Dear Askaboutmoney people (especially Heinbloed if he is still around...)
We've been researching solar water heating for the summer when our Rayburn is off. We live in an old farmhouse and intend to put the panel on the side of the house below the hot water cylinder and not on the roof due to the severe weather we get in the winter and the weight of the welsh slate roof (new, that's bye bye SSIA) we are about to put on.
We decided against getting a ready-made solution even though this means we can't get a grant because we are not convinced the IR tubes can cope with coastal Irish weather and because of the cost - even without a grant it seems to be cheaper to do it yourself (clearly it helps that my husband is an electronics engineer and can do basic plumbing and I realise not everyone has access to these skills). Also we know DIY works as we had an old radiator painted black on the roof 20 years ago in England that did a great job!
For anyone who is in a similar situation you really should check out the Centre for Alternative Technology in Machynlleth in Wales http://www.cat.org.uk. They have excellent DIY publications on topics like solar water, domestic turbines, mini hydro schemes etc which are mostly available for a small fee online. We also found that Navitron http://www.navitron.org.uk had excellent documentation relating to the tube panels with good diagrams (see method statement).
We are looking at using a direct system with fairly large bore plumbing that will probably work mainly by convection although we will plumb it so we can add a pump if needed as direct systems are easy to retrofit. Normally the problem with direct systems is they fur up with limescale and become inefficient but if you use reasonably large bore it extends the lifetime.
Our question relates to the plumbing element. A direct system takes a T-feed off the pipe from the cold water tank to the hot water cylinder. It runs it into the bottom of the solar panel. The hot water at the top of the panel is fed back into the top of the hot water tank by means of another T-connection. If a pump is required, it is placed in the cold flow to the solar panel.
So... when the pump is on, why does it not also draw water from the cold water tank through the tee feed as well as from the bottom of the hot water cylinder and return it to the cold water tank via the hot water pressure vent? Is it a function of the speed of the pump?
Thanks for any thoughts...
Imogen
We've been researching solar water heating for the summer when our Rayburn is off. We live in an old farmhouse and intend to put the panel on the side of the house below the hot water cylinder and not on the roof due to the severe weather we get in the winter and the weight of the welsh slate roof (new, that's bye bye SSIA) we are about to put on.
We decided against getting a ready-made solution even though this means we can't get a grant because we are not convinced the IR tubes can cope with coastal Irish weather and because of the cost - even without a grant it seems to be cheaper to do it yourself (clearly it helps that my husband is an electronics engineer and can do basic plumbing and I realise not everyone has access to these skills). Also we know DIY works as we had an old radiator painted black on the roof 20 years ago in England that did a great job!
For anyone who is in a similar situation you really should check out the Centre for Alternative Technology in Machynlleth in Wales http://www.cat.org.uk. They have excellent DIY publications on topics like solar water, domestic turbines, mini hydro schemes etc which are mostly available for a small fee online. We also found that Navitron http://www.navitron.org.uk had excellent documentation relating to the tube panels with good diagrams (see method statement).
We are looking at using a direct system with fairly large bore plumbing that will probably work mainly by convection although we will plumb it so we can add a pump if needed as direct systems are easy to retrofit. Normally the problem with direct systems is they fur up with limescale and become inefficient but if you use reasonably large bore it extends the lifetime.
Our question relates to the plumbing element. A direct system takes a T-feed off the pipe from the cold water tank to the hot water cylinder. It runs it into the bottom of the solar panel. The hot water at the top of the panel is fed back into the top of the hot water tank by means of another T-connection. If a pump is required, it is placed in the cold flow to the solar panel.
So... when the pump is on, why does it not also draw water from the cold water tank through the tee feed as well as from the bottom of the hot water cylinder and return it to the cold water tank via the hot water pressure vent? Is it a function of the speed of the pump?
Thanks for any thoughts...
Imogen