Pipe for solar collectors?

[TimSR2]

 I am planning a solar heated and solar powered preheat tank for my house. If I can get it working well enough it will replace my boiler for the summer months. Can anyone advise what would be suitable piping for a solar collector. This piping would go from roof mounted flat plate collectors, ten feet or so through an exterior wall vertically, and into a crawl space to a storage tank. System will be using an antifreeze solution, glycol of some sort. Probably RV antifreeze. Copper is king of course but it is expensive and conducts heat rather too well for my purposes.

Pump will be an El Sid running off a solar panel, a dead simple arrangement that requires no differential controller or electric supply.

Anybody know the temperature and other limitations of PEX, superpex, etc? I need a primer on the topic. I don't know anything about the stuff.

Thanks,

Tim

[Ronmar]

I know they use PEX extensively for outside boilers, and it is approved for domestic hot water plumbing, so it should be OK for your application...  You shouldn't be transfering water in excess of 120F or so anyway right? 

[WGB]

Pex doesn't handle UV at all!! So it must be covered.

[BruceM]

I have both El SIDs and the newer DC pump by Laing (D5), so I thought I'd pass on my in depth experience with them.

The Lang is superior in performance, is a very good mechanical and electronics design and is relatively good on EMI.  If I was starting over, I'd just filter the Lang, but it wasn't available when I started.  I do use the Lang for a hot water return loop to the remote hot water heater. Lang has an adjustable model, so you can dial in the flow rate, and save a bit of power, and it's max output exceeds the El-SID.  The Lang is slightly more efficient.

The EL SID electronics are very crude, the pumps generate a tremendous amount of EMI, as the H bridge drive has a few nanoseconds of timing overlap which causes a big spike on every bridge switch.

The EL SID 20, in order to save $, has half the drivers as th EL-SID 10. (A single H bridge and hall effect sensor.)  It generates a pulsing drive, which resulted in a slight vibration hum in the house, 50 feet away by pex, despite rubber hose connection of the pump.  The EL SID 10 has enough power since I over-sized my in floor heat system for low flow resistance (8 100 foot circuits in parallel), and it is quiet.

For my own use, I reverse engineered then redesigned the electronics for an EL SID and made them external, only the hall effect sensors and coils are used.  My unit is extremely quiet, EMI, wise, by using oversized MOSFETs in the two H bridges, and slowing the gate rise/fall time to a symetrical 200 usec.  There is no change in performance or power consumption.  I have pcbs for this.

The 1st photo is of a hand prototype circuit (single H bridge) driving an EL SID 20.
The PCB model (second photo) has both LV thermostat and fiber thermostat inputs, and needs no external relay.

[Curbie]

Anybody know the temperature and other limitations of PEX, superpex, etc? I need a primer on the topic. I don't know anything about the stuff.

Tim,

http://www.builditsolar.com/Experimental/PEXCollector/PEXALPEX.htm

In my view the builditsolar site is an exceptional place or anything DIY solar, lots of valuable reading there.

Good luck,

Curbie

[Halfcrazy]

we use a hose called Onyx it is black and kind of like fuel line. pex will not handle the heat and pressure if anything doesnt work perfectly. All it takes is a 20 minute power outage and pex will burst as the temp rises.

[BruceM]

Interested in Onyx because of your post and the cost of copper, I googled and found some disturbing posts on Onyx problems:
http://radnet.groupee.net/eve/forums/a/tpc/f/4771065301/m/1041096263

Class action activity...not good.

[Desperate]

Hi all, first post here.

Over here with Vac tube panels we can see temps in excess of 120 deg c(dunno what that is in F) so any kinda plastic is a no no. Mostly we use 10 or 12mm copper that comes on a 25m roll and all wrapped in high temp insulation.

HTH

Desperate

[mike90045]

we use a hose called Onyx it is black and kind of like fuel line. pex will not handle the heat and pressure if anything doesnt work perfectly. All it takes is a 20 minute power outage and pex will burst as the temp rises.

Looks like Onix uses an aluminum layer to provide an oxygen barrier, which is fine, till all the aluminum is converted to aluminum oxide (hard abrasive!) Then nothing to stop the oxygen after that except the iron parts in the system.

Wonder what PEX uses for a barrier ?

[Ronmar]

From what I understand the aluminum barrier pex is also refered to pex-al-pex, representing the aluminum layered between two layers of pex.

[LowGear]

Just set down and do the math on copper.  It just ain't that expensive when compared to all the factors you're dealing with in this thread.  And it works and works and often even works some more.

I buy it for about 60 cents on the dollar on craigslist.

Casey

[Desperate]

Hear hear Low Gear

If you really want to save a few bob, why spend loadsa money trying to do the green thing on the cheap??
The average install costs about 40 quid for pipery and say 1500 for everything else, whats the problem?

Seeya

Desperate

[Carlb]

I have only one word and that is copper, copper, copper  (well insulated)

[LowGear]

Hi,

Just re-read the thread.  If you think a hot water solar panel is only going to about 120 F you're in for a very big surprise.  They get as hot as car hoods in Las Vegas on the 4th of July.  Expect to cook eggs up there or you got her pointed North.

Casey