Solar hot water, worth the expense?

[Alan HeatherMember]

Just chuck a roll of poly pipe on the roof axel and hook a pump to it ,the water will get pretty dam hot.

[Nick JacksonMember]

axel wrote:

I’ve got a 400L electric power sucking machine like the dead one Mick has and was thinking about hooking it up to some solar tubes on the roof (+ thermostats, 10w pump, non return valve etc). Anyone done this before? Might be the go for summer at worst.

If you bought a controller with sensors etc it could be done but you need to be careful of expansion when the water heats up. Some of the tube type solar got water systems can heat the water in your pipe work to well above boiling and I have seen some systems melt through plastic pipe work and cables in the roof. Their are specific pressure release valves used to stop this so unless you have a lot of experiance it could end up being bloody dangerous.

Nick

[SteveMember]

Your right Nick. Majority of them pump out 180 Deg .They melt the green laggin off the pipe.
Have another happy pill and go to bed.DR orders.

[AlexMember]

180C holy smoke.
Copper is the go, surely. Look if the cycling pump fails then yes I’d believe the temp up in the vacuum header sections will get insanely hot but otherwise I’d eat my socks if all the water in the pipes + 400L water tank will get to 180C…
There are pressure reliefs all over the current electric water heater. Another one up on the header tank will deal with the roof unit. Bleed off excess pressure by copper pipe to the ground.
I have 0 experience but after some reading and discussion with a dash of common sense no human or animal should die.

Bigger Al I have Poly on the roof for our small kids pool. I throw it up there in the summer months. Works OK for the pool.

[Nick JacksonMember]

Copper is the ONLY go Axel , I was talking more about keeping good distances from cables and other pipes that may be PVC in the roof. I saw a tube type solar system in Yamba get so hot it’s copper flow and return pipes to the collector melted an adjacent PVC pipe flooding the whole house while the owners were on holiday. They estimated that the pipes got to over 200c as no water was being used and no cold mixing in the system. Sounds like a pressure relief fault helped the problem too.
I’m sure your onto it axel but if you do have an issue and its your system I’m not sure how you’ll go with insurance claims !!

Nick

[AlexMember]

Thanks Nick, good points, especially the insurance problem. I’ll keep on researching.

[Author]

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