24 degrees in the summer months as I have 35 tosai in there that I am trying to stretch.If I can do it by just diverting some water then happy days I thought. Looking good so far.
Kim how about an old aquarium with a lid on? I think the key to it is to have glass, our conservatory used to get unbareable until we changed things about.
Justin
Using waste heat from pumps to heat the water they are pumping is a brilliant idea but I'm afraid you can't patent it and become millionaires, it's already common practice.
I've even seen one portable self contained spa bath that doesn't have a heater, just coils of thin copper tube wrapped around the filter pump to heat the water with the pump's waste heat. As you would expect, the temperature rise is slow but the heat is free and when it gets up to temperature it maintains it easily. So the idea works well enough to be used commercially.
As to flow rates to get the optimum heat transfer, this may help:
There are two ways to heat a volume of water, you can either add a small amount of very hot water or a larger amount of tepid water, but there are larger heat losses if you go down the route of heating with small amounts of very hot water.
If you measure the temperature of the water going into the box and adjust the flow rate so that the temperature of the water coming out is one or two degrees warmer, that would be about the best heat transfer rate and the lowest heat losses that you are likely to get.
That sounds good Justin, what pump are you using and what's the lift?
I was trying to get Kim to use the lowest possible wattage pump and keep the heat box only just above the pond water level so no lift and less power required.
Would love to see some pics of yours, 75 metres is a lot of heating pipe! Sounds like it is working really well and will keep them Tosai growing really well
I've seen a few versions of this over the years, they always work and it's a cheap way to heat the water!
I love the sound of your set up and the heat you are getting is great, I have the problem of not being able to get on a roof so when Bob suggest this it sounded like a great idea. The one I made yesterday is just to see how much heat I can get, It was to small to be effective but as soon as I have some readings I can try and work out what size I will go. Bob has alredy said about using glass. But what I am trying to find out at the mount is the amount of water in the pipework and for how long.
While writting this I have had a thought of how I can increase the size with a scaled down version of yours, not to go on the roof though but still sitting in the sun, also Justin do you think that black is better, what Bob has suggested to me to use is the silver bubblewrap type insulation.
No Your ok Manke I dont think we are rushing off to dragons den, to let them know we have reinvinted the wheel. What we have done is put something we have heard things about into practise.
Hay Kim I just went with black as it holds heat and just soaks it up. My panel would work just as well on the floor as it would on a roof, just put it on the roof so its out of the way and it gravity feeds back to the pond. It trickles back inside my filter house into my skimmer.
Bob I am pumping about 1200mm above water level, and all I do is divert water from one of my main pumps. I will get Amanda out there this afternoon to take a couple of snaps.
Bob I left you a voicemail in the week mate.
Justin
Well my little box managed 1 degree increase not alot by any means but an increase, the other thing I noticed was the pond held it's heat for a lot longer. So the bigger newer version is being designed just a few things to got and I should be able to set it.
Something i was playing around with last year, problem was during the heat of summer and after i put perspex on it, i found it too efficient and it melted and distorted.
That hyperlink wasn't to a particular image, it was to a web page so I've downloaded it, copied the pictures and uploaded them as an attachment.
We're a bit fussy on here about posting pictures we don't own the copyright to and I obviously don't own the copyright to this one, but I'm sure this is what you wanted to post. If I'm mistaken, let me know and I'll delete it.
Yes thanks for doing that, i was thinking about the rights of,at the time and thought it would be ok because i 'own' the rights, i produce and edit the mag. i wanted the text on so it would explain the outcome. So i saved from .pdf to .jpg to upload in its entirety. But again i see what your on about and wouldn't want any problems.
john
There's no problem posting information and pictures as long as you own whatever you post, I just didn't want to have to ban myself for plagiarising another website.
How's this?
johnb105941_June_2011_10_5_opt.jpg (322.43 KiB) Viewed 23247 times
Thanks Syd
i should have thought about what i was doing, and explained upfront to have saved this confussion. Any way as long as others can see the out come of my little trial then all well and good.
regards
john
If I can poke my nose in on your design and make a suggestion that might make the heat transfer a little better (so the theory says), The pipework looks shiney, and shiney surfaces reflect back heat and light so it might make the heat pick up just that little bit better if you took the shine off the pipework with one of those green pan scourer thingies.
. So I have now increased the flow a little and today was at 26degrees. I know this will be no good in the winter months and will go back to a normel temperature control method. I just wanted to get up to a steady 24 degrees in the summer months as I have 35 tosai in there that I am trying to stretch.If I can do it by just diverting some water then happy days I thought. Looking good so far.
