Solar Tank Repeatedly leaks- pH problem ?

BMurr

My parents installed solar system in their house about 4 years ago. The tanks in their hot press(collector tank?) has leaked about 4 times now, each time needing a replacement tank:eek:. All of this work done under warranty but it is a PITA for them as the whole tank and all the pipework has to be taken out each time. The plumber is now saying that there is a problem with the pH of their water, claiming it to be 6.7 and that this is corrosive to the tanks connections/joints. Now to me 6.7 seems very close to 7 which is completely neutral and I find it hard to imagine how a pH6.7 supply of water can corrode the tank or its joints to such an extent as to cause these leaks. Their water supply is well water and does have some iron in it, however this has been the case for the last 30 years and it never caused a problem for their conventional hot water system prior to installation of solar system. Plumber says that the fact that hot water system is probably always hot and this in combination with pH6.7 water is causing the problem. I can't help but think that the plumber might be wrong, especially since he has never opened up and inspected the leaking tanks to see what has happened. I wonder if the probklem might be more to do with excess pressure being generated in system. Does anyone here have any idea what an acceptable pH level would be in a solar water system, or any experience of repeated failures on these storage tanks?

heinbloed

The plumber doesn't seem to be competent to deliver a working system which meets expectations.
Get a second opinion from a heating engineer. In writing, this could then be used to tackle the original plumber.

Since you don't know if the tank has leaked or the sealings or the joints no one can answer your questions.

All components used must meet certain standards.
Without knowing the (failed) components no analysis of the problem can be done.

Have you spoken to the manufactures? Pressure wouldn't be a problem, I have come across this problem with well water and either a filter must be found to give you water the manufactures are happy with or change the cylinder make to match the water you have, if you don't then this problem will continue.

shedweller

Sounds dodgy to me. I know low (or high) pH causes problems in indsustrial boilers but this is at very high pressures and temperatures. Much higher than domestic setups.
And aren't all these fancy new solar tanks supposed to be stainless, ie: very resistant against corrosion?
If the plumber says the system is corroded then ask to see the EXACT pipes that were eaten through. Make sure they were from your system too, not some stuff he dug up from a tank of acid or what have you. Shenanigans!Cowboys Ted!!!!

sanbrafyffe

could electrolisis be playing a part here some where

shedweller

shedweller wrote: »

Sounds dodgy to me.

It's not

shedweller wrote: »

I know low (or high) pH causes problems in indsustrial boilers but this is at very high pressures and temperatures. Much higher than domestic setups.

pressure isn't an issue.

shedweller wrote: »

And aren't all these fancy new solar tanks supposed to be stainless, ie: very resistant against corrosion?

The stat pockets are likely to be a different material and a week spot, well water can have a corrosive effect on cylinders/components, manufactures should be able to say what Ph level can have a negative effect on their product, what installer whould be happy to replace a cylinder 4 now 5 times?

DGOBS

As far as I am aware, there is some issue around stainless steel cylinders on well water with repeated failures, the manufacturers claim it's something to do with the high chlorination levels in private wells (not 100% on the background) but as far as I heard some manufacturers are now not warrantying any on private wells

DGOBS

As far as I am aware, there is some issue around stainless steel cylinders on well water with repeated failures, the manufacturers claim it's something to do with the high chlorination levels in private wells (not 100% on the background) but as far as I heard some manufacturers are now not warrantying any on private wells

BMurr

Cheers for replies so far, they are all very helpfull. The electrolysis idea is good too, I wonder does anyone fit a sacrificial anode to any of these systems?

It hasn't cost my parents a cent to have the cylinders replaced, all costs borne by plumber/supplier but its a lot of hassle for them.

I think I will ask to see the last cylinder which was removed if it hasn't been dumped and have a look at source of leak.

I must get a pH testing kit and run a few tests over a few weeks to see what shows. Then after all that for peace of mind some sort of filtration system or pH regulation system might be worth pricing up.

I would send a sample to one of these online testing companies. You can get immersions with sacrificial anodes but that may not help you as with well water it can ignore the anode. looking for the leak may not help as the leaks tend to be pin pricks. Needing a fifth cylinder is just silly, talk to the manufactures as they should be having a bigger input, if it was one of my cylinders then once the issue was identified I would have offered you your money back or given you a new cylinder with the understanding the water issue is dealt with first as otherwise the cylinder will just keep leaking.

Pump101

If the Ph is between 6.5 to 9 it is within EU regulations.

DGOBS

I was led to believe it's a chlorine issue no ph at all, have you ever had a full analysis done on your well water?

slavetothegrind

probably is chlorine problem , especially if the cylinder is a poorer quality stainless like 304 or even 312

see linky below,

http://www.cip.ukcentre.com/rust2.htm

as gary said have the water tested yourself for your own information, it's not that expensive and worth knowing what is in there!!
get the bacterialogical test done as well as the usual tds and mineral tests.

BMurr

previous water test says nothing about chlorine. Results were pH 6.7, TDS 304, Conductivity 526, Total hardness 238, Total alkalinity 216, Total Iron 0.64, Manganes 0.12, Nitrates <1. The well water is pumped from their own private well and does not get chlorinated, so if there is chlorine in it where would it come from?

heinbloed

Good question, BMurr.
Your water seems to be fine. Your plumber not.

Chlorine usually does not come on it's own, it's a very agressive chemical and hardly found in nature in it's pure form. I don't know why posters point towards it.

heinbloed

heinbloed wrote: »

Good question, BMurr.
Your water seems to be fine. Your plumber not.

Chlorine usually does not come on it's own, it's a very agressive chemical and hardly found in nature in it's pure form. I don't know why posters point towards it.

How many unvented cylinders fed from wells have you repaired/replaced or delt with to point the finger of blame at the plumber?

For the last seven years I have signed off on pretty much every cylinder needing to be replaced under warranty by a major manufacturer in this country, in that time I have come across 3/4 installations where well water has had a negative effect on a cylinder, I would ask for a water test, the findings of which were sent to cleverer men than me to confirm the water was at fault, then either a filter was fitted and a new cylinder was given or we would put our hands up then return the cost of the cylinder. After 4 cylinders the idea that the installer is to blame like the cylinders doesn't hold water and what installer would be happy to fit 5 cylinders? I would guess the installer would happy to get to the bottom of this as well.

OP, have the manufactures spoken to you yet?

slavetothegrind

Merely offering possible reason, not the most probable

Pump101

From experience i have seen this before with a stainless steel cylinder where the sleeves into the cylinder for the stats are brass and the cylinder is ss, ive seen the two metals react and the brass breakdown. This guy had a low PH and hard water, your PH is marginally inside the 6.5 but your water is hard at over 200. This maybe your problem. Can you find out exactly where it has been leaking??

BMurr

Ok. I still have no news on availability of cylinder to inspect. pumber apparantly showed my parents some staining near one of the pipes entering the tank and seemed to imply thats where the leak was from. However I'm guessing that if the leak was elswhere the water would still only be able to escape from the jacket at some point such as the gap where pipes enter. I'll hopefully have news soon on availiability of leaking tank.

DGOBS

Speaking with someone to confirm, my apologies, it wasn't the high chlorine content, it was limescale that caused the issue!

Hey Gary, my better half is very annoyed with you! as you commented a 'better man that you for water testing' .....it's HER thing (she runs a water lab)

DGOBS

Sorry for the revisit ti this post, but just had some really interesting info

The cause of stainless steel tank failure is actually due to the low oxygen content found on some wells or bore holes in comparison to mains water which is oxygenated during agitation and other processes used for water treatment

Oxygen you say.......so what

Low oxygenated fresh water will ROT or RUST stainless steel!!!!

My jaw is firmly on the floor, but it is 100% true!

Recommendations for unvented cylinders on private wells or water schemes is now a copper unvented cylinder rated to 2 bar

DoneDL

DGOBS wrote: »

Sorry for the revisit ti this post, but just had some really interesting info

The cause of stainless steel tank failure is actually due to the low oxygen content found on some wells or bore holes in comparison to mains water which is oxygenated during agitation and other processes used for water treatment

Oxygen you say.......so what

Low oxygenated fresh water will ROT or RUST stainless steel!!!!

My jaw is firmly on the floor, but it is 100% true!

Recommendations for unvented cylinders on private wells or water schemes is now a copper unvented cylinder rated to 2 bar

Nice one, good to know.

heinbloed

Low oxygenated fresh water will ROT or RUST stainless steel!!!!

I was led to believe it's a chlorine issue no ph at all,....

As far as I am aware, there is some issue around stainless steel cylinders on well water with repeated failures, the manufacturers claim it's something to do with the high chlorination levels in private wells (not 100% on the background) but as far as I heard some manufacturers are now not warrantying any on private wells

Any sources or links you have for these believes, DGOBS ?

DGOBS

Nope, just a conversation I had today with the owner of a major boiler manufacturer, he said these were the final conclusions after all the water testing and metal testing etc have been completed.

And the testing had proven the failure cause

2 stroke

DGOBS, at first I thought you had solved a 20 year old mystery for me, but now I have my doubts. Isn't all water low oxygenated when heated over 60 degees.

Edit. I guess in a pressurized system, oxygenated water remains oxygenated. It all makes sense now. I fell foul of stainless steel and presurised systems in the 80's, problem could very easily have been oxygen related.

heinbloed

Mysteries are the trade's bread and butter, 2 stroke. It keeps incompetent installers in the job and feeds

the owner of a major boiler manufacturer

.

@ DGOBS: would you mind telling the baffled public/us which boiler brand this person is representing ?

DGOBS

I am an independent installer, hence I intentionally did not mention who the manufacturer was! So I really don't understand that comment, I don't work for the manufacturer was there on a site visit only...paranoid, some of the other posters here know me personally and can vouch for that

Heated water will deoxygenate, but would be drawn off and oxygenated water drawn in to compensate (I would assume) I did query about oil secondary heat exchangers and plate to plates not suffering the same fate, but have not got satisfactory answers to it other than volume, but debate is still raging.

Joey the lips

Can we just stick to information folks. Either confirm or refute it but keep the attacks down. Its not supporting the notion of flowing information.

heinbloed

heinbloed wrote: »

Mysteries are the trade's bread and butter, 2 stroke.

How much do you think a cylinder manufacture makes when they pay to have a cylinder replaced and supply the cylinder under warranty?

BMurr

Ok. Looks like the old leaky cylinder(s) are not available for inspection. Been told that they were scarpped. I have looked at the new cylinder that was fitted. It is stainless steel and the sleeves coming out of it are stainless steel with brass fittings then bolted on( compression type fittings) I guess if this one leaks it will leak in such a way that it will be easy to see the actual leak if it occurs at the sleeve. manufacturer of current tank is Joule energy Solutions so fingers crossed that it lasts the course. Pic of current set up shown here.