Solar excess heat dissipation

tippgaafan

I have got some quotes to install solar tubes and a 300l cylinder. I have also got some conflicting advice with regard to excess heat generated by the solar tubes (In hot sunny days). One company have said that a 30 tube system would be sufficent for a 300l tank and that there would be no need for a motorised valve to take excess heat away. Another company recommends a 40 tube system which will need to have a motorised valve and rad in the attic. My persornal opinion is that the more tubes the better. The water can be heated to a higher temperature and will last longer (With thermostatic mixing valve on output). Also would it be possible to use the circulating pump on the boiler to take excess heat from system instead of attic rad. !!

homer911

I have 40 tubes for 300l and I'm pretty sure its a standard enough configuration. I also have a thermostatic valve and a cooling radiator. Overheating is set to 85C and in 20 months I've only clocked 15 hours in excess of this.

The Boiler pump would, in theory, draw hear from the tank, but this would be difficult to wire/configure and as the coil is not near the top of the tank, it wouldnt make a lot of difference

AckwelFoley

tippgaafan wrote: »

I have got some quotes to install solar tubes and a 300l cylinder. I have also got some conflicting advice with regard to excess heat generated by the solar tubes (In hot sunny days). One company have said that a 30 tube system would be sufficent for a 300l tank and that there would be no need for a motorised valve to take excess heat away. Another company recommends a 40 tube system which will need to have a motorised valve and rad in the attic. My persornal opinion is that the more tubes the better. The water can be heated to a higher temperature and will last longer (With thermostatic mixing valve on output). Also would it be possible to use the circulating pump on the boiler to take excess heat from system instead of attic rad. !!

Im lost.

Why the rad in the attic?

When the cylinder reaches max temp the solar loops stops circulating... the expansion tank on the solar loop then takes the expanding solar liquid..

Trying to use the rads to cool the tank would be almost pointless, as the heat transfer from the tank to the coil would be minimal

MickLimk

snyper wrote: »

Im lost.

Why the rad in the attic?

When the cylinder reaches max temp the solar loops stops circulating... the expansion tank on the solar loop then takes the expanding solar liquid..

Trying to use the rads to cool the tank would be almost pointless, as the heat transfer from the tank to the coil would be minimal

This is what's being taught on the SEI-approved courses these days. Divert from the cylinder coil into a heat dump circuit (rad in the attic, bathroom or outside (!)) when the cylinder has been satisfied. The rad is supposed to be sized based on the panel's max output bearing in mind the lower delta T you may find if the rad is in an attic on a hot day.

Having the heat dump in place is supposed to prevent the system from stagnating as often and therefore prolong the life of the system. The expansion vessel should be sized to be able to handle stagnation if the heat dump fails in case of a power cut etc.

Not saying that I agree with this in all cases but it's what's being taught. I also know of a system where instead of a separate heat dump rad, the main circulating pump for the central heating kicks in instead with a zone valve also opened. It certainly is capable of removing heat from a cylinder quite effectively.

AckwelFoley

MickLimk wrote: »

This is what's being taught on the SEI-approved courses these days. Divert from the cylinder coil into a heat dump circuit (rad in the attic, bathroom or outside (!)) when the cylinder has been satisfied. The rad is supposed to be sized based on the panel's max output bearing in mind the lower delta T you may find if the rad is in an attic on a hot day.

Having the heat dump in place is supposed to prevent the system from stagnating as often and therefore prolong the life of the system. The expansion vessel should be sized to be able to handle stagnation if the heat dump fails in case of a power cut etc.

Not saying that I agree with this in all cases but it's what's being taught. I also know of a system where instead of a separate heat dump rad, the main circulating pump for the central heating kicks in instead with a zone valve also opened. It certainly is capable of removing heat from a cylinder quite effectively.

Thanks Mick.

I do know that prolonged stagnation and expansion of the system is not a good idea, i just really doubted that the coil would be effective at removing the heat from mthe tank, but i stand corrected

yellabelly

We just got 50 tubes on a SW roof installed for a 300l cylinder. I notice that our system has been stagnating on the full sun days when it goes over 140C.
The installer view was the extra expense of a heat dump was not necessary. I'm wondering now if the controller could bring on the CH pump to get rid of the excess heat from the cylinder. This would be much cheaper and easier than the radiator in the attic.

MickLimk

yellabelly wrote: »

We just got 50 tubes on a SW roof installed for a 300l cylinder. I notice that our system has been stagnating on the full sun days when it goes over 140C.
The installer view was the extra expense of a heat dump was not necessary. I'm wondering now if the controller could bring on the CH pump to get rid of the excess heat from the cylinder. This would be much cheaper and easier than the radiator in the attic.

140°C isn't too bad on a tube system. Depending on the brand, the temp on the heat pipe could hit 200°C on a good day!

Any idea what controller you have? Some of the least expensive ones are purely delta-T controllers - switch on the pump when the collector temp > cylinder temp by a set number of degrees and switch off when the cylinder temp gets closer to the collector temp.

Most of the controllers are slightly more intelligent than that and have a few variables that can help reduce stagnation occurrence but there are some other factors that need to be taken into account:
What temperature does the cylinder reach when the collector hits 140°C?
What kind of cylinder do you have, stainless or copper?
Are you in an area of hard water?
Do you have an anti-scald valve fitted on the output of the hot water cylinder?

If you post the controller model, there may be a few things that could be adjusted depending on your circumstances. Other than that, we'd need more info on your Central Heating controller and wiring...

AckwelFoley

MickLimk wrote: »

Do you have an anti-scald valve fitted on the output of the hot water cylinder?
QUOTE]


He has to have that under regs.

yellabelly

MickLimk wrote: »

140°C isn't too bad on a tube system. Depending on the brand, the temp on the heat pipe could hit 200°C on a good day!

Any idea what controller you have? Some of the least expensive ones are purely delta-T controllers - switch on the pump when the collector temp > cylinder temp by a set number of degrees and switch off when the cylinder temp gets closer to the collector temp.

Most of the controllers are slightly more intelligent than that and have a few variables that can help reduce stagnation occurrence but there are some other factors that need to be taken into account:
What temperature does the cylinder reach when the collector hits 140°C?

What kind of cylinder do you have, stainless or copper?
Are you in an area of hard water?
Do you have an anti-scald valve fitted on the output of the hot water cylinder?

If you post the controller model, there may be a few things that could be adjusted depending on your circumstances. Other than that, we'd need more info on your Central Heating controller and wiring...

The collector temp got upto about 170C at its peak with the top of the cylinder reaching about 65C.
Controller is a BS4 which I believe is one of the better ones.
Our water is hard.
We have no anti-scald value although I was considering putting one on.
Cylinder is a stainless one from DJG .

One problem I think we will have from stagnation is the long delay before the system comes back on. After shutting down, the pump didn't start up again until very late in the day when the collector temp dropped back to 130C. This is despite the bottom of the cylinder being fairly cool and requiring heat.

MickLimk

snyper wrote: »

MickLimk wrote: »

Do you have an anti-scald valve fitted on the output of the hot water cylinder?
QUOTE]


He has to have that under regs.

I know it should be included but a lot of installers still aren't putting them in. Surprising that the SEI commissioning form still has the box on there to tick 'No' to whether a Thermal Mixing Valve in installed or not...

yellabelly wrote: »

The collector temp got upto about 170C at its peak with the top of the cylinder reaching about 65C.
Controller is a BS4 which I believe is one of the better ones.
Our water is hard.
We have no anti-scald value although I was considering putting one on.
Cylinder is a stainless one from DJG .

One problem I think we will have from stagnation is the long delay before the system comes back on. After shutting down, the pump didn't start up again until very late in the day when the collector temp dropped back to 130C. This is despite the bottom of the cylinder being fairly cool and requiring heat.

The reason I asked the other questions was in the hope that you could increase the max temperature of your cylinder safely therefore getting more energy from your panels and reducing stagnation occurrences.

As it is right now, you can't. As Snyper correctly pointed out, you should have an anti-scald valve on the hot water output of the cylinder given the temperatures that can be reached especially in a solar system. Given the fact that you're in a hard water area, increasing the temp of your cylinder even with an anti-scald valve in place is likely to cause you more trouble than benefits. Once you go greater than about 65°C, furring will start to occur similar to what you see in your kettle. Eventually this could cause a reduction in performance of the cylinder as the coil gets covered in limescale.

That's a Resol controller right? I think there is a setting in there for absolute shutdown but I thought that this was supposed to be based on the cylinder temp and not the panel temp? I'll dig up the manual and see what settings are available on there. It could be that a temp sensor was connected to the wrong terminal or that there's a hysteresis setting that could be improved in there. Can you post your existing controller settings?

yellabelly

It is a Resol and the settings are
Arr=1,DTO=6.0K,NMN=30,DTS=10K,RIS=2K,SMX=60C,EM=140C,OCX=OFF,CMX=OFF,OCN=OFF,OCF=OFF,ORE=OFF,OTC=OFF,OHQM=OFF,HND1=AUTO,HND2=AUTO,PROG=69.3,VERS=1.05

I was offered the anti-scald as an optional extra and I wish I had gone for this from what I have since learnt.

Thanks

MickLimk

yellabelly wrote: »

It is a Resol and the settings are
Arr=1,DTO=6.0K,NMN=30,DTS=10K,RIS=2K,SMX=60C,EM=140C,OCX=OFF,
CMX=OFF,OCN=OFF,OCF=OFF,ORE=OFF,OTC=OFF,OHQM=OFF,HND1=AUTO,
HND2=AUTO,PROG=69.3,VERS=1.05

I was offered the anti-scald as an optional extra and I wish I had gone for this from what I have since learnt.

Thanks

Quick question: How many temperature probes do you have on your cylinder? Arr=1 suggests a single cylinder temp probe. If that is the case, where on your cylinder is it?

yellabelly

MickLimk wrote: »

Quick question: How many temperature probes do you have on your cylinder? Arr=1 suggests a single cylinder temp probe. If that is the case, where on your cylinder is it?

We have 2 cylinder probes - top and bottom. the middle one isn't used. They are displayed as S3 and TST on the controller.

MickLimk

yellabelly wrote: »

We have 2 cylinder probes - top and bottom. the middle one isn't used. They are displayed as S3 and TST on the controller.

I really don't want to be seen to question or disrespect someone else's work especially not having seen the install but personally I would have set up your system slightly differently.

I'll make a couple of suggestions here but if you have the slightest doubts at all about touching your system then you should get your installer back to have a look at it if you're not 100% happy.

Proceed from here at your own risk!
Do you happen to have a copy of the controller manual? If not, it's available here. http://www.resol.de/PDF/DeltaSol_BS.mon.en.pdf

Unless I've misunderstood your settings, you're set up in Arrangement 1. Look at page 10 of the manual and you'll see that in this case, you are reading temperatures TST (Temperature Store) and S3 (Sensor 3). If I were installing this system, I would have changed to Arrangement 2 where you are reading TSTL (Temperature Store @ Bottom of cylinder) and TSTU (Temp Store at top of cylinder).

The difference here between the two setups is that when set up with Arr=2, the controller can use both the cylinder temperatures to optimise the operation of the pump, whereas with Arr=1 only one of the temperature probes is used to compare the cylinder temp with the panel temp and therefore the running of the pump.

A 300l cylinder can be quite tall and the difference in temperature between the top and bottom probes could be quite large so it's worth the controller being able to monitor both ends of the cylinder to ensure the most heat possible is obtained from the panel.

Even if you decide not to change your system to Arr=2, you really should check that your temp probes are wired correctly: Collector probe to S1, Cylinder bottom probe to S2 and cylinder top probe to S3. See Diagram 1.2.2 on Page 6. I didn't see it in your settings list but I'm assuming that your DTF is at 4.0K?

I'll keep saying it as I don't want to insult anyone but again if it were me, I'd have an anti-scald valve installed (make sure it's one that can handle the flow rates required and not a basin one) and up the maximum cylinder temperature (SMX) to 65°C. This shouldn't cause any furring issues even though you are in a hard water area and has the benefit of getting you more hot water and reducing the stagnation events.

yellabelly wrote: »

We just got 50 tubes on a SW roof installed for a 300l cylinder. I notice that our system has been stagnating on the full sun days when it goes over 140C.

This is also caused by a setting in the controller (EM=140C) where this is the emergency shutdown temperature. I don't think it's programmable but it's probable that there is a 10°C hysteresis on this too that the system is completely shut down until the panel temp drops back to 130°C. In theory, you could increase this shutdown temp or activate the recooling function on the controller. I'm not recommending either of these but they may be viable options only if you have an anti-scald valve in place. I can't stress enough for you not to even consider it otherwise.

yellabelly wrote: »

The installer view was the extra expense of a heat dump was not necessary. I'm wondering now if the controller could bring on the CH pump to get rid of the excess heat from the cylinder. This would be much cheaper and easier than the radiator in the attic.

Apologies for veering off course on your initial question! I just think it would be a shame to be dumping heat if it were possible to store more of it with a few tweaks to the controller. To answer what you asked, yes, your controller can control a heat dump and could certainly control a C/H pump if it were wired correctly though it make need a relay for this to function correctly depending on your C/H controller.

Just for my own interest do you know are they 47mm or 58mm tubes you've installed? Any idea what brand? To be honest, 300l of hot water is nothing to be sniffed at and a lot of people would be well impressed having a problem of too much heat! I guess from your name, you're in the sunny south-east in Wexford!

yellabelly

MickLimk, thanks for the detailed reply. It's a great help to have other opinions. The tubes we have are the smaller ones and we are in Meath rather than sunny Wexford.

I am happy with the installer, I guess I tried to understand the system but I overlooked the importance of the anti-scalding valve. It was only strongly recommended if we wanted the store above 60C and the system appears to be set to 60C. I'm very interested in fine tuning to maximize the efficiency. I can still do this with the installer. It must get complicated when a solar system has to work with various different types of CH systems. It is understandable that solar installers want to keep their system simple and independent.

I would like to increase the store temperature and switch on the CH pump as a heat dump. Switching on the CH pump is a bit harder than I thought. We already have a switching valve to stop the boiler heating the cylinder beyond a certain temperature. I'm not sure how useful this is with an anti-scald valve. When we do a heat dump we need to make sure another switching valve is open to pump around the radiators.

How would you set a boiler controller to heat hot water in the colder months when the boiler will be on most of the time? You might prevent water being heated at all during sunshine hours. If the boiler is on you could heat the cylinder to say 55C and let solar take the temperature higher. I'm not sure what to expect from solar in the winter months.

homer911

I was trying to work out how your collectors could get to 140C and your water only get to 60/65C, the last posting makes is clear - seems like an awful waste of heat or too many collector tubes to me. My cooling rad is in the attic - another option was a towel rail in the bathroom.

I'm in a soft water area (no fur in the kettle) and let the temp get up to 85C, although this happens rarely - 70C is usually tops. I have a temp mixing valve but note that my installer locked it at a certain level, which seems odd - surely you want flexibility to adjust it based on the temp of your tank?

My shower is a separate half-inch feed with no mixer.

I was also told I needed a timer on my emersion to ensure the temp was at least 60C every day for 30 or 60 minutes to prevent risk of legionaires disease! (Put it in anyway, but dont use it - gas in winter, solar in summer)

yellabelly

I don't think there are too many tubes. The roof is SW so can take a few more tubes than if it had been S. We are into the peak months so the extra tubes will be beneficial throughout the rest of the year. I haven't been around to monitor exactly what happens to cause the shutdown. I think hitting the SMX value would cause the solar pump to switch off. The collector temperature may have only increased above 140C after stagnation. I believe the tubes are rated at 230C max.
The main problem I find having hit stagnation is the time it takes to get heating again. You could use all the water from the store but the solar pump will not come on until the temperature drops to 130C. This might not be until evening time.

MickLimk

yellabelly wrote: »

MickLimk, thanks for the detailed reply. It's a great help to have other opinions. The tubes we have are the smaller ones and we are in Meath rather than sunny Wexford.

No worries. Sorry, thought the only yellabellies in the country were the Wexford lads!

yellabelly wrote: »

I am happy with the installer, I guess I tried to understand the system but I overlooked the importance of the anti-scalding valve. It was only strongly recommended if we wanted the store above 60C and the system appears to be set to 60C. I'm very interested in fine tuning to maximize the efficiency. I can still do this with the installer. It must get complicated when a solar system has to work with various different types of CH systems. It is understandable that solar installers want to keep their system simple and independent.

Can understand that point of view alright but I personally would always install an anti-scald valve. In the worst case of some kind of failure mode or even someone changing settings on a controller, you could end up with 95°C water coming out of the top of your cylinder. I can think of nothing worse than the potential consequences of that...

yellabelly wrote: »

I would like to increase the store temperature and switch on the CH pump as a heat dump.

Increasing the store temperature can be a simple way of gaining more from your solar install (once you've an anti-scald valve in!) but if you are in an area of very hard water, it could potentially have a knock-on effect that ends up causing more problems than it's worth. As an example, in my folks house, kettles last about 6 months before the element is completely covered, overheats and trips the MCB. They won't use softened water for tea because they 'like the taste' of the hard water! Electric showers used to last about a year or so and washing machines had to be regularly descaled before a water softener was installed. Now in that house, there's no way that the cylinder temperature should be set over 65°C as it will start to cause limescale to build up on the heating coils on the inside of the cylinder and eventually lead to having to replace that at a cost probably >€1000 or so. Is is worth that hassle for the increase in store temp? Even a reasonably small amount of limescale on a coil will start reducing it's heat transfer capabilities reducing the overall system inefficiency...

yellabelly wrote: »

Switching on the CH pump is a bit harder than I thought. We already have a switching valve to stop the boiler heating the cylinder beyond a certain temperature. I'm not sure how useful this is with an anti-scald valve. When we do a heat dump we need to make sure another switching valve is open to pump around the radiators.

It's extremely difficult to say exactly how improvements could be made to your system without seeing every part of it. I can make a few more guesses as to your central heating setup but they may well prove way off the mark if any of my assumptions are wrong. Here goes anyway!:
What you may have is a cylinder thermostat that is used to control a motorised valve. When your cylinder reaches the set temperature, the motorised valve turns off and the central heating system doesn't circulate through that coil in the cylinder. Depending on the temperature that your boiler is set to, whether or not the rest of your heating system uses zone valves, what heating controller you're using and how this is wired this may have the effect of being able to shut down your boiler & pump when no zone requires heat and the cylinder is up to temperature. This is a very efficient way of running a system as otherwise constant circulation of hot water when it's not needed can result in losses from pipework etc and keep the boiler cycling unnecessarily.
Again, this is a guess as I don't know how your system is set up but I think you could possibly activate a heat dump by using a 3 pole relay/contactor. Your solar controller would turn on the relay which would supply three separate live signals to the central heating pump, hot water cylinder motorised valve and one other motorised zone valve. This is something that you'd want to get an electrician to look at as your central heating controller and solar controller should be on the same supply and the neutrals for the zone valves and c/h pump shouldn't be switched.

yellabelly wrote: »

How would you set a boiler controller to heat hot water in the colder months when the boiler will be on most of the time? You might prevent water being heated at all during sunshine hours. If the boiler is on you could heat the cylinder to say 55C and let solar take the temperature higher. I'm not sure what to expect from solar in the winter months.

My take on this is that during the winter you should set your central heating controller to provide hot water when you need it as you would have done before you had solar installed. During the winter, it's generally accepted that solar will raise the temperature of the incoming cold water so the boiler won't have to use as much energy heating the water in the cylinder to the required temperature. I don't think that the solar will be able to 'top up' the water heated by the boiler, it's usually the other way around. Your solar coil is at the bottom of the cylinder (where the cold water comes in) and the central heating coil is at the top of the cylinder. Stratification plays a big part in this but this post is far too long already without going further into that!

homer911 wrote: »

I'm in a soft water area (no fur in the kettle) and let the temp get up to 85C, although this happens rarely - 70C is usually tops. I have a temp mixing valve but note that my installer locked it at a certain level, which seems odd - surely you want flexibility to adjust it based on the temp of your tank?

The mixer/anti-scald valve is primarily a safety device. I would hope that it's a thermostatic mixer valve and not just one that mixes a fixed quantity of hot and cold water regardless of the temperature. It should be set at a fixed temperature and locked at that. What temperature it is set at is a different question...

homer911 wrote: »

I was also told I needed a timer on my emersion to ensure the temp was at least 60C every day for 30 or 60 minutes to prevent risk of legionaires disease! (Put it in anyway, but dont use it - gas in winter, solar in summer)

Again, this is more than recommended but it's completely up to you if you decide to ignore it at your own risk. If I had a spell of weather where the cylinder temperature didn't reach 60°C over a couple of days, I'd certainly give the immersion or the central heating a 30 minute boost. I'm obviously overcautious though!

yellabelly wrote: »

I don't think there are too many tubes. The roof is SW so can take a few more tubes than if it had been S. We are into the peak months so the extra tubes will be beneficial throughout the rest of the year. I haven't been around to monitor exactly what happens to cause the shutdown. I think hitting the SMX value would cause the solar pump to switch off. The collector temperature may have only increased above 140C after stagnation. I believe the tubes are rated at 230C max.
The main problem I find having hit stagnation is the time it takes to get heating again. You could use all the water from the store but the solar pump will not come on until the temperature drops to 130C. This might not be until evening time.

As I said there are options here such activating the recooling function on the controller or increasing the EM value. Funny as it may sound, the heat dump may actually fix this problem as it could prevent the EM temperature being reached! So having a heat dump may increase your hot water quantities and improve performance!

Apologies to all for the length of the post...

homer911

Thanks MickLimk - this is great stuff that's hard to find anywhere else and you dont tend to hear from your installer..:)

I've got a feeling that my anti-scald device is NOT thermostatic! - its got a min/max setting but no temp scale

No6

Slightly digressing from the technical points above in the early 90's I looked at solar panels for my parents house which i was designing, the heat dump reccomended then was a swimming pool!!! Happier times!! although we didnt put in solar panels or a pool....

ircoha

Just wonder what the issue is:

re the heat dump, we should be looking at these ideas instead
http://www.jenni.ch/index.html?html/English/english.htm

yellabelly

Nice cylinders, wish I had the space for one.

I have 3 issues with my current system.
- not maximizing solar input on the good days (stuck at 60C)
- unnecessary stress being placed on tubes by stagnating at high temperatures
- complete loss of an afternoon's solar energy - after shutdown my system doesn't come back on until 9PM

I'm still in the process of fixing these problems by implementing the suggestions in this thread.

nmacc

Adding my two cents to the pot:

Mick's advice is all very sound. If I were you I'd invest in a water softener, especially if you want to get more heat into the cylinder. Some copper solar cylinders (e.g. Coppercraft) use finned piping for the solar coil to increase the surface area. This works fine with soft water, but in hard water areas the limescale will clog up the coil very quickly.

I've fitted quite a few systems using the standard boiler coil as the heat dump, but the wiring can get quite complicated. It has occasionally been necessary to add two 4-pole relays just to get the motorised valves and CH circulating pump to oblige without affecting the efficient operation of the heating system.

If you're getting an anti-scaled valve, make sure it's at least one size larger than the pipework. In other words, if your hot water pipe out of the cylinder is 3/4", use a 1" valve. All TMVs will slow down the flow and the extra bore will partially compensate for this.

If the shower that is fed from the second cylinder outlet is thermostatically controlled, you may only need one TMV, but check the paperwork. Make sure it can take the higher temperature that you plan to feed it. Same for the shower pump if fitted.

I frequently set the maximum cylinder tempeature a little over 80C and set the controller to ARR 2. With AHO set to 78 and AHF set to 76 the cylinder will hover around 77C depending on the position of S3 relative to the boiler coil.

One thing to beware of is the immersion heaters. Some of the newer immersions have a second cut-out wired in series with the stat, designed to prevent overheating. These are usually set for 80C, and with the setup that I've described the cylinder could reach that for short periods. If your immersion was a bit sensitive the cut-out could pop. No damage done, but you could be stumped if you switched it on expecting heat.

tippgaafan

Since I started off this topic I purchased a 40 tube system with 300l cylinder. I have integrated the wiring of the solar system with the central heating using a Mitsubishi alpha logic controller. The logic controller has 3 inputs. 1. Call for heat from zone valve 2.Solar over temp 3.Frost stat for boiler. The controller has 2 outputs. 1.Boiler 2.CH pump.
The central heating is controlled with a 3 zone time switch. One zone is for hot water and the other two are for heating. If HW zone is on, the timeswitch supplies power to cylinder stat (mounted halfway up tank). If stat is not satisfied, power is then sent to open zone valve. When zone valve opens, limit switch within valve close and supply input 1 to PLC. The process for central heating zones is the same but instead of using a room stat I have installed TRV's on all radiators (Except for towel rail in batroom with is connected directly across boiler supply and return).
If the solar max temp limit is exceeded, the solar control panel sends an output to the PLC (input 2) and to the HW zone valve. The PLC will then turn on the CH circulating pump but not the boiler.
The solar controller has 3 sensors. T1 Panel, T2 Tank bottom, T3 Tank top. It has an integrated timer which will check the temp of T3 at preset times and turn on the immersion if T3 is not at the required temperature.
Just got the system up and running this week, so no real feedback yet on performance.

MickLimk

Well done, sounds good! Now all we need is just a little more sun!

What brand/model of controller did you go for? What size tubes?

tippgaafan

Tubes are 58mm Diameter & 1800mm length. They are made by Xinwang Green Energy. The control panel is also Chinese made (Shuangri) http://www.shuangri.com/download/SR530C6English.pdf. It has 4 sensor inputs and 4 outputs.
Inputs: 3 solar sensors and 1 sensor on the hot water circulation pipe return. The 4th sensor is for systems where the hot water outlets are plumbed with a supply and return. This means that there will be instant hot water at the outlet and no waiting for water to heat up due to distance from cylinder and cold pipework.
Outputs:Solar pump, Immersion,Hot water circulation pump and panel over temp.

mad m

I have a windhager 3 intergrated panel system in roof (SE direction) with a windhager 300L cyclinder,have the anti-scald valve. The temps on my cyclinder at present are just over 40 degrees. On the really hot days a couple weeks back it was just over 62...Should it be more? The clock is set to auto...New to all this.