Seals\Washers failing on manifold connection in solar thermal system

sas

Hi,

First off, if this is deemed more suitable to the renewable energies forum, then can a mod please move it there?

I'm choosing the plumbing forum because I see this more linked to the general plumbing side of my solar installation than the renewables part.

The flow\return pipes between our hot water tank and the tubes we have are one of those flexible stainless steel pipes that comes pre-insulated in that black insulation material.
Mods: please note I am purposely avoiding brand names. All components were supplied from 1 manufacturer. I would say that most people could figure out who it is very quickly.

We are having issues in that the seals where that stainless steel pipe is connecting to anything else (e.g manifold) the joints are weeping refrigerant.

The system was installed in March 2012. That wasn't a particularly fantastic summer (wettest june on record etc) so the system wasn't exposed to sustained periods of high temp. By September I noticed that the system was giving an hydraulics error and at further inspection noted that there were stains on the floor beneath the manifold.

I contacted my installers who promptly returned to site. They commented that they had had this issue before on a prior installation. On that occasion the manufacturer still had an on the road support person who attended that site 5 times before he successfully managed to fix the issue.

My system failed at the same joints again in Oct 2013. The issue I have now is that my installer is out of business. Their plumber who is an approved installer for the system however has accommodated me twice as he is trying to set up his own business. However, we've reached the point where he can't continue to fix my system for nothing while the manufacturer is pleading no knowledge of this issue. This is frustrating seeing as this was reported by the company I dealt with on 2 previous occasion so they most certainly are aware of it.

Last week I spoke to a different supplier of a different brand but virtually identical pipe. They claimed that there was a known issue with the washers on similar systems but that they were happy now that the current ones they used were very good. Those washers I can get and use in my system if needs be.


I believe this isn't workmanship related. I saw him redo the pipes, he followed the instructions exactly and with care. Also, as the system is fine for a period this too leads me to blame materials.

So my question is if any of you have encountered this issue? Is this something common to solar setups or have I been unlucky. At this stage I'm expecting to have to annually replace washers and add refrigerant along with the associated labour costs. That will mean that my system is costing me money, not saving me. This won't do. I consider dumping it on that basis.

When working, the system is fantastic. It provides vast amounts of hot water, bordering on limitless in summer. I would like to fix this with confidence its going to work for a sustained period.

Any advice anyone can offer I'm happy to take.

SAS

sky6

I haven't heard of any such problem. Solar Systems are very reliable once installed correctly and give very little trouble. so I think you have just been unlucky. You could get it plumbed in copper which would cure your problem although the flexy pipe is easier.
Where are you located I might be able to give you a nome of a real exxpert in solar. you can pm me if you wish.

Irish Steve

Not on a solar system, before Christmas, I spent a good few hours tracing an underfloor leak, and fixing a number of other joints that were weeping on a heating system, and in all the cases, the issue was that the 'O' rings had become hardened, and couldn't flex enough with the change in size of the plastic pipe, which does expand and contract considerably with changes in temperature. The under floor leak was massive, the joint had blown completely, and was faster than the header tank 3 floor up could fill!. Yeah!

This was on an old Acorn Plastics installation, it had been there about 20 years, and in theory, the 'O' rings are supposed to be good for 50 years. They were a pain to change, as the early Acorn didn't have the ability to break a joint, the grip rings were inside the 'O' ring, so the grip ring had to be destroyed in order to get the 'O' ring off. The later fittings were made to be removable, but were not interchangeable as such.

I can't recommend a suitable source of 'O' rings that will retain their flexibility for this issue, but it is going to be a case of finding a source of supply of rings that are made from a material that will retain flexibility when heated to the sort of temperatures that are normal on the solar system, and I suspect that they are operating over a wider band than a normal heating system.

The only other thing I can think of is to check the ends of the pipes when changing the rings, in case they were cut with a hacksaw or similar, and as a result have minor serrations on the end that are scoring the 'O' rings as they are being fitted, I often wondered why the suppliers say to use a cutting blade to cut the pipe, it's only when you look at the end of the pipe under a strong magnifying glass, and then look at the inside sealing surface of the 'O' ring with the same glass that the reason becomes clearer.

freddyuk

Are the washers green or white in colour?
Is the pipe annular or Helicoil? ie. do the ridges go all the way round or are they a spiral ?
What size is the pipe ? DN16?