Pretty good video but lots of information missing. For example, when deciding between active and passive solar hot water systems, keep in mind that active systems almost always outperform passive (thermosiphon) systems. They simply collect more Btus per day. Evacuated tubes almost always outperform flat plate collectors but are prone to overheating, so the fluid (typically non-toxic propylene glycol) must keep moving when the sun shines. The pump must be reliable and requires automatic backup battery power. There's certainly more to go wrong with the more complicated active system. But still, they sure do perform! I have an active system with 3 x 20 evacuated tubes. A heat dump, really a type of fan-cooled radiator on the gable end of my house, dissipates excess heat if the system is in danger of overheating. Yes, there is a T&P valve but only for emergencies that have never arisen. If glycol overheats it oxidizes, turns very dark and is ruined. The system must be drained, cleaned and refilled, which is no easy task. Never let your system overheat. Having said all this, it's not rocket science. I live in the Great White North of Canada, and my system makes a great deal of hot water at outside temperatures down to about minus 16-18C. Flat plate collectors cannot do this, as they 'leak' too much heat at low temperatures.
Great video and good advice. .... but I'm not sure on the need for pressure relief valve (in a passive system). If pressure builds in the system, wouldn't the water just flow back into the mains pipe?
It's not only for keeping your tank safe, it's also for making sure the hot water in the tank wouldn't flow back to the cold water pipe when you open the cold water in the tap as it would create a low pressure there. You could install a simple check valve instead of pressure relief valve in order to prevent that but then you put your tank at risk due to thermal expansion.
In most municipal water supply systems in the US and many parts of the world, the incoming water meter has an integrated backflow valve, which prevents water in the building pipes from reentering the main and creating potential contamination situation. To avoid the T&P (temperature and pressure) relief from bleeding water, an air gap expansion tank is added to the system. The T&P is a required safety device on all water heaters in the US to protect the user and the structure from damage due to excessive pressure buildup or temperature increases.
@@Bear-cm1vl many tanks in Australia will still end up releasing water when we've got an extremely hot day, so solar heaters during an extremely hot day often drip in a controlled way at the side of a house, similar to how an air conditioner or even fridge/coolroom compressor expell water
G'day Grant... I'm trying to build an off-grid solar hot water system at my camp near Lightning Ridge. I have the panels and a tank and I'm thinking that I will just connect a solar PV panel to a small dc recirculation pump and move the cold water from the tank through the hot water panel back to the storage tank and keep it recycling while the sun shines. It is a pressurised system. I am worried about excessive heat buildup in the system as it gets very hot out our way and wondered if I need to have some sort of pressure relief valve (besides the one that is already in the storage tank) near the hot water panels if the water should stop recycling (pump failure etc). Do you have any thoughts on this please, Chris
Well, this reply is a year late, but...….Always install a T&P valve in your system. A 30psi valve is commonly used as system pressures are usually about 15psi. Running a low-voltage pump off a PV panel (we call that 'PV direct') is an excellent idea but make sure the PV wattage is at least double the pump wattage. My 12V 15W pump is driven by a 30W panel. As far as overheating goes, yes, it's a bit complicated. Making a fully automatic control system that will work flawlessly when you're not around is difficult. My system uses an aquastat to activate a fan-cooled heat dump; of course this has to run on a constantly charged battery. Mains power just isn't reliable enough. When you're home, and your water has reached full temperature, simply throw a tarp over the solar hot water panel(s).
This is in Aus so it's referring to the southern hemisphere where it's best to face them north. In the northern hemisphere it's best to face them south.
North in North America would be pretty goofy. Remember, RUclips is a world wide tool, please be a bit more global in your approach. otherwise good straight forward info.
There was a question that did not show up on here about what I meant by "reversed"... North of the Equator, fixed solar collectors have their collection face turned roughly South to see as much sun throughout the day as possible. South of the equator, the collector face is pointed roughly North and at the equator, the face is pointed roughly straight up. This is easier visualized, however I can't even seem to find a picture on the web right now to link to, darn it.
I know it may seem silly, but I have this issue in reverse all the time, most videos only take into account the location they're made in. Even something like a water tank, often a video will state "what is allowed" without referring to the fact it will vary from place to place. This video at least references Australia, it looks like a TAFE training video; TAFE being gov owned, state run trade school in most states of Aus). If someone was installing a pannel I'd like to think they watch multiple videos and hope they'd figure it out.
@@Chrazzari I think, if someone needs different video to install their solar facing to the sunny-side of their particular location's sky, then it might be better not touching to the project at all. 😀🤦🏻♂️
I look at an interesting upload, how it's done etc., Then why do I have to look at someones face !!!!!! show the project. Do the commentry. You are not the star !!!!!!! the project is
Pretty good video but lots of information missing. For example, when deciding between active and passive solar hot water systems, keep in mind that active systems almost always outperform passive (thermosiphon) systems. They simply collect more Btus per day.
Evacuated tubes almost always outperform flat plate collectors but are prone to overheating, so the fluid (typically non-toxic propylene glycol) must keep moving when the sun shines. The pump must be reliable and requires automatic backup battery power. There's certainly more to go wrong with the more complicated active system. But still, they sure do perform!
I have an active system with 3 x 20 evacuated tubes. A heat dump, really a type of fan-cooled radiator on the gable end of my house, dissipates excess heat if the system is in danger of overheating. Yes, there is a T&P valve but only for emergencies that have never arisen. If glycol overheats it oxidizes, turns very dark and is ruined. The system must be drained, cleaned and refilled, which is no easy task. Never let your system overheat.
Having said all this, it's not rocket science. I live in the Great White North of Canada, and my system makes a great deal of hot water at outside temperatures down to about minus 16-18C. Flat plate collectors cannot do this, as they 'leak' too much heat at low temperatures.
Great video and good advice.
.... but I'm not sure on the need for pressure relief valve (in a passive system). If pressure builds in the system, wouldn't the water just flow back into the mains pipe?
It's not only for keeping your tank safe, it's also for making sure the hot water in the tank wouldn't flow back to the cold water pipe when you open the cold water in the tap as it would create a low pressure there.
You could install a simple check valve instead of pressure relief valve in order to prevent that but then you put your tank at risk due to thermal expansion.
In most municipal water supply systems in the US and many parts of the world, the incoming water meter has an integrated backflow valve, which prevents water in the building pipes from reentering the main and creating potential contamination situation. To avoid the T&P (temperature and pressure) relief from bleeding water, an air gap expansion tank is added to the system. The T&P is a required safety device on all water heaters in the US to protect the user and the structure from damage due to excessive pressure buildup or temperature increases.
@@Bear-cm1vl many tanks in Australia will still end up releasing water when we've got an extremely hot day, so solar heaters during an extremely hot day often drip in a controlled way at the side of a house, similar to how an air conditioner or even fridge/coolroom compressor expell water
G'day Grant... I'm trying to build an off-grid solar hot water system at my camp near Lightning Ridge. I have the panels and a tank and I'm thinking that I will just connect a solar PV panel to a small dc recirculation pump and move the cold water from the tank through the hot water panel back to the storage tank and keep it recycling while the sun shines. It is a pressurised system.
I am worried about excessive heat buildup in the system as it gets very hot out our way and wondered if I need to have some sort of pressure relief valve (besides the one that is already in the storage tank) near the hot water panels if the water should stop recycling (pump failure etc).
Do you have any thoughts on this please, Chris
Well, this reply is a year late, but...….Always install a T&P valve in your system. A 30psi valve is commonly used as system pressures are usually about 15psi. Running a low-voltage pump off a PV panel (we call that 'PV direct') is an excellent idea but make sure the PV wattage is at least double the pump wattage. My 12V 15W pump is driven by a 30W panel.
As far as overheating goes, yes, it's a bit complicated. Making a fully automatic control system that will work flawlessly when you're not around is difficult. My system uses an aquastat to activate a fan-cooled heat dump; of course this has to run on a constantly charged battery. Mains power just isn't reliable enough. When you're home, and your water has reached full temperature, simply throw a tarp over the solar hot water panel(s).
I'm Michigan, USA they should face South.
This is in Aus so it's referring to the southern hemisphere where it's best to face them north. In the northern hemisphere it's best to face them south.
North in North America would be pretty goofy. Remember, RUclips is a world wide tool, please be a bit more global in your approach. otherwise good straight forward info.
This is information for locations in the Southern hemisphere. North of the equator would be reversed.
There was a question that did not show up on here about what I meant by "reversed"...
North of the Equator, fixed solar collectors have their collection face turned roughly South to see as much sun throughout the day as possible. South of the equator, the collector face is pointed roughly North and at the equator, the face is pointed roughly straight up. This is easier visualized, however I can't even seem to find a picture on the web right now to link to, darn it.
I know it may seem silly, but I have this issue in reverse all the time, most videos only take into account the location they're made in. Even something like a water tank, often a video will state "what is allowed" without referring to the fact it will vary from place to place. This video at least references Australia, it looks like a TAFE training video; TAFE being gov owned, state run trade school in most states of Aus). If someone was installing a pannel I'd like to think they watch multiple videos and hope they'd figure it out.
@@Chrazzari I think, if someone needs different video to install their solar facing to the sunny-side of their particular location's sky, then it might be better not touching to the project at all. 😀🤦🏻♂️
I look at an interesting upload, how it's done etc., Then why do I have to look at someones face !!!!!! show the project. Do the commentry. You are not the star !!!!!!! the project is
Nobody owes you free professional information