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DIY pool heater project
- Thread starter wmrcomputers
- Start date
wmrcomputers
Stafford PC & laptop repair specialist
First day experimentation - My findings, opinions and theories. (for those who are following with interest and especially @hop who wanted keeping up to date)
Okay, so today the sun actually paid us all a lovely visit and so I was able to put the solar collector into action. The solar pool cover was also in place.
11am pool temperature - 15.2c
4pm pool temperature - 18.0c
6pm pool temperature - 18.7c
At 4pm I took a reading that I decided might be good to use as an average for the day, as there will have been less effective times and more effective times. The water leaving the pool was 18c and the return from the solar coil was 23.8c. Take into account that the water flow was approximately 200 litres per hour this is hardly going to make a massive effect on 16,000 litres of water - but nevertheless it was still 200 litres of water each hour being heated by almost 6c. Across the 7 hours this is likely to equate to (very roughly) 0.5c temp increase on the entire 16,000 litres. That's still fairly impressive for just a trickle of water passing through a length of black hose!
This theoretically means that the solar cover itself was responsible for providing around 3c of the overall increase across those 7 hours.... which is probably about right based on my findings when I first started using the solar cover.
Other tests included wrapping a clear polythene sheet over the coil of pipe. I left it in place for a good half hour during which the temperature was LOWER coming out at 23.2c. When I removed it again I felt the heat that had been kept in beneath it BUT the water out temperature instantly rose to a steady 23.8c. Without the polythene I then monitored my output temperature for nearly half an hour. When the breeze got quite sharp for a few minute period it barely had any effect on the output temp of the coil. 23.6 to 23.8c but mostly around 23.8c. I have therefore come to a few conclusions, or rather opinions, of my own.
1. I have decided that a solar cover for the actual surface of the pool is DEFINITELY the wisest investment. I have prroved that they DO actually help to heat as well as insulate the pool from losses caused by evaporation etc.
2. Solar coils made from LDPE pipe (I used 13mm x 100m) definitely heat the water. Whilst they're no where near as effective as a solar pool cover they have the bonus of being limited only by garden space and funds, whereas a pool cover is limited by the surface area of the pool. On that basis I would advise anyone thinking of buying a pool to consider offsetting depth against surface area. For example a 15ft diameter 3 ft deep pool being a better choice than a 12ft diameter 4 ft deep pool if you want a solar cover to help you out better at keeping the chill off.
3. Due to my own findings I have come to the conclusion that this is all about DIRECT SOLAR ENERGY contact with the black pipe coil. I dont think the pipe is as good at drawing in the surrounding heat in the air, and indeed even wind on the pipes didnt seem to cool it as was expected. I think it is all about what sun hits those pipes directly. I plan on eventually increasing to an additional 2 or 3 pipe coils as I have plenty of room for them, but they will definitely be left open to the air. At best I might put some edges on the boards just to shelter from major wind but I definitely don't think any kind of "window" on the front is worth doing at all.
Obviously if the weather keeps up I'll try to monitor how my losses stand overnight, and whether I manage to slowly increase temperature over several days. I also intend to run the temperature tests during a cloudy day just to make sure that the coil doesn't act as a cooler if left to run when the sun isn't great. After all it is known that solar energy exists even when clouded over. As long as it doesn't cool the water on the cloudier days then I'll just put the pump on a daily timer for daylight hours, as it costs only around 3p per day (8 hours) to run so isn't worth worrying about in that way.
Sorry for the long post, but wanted to share every detail possible. All based on my own findings and opinions of course. What works for me might not work for someone else, but hopefully one day this might be of use to someone.
Okay, so today the sun actually paid us all a lovely visit and so I was able to put the solar collector into action. The solar pool cover was also in place.
11am pool temperature - 15.2c
4pm pool temperature - 18.0c
6pm pool temperature - 18.7c
At 4pm I took a reading that I decided might be good to use as an average for the day, as there will have been less effective times and more effective times. The water leaving the pool was 18c and the return from the solar coil was 23.8c. Take into account that the water flow was approximately 200 litres per hour this is hardly going to make a massive effect on 16,000 litres of water - but nevertheless it was still 200 litres of water each hour being heated by almost 6c. Across the 7 hours this is likely to equate to (very roughly) 0.5c temp increase on the entire 16,000 litres. That's still fairly impressive for just a trickle of water passing through a length of black hose!
This theoretically means that the solar cover itself was responsible for providing around 3c of the overall increase across those 7 hours.... which is probably about right based on my findings when I first started using the solar cover.
Other tests included wrapping a clear polythene sheet over the coil of pipe. I left it in place for a good half hour during which the temperature was LOWER coming out at 23.2c. When I removed it again I felt the heat that had been kept in beneath it BUT the water out temperature instantly rose to a steady 23.8c. Without the polythene I then monitored my output temperature for nearly half an hour. When the breeze got quite sharp for a few minute period it barely had any effect on the output temp of the coil. 23.6 to 23.8c but mostly around 23.8c. I have therefore come to a few conclusions, or rather opinions, of my own.
1. I have decided that a solar cover for the actual surface of the pool is DEFINITELY the wisest investment. I have prroved that they DO actually help to heat as well as insulate the pool from losses caused by evaporation etc.
2. Solar coils made from LDPE pipe (I used 13mm x 100m) definitely heat the water. Whilst they're no where near as effective as a solar pool cover they have the bonus of being limited only by garden space and funds, whereas a pool cover is limited by the surface area of the pool. On that basis I would advise anyone thinking of buying a pool to consider offsetting depth against surface area. For example a 15ft diameter 3 ft deep pool being a better choice than a 12ft diameter 4 ft deep pool if you want a solar cover to help you out better at keeping the chill off.
3. Due to my own findings I have come to the conclusion that this is all about DIRECT SOLAR ENERGY contact with the black pipe coil. I dont think the pipe is as good at drawing in the surrounding heat in the air, and indeed even wind on the pipes didnt seem to cool it as was expected. I think it is all about what sun hits those pipes directly. I plan on eventually increasing to an additional 2 or 3 pipe coils as I have plenty of room for them, but they will definitely be left open to the air. At best I might put some edges on the boards just to shelter from major wind but I definitely don't think any kind of "window" on the front is worth doing at all.
Obviously if the weather keeps up I'll try to monitor how my losses stand overnight, and whether I manage to slowly increase temperature over several days. I also intend to run the temperature tests during a cloudy day just to make sure that the coil doesn't act as a cooler if left to run when the sun isn't great. After all it is known that solar energy exists even when clouded over. As long as it doesn't cool the water on the cloudier days then I'll just put the pump on a daily timer for daylight hours, as it costs only around 3p per day (8 hours) to run so isn't worth worrying about in that way.
Sorry for the long post, but wanted to share every detail possible. All based on my own findings and opinions of course. What works for me might not work for someone else, but hopefully one day this might be of use to someone.
wmrcomputers
Stafford PC & laptop repair specialist
Another calculation - 14 coils combined with the solar cover would give me a 10c increase by around 4pm on any sunny day for a late afternoon swim.
Whilst I have space there are a few considerations....
1. Another £400 - £600 needed for pipe and hardware.
2. She'd go bloody mad!
3. It would look like Berty Bassett himself had exploded in our garden.
4. She'd go bloody mad!
Whilst I have space there are a few considerations....
1. Another £400 - £600 needed for pipe and hardware.
2. She'd go bloody mad!
3. It would look like Berty Bassett himself had exploded in our garden.
4. She'd go bloody mad!
bpelectric
Well-Known Forumite
Just a thought here mate ....it would be interesting to take some ground temp measurements at say 6 inches below surface. I'm thinking it maybe worth putting pipes below the surface not only for heat loss but once the grounds warmed up it retains heat into the evening giving you more heat up time
littleme
250,000th poster!
I'm liking that you are taking into account considerations no2 & no4......any thought on writing a handbook for my oh?Another calculation - 14 coils combined with the solar cover would give me a 10c increase by around 4pm on any sunny day for a late afternoon swim.
Whilst I have space there are a few considerations....
1. Another £400 - £600 needed for pipe and hardware.
2. She'd go bloody mad!
3. It would look like Berty Bassett himself had exploded in our garden.
4. She'd go bloody mad!
wmrcomputers
Stafford PC & laptop repair specialist
Interesting thought, but I'd be amazed if it was more efficient than direct sun. Will still investigate though
Gramaisc
Forum O. G.
I have a soil thermometer somewhere, but just digging a hole and putting your hand in will lead you back to the surface - radiation is the key..Interesting thought, but I'd be amazed if it was more efficient than direct sun. Will still investigate though
hop
Well-Known Forumite
A very informative post @wmrcomputers.
Here is my set up 10m x 5m in ground pool.
With an autocover for safety. The cover is opaque so will reduce heat gain compared with a bubble wrap type of clear cover which may have a lensing effect on heating the water. However is some solar gain from the cover and it also reduces evaporative loss and keeps the water cleaner.
The cover is strong enough to take the weight of a horse. In addition to avoid the risk of drowning in the shallow amount of water which accumulated in the surface of the cover a sump type pump is present.
Heating is provided by an air source heat pump
Whilst there may be more theoretical gain with a bubble wrap type solar cover safety is reduced and fences are easily climbed over.
I was thinking about using 20mm black pipe for the loops. Can I ask which submersible pump you used and do think it would be capable of driving the flow through a 20mm pipe ?
I could use the existing pool pump and adapt the pipework as well, guess I will have to sit down and see if I can caculaute the different power draws and work out a way if potentially reducing the flow from the main pump to ensure the water is present in the collector for long enough to have a sufficient solar gain.
Here is my set up 10m x 5m in ground pool.
With an autocover for safety. The cover is opaque so will reduce heat gain compared with a bubble wrap type of clear cover which may have a lensing effect on heating the water. However is some solar gain from the cover and it also reduces evaporative loss and keeps the water cleaner.
The cover is strong enough to take the weight of a horse. In addition to avoid the risk of drowning in the shallow amount of water which accumulated in the surface of the cover a sump type pump is present.
Heating is provided by an air source heat pump
Whilst there may be more theoretical gain with a bubble wrap type solar cover safety is reduced and fences are easily climbed over.
I was thinking about using 20mm black pipe for the loops. Can I ask which submersible pump you used and do think it would be capable of driving the flow through a 20mm pipe ?
I could use the existing pool pump and adapt the pipework as well, guess I will have to sit down and see if I can caculaute the different power draws and work out a way if potentially reducing the flow from the main pump to ensure the water is present in the collector for long enough to have a sufficient solar gain.
Last edited:
wmrcomputers
Stafford PC & laptop repair specialist
wmrcomputers
Stafford PC & laptop repair specialist
Follow up:
Day 1 started at 15.2c and ended at 18.7c (3.5 gained) then lost 1.5 overnight.
Day 2 started at 17.2c and ended at 19.7c (2.5 gained) then lost 1.8 overnight (wasn't as sunny as day 1)
Day 3 started at 17.9c and by 2pm was up to 19.1c.... so I think this gives an overall picture.
I've also just experimented adding a tank full of gas heated water from the house via a hose pipe. This has raised the temp by 0.35c at a cost of around 35p. Therefore in gas equivalent terms I can safely say that a GOOD week of sunshine on just 1 such solar coil produces £2.00 to £2.50 worth of hot water. Fairly impressive! I intend to add another 3 coils eventually so I'll be producing roughly £8 - £10 a week worth of hot water for the expense of probably about 20p a week running a pump - and all from the sun! How cool is that!!
@hop I'm just using a 1500L/hr pond pump at the moment, although it's on full flow and is only shifting around 150 to 200 litres per hour through that coil, so I myself will have to look at alternatives when I expand the setup. There is no way it would be capable of running even one more coil. I think I'll be looking into using the existing filtration pump as that can shift the entire pool contents on around 4 hours so should be more than adequate. I just need to work out the size pipework and diverters etc that I would need.
Day 1 started at 15.2c and ended at 18.7c (3.5 gained) then lost 1.5 overnight.
Day 2 started at 17.2c and ended at 19.7c (2.5 gained) then lost 1.8 overnight (wasn't as sunny as day 1)
Day 3 started at 17.9c and by 2pm was up to 19.1c.... so I think this gives an overall picture.
I've also just experimented adding a tank full of gas heated water from the house via a hose pipe. This has raised the temp by 0.35c at a cost of around 35p. Therefore in gas equivalent terms I can safely say that a GOOD week of sunshine on just 1 such solar coil produces £2.00 to £2.50 worth of hot water. Fairly impressive! I intend to add another 3 coils eventually so I'll be producing roughly £8 - £10 a week worth of hot water for the expense of probably about 20p a week running a pump - and all from the sun! How cool is that!!
@hop I'm just using a 1500L/hr pond pump at the moment, although it's on full flow and is only shifting around 150 to 200 litres per hour through that coil, so I myself will have to look at alternatives when I expand the setup. There is no way it would be capable of running even one more coil. I think I'll be looking into using the existing filtration pump as that can shift the entire pool contents on around 4 hours so should be more than adequate. I just need to work out the size pipework and diverters etc that I would need.
Gramaisc
Forum O. G.
The resistance of the small diameter pipe is mostly why you're only getting 200l/h from a 1500l/h pump - if you add further coils in parallel, the total flow rate will increase.
Running the water slower through the coil will just result in a smaller quantity of warmer water being added to the pool. The actual amount of heat being added will be virtually the same.
Similarly, any 'lensing' by a transparent cover will have no effect on the total amount of energy introduced into the pool.
The bigger the collector area, the more it will collect.
Running the water slower through the coil will just result in a smaller quantity of warmer water being added to the pool. The actual amount of heat being added will be virtually the same.
Similarly, any 'lensing' by a transparent cover will have no effect on the total amount of energy introduced into the pool.
The bigger the collector area, the more it will collect.
wmrcomputers
Stafford PC & laptop repair specialist
Ideally I didn't want to put the coils in parallel as it is known to cause air locks in certain coils - obviously the water would just take the path of least resistance and then you can end up with coils that don't perform at all. BUT I get what you are saying and might just have to chance it. In all honesty it would be nice to continue with the current pump as I'd rather not mess with the filtration one if possible.
I totally agree. This is something some people that have done this just don't understand. There are people adding 15 minute timers thinking that the warmer water for half the time is more beneficial. DOH!
Confirming why I said a 15ft 3 ft deep pool would benefit better from a solar cover than say a 12ft 4 ft deep one. Thankfully I have all the garden I need for solar collector space. I'll just keep adding them as money and demand permits until I'm happy with it's functionailty. I think it's all going to come down to how quickly I want it to reheat after a bad weather spell really, as it's already perfectly adequate with this current weather. If the sun still shines over the next few days enough, I hope we'll be swimming in 23c or warmer water by the weekend
citricsquid
Well-Known Forumite
Here is the post by @hop with the images included.
@hop: you were using the full page URLs for the images (eg: imgur.com/EgN1fGc) when instead you want to use the direct URL, you can get that by prepending imgur.com with i. and appending the URL with .jpg, so imgur.com/EgN1fGc becomes i.imgur.com/EgN1fGc.jpg, alternatively you can get the correct URLs by clicking "Get embed codes" at the bottom right of the image.
@hop: you were using the full page URLs for the images (eg: imgur.com/EgN1fGc) when instead you want to use the direct URL, you can get that by prepending imgur.com with i. and appending the URL with .jpg, so imgur.com/EgN1fGc becomes i.imgur.com/EgN1fGc.jpg, alternatively you can get the correct URLs by clicking "Get embed codes" at the bottom right of the image.
A very informative post @wmrcomputers.
Here is my set up 10m x 5m in ground pool.
With an autocover for safety. The cover is opaque so will reduce heat gain compared with a bubble wrap type of clear cover which may have a lensing effect on heating the water. However is some solar gain from the cover and it also reduces evaporative loss and keeps the water cleaner.
The cover is strong enough to take the weight of a horse. In addition to avoid the risk of drowning in the shallow amount of water which accumulated in the surface of the cover a sump type pump is present.
Heating is provided by an air source heat pump
Whilst there may be more theoretical gain with a bubble wrap type solar cover safety is reduced and fences are easily climbed over.
I was thinking about using 20mm black pipe for the loops. Can I ask which submersible pump you used and do think it would be capable of driving the flow through a 20mm pipe ?
I could use the existing pool pump and adapt the pipework as well, guess I will have to sit down and see if I can caculaute the different power draws and work out a way if potentially reducing the flow from the main pump to ensure the water is present in the collector for long enough to have a sufficient solar gain.
wmrcomputers
Stafford PC & laptop repair specialist
Besides the heating scenario, my pool chemistry is going "swimmingly well" too. My pH is sitting at 7.5, Free chlorine at around 1.5 to 2ppm and the water is as crystal clear as the day I filled it... besides a few small leaves and dead flies floating by the edge of the solar cover.
Note to self - look into a fine pool net
Note to self - look into a fine pool net
Gramaisc
Forum O. G.
Have a full-flow valve for each coil and 'blow' them individually. Once they're each full of water, you should have no further air problems. If a coil does appear to be failing in this manner, then just 'blow' it again, by turning off the other coils. It might be useful to have the returns separate, perhaps just for the early days, so that each coil can be seen to be circulating.
wmrcomputers
Stafford PC & laptop repair specialist
hop
Well-Known Forumite
Thanks for the information @citricsquid - prior post updated. I will try and investigate this in the next few weeks and get my ass into gear with sorting something out. However I had a family bereavement recently and don't have much spare time.
wmrcomputers
Stafford PC & laptop repair specialist
hop
Well-Known Forumite
Well I've resumed this project. I have bought 200m of black irrigation pipe, which could always repurposed to water the flower beds.
I have decided against adapting the plumbing in the plant room, at least initially. The reasoning is that the main pump is very powerful and the pipes very thick also a stand alone system is simpler if things go wrong or air locks occur.
I already have a submersible pump and some suction tubing which I have been using as a stop gap measure on a drain until I can rectify the issue.
I was thinking I might need a different type of subsmerisble pump since I'm operating the pool with a salt cell. This converts regular sodium chrloide (table salt) to sodium hypoclorate / chlorine.
Although the concentration of salt is less than a human tear I think I will err on the side of caution and pick up a marine grade submersible pump.
I've also picked 500w of solar panels to run the machinery in the day.
Will update in a few weeks when I've got it up and running (assuming other tasks don't get in the way, which sadly is usually the case).
I have decided against adapting the plumbing in the plant room, at least initially. The reasoning is that the main pump is very powerful and the pipes very thick also a stand alone system is simpler if things go wrong or air locks occur.
I already have a submersible pump and some suction tubing which I have been using as a stop gap measure on a drain until I can rectify the issue.
I was thinking I might need a different type of subsmerisble pump since I'm operating the pool with a salt cell. This converts regular sodium chrloide (table salt) to sodium hypoclorate / chlorine.
Although the concentration of salt is less than a human tear I think I will err on the side of caution and pick up a marine grade submersible pump.
I've also picked 500w of solar panels to run the machinery in the day.
Will update in a few weeks when I've got it up and running (assuming other tasks don't get in the way, which sadly is usually the case).
wmrcomputers
Stafford PC & laptop repair specialist
Wow, this sounds great @hop keep us updated!
I'm just starting to de-winterise our above ground pool - it has been far better than I expected. A quick brush around and then I've shocked it with Chlorine to keep it at bay for another month or so, then I'll do the same before pumping it all out and starting with a fresh fill for this years swimming season. I'm seriously contemplating a heat pump to help us get more use out of it this year, but I just don't feel too easy about spending several hundred pounds that I don't have on an above ground pool that might not even last another year. It seems to be a crazy spend on a pool worth only a few hundred.
I'm just starting to de-winterise our above ground pool - it has been far better than I expected. A quick brush around and then I've shocked it with Chlorine to keep it at bay for another month or so, then I'll do the same before pumping it all out and starting with a fresh fill for this years swimming season. I'm seriously contemplating a heat pump to help us get more use out of it this year, but I just don't feel too easy about spending several hundred pounds that I don't have on an above ground pool that might not even last another year. It seems to be a crazy spend on a pool worth only a few hundred.