evacuated tube, radiator, thermosiphon

frankwest12345 · 03-04-12, 11:27 AM

Hi, I want to wall mount an evacuated tube collector then connect it to a radiator in an upstairs room (the radiator just above the top of the collector) so it will thermosyphon rather than pump it and with a feed tank in the loft for the water/antifreeze mix.

I was just wondering why I would need a return circuit to the collector as surely a single pipe to the radiator would suffice, as the heat would flow from the collector to the radiator and then into the room so as long as the water can expand via the feed tank if it gets too hot. it would not need to be circulated back to the collector (unlike if I was using it for hot water)?

Ryland · 03-04-12, 01:03 PM

A loop will give you better flow and the only radiators that I know of that are designed for a single pipe to hook up to are steam radiators, hot water radiators have an inlet and an outlet.
If you have a steam radiator (cheap to buy here in the USA because no one has steam boilers) then you just need a little bit of distilled water in your pipes and let the evacuated tube solar collector boil it, of course freeze protection would be required to keep it from bursting at night, or a small enough amount of water that it has space to freeze and not burst.

03-04-12, 11:27 AM	#1
frankwest12345 Lurking Renovator Join Date: Aug 2011 Location: Swindon UK Posts: 13 Thanks: 0 Thanked 0 Times in 0 Posts	evacuated tube, radiator, thermosiphon Hi, I want to wall mount an evacuated tube collector then connect it to a radiator in an upstairs room (the radiator just above the top of the collector) so it will thermosyphon rather than pump it and with a feed tank in the loft for the water/antifreeze mix. I was just wondering why I would need a return circuit to the collector as surely a single pipe to the radiator would suffice, as the heat would flow from the collector to the radiator and then into the room so as long as the water can expand via the feed tank if it gets too hot. it would not need to be circulated back to the collector (unlike if I was using it for hot water)?

03-04-12, 01:03 PM	#2
Ryland Master EcoRenovator Join Date: Mar 2009 Location: Western Wisconsin. Posts: 913 Thanks: 127 Thanked 82 Times in 71 Posts	A loop will give you better flow and the only radiators that I know of that are designed for a single pipe to hook up to are steam radiators, hot water radiators have an inlet and an outlet. If you have a steam radiator (cheap to buy here in the USA because no one has steam boilers) then you just need a little bit of distilled water in your pipes and let the evacuated tube solar collector boil it, of course freeze protection would be required to keep it from bursting at night, or a small enough amount of water that it has space to freeze and not burst.