Navitron Renewable Energy and Sustainability Forum

SOLAR THERMAL => Solar Thermal Systems => Topic started by: neilglos on April 19, 2016, 12:01:12 PM



Title: new to the world of Solar Thermal
Post by: neilglos on April 19, 2016, 12:01:12 PM
Hello, new to the world of Solar Thermal, I have just installed the Navitron designed and sized system - 30 TUBE 58MM ALU. LOW PROFILE PANEL, Single Line pump station with Grundfos UPM3 HE pump, MTDC CONTROLLER, 255L TWIN COIL UNVENTED STAINLESS STEEL & Spirovent 3/4" H with auto close. South facing in North Gloucestershire.

I have a few questions -
1.   Programme settings on the controller - is it best to leave settings @ default, eg sensor temps, recooling off etc?
2.   Should I change the pump speed on my Grundfos UPM3?
3.   Are there any procedures to take during holidays, cover tubes with a Tarp, change the controller settings to holiday mode?
4.   How often should I replace the Antifreeze?
5.   During the last week mid-April, I have managed to collect a full tank of ~50 degree water, will I have problems with overheating in the summer?
6.   I installed the solar loop and tubes myself with my dad, is it possible to get my system checked and signed off to claim the RHI?
Thanks Neil


Title: Re: new to the world of Solar Thermal
Post by: dhaslam on April 19, 2016, 12:59:42 PM
Hello, new to the world of Solar Thermal, I have just installed the Navitron designed and sized system - 30 TUBE 58MM ALU. LOW PROFILE PANEL, Single Line pump station with Grundfos UPM3 HE pump, MTDC CONTROLLER, 255L TWIN COIL UNVENTED STAINLESS STEEL & Spirovent 3/4" H with auto close. South facing in North Gloucestershire.

I have a few questions -
1.   Programme settings on the controller - is it best to leave settings @ default, eg sensor temps, recooling off etc? 
The only setting that might take some consideration is the cut out temperature, particularly with an unvented cylinder  you probably have to limit the temperature.   
2.   Should I change the pump speed on my Grundfos UPM3?
Generally you should use a variable speed setting on the controller and a medium or high setting on the pump. That allows slow steady transfer of heat in low light conditions.

3.   Are there any procedures to take during holidays, cover tubes with a Tarp, change the controller settings to holiday mode?
That is a tricky one.  Generally covering tubes is an invitation to burglars  so not very advisable  but leaving the controller to cut out circulation puts a lot of strain on the plumbing. For holidays  a simple way to dump some DHW water into  a  garden tub or  to use  some other heat  dump, to central heating, for example, is  desirable.

4.   How often should I replace the Antifreeze?
It should last at least ten years.

5.   During the last week mid-April, I have managed to collect a full tank of ~50 degree water, will I have problems with overheating in the summer?
Probably not if you are using water constantly.  Heat gain drops off rapidly with rising water temperature.

6.   I installed the solar loop and tubes myself with my dad, is it possible to get my system checked and signed off to claim the RHI?
Worth a try at least but most support systems depend on prior application.   



Title: Re: new to the world of Solar Thermal
Post by: 9fingers on April 20, 2016, 08:29:13 AM
I have installed a similar system to your 30 x58mm tubes on 49 degree south facing roof but I have a 357litre store.
I have found the need to install a heat dump even though my store runs at up to 93 degrees (as close to boiling as I feel comfortable with)

Unless you are drawing off fair amounts of DHW during the day, your system will likely stagnate on a regular basis and that is not good practise in my book and will gradually cook your inhibitor if nothing else.

Search on this forum for details of the ANTMAN Dump which is a very elegant dumping scheme and when implemented will mean you can go away on holiday leaving the system looking after itself safely.

hth

Bob


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 20, 2016, 09:32:36 AM
Thanks for the replies, as ever I have a few more questions.
7. How will I know my system is stagnating?
8. I like the idea of a heat dump for peace of mind;

8.1 D.24 in my controller manual looks like a good fit, Solar + cooling 2

What pump would you recommend from Navitron?
What size radiator would be recommended?
Should in install in a bathroom?
or externally @ the back of my house in the shade?

8.2 D.25  in my controller manual also looks like I can loose heat through my CH, Solar + cooling 3
I assume my Worcester Bosch boiler pump switches on and opens both values? how would I get a switched live? is this a good option vs a dedicated heat dump?

The CH options looks like the easiest option, just a cabling job....

thanks Neil


Title: Re: new to the world of Solar Thermal
Post by: 9fingers on April 20, 2016, 11:42:29 AM
When it stagnates, the rooftop temperature rises dramatically and the top manifold fills with superheated steam pushing the HTF down into the pipework.
Pressure gauge usually goes up and it may blow off into the expansion vessel.
The elevated temperature compromises the buffer solution balance in the HTF which gradually turns acidic and in extremis, eats through the copper pipes.
Although HTF inhibitor should last a good few years, I would check the pH as part of an annual service to check it is still slightly alkaline or neutral. When pH drops below 7 then it is an early warning to drain and refill the system when convenient - usually in the winter when you don't have to manage the draining of hot HTF

If you use the Antman dump system you don't need extra radiators or pump.
I have mine rigged to go through the bathroom radiator and towel rail which has the bonus of nice dry warm towels even in summer as my dump operates on most sunny summer days. NB you might not get as regular dumping as my surplus dregs of PV also goes into the store
You need some relays as well as cabling but yes it is an electrical only solution so no plumbing.
If you have thermostatic radiator valves, remember to open at least one fully during the summer period when the dump might be required.

hth

Bob


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 20, 2016, 01:22:11 PM
thanks Bob, last question I think.

I plan to use the Solar S-Plan+ HD to CH 2RS Nav (BTW only have one heating zone) unless I have missed something,
is it the case to stop the boiler turning on the flame, pump on and just opening the valves circulating the water, I manual set the temperature to say 30 (in the summer only) as my Worcester only has a Switched Live?

** update, I think, I have figured it out, I remove the live from the boiler to the pump and divert it via the relay C1, Switched live triggers the flame....**

Neil


Title: Re: new to the world of Solar Thermal
Post by: 9fingers on April 20, 2016, 02:55:06 PM
thanks Bob, last question I think.

I plan to use the Solar S-Plan+ HD to CH 2RS Nav (BTW only have one heating zone) unless I have missed something,
is it the case to stop the boiler turning on the flame, pump on and just opening the valves circulating the water, I manual set the temperature to say 30 (in the summer only) as my Worcester only has a Switched Live?

** update, I think, I have figured it out, I remove the live from the boiler to the pump and divert it via the relay C1, Switched live triggers the flame....**

Neil

Basically yes. My WB has a single switch to live as a demand for heat. I put a normally close relay contact in series with that. I have a pair of changeover contacts for the pump. Moving contacts to pump, NC contacts to boiler pump control and NO contacts to fused mains. Another NO contact is in parallel with the room stat. All the relay coils are driven by the dump output from the TDC.
Leave  boiler controls alone. You can even switch the boiler off in the summer months.

I'm using no gas for DHW between about mid March to mid-late October.
As I type the store is sitting at 82-83 top to bottom giving me a capacity of around 300 litres of DHW at 50 degrees.

A photo of my calorimeter display taken some time ago.

(http://i115.photobucket.com/albums/n313/9fingersphotos/IMG_0795_zpsaef82e59.jpg) (http://s115.photobucket.com/user/9fingersphotos/media/IMG_0795_zpsaef82e59.jpg.html)

Top row = cyl temps on 7 sensors top (left) to bottom (right)
2nd row actual temp of cold inlet to mixer and mixer output - both drift towards ambient over time
3rd row long term average minimum (trough hold) for the cold inlet, followed by long term average Maximum (peak hold) at the mixer output.
bottom row No of mS since last estimate, no of litres that can be drawn before thermostatic mixer goes out of regulation (calculated from the above)
software version (home brew) single digit down counter in seconds to indicate activity. This should never stop as the watch dog will kick in and reboot it.

In the fullness of time, this volume of available water will be used to decide as and when to fire the boiler. I just have to incorporate a real time clock into the software and way of storing the DHW demand profile I want.

hth
Bob

PS Before anyone asks, I'm not going to publish my software mainly because I don't consider that it meets any acceptable standard and has been hacked together with minimal documentation.


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 21, 2016, 09:18:32 PM
Hi Bob, relay arrived today, I have connected it up without power to the coil to check normal function, it all works.... BUT my boiler reports a H09 error communication problem with the pump, do you have the same error or problem, i have taped/isolated up the original live from th boiler and connected the pump to pin 9 (my boiler in a 24i greenstar only a few month old), may need to concider a different method new pump and rad. cheers Neil


Title: Re: new to the world of Solar Thermal
Post by: 9fingers on April 21, 2016, 09:54:05 PM
Hi Bob, relay arrived today, I have connected it up without power to the coil to check normal function, it all works.... BUT my boiler reports a H09 error communication problem with the pump, do you have the same error or problem, i have taped/isolated up the original live from th boiler and connected the pump to pin 9 (my boiler in a 24i greenstar only a few month old) cheers Neil

Your boiler must be cleverer than mine which does not check for the presence of the pump motor. It does not have a display for error messages. Nice and simple (and dumb!)
Does your H09 error go away by itself when the pump is reconnected or do you have to reset it manually? if the latter which would be a PITA, then wire a low power filament light bulb or maybe a spare relay coil direct to the boiler pump terminals to give it something to chew on.

hth

Bob

PS late afternoon yesterday my dump came on. So even in April, my 30 tubes had taken the store to 93degrees and 101 degrees on the roof when I looked at the controller


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 21, 2016, 10:07:38 PM
The error did not disappear....I also could have done with the dump yesterday, ran the bath quickly....back to the drawing board, I think, I will go for a separate pump and rad a little more research needed, TBH not sure I fancy voiding my warranty. thanks for ur help!!


Title: Re: new to the world of Solar Thermal
Post by: 9fingers on April 21, 2016, 10:15:27 PM
Try using the relay to cut the power to the whole boiler when dumping - that should remove the H09 problem.

Otherwise a second pump in parallel with the boiler one would still  let you use your current rads as the dump.

Lots of way of skinning this cat!

Bob


Title: Re: new to the world of Solar Thermal
Post by: Antman on April 22, 2016, 08:59:30 AM
Hi Neil
The schematics are only meant for Regular boilers with external pumps (not combis and some system boilers create issues with access to the pump wiring integral with the boiler). Searching the WB website I assume you may have the Greenstar i 24kW system boiler which seems to have the digital display and a whole lot more complicated control system electronics.
If so then your only option would be to use a separate pump.

It is worth noting that there are a few regular boilers that use triac/SSR switching in the pump neutral. These would not work with my published schematics either.
The option to overcome this is to use the spare pole 4 of the relay to isolate the pump neutral:
 PumpN from boiler to NC4
 PumpN to C4
 Neutral feed to NO4

This completely isolates the pump from boiler in HD mode.

I am sure someone on the forum has used the older generation Greenstar Ri OK.

Regards
Antman


Title: Re: new to the world of Solar Thermal
Post by: Iain on April 22, 2016, 09:26:45 AM
Hi
My old boiler used the Antman(similar) system and worked well in dumping the heat. I fitted a new boiler and as it is more sophisticated and had a warranty I decided to keep the dump separate.
All I did was to fit a CH pump/ circulator in series with a zone valve. These connected between one leg of the cylinder boiler coil circuit and one leg of the CH circuit.
The dump signal opens the zone valve,which effectively links the CH circuit and the HW cylinder coil circuit, when this opens, the micro switch on the zone valve switches on the pump. The water goes around the boiler coil in the cylinder,removes the heat and sends it around the CH circuit. Works very effectively.
I also added a relay to the circuit that inhibits the boiler just in case it is told to run at the same time.
No mods to the boiler, so warranty OK, works in a similar way to the Antman system and very simple and effective.

Iain


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 22, 2016, 09:33:10 AM
thanks for the update, it is a system boiler - Greenstar i System (24), I do suspect the boiler continually monitors the pump :-( as i have no error when I restore the default wiring.

I was researching last night and my system is sized correctly eg 30 tubes 250l tank ie within 7.5l per tube;
There are two camps here, dump or no dump?
I have set the tank max temp to 75 as I have a TMV and shall monitor, worst case I cover the tubes for holidays...


Title: Re: new to the world of Solar Thermal
Post by: Antman on April 22, 2016, 09:36:47 AM
Sorry, I found the info on the WB site and was updating my original post as you typed.
Antman


Title: Re: new to the world of Solar Thermal
Post by: Antman on April 22, 2016, 09:53:17 AM
In my view a boiler with a pump that has communication monitoring is just way too OTT for the job. I guess you have a 10-yr warranty so OK  whistle

Depending on your plumbing arrangement there is another possibility - thermo-syphon.

With luck, if you simply open the HW zone valve you may get thermo-syphoning around the boiler loop - it usually works best where the pipework runs up through the loft and back down to the boiler elsewhere.

With your system (like mine 20 tubes on 172l cyl) you will only likely need to HD when away on holiday in the summer. Normal hot water useage will keep the cyl below HD trigger point.

So you could try turning off the boiler and manually latching the HW zone valve open (in manual open drain position) and see what happens. If you get circulation then you can either just rmeember to turn off the boiler and open the valve before going away....
or modify the relay wiring to:
1) open the HW zone valve,
2) disable the CFH to the boiler.

Forget the pump over-ride connection as you would not need to run the pump if thermo-syphon is enough.

You may find that opening the radiator zone valve as well would boost the thermo-syphon. You could do this with the spare relay contact. Worth trying.

Antman


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 22, 2016, 09:57:49 AM
thanks Iain, so the new pump would be installed in-between the zone values, and I would keep the Antman relay config (genius BTW), just connect the new pump to the 1st relay rather than the boiler pump; simple question during regular operation how does the idle heat dump pump effect the flow rate?

Hi
My old boiler used the Antman(similar) system and worked well in dumping the heat. I fitted a new boiler and as it is more sophisticated and had a warranty I decided to keep the dump separate.
All I did was to fit a CH pump/ circulator in series with a zone valve. These connected between one leg of the cylinder boiler coil circuit and one leg of the CH circuit.
The dump signal opens the zone valve,which effectively links the CH circuit and the HW cylinder coil circuit, when this opens, the micro switch on the zone valve switches on the pump. The water goes around the boiler coil in the cylinder,removes the heat and sends it around the CH circuit. Works very effectively.
I also added a relay to the circuit that inhibits the boiler just in case it is told to run at the same time.
No mods to the boiler, so warranty OK, works in a similar way to the Antman system and very simple and effective.

Iain


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 22, 2016, 09:59:59 AM
In my view a boiler with a pump that has communication monitoring is just way too OTT for the job. I guess you have a 10-yr warranty so OK  whistle

Depending on your plumbing arrangement there is another possibility - thermo-syphon.

With luck, if you simply open the HW zone valve you may get thermo-syphoning around the boiler loop - it usually works best where the pipework runs up through the loft and back down to the boiler elsewhere.

With your system (like mine 20 tubes on 172l cyl) you will only likely need to HD when away on holiday in the summer. Normal hot water useage will keep the cyl below HD trigger point.

So you could try turning off the boiler and manually latching the HW zone valve open (in manual open drain position) and see what happens. If you get circulation then you can either just rmeember to turn off the boiler and open the valve before going away....
or modify the relay wiring to:
1) open the HW zone valve,
2) disable the CFH to the boiler.

Forget the pump over-ride connection as you would not need to run the pump if thermo-syphon is enough.

You may find that opening the radiator zone valve as well would boost the thermo-syphon. You could do this with the spare relay contact. Worth trying.

Antman

ah my tank and boiler are on the 1st floor, pipework within the floor/around the wall, would this work?


Title: Re: new to the world of Solar Thermal
Post by: Antman on April 22, 2016, 10:20:09 AM

ah my tank and boiler are on the 1st floor, pipework within the floor/around the wall, would this work?

If the boiler is high enough up the wall then possibly.

Best bet is to let the boiler cool down (so you can feel if the pipes warm up) then try it. Shut boiler off so there is no chance of the manual valve opening also operating the microswitch and calling for heat (would defeat the object).

It may take 10-15 mins to 'get going' if it works. If the pipes are well insulated then just the HW valve open to boiler won't be enough - unless you have a bypass rad. Without bypass rad you would need to hope thermo-syphon will work through the rads as well.

Worth a try as no cost quick test.
Antman


Title: Re: new to the world of Solar Thermal
Post by: Iain on April 22, 2016, 10:48:33 AM
Hi
Just a quick diagram.
The dump pipework can go anywhere, but most have the diverter valve / 2 zone valves next to the cylinder so this is an ideal place.

Quote
simple question during regular operation how does the idle heat dump pump effect the flow rate?

Not sure I understand the question


Iain


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 22, 2016, 11:11:21 AM
fab thanks for the picture, I understand, re the question, I was confused thinking the new pump was in series with the boiler loop, I see a parallel loop bypassing the boiler with the pump and valve. cheers


Title: Re: new to the world of Solar Thermal
Post by: Iain on April 22, 2016, 11:51:13 AM
Hi
I use Mo-Mo Zone valves on mine. The valve motor only receives power whilst it is moving. The normal ones have a motor driving against a spring.
My boiler has an inhibit circuit, which has the low water pressure sensor connected to it. I have just put my inhibit relay in series with this.

Not sure how this circuit will work if you have a mid position valve fitted instead of zone valves. the mid position valve has all ports open when in the off position. Even so I would imagine there would be enough flow from the dump pump to overcome this bypass, but not sure.

Iain


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 27, 2016, 09:34:59 AM
Sorry for the school boy questions - what pressure should my solar expansion vessel be set @, I have not changed from the pre-pressure setting, cheers Neil


Title: Re: new to the world of Solar Thermal
Post by: Iain on April 27, 2016, 12:31:10 PM
Hi Neil
Quote
what pressure should my solar expansion vessel be set @, I have not changed from the pre-pressure setting

Should be pre charged to .2 bar below normal system pressure at ambient temp (with no system pressure connected)
I run my system at 1 bar, the EV is precharged to 0.8 bar

It allows for keeping the system pressurised during low temp spells when the fluid pressure would normally drop and will absorb any increase in pressure when the temp increases.

Iain


Title: Re: new to the world of Solar Thermal
Post by: neilglos on April 27, 2016, 01:02:31 PM
thanks Iain, no wonder I thought I had a leak over the last few cold nights as my pressure dropped below 1 bar....my EV is @ the stock 2.5 bar;

Should I just let some pressure out of the EV in the evening when the temp lowers?

do I lower the system pressure to zero 1st, then lower the EV and build up the pressure again in the system?

This forum is fabulous, I wish there was a 101 guide for commissioning & DIY'ers:-)


Title: Re: new to the world of Solar Thermal
Post by: Iain on April 27, 2016, 01:47:47 PM
Hi
Ideally the system pressure should be zero when setting pre charge.
However as you are  at a higher pressure at present you might get away with just reducing the pressure to a more realistic one
and see how it goes and wait to see if you have to do work on the system and finally set it then.
 Or you should only loose a bit of fluid if you do it now, and then it is done. Thinking about it,
 if the EV pressure is high then you probably won't have any fluid in the EV so shouldn't loose much at all if you do it now

Iain


Title: Re: new to the world of Solar Thermal
Post by: neilglos on June 03, 2019, 09:44:34 PM
Our system has been working really well over the previous years; this year I would like a holiday and less baths in the summer - so have fitted a heat dump tapping into the Hot water coil with another pump. I have recommissioned the TDC with D.25 Solar + cooling 3; I have been struggling with the manual again ☹ please could you confirm my setting are ok?

TminS1 20 C
TmaxS2 75 C
^TR1 10 C /3 C
TsetS3 60 C
Hysteresis 10 C
TmaxS3 60 C

We have a house thermal mixing value so happy to run the tank hotter than 60 C

Many thanks Neil


Title: Re: new to the world of Solar Thermal
Post by: dimengineer on June 04, 2019, 03:26:47 PM
thanks for the update, it is a system boiler - Greenstar i System (24), I do suspect the boiler continually monitors the pump :-( as i have no error when I restore the default wiring.

I was researching last night and my system is sized correctly eg 30 tubes 250l tank ie within 7.5l per tube;
There are two camps here, dump or no dump?
I have set the tank max temp to 75 as I have a TMV and shall monitor, worst case I cover the tubes for holidays...

I'm in the No Dump camp - I'd suck it and see this summer. I have a 250 litre store, and a 21 x 58mm tube Kloben panel. So a little less powerful than yours. I've never ever had it stagnate. Max temperature I've ever seen was about 75C in last years heatwave. That's in 10 years.
Basically, as the temperature climbs, the losses climb too. In my case they equilibrate at about 75C.


Title: Re: new to the world of Solar Thermal
Post by: Iain on June 04, 2019, 04:29:58 PM
Hi
Just looked at my settings.

Min Speed 40%
Delta T on 9
Delta T off 6
Max T 78

My max store temp is set to 78 deg C. This triggers the heat dump and works well.
It used to be 85 deg C but this caused the emergency thermostat trips to trip. As they were a manual reset trip it caused problems. with the setting to 78 the emergency trips stayed closed.

Iain