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Author Topic: new to the world of Solar Thermal  (Read 4563 times)
Antman
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« Reply #15 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  whistlie

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
« Last Edit: April 22, 2016, 09:55:18 AM by Antman » Logged

20 x 47mm, 172 l cylinder, Heat Dump, 15 x Sanyo HIT-H250E, SB4000TL,  Nestor Martin IQ13 WBS
DIY Solar System Support at http://www.handyantman.co.uk/antman.html
All support is voluntary and free of charge. I'm not employed by Navitron so responses may not be same-day
neilglos
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« Reply #16 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
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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
neilglos
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« Reply #17 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  whistlie

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?
« Last Edit: April 22, 2016, 10:02:58 AM by neilglos » Logged

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
Antman
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« Reply #18 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
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20 x 47mm, 172 l cylinder, Heat Dump, 15 x Sanyo HIT-H250E, SB4000TL,  Nestor Martin IQ13 WBS
DIY Solar System Support at http://www.handyantman.co.uk/antman.html
All support is voluntary and free of charge. I'm not employed by Navitron so responses may not be same-day
Iain
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« Reply #19 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


* IMG_1796.jpg (59.55 KB, 800x561 - viewed 533 times.)
« Last Edit: April 22, 2016, 10:50:07 AM by Iain » Logged

1.98kWp PV (11 x Sharp 180 and SB 2.5)
20 x 65mm Thermal and 180ltr unvented
Powervault 4Kw - G200 Lithium-Ion (LiFePO4)
9000ltr rainwater storage   Plymouth
neilglos
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« Reply #20 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
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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
Iain
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« Reply #21 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
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20 x 65mm Thermal and 180ltr unvented
Powervault 4Kw - G200 Lithium-Ion (LiFePO4)
9000ltr rainwater storage   Plymouth
neilglos
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« Reply #22 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
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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
Iain
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« Reply #23 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
« Last Edit: April 27, 2016, 12:33:00 PM by Iain » Logged

1.98kWp PV (11 x Sharp 180 and SB 2.5)
20 x 65mm Thermal and 180ltr unvented
Powervault 4Kw - G200 Lithium-Ion (LiFePO4)
9000ltr rainwater storage   Plymouth
neilglos
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« Reply #24 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:-)
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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
Iain
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« Reply #25 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
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1.98kWp PV (11 x Sharp 180 and SB 2.5)
20 x 65mm Thermal and 180ltr unvented
Powervault 4Kw - G200 Lithium-Ion (LiFePO4)
9000ltr rainwater storage   Plymouth
neilglos
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« Reply #26 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
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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
dimengineer
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« Reply #27 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.
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Iain
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« Reply #28 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
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1.98kWp PV (11 x Sharp 180 and SB 2.5)
20 x 65mm Thermal and 180ltr unvented
Powervault 4Kw - G200 Lithium-Ion (LiFePO4)
9000ltr rainwater storage   Plymouth
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