Does it sound like my Solar tubes are working correctly?

Grumpypants · 13-05-2019 2:15pm #1

Hi All,

I bought a second hand house 4 years ago. The House is 11-12 years old. It has solar tubes on the roof. A pump in the hot press with a 300l hot water cylinder. It is working as it will pump the water around if the roof temp gets to 7 degrees over the water temp (that's what the guy who serviced it set it to) and it does heat the water a little.

For example on a scorching hot day like today (21 degrees at 2pm) it say the temp on the roof is 30 and the water in the tank is 23 degrees.

The first three days we moved in was a heat wave in April and i remember having hot water all the time. But the hottest I've ever seen it since was around 42 on the roof and it got the water to about 35 degrees.

We have to put the oil on to get it up to 60 pretty much every day. We only use it in the evening so the hot water top up is done around 6pm

It's a 300l twin coil cylinder. On the roof we have two sets of 18 tubes (36 in total). I don't know a whole lot more about the system.

But does that sound about right? I've heard others saying i should get 50-60 degrees in the summer. Others say it should only do 20-40% of the work and that's how you save money. So 30 sounds about right in that context.

rolion · 13-05-2019 4:18pm

Defo something wrong there !!!

Could be that the sensor is out of the mixer and is not reporting corect values down / back to the controller (sensor mounted on the roof);
Could be that the pressure is not enough for the liquid to flow ;
Could be that there is air inside the piping (pipe for the solar agent);
Possible but unlikely, the pump is setup on fast speed 100% and doesnt have the timp to transfer the heat from tubes to agent.

Take few photos of the pump settings switch,the pressure meter and the controller.

All above,subject to public boards F o C consultation !

PS
My 30 tubes today,at 3pm:

Charlie-Bravo · 13-05-2019 4:40pm

Hey Rolion, what software is that you have? I don;'t have anything like that for my system and would like to get an app to view info remotely.

unkel · 13-05-2019 4:50pm

Even if the pump is not working, if you have air locks, if the pressure is too low, in any of those situations the temp sensor on the roof should still report the correct temp (around 100C today, not the 30C or 42C max you have been seeing), so my money is that the temp sensor on the roof is faulty.

rolion · 13-05-2019 5:03pm

astrofluff wrote: »

Hey Rolion, what software is that you have? I don;'t have anything like that for my system and would like to get an app to view info remotely.

May i ask you what system do you have !?

unkel wrote: »

Even if the pump is not working, if you have air locks, if the pressure is too low, in any of those situations the temp sensor on the roof should still report the correct temp (around 100C today, not the 30C or 42C max you have been seeing), so my money is that the temp sensor on the roof is faulty.

I had to move my tubes to make place for the PVs panels.
When the sensor went in the cover,i didnt fully pushed and sealed... it didnt reached the whole tube / full length of the contact with mixer. The controller was reporting very low temperatures,as the OP situation. All was workign fine just no hot water. Went back on the roof and found it,pushed and sealed,happy day.

Could be the sensor alright but not necesarily faulty ... or could be the controller faulty ?

unkel · 13-05-2019 5:09pm

Performance of my own system is not great at the moment. Regulary get an err -1 error on the SC400 control panel. Rang the installer a few weeks ago and he reckons it's an air lock. He could be right. Any easy way to fix this myself Rolion?

The system is in only 2.5 years now, don't really want to spend €€ on getting a service done (because if we got the man in, we might as well replace the glycol). Was hoping the service interval was about 5 years. It's a Kingspan Thermomax system, which limits the temps of the glycol to 95C (and self vents at the tube should temp go over this), which is nothing and should give a long life span

Bottom of the tank is now 43C (top 53C), should really be the max of 63C after a day like this. We did have 2 long showers during the day though.

Grumpypants · 13-05-2019 8:33pm

This is the set up in the hot press.

Charlie-Bravo · 13-05-2019 10:35pm

rolion wrote: »

May i ask you what system do you have !?

I have 4 flat plate 2x1m panels, hooked up to a large joule hot water cylinder. The info digital panel I have on the landing is from Nutech Renewables, some proprietary system but does not have any 'internet of things' capability. There is a diverter which appears to dump excess heat from the panels to a Dimplex smart rad on the landing, in case the panels get too hot. On the display, I can see the solar panel temps, hot water cylinder top and bottom temps, but would be good if I could read everything from an app which these Nutech guys don't do.

rolion · 14-05-2019 9:15am

unkel wrote: »

Performance of my own system is not great at the moment. Regulary get an err -1 error on the SC400 control panel. Rang the installer a few weeks ago and he reckons it's an air lock. He could be right. Any easy way to fix this myself Rolion?

The system is in only 2.5 years now, don't really want to spend €€ on getting a service done (because if we got the man in, we might as well replace the glycol). Was hoping the service interval was about 5 years. It's a Kingspan Thermomax system, which limits the temps of the glycol to 95C (and self vents at the tube should temp go over this), which is nothing and should give a long life span

Bottom of the tank is now 43C (top 53C), should really be the max of 63C after a day like this. We did have 2 long showers during the day though.

Can't help sorry.i know my limits here.
I know when they changed the heating agent,the guys brought a big noisy pump and they kept saying it has to be bubble free, no air and well insulated /sealed.
But those figures looks low alright but my system is being topped up by the PV diverter as well. Bottom always is the colder due to the cold water feeding in. Check collector and top cylinder.

Grumpypants wrote: »

This is the set up in the hot press.

Sorry, but never seen a system like in the photos.
I suggest to call out a pro as it may create a problem "tomorrow"...

astrofluff wrote: »

I have 4 flat plate 2x1m panels, hooked up to a large joule hot water cylinder. The info digital panel I have on the landing is from Nutech Renewables, some proprietary system but does not have any 'internet of things' capability. There is a diverter which appears to dump excess heat from the panels to a Dimplex smart rad on the landing, in case the panels get too hot. On the display, I can see the solar panel temps, hot water cylinder top and bottom temps, but would be good if I could read everything from an app which these Nutech guys don't do.

Well, my Joule system uses a german RESOL standard controller that can be controlled and automated in industry standards. They even give you access to SDK. More H E R E .

Not sure what controller you have, any pictures or names ?
Sometime,the supplier does not have "the minds" that can think out of the box and run all the IoT things...so maybe your controller can be remotely monitored just needs to do some "homework" yourself ?

Grumpypants · 16-05-2019 11:44am

I'm leaning towards to roof sensor not working right. Just testing yesterday it said 22 degree on the roof. i hit the manual pump button and it pumped the roof water down. I was holding to pipe to see if it got hot, and it got roasting, I couldn't hold the pipe for more than a second it was so hot. Easily 70-80+.

It only lasted for a 10-15 seconds before going cold again but no way it was 22 degrees. And I'm sure if it was regularly adding 10 seconds of 70 degree water to the tank it would get the overall well up over the day.

dathi · 17-05-2019 10:13am

if you cut some down-pipe bends lengthwise with handsaw and reattach them with cable ties you can tidy up the solar pipe and stops wind/birds disturbing the temp probe

Grumpypants · 19-05-2019 10:26am

It was definitely the roof sensor, nothing wrong with it, it was just put in by someone with zero idea what they were doing. Like most of the stuff in this house.

There was a hole with the hot water pipe coming off the roof into the attic. The wire was shoved up there into the cavity and stuffed with attic insulation.

I tipped it and could hear it scrapping around so it wasn't even connected to anything.

there was basically a black plastic box that sits on the roof to stop the rain getting in. The black pipe comes out from the tube system then turns and passes through the box to get inside. So the sensor wasnt connected to the tube system at all. It sat in this box next to it and only picked up the heat inside that black box. It only got hot because the pipe acted as a radiator and would heat the space.

To test it out i pulled the senor down and attached it to the pipe in the attic. Instantly popped to 30 degrees on the reading and started pumping and heating the water. Brought the tank from 20 to 23 while i was eating breakfast. And that was at 9.30 in the morning.

I just now need to figure out how to connect it properly so it gives maximum efficiency and it should make a big difference.

Grumpypants · 19-05-2019 1:18pm

Up to 30 degrees in the tank now. It's about 14-15 degrees outside and overcast. So there is defo an improvement. Looking forward to the next hot day to really test it.

Grumpypants · 28-09-2020 7:36pm

Was getting the roof cleared today so got them to pop back in the sensor. I was getting 41degrees on the roof at 5pm at the end of September!!

It was a pretty warm sunny day but that was good going. It had the hot water tank up to 34 degrees by half past 5. Dropped off then as it got cooler.

dathi · 30-09-2020 9:11am

Grumpypants wrote: »

Was getting the roof cleared today so got them to pop back in the sensor. I was getting 41degrees on the roof at 5pm at the end of September!!

It was a pretty warm sunny day but that was good going. It had the hot water tank up to 34 degrees by half past 5. Dropped off then as it got cooler.

had 62* top and bottom of cylinder on the 28th 30 tubes into 2oo litre cylinder

Does it sound like my Solar tubes are working correctly?

Comments