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Author Topic: Solar hot water system problem  (Read 8242 times)

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Offline Plumber

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Re: Solar hot water system problem
« Reply #15 on: May 11, 2013, 09:09:16 PM »
biologists and plumbers, pretty much the same thing  :)

As a flooded system there should be no air in the system and no bubbles. If the air vent has been overheating and/or is damaged then there is a possibility air is finding its way into the system causing bubbles. Another way for this to happen is on a sunny day when your tank is up to temperature then your pump will stop bringing hot water down from the roof. At that point the water will stagnate, boil and steam inside the panel possibly evaporate through the air vent leaving air pockets in the panel. Then when the pump finally turns on it will push the air in to the tank. I can not say for sure though. Really need to look at such an installation. The problem can also relate to your existing plumbing. If air finds its way in then again it will be drawn into the tank when you use hot water. If your not using hot water then no cold water can enter the tank and hence the bubbles/air issue will be on your solar side. Let us know how you go with the repair

Please note that the advice I am giving is only my opinion and not necessarily a fact.  Please refer to our terms and conditions.

Offline Badger

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Re: Solar hot water system problem
« Reply #16 on: May 11, 2013, 10:18:58 PM »
just wondering where your water comes from, is it a town supply, or perhaps a well? had a problem on a job where the water came from a creek running off hills with lots of limestone and there was a lot of CO2 held in solution in the water caused heaps of air locks and could only be solved by having an open vent to allow it to off gas.

Just brain storming.
You can't choose who you are.....but you are the sum of your choices.......

Offline Corylus

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Re: Solar hot water system problem
« Reply #17 on: May 11, 2013, 11:09:08 PM »
Hello again Integrated. I've been studying your #7 reply more fully. I did not know the HWC had a baffle at the inlet. Interesting. It certainly seemed an odd idea to heat the water and then just suck it out again from the same place it went in. I'm wondering if my cylinder actually does have baffles. I certainly had discussions early on with the solar guy about why we had hotter water in the bottom of the tank than at the top. It seems to take forever to get up there, unlike the immersion heater which seemed to do it fast. I use the past tense because nowadays it doesn't seem to get beyond 49.

The plumber who did the installation must surely have drilled the baffle already? What are they made of? How thick? Could an assault by steam bubbles from the collector dislodge/bend them? Certainly at one point it sounded like there was something in there banging about.

And a question. As an experienced plumber, if you were installing a solar water heater into a cylinder with a header pipe (open loop?) how would you go about protecting the collector from overheating. ie how would you arrange for steam to escape from the manifold so that it didn't have to escape via the HWC. I'm sure that it can't be usual for HWCs to make the sort of noise mine makes, not to mention the shaking and shuddering that goes on.

Thanks for your post Integrated.


Offline Corylus

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Re: Solar hot water system problem
« Reply #18 on: May 11, 2013, 11:22:03 PM »
Hello Badger.( Better not go to England. You'd be at risk of being exterminated - even with Brian May sticking up for you.) Thank you for brainstorming - exactly what I was hoping for! Brains being used! We live in a rural township and are on the town supply. I don't know what the pH is. Good point. We are first off the supply and we tend to get air bubbles every time they do work on the waterworks and indeed when there is a power cut. They are a nuisance, but they have never caused trouble.

The solar system was working just fine all summer and went odd very suddenly, so I don't think it can be dissolved gases. When this trouble started I assumed it was due to council work. But it didn't settle down and I asked a contact I have there to get some facts. There was no work being done and the pressure had not been changed. My meter was checked to see if there was a spike and it was normal. They have since put in something at the toby to try to reduce the problem.


Offline Corylus

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Re: Solar hot water system problem
« Reply #19 on: May 11, 2013, 11:50:48 PM »
Hello Plumber

I'm not sure what you mean by the term "panel" I gather the heat exchange is effected by a water bath called the manifold running  along the top of the vacuum tubes which have copper pipes inside them, the hot ends of which protrude through into the manifold. Water is pumped through the manifold and returned to the HWC. When the HWC is at 85 the pump is supposed to stop and the manifold vents when it overheats through the air valve. But it doesn't. It sends the steam into the HWC where it creates chaos and quite possibly damage.

I will certainly let you know what happens - wonder how long I'll have to wait.

PS I think you might be wrong about biologists and plumbers being the same thing - or I wouldn't have found this apprenticeship so hard! You'd have laughed if you'd seen me trying to work out what goes on in that 5way valve when the pump is running and someone puts the hot tap on. I presume there must be a reason for using something so mindbendingly devious rather than a simple heat exchanger in the HWC? Tellya what. Sure keeps Altzheimers at bay, even if it nearly drove me demented!

Goodnight and thanks again

Offline Corylus

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Re: Solar hot water system problem
« Reply #20 on: May 11, 2013, 11:52:57 PM »
BTW I never thought I'd ever be a junior member of a Plumbers' Forum. My husband is very impressed!

Offline integrated

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Re: Solar hot water system problem
« Reply #21 on: May 12, 2013, 09:36:00 AM »
hi corylus - I dont let the hwc/collectors get to steaming/boiling point, will pm when i have the time with all details you need

thanks, Integrated

Offline Badger

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Re: Solar hot water system problem
« Reply #22 on: May 12, 2013, 12:00:03 PM »
Hi Corylus, I am from Wales and could do with Brian May's help hahaha.....welcome to the forum.

When your hot water comes out of the tap is it milky, but clears over ten mins from the bottom to the top? best seen in a clear glass

The job I was on about was on a rural town supply, also whenever they worked on the filters down stream air/gases would come through to the dwellings.

May be the gases are accumulating at the top of your panel/collector, but this would only happen on a open system, not a sealed system.


Offline Badger

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Re: Solar hot water system problem
« Reply #23 on: May 12, 2013, 12:04:25 PM »
and if an air pocket surrounds the impeller inside your pump it can spin within the bubble and not move your water, basically stops the pump being effective and doing its job, no circulation. You can bleed the pump, but do it when its cool....seen steam come out of one once and badly scold a bloke that was teaching me when I was an apprentice.....lesson learnt.

Offline Plumber

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Re: Solar hot water system problem
« Reply #24 on: May 12, 2013, 12:28:13 PM »
Good point with the pump Badger, very true.. Sorry bad habit with "panel" I meant the solar panel/evacuated tubes. Your right Corylus the water pumps through the manifold back to the HWC.

Offline Corylus

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Re: Solar hot water system problem
« Reply #25 on: May 12, 2013, 06:16:10 PM »
Thanks guys - back later

Offline Corylus

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Re: Solar hot water system problem
« Reply #26 on: May 12, 2013, 09:58:13 PM »
Hello Badger. Are you a Queen fan then?Thanks for the welcome.  Our water is clear - except we had  one episode of sediment at Xmas. My daughter in law wasn't pleased when she saw what she'd been drinking through the night. Once in twenty years though - not bad.

The thing to get hold of about this problem is that it arrived suddenly. We had a trouble free summer (for once), possibly because we were at home all day. Then mid Feb we were once more able to go to town and a couple of times came back and found it up to its old tricks, screeching and bubbling. Then this problem appeared between breakfast and lunch one day - again when we were out. And it has been like that ever since (25 Feb), gradually getting more difficult to manage. I have to screw the Ajax down eight and a half turns now. Talk about a screw loose. The point is - something changed and we need to find out what that was. And it's looking like a blockage preventing an adequate flow from the HWC to the pump.

As a customer, I have this odd belief that the thing is not fit for purpose if you can't leave it. Can't wait for Integrated to tell me how he manages to keep his solar from overheating. We get long hot sunny days here, and if we are not around to run some hot water off, we are likely to get steam backing into the HWC which doesn't like it.

As a matter of interest, how do you suggest looking after the S.O.B when we go on holiday mid summer? I was stunned when it was suggested we go up on the roof and put a tarp over it. The problem is, when you buy state of the art tech - you don't know what questions you should be asking. I know them now! There are several reasons why I would not have bought this system. Any one of them would have been enough - this being one of them. Seems to me that an automatic sunshade wouldn't be too difficult to incorporate into the design.

It must be quite a challenge for you guys having to fit high tech systems to existing elderly hot water systems, which I suppose you must have to do. We got a new HWC to try to avoid this problem as far as possible - but now I discover there are HWCs and HWCs. I seriously doubt this one has baffles. Certainly the old one didn't. I know that because I had it cut it up lengthwise and made a couple of splendid planters out of it. And I suspect this new one is of a similar kind.

Time will tell if I can ever find a plumber. This one isn't answering his answer machine. Perhaps he likes his weekends free and sticks his phone in the sock drawer.

I was shown how to bleed the pump - but not warned about the risks. Thank you for pointing them out. I've never done it. I just put the controller off for a while, set the pump on 3 and hope to belt the bubble out of the way when I put the pump on. Sometimes it works, Sometimes it doesn't. I expect that's bad practice. But it's a bad system so I'm not about to feel guilty. To be honest - I'm seriously thinking about putting an advert on Trade Me that says whoever will pay to have it removed and have me restored to the Ripple System can have the damn thing. Any offers?


Offline robbo

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Re: Solar hot water system problem
« Reply #27 on: May 13, 2013, 10:30:25 AM »
Hi guys/Corylus, just read all of your correspondence on your solar system. In my opinion your system is not `Balanced` that is size of panel to size of h/w cylinder, I would not put a 20 tube panel into anything less than a 270ltr cylinder or even 300ltrs, if you are getting `free` hot water then the more the better. I believe that your system gets continually overheated. I did not see any mention of a `check valve` which I presume is the fitting on the outlet/flow position of the pump, could it be faulty and not letting full flow to the panel? If your system overheats and blows water out of the exhaust pipe, is it being replaced quickly enough so that air is not accumulated in the system? Cheers and good luck.

Offline Enn

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Re: Solar hot water system problem
« Reply #28 on: May 13, 2013, 07:46:33 PM »
Hi all,
 the way I see it is with all the variables involved in this situation, the best course of action for a safe and positive outcome is to get a  solar experienced plumber to look at it.

''Never have so many been fooled by so few''
Plumbing is not a career it is a disease....

Offline Badger

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Re: Solar hot water system problem
« Reply #29 on: May 13, 2013, 07:56:37 PM »
I agree mate


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