Hi, I am new to all this solar technology, I have a 1.5kW solar array facing north in Brisbane with a cms2000 inverter which at the moment is producing between 5.5kWh to 6.5kWh a day, we also have evacuated tube system facing west with a 20 degree pitch, I was wondering if it is normal practice to have to turn your booster on during cloudy days this time of the year in Brisbane, at 1pm our hot water is just warmish, you could say the cold chill has been taken out, but its not just warm enough to have a nice hot steamy shower? is this normal, I heard that evacuated tubes were used in sub zero conditions and still produced hot water, we are far from sub zero here in Brisbane at the moment and our hot water is just warm? do I have a problem?
Evacuated tubes operating in Brisbane during cloudy days in winter
(37 posts) (10 voices)-
Serg77
MemberYou can all stop researching my question now, I changed my search and found out what I wanted, it seems that through some cruel twist you can't produce energy out of nothing! what the? basically, if you get bugger all sun your evacuated tubes produce bugger all hot water, have i understood this correctly? I was led to believe by shady sales men that evacuated tubes are used in siberia to produce steaming hot water, perhaps exaggerated?
http://www.ata.org.au/forums/topic/solar-hot-water-heating-in-winter#post-6976
Posted Sunday 22 May 2011 @ 3:28:02 am from IP # -
shady sales men...perhaps exaggerated?
sign of the times .
greenwash abounds.
as you no doubt know facing west is less than ideal .
but nonetheless there are numerous other factors .. pipes lagged etc.
length of pipe run , size of tank , amount of hot water you use, time of day of use , t goes on.Posted Sunday 22 May 2011 @ 3:39:00 am from IP # -
if tanks is insulated properly, that idea is a nonsense . west was best because the roof was west facing , sorry but i have heard so much spin i am a tad skeptical
Posted Sunday 22 May 2011 @ 8:19:41 am from IP # -
Serg77
MemberSorry Dave I am not sure what you mean? are you saying that even on cool cloudy days we should have steaming hot water? do you think our tank is not insulated correctly? today was cloudy all day, our water was barely warm, we had to turn on the electric booster.
Posted Sunday 22 May 2011 @ 10:34:18 am from IP # -
no i don't mean that . what i meant was north facing panels get benefit of sun for most of the day and most tanks will retain that heat , thus argument about west facing panels redundant IMO .
how many people using water ? what size tank ? any teenagers spending half an hour in shower ?Posted Sunday 22 May 2011 @ 12:12:42 pm from IP # -
Serg77
MemberOh I see, yes we are aware that North is best, but unfortunately for us our North roof is small and is filled up with Solar Panels, we had the option to go east or west for the evacuated tubes, we chose West because "they" say the western sun is hotter....
I was also told that the holding tank should be able to maintain heat in the water for at least 2 days, so how come if we turn the booster on all day and turn it off in the evening, it is not hot the next day? it's not that cold at the moment I would think.Posted Sunday 22 May 2011 @ 1:17:19 pm from IP # -
Benny
MemberET HWS probably could produce hot water in Siberia Serg, even if the air temp was close to 0C, but thats only if the sun is shining. If you've ever sat on a sunny verandah on a ski field on a clear,sunny day, you'll appreciate that the solar radiation can still be intense and so would heat water. The ET vacuum insulation just means that the heat then gets in to the tank before its all lost, as long as the pipes are insulated of course. It doesn't matter if its 30 degC in Brisbane, if the clouds are really thick and solar radiation weak, the water won't get hot.
Posted Sunday 22 May 2011 @ 1:48:09 pm from IP # -
do you know where the heating element is in the tank ? some tanks have heating element near the top of the tank , some in the middle and some down low . advantage of near the top is does not take long to heat some of the water (at low cost ) but disadvantage is that it only heats a small amount of water . horses for courses i guess .
Posted Sunday 22 May 2011 @ 9:22:10 pm from IP # -
Sunshine
MemberSerg77,
I am also in Brisbane with an evacuated tube system, also facing west as solar PV panels are facing north, except the evacuated tube system collector is facing west at around 45 degree pitch to the west.
Suspect your system is either undersized for your family size or has a fault. Has it always been like this, what size system and family?
I have a 30 tube system, with 315 litre tank, and only boosted once in 2 and a half years.Posted Sunday 22 May 2011 @ 9:36:38 pm from IP # -
Serg77
MemberHi Sunshine, it's a 25 tube system with 300 liter tank, all connections appear to be insulated, the system faces pretty much directly west and it is pitched 20 deg., in our household we have 2 adults and a toddler and a baby, we really do not use that much hot water. Since we have had it installed about a week ago we have had to use the electric booster every day? we have really only had one full sunny day in that time - we can also hear the pump operating frequently, but without turning on the booster we would just have warmish water, which is not good! do you think it may need a couple of days of full sun to become operational?
Posted Sunday 22 May 2011 @ 10:32:50 pm from IP # -
Serg77
MemberHi Dave, I do not know where the element is situated, the element appears to work no problem, after switching it on we have hot water in about 2 hrs, sort of defeats the purpose of buying solar panels when you keep having to turn the electrics on...
I have called the installers and they seem to think that maybe I could have air in the system stopping the pump from working properly, or I could have a faulty controller box... great.Posted Sunday 22 May 2011 @ 10:45:49 pm from IP # -
Sunshine
MemberSerg77,
We go 4 days with no sun, before we require boosting on the 5th day, so it sounds your system has a problem. We are a family of 3 with average usage I suppose. I even connected the dishwasher to the hot water as we just about never run out of hot water.
It will heat even in cloudy conditions, heavy cloud no, but lighter cloud yes.Posted Monday 23 May 2011 @ 1:03:04 pm from IP # -
Serg77
MemberWell then I guess its settled, we certainly have an issue with ours - it has only been in a week and we have yet to experience an electric free hot shower, at best its been barely warm and we have had at least one full day of sun, mostly cloudy and a couple of rainy, but all in all I think we have had enough sun on the tubes to give us hot water from what ppl are saying, I have rung the company and now sit and wait.... I don't know if I mentioned that I could hear our pump for the solar hot water operating at night, this also is not supposed to happen in a healthy system I am told.
Posted Monday 23 May 2011 @ 11:11:29 pm from IP # -
hamish05
MemberI also have been disappointed with the performance of my SHW and have been consulting with the manufactures representative, and achieved some improved performance.
In that the distance from the collector (tubes) to my tank is longer than what is considered normal, It was decided to increase the "pump on temp" to 18 deg. (Was set at 12)
Increasing the "pump on temp" allows the collector to heat the water more, before returning it back to the tank. i.e. The pump now is returning "hotter" water back to the tank.
My feeling is that this small change could help many SHW systems perform better.
I will still need to electric boost, however it is winter in Melb, and most days are cloudy.
Posted Monday 23 May 2011 @ 11:44:17 pm from IP # -
Serg77
MemberSo I have steaming hot water today? sun was out pretty much all today and we turned off the electrics on the tank at about 8am this morning, it had been turned on for all of yesterday, so do I have hot water because it has remained heated in the tank from when it was heated by electric element? or is it hot this evening because it had a full day of sun and system works as expected? who can tell? I guess all I can do is leave booster off and see! I hate not knowing whats going on.
Posted Tuesday 24 May 2011 @ 7:26:47 am from IP # -
Sunshine
MemberSerg77,
I think half your problem is the pump running at night, all that is doing is cooling the water down.
I must also mention my pipe run is very long, at least 30 metres (2 x 15m), but doesn't seem to affect the performance too much.
Also, I'm concerned that you can hear the pump. I can't hear mine at all, the only way I can tell is by touching it and feeling the vibration, plus the controller has a "pump on" lamp.Posted Tuesday 24 May 2011 @ 11:43:36 am from IP # -
kesa32
MemberSerg , the pump should'nt be running all the time , especially at night......you either have an air lock ( doubtful) or a controller problem
When we first installed ours the pump was running for a few minutes but nothing happening circulation wise, the temp at the evacuated tube header started rocketing up as the pump was air locked............we bled the system and it instantly settled down, so based on my experience l'd say your controller is at fault and the pump is actually cooling the system by it's constant running ( get the installer back mate as the pump wont be happy )Cheers ken
Posted Tuesday 24 May 2011 @ 9:54:40 pm from IP # -
Serg77
MemberThanks guys, woke up this morning and still had piping hot water? did not hear the pump last night and wife says she did not hear the pump at all during the day (I was at work), I bled the system a lot in the first few days because the pump was making a hell of a noise, due to air in the system I am told, so I am hoping that things have settled down with the SHW and it is now operating correctly, but really still not sure, I have contacted the installers and they will be sending someone out to check - can anyone tell me if it is normal for the pump light on the controller to be off? the power light is on but the pump light is off, this is at 9am today - does the pump light only come on when the pump is actually working? or should it be on all the time? regards Serg.
Posted Tuesday 24 May 2011 @ 10:56:55 pm from IP # -
kesa32
MemberYep , the pump light will only come on when it's running .....power light stay on 24/7
You should have some buttons to view the temp in the HWS .....when the difference of temperature between the bottom tank sensor temp and the temp up on the roof differs by a pre set amount ( usually around 12c ) the pump will turn on and go until the temp diffence is lowered and then turns off until the cycle starts againPosted Wednesday 25 May 2011 @ 2:19:40 am from IP # -
Serg77
MemberOk thanks, I am hoping things are working as they should now, I guess the pump would be working during the day and my wife is too busy watching oprah to go out and check it, I get home from work too late to see it running, the water was still hot this evening so I am assuming its working, we have not had the booster on for 2 days now, no more strange noises from the pump either. The water this evening did not feel as warm as yesterdays, even though it was a full sunny day like yesterday - the general air temp today was cooler however, would this account for less heat in tank water? we had to have hot water tap on only, no cold tap on to have a hot shower tonight, whereas yesterday evening we had to have some cold water turned on with the hot water otherwise it was too hot, I am thinking the cooler weather today compared to yesterday may account for this difference? thoughts? cheers
Posted Wednesday 25 May 2011 @ 8:48:21 am from IP # -
Serg77
MemberWell, who knows really, everyone up here seems to think that I should not need to boost hardly ever, then others tell me that in winter I should be boosting frequently? confusion... I guess all I can do is let the "experts" take a look at it, they will be here today and I will post what they find.... my system is a 25 tube evacuated with a 300ltr tank, all lines insulated and line distances are not long, a few meters, normal distance you could say, our solar collector faces west and gets sun from about 10am through to 3pm, getting the best sun from midday onwards, it has some shading after 3pm, but the sun is weaker then so I am assuming this would not have a huge impact on overall operation, its at a pitch of 20deg on the roof, our usage is one shower in the morning, two in the evening, about 10 minutes each, I don't think we really use a lot of hot water, we are on trickle feed, and have a pump onsite which services our house, so I dunno, lets see what mr expert has to say about the situation.
Posted Wednesday 25 May 2011 @ 11:09:01 pm from IP # -
hamish05
MemberSerg77 with the shading and west orientation 22T x 300L tank doesn't sound like a good combination. I suspect you may require additional tubes!!
Suggest you refer my previous post on collector temps to your "Mr. Expert", a change may assist, certainly has helped me.
Posted Thursday 26 May 2011 @ 1:19:26 am from IP # -
Solgen
MemberSerg77, As others have said I don't think you have enough tubes for your setup. I am in Sydney and for our 315l tank we have 30 tubes and yet after 3-4 days of cloudy weather at this time of the year we have to boost. We rarely need the boost for the rest of the year but May and June are the worst for solar gain.
Posted Thursday 26 May 2011 @ 7:21:30 am from IP # -
Serg77
Memberthanks Hamish/Solgen - we have 25T not 22T "expert" man came today and discovered that we had the incorrect pump installed for our system? not too sure on the details as I was away and not able to quiz the "expert", I am relying on what my wife tells me, she says he said "those drongos 'ave installed the bloody wrong pump, jesus christ", how competent I thought, I hope he is right and that things are fixed now - the pump installed was for use with a town water connection, we are connected to town water but not full pressure, we are on trickle feed and apparently the pump which was originally installed could not handle the different pressure fluctuations of our pump at home, so he upgraded the pump and said, "she should be as good as gold now cobba, good as gold" and with that he and his dog left. Time will tell, my confidence is low. The company I used has made so many mistakes - firstly they installed my solar panels on the eastern side of my house which is heavily shaded, and gets no afternoon sun! they did this after the sales man specifically told me that the panels would be going on our north roof! I was unable to stop them as I was at work and my wife was none the wiser, so I had to get them back to move them onto our north roof, and now it appears that they have ballsed up the SHW also.
Posted Thursday 26 May 2011 @ 7:31:00 am from IP #
