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Not to Forget => Solar Heating and Heat Pumps => Topic started by: Corylus on May 09, 2013, 03:14:29 PM

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Title: Solar hot water system problem
Post by: Corylus on May 09, 2013, 03:14:29 PM
Our solar water heater suddenly went nuts. Cold water is getting across the 5way valve instead of taking water from the bottom of the HWC which causes water to shoot out the header pipe and cooling of collector -->pump going on and off all day like this, banging noises on roof, air bubbles in the system.
Replaced the Ajax-->no change. And nothing wrong with the old one.So not a pressure problem. Replaced pump-->no change. Reducing the pressure at Ajax allows the circuit between bottom of tank and collector to be initiated but it is slow to heat and tends to lose a little water through the header pipe. Too much reduction causes failure in the circuit, overheating in the collector and steam bubbles coming down into the 5way valve and the tank. Shutting off the cold water altogether led to system rapidly filling up with air bubbles at which point I stopped the experiment. But overheating and steam bubbles would likely have been the result.

Looks like the pump is unable to extract the water from the bottom of the HWC as it should leading to a partial vacuum in system, so that at normal pressure the cold water enters instead. And at reduced pressure, what goes up to the pump is a mixture of cold and water from the bottom of the HWC? And if it can't get the cold water at all or if the pressure is reduced too far, a partial vacuum occurs sucking air in - from wherever, possibly the leak at the isolating valve at the intake end of the pump.

NB The air vent on the collector has never worked. When the temperature in the tank gets to 85 degrees, and the temperature at the collector is much higher than that, steam bubbles come down and into the tank causing shrieking noises and massive vibrations.

And all this seems to defy analysis of our local plumbers who can't seem to think beyond "it's got to be the Ajax" or "we need to see where the air is getting in". I need to know WHY the air is getting in. Is my analysis reasonable? If so what do you suggest?
Title: Re: Solar hot water system problem
Post by: Plumber on May 09, 2013, 05:34:09 PM
Can you give us more details on what kind of solar system you have please? Layout and possibly a picture of the tank and panels? There are several things I can think of but want to see what you have first.
Title: Re: Solar hot water system problem
Post by: integrated on May 09, 2013, 09:11:52 PM
you have a blockage in the 5 way valve

you need to ask a plumber to take it out - clean it and check for blockages - while it is out check to make sure the baffle is drilled for the longer smaller dia flow pipe from the colector

Title: Re: Solar hot water system problem
Post by: Corylus on May 10, 2013, 12:25:22 AM
Thanks to all who replied. It is a Solar Technology Sunsaver 20 tube 58Dia/1800mmcollector. It was installed in Nov 09. We had it fitted to a new180 ltr 560x1200mm Prewired Elec HWC with a header pipe, working head 7.6 metres.

Good advice about the 5way valve - I couldn't work out what could block it. It just looks like a hefty bit of brass from the outside and I haven't been able to get anyone to tell me what the internal structure of it is like so I'd no idea what might have happened to it. I know it has the return pipe from the collector going right through the middle of it into the HWC through a sleeve through which the water from the bottom of the HWC is drawn up to the pump.

While we are on the topic, I'd love to know what normally keeps the cold water from entering the system when the pump goes on. At rest, it's all just sitting there in the cross piece of the valve and the cold water can go straight across while the HWC water has to go round a bend. It looks like it would be easier for the cold to enter than the warm. So is this right? When the pump goes on, it simultaneously pulls water out of the HWC and belts the hot water into the HWC so the warm water at the bottom of the tank gets a kick from behind and a pull from the front? (you guys are allowed to laugh! As an 80 year old female, I feel like I'm doing an apprenticeship and so far haven't found any good teachers. Finding this website was a miracle) And this brief increase in pressure is enough to also kick the water level up the header pipe? And out on the roof if the pressure isn't right at the Ajax? I tellya, this 5 way valve takes some getting your head around, what with the cold water going in through the sleeve in the opposite direction to the warm water coming out when you put a hot tap on when the pump is running.

I'd like the Ajax explained as well please. I have one sitting here in bits and can see how the diaphragm works. But there is obviously more to it than that. I can see that the outlet is wider than the inlet, which must reduce the pressure to start with? But what is the bit in the middle for - the bit under the black cap? I'm having to reduce the pressure by 5 to 6 whole turns and the screw feels pretty loose at that point. What is happening in the HWC when I do this?  Does it actually reduce the pressure in the tank? I can't see why it would do that unless you run some hot water off - and I don't. Whatever it does, it lets me get the circuit operational - if I get it dead right. I've been doing it since 25 Feb, which can't be good for the screw? It looks pretty soft metal. Why so long? Because I want someone to think it out BEFORE they come and try to fix it. Have you guys any idea how scary it is to have a plumber spend a whole day scratching his head getting nowhere? I'm still saving up to pay the last one for not managing to fix it.

Thanks for the website. Wish I'd found it sooner!
Title: Re: Solar hot water system problem
Post by: Plumber on May 10, 2013, 01:19:57 AM
Hi Corylus, I'm very impressed that with 80 years you managed to dissect an apex valve  :)

A quick thought before I go to bed (should really go now) You mentioned that your system suddenly started making these noises, running the pump on/off etc.. In many cases this can relate back to the the freeze protection settings on your controller. Now that the weather is getting colder the system is naturally protecting the panels creating a reverse function. This will cause the pump to go on  and off randomly and in the middle of the night. Check the settings and adjust to the panel manufacturers recommendations. If you had a power outage the controller settings could have reset causing this. I don't believe in air vents on an open loop system and would get in touch with the manufacturer in this regard. The open vent flood level should be well above the panels. As you say these levels should be investigated and possibly adjusted. Might add a few more comments tomorrow.. OK bed now.. long day tomorrow. night..
Title: Re: Solar hot water system problem
Post by: Plumber on May 10, 2013, 01:27:31 AM
One more question, I can see a yellow pressure relief valve on your solar circuit, being 7.6 meter open vented system I would be interested to know what its rated to. OK off now!
Title: Re: Solar hot water system problem
Post by: Corylus on May 10, 2013, 06:21:44 PM
I see I am labelled a "newbie". Well that's the truth! Please remember guys that I don't talk "plumb". Think of me as a complete ignoramus. That would be true too. So Integrated (reply 2) I'm not sure what the baffle is in the 5 way valve. I'm hopeful that it is in fact a way of discouraging cold water from entering when it shouldn't? It seemed to me that without a way of separating the two flows, it was operating on fond hopes rather than good design. But I was assured it was just empty space in there. If you could send me a link that would show me the internal structure of this bit of brass, I'd be very grateful. I've been trying to find out for weeks.

Similarly Karma (number 4) Open loop? open vent flood level? Is this what I've been calling the level in the header pipe? If so, the top of it is well above the panels - but maybe not far enough. I assume you are saying that in your opinion an air vent on the collector isn't compatible with a header pipe? ('scuse my newbie vocab). It certainly doesn't work. Neither it nor the thingie with the yellow cap have ever seen action as far as I can tell. Which tells me my safety mechanisms aren't functional. You can see then why I called a halt when instead of identifying the cause of this sudden change, it was suggested that a valve be put in the header pipe, which I gather was supposed to increase the pressure in the tank? This was apparently like extending the height of the header pipe and would give me more pressure in the hot water system ( and stop the water from escaping out onto the roof). Having experience 180 litres of scalding hot water dancing about in my airing cupboard as steam bubbles fought to get out the header pipe, I wasn't keen to make it any more difficult for them to get out.

I can't answer your question about rating right away. But I will try to find out.

The settings on the collector have all been checked. However, since it is totally unable to keep time, I have no faith in its other functions. This is a sticking point with the installer as yet unresolved. He has a tendency just to not answer awkward questions.

The sudden change occurred on the morning of a hot sunny day. OK at breakfast. Loopy by lunchtime.

We get heaps of power cuts. But I always reset the controller. And since it is a rotten timekeeper and I'm forever putting the thing off and on as I try to get the circuit operating without just dribbling it out the roof, it is reset timewise several times a day. Perhaps it is as confused as I am.

I've checked fairly carefully that what is happening is that cold water is entering when it should not. At normal pressure, when the pump goes on, Cold water enters the 5way valve and cools the collector quickly, reducing the temperature differential and putting the pump off. It also increases the pressure in the HWC and shoots water out the header pipe. The diff. picks up quickly, starts the pump and the whole thing repeats. I'm trying to persuade the solar guy to send this controller to wherever they go when they go psycho and let me have another in the meantime.

Thanks guys.

Teatime. Cooking calls.

Title: Re: Solar hot water system problem
Post by: integrated on May 10, 2013, 06:43:40 PM
Thanks to all who replied. It is a Solar Technology Sunsaver 20 tube 58Dia/1800mmcollector. It was installed in Nov 09. We had it fitted to a new180 ltr 560x1200mm Prewired Elec HWC with a header pipe, working head 7.6 metres.

Good advice about the 5way valve - I couldn't work out what could block it. It just looks like a hefty bit of brass from the outside and I haven't been able to get anyone to tell me what the internal structure of it is like so I'd no idea what might have happened to it. I know it has the return pipe from the collector going right through the middle of it into the HWC through a sleeve through which the water from the bottom of the HWC is drawn up to the pump.

While we are on the topic, I'd love to know what normally keeps the cold water from entering the system when the pump goes on. At rest, it's all just sitting there in the cross piece of the valve and the cold water can go straight across while the HWC water has to go round a bend. It looks like it would be easier for the cold to enter than the warm. So is this right? When the pump goes on, it simultaneously pulls water out of the HWC and belts the hot water into the HWC so the warm water at the bottom of the tank gets a kick from behind and a pull from the front? (you guys are allowed to laugh! As an 80 year old female, I feel like I'm doing an apprenticeship and so far haven't found any good teachers. Finding this website was a miracle) And this brief increase in pressure is enough to also kick the water level up the header pipe? And out on the roof if the pressure isn't right at the Ajax? I tellya, this 5 way valve takes some getting your head around, what with the cold water going in through the sleeve in the opposite direction to the warm water coming out when you put a hot tap on when the pump is running.

I'd like the Ajax explained as well please. I have one sitting here in bits and can see how the diaphragm works. But there is obviously more to it than that. I can see that the outlet is wider than the inlet, which must reduce the pressure to start with? But what is the bit in the middle for - the bit under the black cap? I'm having to reduce the pressure by 5 to 6 whole turns and the screw feels pretty loose at that point. What is happening in the HWC when I do this?  Does it actually reduce the pressure in the tank? I can't see why it would do that unless you run some hot water off - and I don't. Whatever it does, it lets me get the circuit operational - if I get it dead right. I've been doing it since 25 Feb, which can't be good for the screw? It looks pretty soft metal. Why so long? Because I want someone to think it out BEFORE they come and try to fix it. Have you guys any idea how scary it is to have a plumber spend a whole day scratching his head getting nowhere? I'm still saving up to pay the last one for not managing to fix it.

Thanks for the website. Wish I'd found it sooner!


due to pump being of the circulating/flow type it is sucking and creating flow below the working pressure of the hot water system - whatever positive pressure that is created is balanced out by the negative pressure that it is also creating at the same time - technically the pump creates the vacuum prior to anything else happening



to a certain extent your observations are correct - the FLOW - ie hot water from the collector runs straight up the guts through a smaller diametre pipe 3/8"? maybe 1/4? - the key to this is that it is longer and penetrates the cylinder maybe a foot - it has the end blanked off with a series of small holes to distribute heat effectively minimising disturbance to the stratification within the hwc

withing the inlet to the hwc there is a baffle - the objective of this is to minimise startification also, by disrupting and directing flow in a uni-directional manner - it is this baffle that must be drilled to allow the 5-way to locate and function properly within the hwc.

so the idea of the 5-way is that cooler water is drawn from the bottom of the hwc - in and around the inlet/baffle - and the hotter heated water is returned back to the hwc past/higher than the drawn water - I ALWAYS put a curve/bend in my smaller diameter flow pipe from the collector to discharge towards the upper portion of the hwc on side entrys as this increases efficiency

the only time efficiency really drops off with 5-way valves is when there are large draw offs within the household creating a cold water sandwich due to the cold water inlet to the hwc being in the same location

it will be at this point that you will find a blockage - and it must be a partial blockage as you said if you wound the pressure right out on the ajax it comes right? by doing this you are restricting the flow to the hwc to match the restricted oriface/opening within the 5-way - so the problem lies in the return section of the 5-way - when the collector is up to temp it is switching the pump on which would normally draw from the bottom of hwc but this is partially blocked so the next best place for it to draw from is the cold water inlet, so it does but then the system is out of balnce so the pump keeps pumping but out the only oriface it can - your hwc exhaust

the collector is stagnating - resulting in steam/air in system

there must be a service rep somewhere handy - most of the solar tech stuff is Solarcity, check for those in your area - if not let us know what area you are in and I could help - I am an agent for the aforementioned


Title: Re: Solar hot water system problem
Post by: integrated on May 10, 2013, 07:07:47 PM
I see I am labelled a "newbie". Well that's the truth! Please remember guys that I don't talk "plumb". Think of me as a complete ignoramus. That would be true too. So Integrated (reply 2) I'm not sure what the baffle is in the 5 way valve. I'm hopeful that it is in fact a way of discouraging cold water from entering when it shouldn't? It seemed to me that without a way of separating the two flows, it was operating on fond hopes rather than good design. But I was assured it was just empty space in there. If you could send me a link that would show me the internal structure of this bit of brass, I'd be very grateful. I've been trying to find out for weeks.

Similarly Karma (number 4) Open loop? open vent flood level? Is this what I've been calling the level in the header pipe? If so, the top of it is well above the panels - but maybe not far enough. I assume you are saying that in your opinion an air vent on the collector isn't compatible with a header pipe? ('scuse my newbie vocab). It certainly doesn't work. Neither it nor the thingie with the yellow cap have ever seen action as far as I can tell. Which tells me my safety mechanisms aren't functional. You can see then why I called a halt when instead of identifying the cause of this sudden change, it was suggested that a valve be put in the header pipe, which I gather was supposed to increase the pressure in the tank? This was apparently like extending the height of the header pipe and would give me more pressure in the hot water system ( and stop the water from escaping out onto the roof). Having experience 180 litres of scalding hot water dancing about in my airing cupboard as steam bubbles fought to get out the header pipe, I wasn't keen to make it any more difficult for them to get out.

I can't answer your question about rating right away. But I will try to find out.

The settings on the collector have all been checked. However, since it is totally unable to keep time, I have no faith in its other functions. This is a sticking point with the installer as yet unresolved. He has a tendency just to not answer awkward questions.

The sudden change occurred on the morning of a hot sunny day. OK at breakfast. Loopy by lunchtime.

We get heaps of power cuts. But I always reset the controller. And since it is a rotten timekeeper and I'm forever putting the thing off and on as I try to get the circuit operating without just dribbling it out the roof, it is reset timewise several times a day. Perhaps it is as confused as I am.

I've checked fairly carefully that what is happening is that cold water is entering when it should not. At normal pressure, when the pump goes on, Cold water enters the 5way valve and cools the collector quickly, reducing the temperature differential and putting the pump off. It also increases the pressure in the HWC and shoots water out the header pipe. The diff. picks up quickly, starts the pump and the whole thing repeats. I'm trying to persuade the solar guy to send this controller to wherever they go when they go psycho and let me have another in the meantime.

Thanks guys.

Teatime. Cooking calls.

1 - yes  generally 1metre is enough standing height above the highest point of collector
2 - the air vent has a wee dial that should be loosened and left - how can you tell if air is or isnt being released?
3 - technically these features are not required as you have an open vent system - these are installed as per manufacturers/suppliers instructions as part of the agreement with councils for streamlined consent processes, quite often you get the inspector who knows diddly about solar and/or alternative heat sources or hot water systems in general who loves to wave his stick around, much easier to just install them as a standard measure to avoid this, also get you into the habit of thinking about safety valving in general at a precautionary level
4 - was it installed through solarcity or independant? there are one or two others that use solar tech as well - is the controller a resol unit?
5 - this has been answered



if you have problems with power going on and off all the time you should have a surge protector in place, as this will fry the controller - invest in a ups - uninterupted power supply

thanks - good luck!!

the contro


Title: Re: Solar hot water system problem
Post by: Plumber on May 10, 2013, 07:34:56 PM


I'd like the Ajax explained as well please. I have one sitting here in bits and can see how the diaphragm works. But there is obviously more to it than that. I can see that the outlet is wider than the inlet, which must reduce the pressure to start with? But what is the bit in the middle for - the bit under the black cap?
Thanks for the website. Wish I'd found it sooner!

Have attached an image for you that explains it pretty well.
Title: Re: Solar hot water system problem
Post by: Corylus on May 10, 2013, 08:19:17 PM
Hey thanks everybody. I'll study the content and get back to you later. Have guests. Your replies are truly appreciated.
Title: Re: Solar hot water system problem
Post by: Corylus on May 11, 2013, 01:28:25 PM
Hi folks. I see my carefully considered rely has not turned up. Am I allowed to say "bugger!"? Must be doing something wrong. I'll do them in short bits next time.

I'll start with Integrated.  Point 2. Air vent. I can tell if it is working by going up on the roof to look when the tank is trying to jump out of the airing cupboard. Diddly. No sound. No steam. Also, steam would not be coming down the return pipe if it could get out the vent huh? 

I've had a look at one of those. It's a Caleffi Solar.Tmax 180degreesC P max(can't read this clearly) 10bar  150 psi. It is apparently the only one the solar chap has ever seen used locally.

Not being able to see inside it, I'm wondering if this might be a point where air can get into a system that has developed a partial vacuum? Is it a one way valve?  Just had the solar chap come to replace it with another anyway. He has checked up there and everything appears to be in order.

point 3. Yeah, I rather thought as much. A great length of expensive copper tubing for no great reason other than a penpusher signing a chitty. Loved your description.

Thanks Integrated.

4. The solar chap has his own business, the name of which includes the words Solar Technology Systems, because historically he was involved with the Nelson lot that was bought out by Solarcity. But he wasn't. Confusing? tell me about it! He has already replaced the pump to eliminate it from the puzzle. He's OK. Just difficult to pin down.

resol? Is this an anagram of Sorel? TDC 2. Undoubtedly fried. No computer can take the on/off treatment this one has had. When the plumbing is dealt with we will exchange it for another one and send this one off to rehab.
 
Title: Re: Solar hot water system problem
Post by: Corylus on May 11, 2013, 01:39:52 PM
Reply to Plumber. Thanks for the pics. They don't look a lot like the UFO I have in the airing cupboard. I'll have to study them to see if I can relate them to this dismembered bit of brass in front of me.

I have to confess that my husband did the dissection of our Ajax - and binned it before I got a chance to see it. So I think what we dug out again might have a bit missing. Hence the puzzle.

The yellow thingie on the quite unnecessary? discharge pipe is rated "Low bar"

Can I ask the reason why you are not a fan of air vents with an "open loop" sytem?
Title: Re: Solar hot water system problem
Post by: Plumber on May 11, 2013, 03:57:54 PM
Air vents are usually used on closed loop systems, in your case once flooded if should not be necessary. I assume the yellow relief valve is on the solar loop because they put ball valves on the flow and return (actually not approved), if anyone isolated both the panels would over pressurize, hence maybe the relief valve. You mentioned before that someone recommended putting a vacuum valve (relief valve)  on the open vent to increase pressure, this would also not comply being a solar system it is still considered an uncontrolled heat source with some councils. I would strongly recommend getting another opinion on the setup and problems you are describing. With regards to the image the top one is the UFO. Good luck
Title: Re: Solar hot water system problem
Post by: Corylus on May 11, 2013, 06:15:59 PM
Hello Plumber. Thank you for your post. I had a sneaky feeling that the air vent was more to look after the panel than it was to look after me! Fair enough. One must look after one's assets. I'm presuming a ball valve is a non return valve? Yup. I think the idea is to allow you to isolate the panel temporarily while you investigate what the **** is wrong with the rest of it.

So could the air vent be the source the air bubbles? If there was a vacuum in the circuit? Otherwise, there is a slight leak at the isolating valve on the flow pipe to the pump, I sometimes think there might be air bubbles in the cold water coming into the system. I hope not. That pipe is under the house and I can't access it. I can't imagine a slight leak in a mains pressure pipe could let air in??

You seem to be slightly alarmed about the problems I am experiencing. Join the club! Second opinion? That's why I'm asking you guys.  And very glad to have found you.I can't find anyone here who is prepared to actually think. Mind you, I'm going on what the solar guy is saying. He has been asking all the plumbers he can find and I don't know what he is telling them. The one who was recommended by various sources simply hasn't bothered to read the logical summary I sent him, which had no input from me other than observations. I wanted to know what the observations meant to him.  He just hasn't bothered to read them. All he can come up with is a quote for $1000 to come and install his own controller and to have a look. Other than that he has set the solar guy looking for where air could be getting in. I'd like him to do his thinking before he comes - is that unreasonable? Sigh. It doesn't pay to be female. You tend to be ignored - written off as a panic merchant who hasn't a clue what is going on. And being ancient doesn't help - what would an old woman know about anything huh??? (I once taught 6th form physics, but am the first to confess, it doesn't always relate to things like 5 way valves etc. when you can' find out what they look like inside)

UFO? Yup. I realise that it was the top one. But I have to tellya, it comes from a different planet from mine!

Time to cook. Us females have our uses. PS The irony is, my husband was head physics teacher for years at the local girls' college. But he has had a stroke and his knowledge is not accessible to me. I'm just a biologist with Physics as an 01 subject, and I didn't do it at school. so it's not my best shot by any means.
Title: Re: Solar hot water system problem
Post by: Plumber 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

Title: Re: Solar hot water system problem
Post by: Badger 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.
Title: Re: Solar hot water system problem
Post by: Corylus 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.

Title: Re: Solar hot water system problem
Post by: Corylus 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.

Title: Re: Solar hot water system problem
Post by: Corylus 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
Title: Re: Solar hot water system problem
Post by: Corylus 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!
Title: Re: Solar hot water system problem
Post by: integrated 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
Title: Re: Solar hot water system problem
Post by: Badger 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.

Title: Re: Solar hot water system problem
Post by: Badger 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.
Title: Re: Solar hot water system problem
Post by: Plumber 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.
Title: Re: Solar hot water system problem
Post by: Corylus on May 12, 2013, 06:16:10 PM
Thanks guys - back later
Title: Re: Solar hot water system problem
Post by: Corylus 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?

Title: Re: Solar hot water system problem
Post by: robbo 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.
Title: Re: Solar hot water system problem
Post by: Enn 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.

Title: Re: Solar hot water system problem
Post by: Badger on May 13, 2013, 07:56:37 PM
I agree mate
Title: Re: Solar hot water system problem
Post by: Corylus on May 13, 2013, 11:48:58 PM
Hello folks. What a day, I've been plumber hunting but like all good badgers they seem to go to ground when they are alarmed. Enn, you are right on the button. That's exactly what I need. An experienced solar plumber. Easier said than done. A good test is to ask them how a 5 way valve works. The word gets round and they disappear.

Robbo - an interesting post. Again, you've nailed it. We obviously didn't need this installation in the first place. We don't use nearly enough hot water to merit it. When ordinary mortals buy something like this they are at the mercy of the "expert" who has all the information. In hind sight, I would have liked to have been asked about our hot water usage, the reliability of our power supply and whether there were any problems with the water supply. Better to lose a sale than end up trying to sort a problem like this one. I bet he's sorry now! I know we are.

One of life's little ironies is that in summer when your hot water cylinder is simmering in the airing cupboard and you have more hot water than you know what to do with, all you want is a cool shower :-) I have to say though, that the 20 tube panel is barely adequate in winter. I suppose a lot depends on the orientation of your house. We have an HRV which is the best thing we've bought for decades - it just happens to suit our home. But other people aren't so lucky.

The pump has an isolating valve and a non return valve before and after, to allow it to be removed "for servicing". Is this what you mean by a "check" valve -  the non return? Could such a thing suddenly develop a fault? Between breakfast and lunch? Not sure how fast the cold water is getting in to replace what it chucks out. I simply couldn't get it to function today without just losing water out on the roof (metred water I may say). So I screwed the Ajax down 20 half turns and shut the cold water off, let the collector heat up good and hot, set the pump on 3 and let her rip, Worked a treat. It raised the whole tank by 9°C from a late start. Nearly made up for it losing 10° overnight due to the controller going psycho again. I don't blame it mind. No computer likes being put on and off as this poor thing has to put up with. Talking of which I'd better go and put it to bed. 'night all.
Title: Re: Solar hot water system problem
Post by: Corylus on May 14, 2013, 12:04:29 AM
Integrated - you wanted to know the height of the exhaust above the solar. I've attached a pic. The collector is barely visible, but I'm sure you'll be able to identify it. The cherry tree had to go.
Title: Re: Solar hot water system problem
Post by: Badger on May 14, 2013, 07:11:55 AM
Not gone to ground, just doing a job blind, with out seeing it, could end badly, more than happy to have a look if you are top of the South Island.
Title: Re: Solar hot water system problem
Post by: Corylus on May 14, 2013, 05:53:16 PM
Yes well. That makes a whole lot of sense Badger. I'd do the same.

I'm in Blenheim. Does that help? Come for lunch. What do badgers eat?

While I'm here, I'll attach a diagram of what I was expecting when I got a Solar hot water heater, never having heard of 5 way valves. So what's wrong with this idea apart from it a bit messy in practice?
Title: Re: Solar hot water system problem
Post by: Badger on May 14, 2013, 07:02:00 PM
Sorry I am in Takaka and Badgers eat a dollar a km and $60 per hour door to door for a specially requested one off trip.

Like I said happy to have a look, and if I was passing or had a big job in the area I would be more than happy to pop in to have a look see for nothing, but I do have to cover costs for a full day and travel other wise.
Title: Re: Solar hot water system problem
Post by: Corylus on May 14, 2013, 08:38:50 PM
:-) You do make me laugh Badger. Which is nice. I wasn't expecting miracles! And you'll be glad to know I've managed to flush out a plumber at last and I like the way he's thinking.

Any time you're passing through though you are welcome to come and see the inside of my airing cupboard. I might even have a spare 5way valve I can give you for your collection of spare parts!

Thanks for the smile.

Title: Re: Solar hot water system problem
Post by: Badger on May 14, 2013, 10:19:03 PM
All good, I really do hope you find a solution and I would be very interested in how it is rectified and what the cause was, as would all the guys on here I should imagine.

Through sharing the knowledge we can fix these problems and learn to help the next person who's stuck.

All the best, if I am passing through Blenheim I'll let you know...

FYI.. badgers also eat slices of pecan pie, choccy biscuits with a nice cup of tea. ;)
Title: Re: Solar hot water system problem
Post by: robbo on May 14, 2013, 11:06:36 PM
Hi guys/Corylus, as badger says we do hope that you have found someone who can help you. As you have found out this forum is very friendly and helpful (unless we are talking about the `pgdboard`) I think that we could award you some C.B.Licencing points for all the knowledge that you have now gained.  Just remember that like beer there are no bad plumbers it’s just that some are better than others , good luck with the fix,cheers
Title: Re: Solar hot water system problem
Post by: Corylus on May 15, 2013, 03:20:32 PM
:-) Thank you both. Indeed, thank you all. You have made such a difference. I was feeling quite abandoned and now I have found new friends, not to mention upgrading my knowledge  a zillion percent. That's what was so hard. I couldn't get anyone to either tell me what I needed to know or to criticise my own thinking. You need to know when your ideas are rubbish huh? And they were at one stage. Utter nonsense. I read my early notes and musings now and laugh. I should write a book.  Fifty Shades of Plumb? The Ins & Outs of a 5way Valve? Plumbing for Elderly Ladies? (Nah don't like that one) Friends in Unlikely Places? Debunking the Solar Myth - does it really save you money?????? (Answer - NO!) Denbunking the Solar Myth 2. Does it really save the environment? or how to use/lose more hot water than you ever did before.

:-) again. Off to check the HWCupboard for recent developments.

Great website. Best thing ever.

Title: Re: Solar hot water system problem
Post by: Badger on May 15, 2013, 05:20:15 PM
 :D
Title: Re: Solar hot water system problem
Post by: Corylus on May 15, 2013, 05:23:08 PM
Choccy bikkies and cups of tea always available Badger. Can't promise the pecan pie.  It's a long way from Takaka, but I have hopes. One of these days. . .
Title: Re: Solar hot water system problem
Post by: Victor steel on May 22, 2013, 05:00:17 AM
If there is a discharge of more than 10 liters per day from any of the system’s valves, it indicates there is a problem that requires a service call.
Title: Re: Solar hot water system problem
Post by: Corylus on May 22, 2013, 06:13:37 PM
Thank you Victor s. That's a useful thing to know. How would I measure it though? I've had the council check my meter and they weren't particularly alarmed by our usage. I bet we'd be losing at least that amount if I didn't run around like a headless chook trying to prevent it though. We are first off the village water supply and other people can't get water if we waste it, so I've been desperately trying to avoid inconveniencing them.

I'll have a word with my water usage contact in the council and let her know this fact. I'll give her the latest reading and see if there's a spike.  Very useful. Thanks

When you say "service call" - do you mean from the council or from the installer?