Solar Pump Failure ? Help

garyh3 · 12-04-2020 1:31pm #1

Ok Yesterday I notice that our solar system was very hot 140 degrees and that the pump on the display was turning but the water in the tank was not getting any hotter.

Went up into the attic and the pump was very hot it was making a noise like it was turning. The pressure gauge was at 1.6 bar and the temp gauge was really high.

On the Night when it was cool I took out the screw on the pump and turned the motor seems to run fine? is the pump busted?. was only replaced about 3 years ago with the glycol.

Any ideas? should I run off the solar system?

I also notices that the installers didn't put any stop valves between the pump so it looks like the system will have to be drained to replace the pump if needed ? Any help appreciated?

The pump is a grundfos ups 25-60 180

garyh3 · 12-04-2020 1:34pm

Here is a pic of the pump

spose · 12-04-2020 3:00pm

If it’s reading over 60 at the pump then to me that says it was moving the glycol around the system. If you have a bypass circuit was it circulating through that instead of to the tank. My guess is something within your settings to not allow temperature that high to sent to the water tank. Should be running ok today if nothing mechanically wrong

garyh3 · 12-04-2020 3:17pm

spose wrote: »

If it’s reading over 60 at the pump then to me that says it was moving the glycol around the system. If you have a bypass circuit was it circulating through that instead of to the tank. My guess is something within your settings to not allow temperature that high to sent to the water tank. Should be running ok today if nothing mechanically wrong

Sorry when i took the pic it was early morning but the temp gauge was upto 140

spose · 12-04-2020 4:38pm

If the pump wasn’t moving the glycol I would expect the gauge near the pump to stay cold so my guess fault is elsewhere. Even with terrible weather today should still be putting some heat in the tank. Your display should give you temperature at the panel and bottom of tank.

garyh3 · 12-04-2020 5:14pm

spose wrote: »

If the pump wasn’t moving the glycol I would expect the gauge near the pump to stay cold so my guess fault is elsewhere. Even with terrible weather today should still be putting some heat in the tank. Your display should give you temperature at the panel and bottom of tank.

The hot water tanks display S1 panel’s were 140 but S3 didnt change which is top of the tank so i presume the water from the panel's didnt get circulated around the system?

freddyuk · 13-04-2020 9:02am

Possibly pump Capacitor has failed. Easy to replace without draining down. You can run the pump and remove big screw (bucket underneath) and check if the rotor is actually spinning - gently touch rotor with screwdriver as it can hum but not actually pump. If the capacitor has failed pump will get hot. Don't mess with capacitor until you know what you are doing as they hold a high charge. You could swop the capacitor from your central heating pump just to check once it has been discharged.

garyh3 · 13-04-2020 10:26am

freddyuk wrote: »

Possibly pump Capacitor has failed. Easy to replace without draining down. You can run the pump and remove big screw (bucket underneath) and check if the rotor is actually spinning - gently touch rotor with screwdriver as it can hum but not actually pump. If the capacitor has failed pump will get hot. Don't mess with capacitor until you know what you are doing as they hold a high charge. You could swop the capacitor from your central heating pump just to check once it has been discharged.

Ok thanks will get my multimeter out and check capacitor. Will check carefully if it has any charge currently. Ive already tested the pump and it does turn with a screwdriver

mordeith · 13-04-2020 10:32am

garyh3 wrote: »

Ok thanks will get my multimeter out and check capacitor. Will check carefully if it has any charge currently. Ive already tested the pump and it does turn with a screwdriver

We had a similar issue where the tank wasn't getting hotter. I don't know much about it but there is a gauge attached to the pressure vessel and it was lower than the it should have been so water wasn't circulating properly. Plumber sorted it by adding glycol. Not sure if he drained old stuff first or not (as I say I'm too familiar with the workings?

garyh3 · 13-04-2020 11:24am

mordeith wrote: »

We had a similar issue where the tank wasn't getting hotter. I don't know much about it but there is a gauge attached to the pressure vessel and it was lower than the it should have been so water wasn't circulating properly. Plumber sorted it by adding glycol. Not sure if he drained old stuff first or not (as I say I'm too familiar with the workings?

Pressure is just below 2 so would expect to some heat to get into the tank

garyh3 · 13-04-2020 11:28am

garyh3 wrote: »

Ok thanks will get my multimeter out and check capacitor. Will check carefully if it has any charge currently. Ive already tested the pump and it does turn with a screwdriver

Ok unit seem to be a complete power unit so I dont see a way to remove and replace just the capacitor. There was 0 V on the capacitor which I would expect as its not been on for a while. Can you buy just the power assemble of the Pump ?

Thanks for your help

garyh3 · 13-04-2020 7:22pm

ok pulled capacitor out 0 on the multi meter not taking a charge

does anyone know where to get one of these capacitors

has 2 wires coming out from a resin top

MD MKP
2.5/400
mkp 2,5 uf +- 5%
400v ac 30000h/KIA
460 ac 10000/KIB
25/85/21
400v ac 10000h/KIB
25/100/21
50/60Hz

en 60252
04.02

Size is about 2.5Wide x 4.8High cm

freddyuk · 28-04-2020 12:57pm

Digikey....

garyh3 · 28-04-2020 2:52pm

put in a new capacitor docent make any difference I think the pressure is low ? below 1 bar when cold

freddyuk · 29-04-2020 11:14am

Pressure will not affect flow if the pump is actually pumping. It may be an airlock between collector and pump. Is there a valve on the collector or high up in the system where you can bleed it? (there should be).

garyh3 · 29-04-2020 11:47am

hi freddyuk let me take a few photos, docent seem to much to the system. Would love to know what i can do to resolve this.

The only think i do not see is any isolation valves between the pump.

Pump is a 25-60 180 what can i use to replace this Grundfos pump if it is gone?
is it possible to use a 130 and put isolation valves between the pump ?

thanks

Gary

garyh3 · 29-04-2020 1:41pm

Photos of System

John.G · 29-04-2020 9:16pm

That pressure of < 1.0 bar when cold is certainly too low as it probably can't overcome the static head, it should be 1.5/2 bar when cold, mine is 2.6 cold and ~2.8/2.9 hot.
Just get it topped up, I would be surprised if it is the pump, it will also require venting while topping up.

freddyuk · 30-04-2020 8:03am

If the pump station is in the attic?? - there wont be much static head? ... so first thing is to vent the system from the roof vent (if there is one) or simply crack the joint at the collector when its cold. If you get air leaking but no fluid then that's your problem.

homewardbound11 · 30-04-2020 8:07am

It sounds like it’s air locked

John.G · 30-04-2020 9:11am

Also check the pressure (tyre pressure gauge) at the air end with system cold, should be ~ 2 bar.

garyh3 · 30-04-2020 9:20am

the Expansion Vessel is at .8 bar ? should I increase to 2.5?

When you say "crack the joint at the collector when its cold" can you explain.

thanks

Gary

John.G · 30-04-2020 9:33am

Increase it to until it reaches 2/2.25 bar, if the "water" end pressure is the same then you will not have lost any water/glycol mix and it should be OK without venting.

garyh3 · 30-04-2020 9:45am

thanks John Ill get me bike pump out !

John.G · 30-04-2020 10:07am

As you are pumping it up, stop pumping if the (water end) pressure stops rising before you have reached 2 bar, that will give a fair indication of whether you have lost any liquid.

garyh3 · 30-04-2020 5:58pm

pumped the expansion vessel to 1.6 bar and nothing moved !

John.G · 30-04-2020 7:11pm

You said in first post "On the Night when it was cool I took out the screw on the pump and turned the motor seems to run fine? is the pump busted?. was only replaced about 3 years ago with the glycol." I take it you just turned the motor shaft with a screwdriver?, you also said that during the day it seemed to be getting a call to run (controller display) so I think the only other thing to do is either check with a m.meter at the pump terminals for voltage when it is being called to run from the controller and/or run a separate supply to the pump and see if will it run, can't think of anything else. If you do decide to run it off a separate supply just give it a few seconds as you don't want to thermally shock the system if the collector temperature is still very high.

For interest what is your controller make/model and do you have E,Tubes or F.Plates?

Also, have you any error codes displayed on the controller?.

garyh3 · 30-04-2020 10:03pm

John.G wrote: »

You said in first post "On the Night when it was cool I took out the screw on the pump and turned the motor seems to run fine? is the pump busted?. was only replaced about 3 years ago with the glycol." I take it you just turned the motor shaft with a screwdriver?, you also said that during the day it seemed to be getting a call to run (controller display) so I think the only other thing to do is either check with a m.meter at the pump terminals for voltage when it is being called to run from the controller and/or run a separate supply to the pump and see if will it run, can't think of anything else. If you do decide to run it off a separate supply just give it a few seconds as you don't want to thermally shock the system if the collector temperature is still very high.

For interest what is your controller make/model and do you have E,Tubes or F.Plates?

Also, have you any error codes displayed on the controller?.

No error codes
Grundfos 25-60 180
Solar evac tubes
Now if i unplug the cables from the pump and turn on call the wires are live with multimeter
When i connect them to pump and call there dead? Is there a short maybe?

Gary

John.G · 30-04-2020 11:26pm

Hi Gary,
Some controllers output a variable speed signal to the pump so could be a fault at that end despite your readings, I would just supply a external power supply to the pump and see if it drives it.

Controller make/model??.

garyh3 · 01-05-2020 8:58am

think is Sorel TDC3 controller been in about 15+ years now

garyh3 · 01-05-2020 9:34am

John.G wrote: »

Hi Gary,
Some controllers output a variable speed signal to the pump so could be a fault at that end despite your readings, I would just supply a external power supply to the pump and see if it drives it.

Controller make/model??.

Ok Ill get some extension lead and plug I have some flex cable somewhere and connect direct to power. See if that works

CHeers

John.G · 01-05-2020 10:14am

There are two relay outputs on that controller, R1 is the electronic(speed) output and R2 is the mechanical fixed speed output, so depending on what your test, above, shows, you may be able to use R2 (if R1 is currently in use) and just run off the collector/store temperature differential (like mine) until you decide what to do.
If the pump doesn't rotate on its present setting, you could try one of the other settings 1,2 or 3 and see if that gets the pump going as a temporary fix.

garyh3 · 01-05-2020 10:25am

Looking though options

ABS R1 set Relay 1 @ 12 for 5 seconds (frost protection)

ABS R2 Relay 2 @ 12 for 5 seconds (Anti Seizing)

Thats what there currently set at

Gary

John.G · 01-05-2020 10:38am

Not sure re frost protection on R1 but I certainly know that my controller pulses the pump on for 5 secs at noon (12) each day if the pump hasn't ran in the past 24 hours.
Anyhow carry out your test and see what it shows up.

garyh3 · 01-05-2020 12:18pm

Ok Hot wired it and it came on making a bit of noise though. The S1 temp tubes went down but S3 remained at 30 Degrees ??? Didnt go up as was expecting. (S3 not faulty) ?

any ideas

John.G · 01-05-2020 12:53pm

Not familiar with that controller but generally speaking S1 is the collector (tube) temperature, S2 is probably the store (bottom of cylinder, just above the top of the solar coil) temperature and S3 might be the cylinder Top temperature, I would expect T2 to rise gradually and eventually, depending on the cylinder temperature gradient, S3 to start rising at the same rate as S2 provided no body is drawing hot water off.
Anyhow since S1 is decreasing and you know that the pump is operating, you might just switch the pump setting, and see if still noisy, select it to the lowest least noisy setting. You could then try it back on relay R1 and see if it runs, if not c/o wiring to output R2 and see what happens. You might also see what programme the Controller is currently set to and I can have a look at it.

garyh3 · 01-05-2020 1:23pm

thats correct John

S1 tubes
S2 Bottom of tank
S3 Top of Tank

When hot wired it nothing changed except S1

I would expect S2 and S3 to go up

Gary

John.G · 01-05-2020 1:44pm

Was the sun out??, the heat has to be going somewhere, obviously if you are running the pump manually then once S1 is equal to S2, then no heat will be transferred, the way I have set mine up is Pump ON when (S1-S2) = 10C and Pump OFF when (S1-S2) = 3C.

You will have to get your pump running from the controller, either via R1 or R2 before you can form any real opinion except you sit in front of the display and operate the pump roughly based on my settings above.

garyh3 · 01-05-2020 2:35pm

John.G wrote: »

Was the sun out??, the heat has to be going somewhere, obviously if you are running the pump manually then once S1 is equal to S2, then no heat will be transferred, the way I have set mine up is Pump ON when (S1-S2) = 10C and Pump OFF when (S1-S2) = 3C.

You will have to get your pump running from the controller, either via R1 or R2 before you can form any real opinion except you sit in front of the display and operate the pump roughly based on my settings above.

Sun was out about 120 on the tubes but S2S3 didnt move very strange could there be a problem with the control unit?

John.G · 01-05-2020 2:58pm

If S1 fell substantially below 120C and S2 didn't move then it points to air in the system.

dathi · 01-05-2020 4:21pm

https://www.nn-energy.se/doc/tdc3_english_72013.pdf

have a look here the settings are t-min s1 tmax s2 and aTr1 they are in settings which is no5 on list on controller still say you need to refill

John.G · 01-05-2020 7:12pm

Whatever settings are there at the moment have served Gary well for the past 15 years or so, but may have to modified slightly if the pump was changed over to run on/off as against it's presumably variable speed mode. The problems possibly started when the pump gave up and the E.tubes then reached stagnation temperature which can be up to 240C, when this happens the solar fluid starts vaporising and blows the remaining liquid down into the E.vessel, when the temperature falls the vapour condenses and returns to its liquid state, the problem is that air can form when this is happening, presumably when the liquid turns into a vapour, and then has to be purged from the system. E.tubes are far worse in this regard as F.Plates do not reach stagnation temperatures as easily because they are not as efficient.

I would agree that the system needs purging and probably refilling/recharging but the pump problem will have to addressed first, probably a new pump. another item that's overlooked is that when the system is being commissioned or/and recharged that not enough attention is paid to the pre charge pressure and the filling pressure, the filling pressure should be ~ 0.3 to 0.5 bar higher than the pre charge pressure to give a reserve of solar fluid, for example my 18 litre E.vessel was pre charged to 2.0 bar and filled to 2.5 bar which gave a reserve of around 2.5 litres and has never required topping up, (obviously, no leaks either).

garyh3 · 01-05-2020 7:32pm

dathi wrote: »

https://www.nn-energy.se/doc/tdc3_english_72013.pdf

have a look here the settings are t-min s1 tmax s2 and aTr1 they are in settings which is no5 on list on controller still say you need to refill

Mine are set to Tmin S1 15 degrees C and Tmax S2 70 Degrees C
tr1 16 degrees C Tset is 65 hystersis 65

garyh3 · 01-05-2020 7:33pm

also tubes are old is it possible to get replacements as I suspect that some of the tubes have failed

wimex pannels
58mm x1800mm
22 mm copper

garyh3 · 01-05-2020 7:34pm

John.G wrote: »

If S1 fell substantially below 120C and S2 didn't move then it points to air in the system.

Exactly what happened

garyh3 · 01-05-2020 7:37pm

John.G wrote: »

Whatever settings are there at the moment have served Gary well for the past 15 years or so, but may have to modified slightly if the pump was changed over to run on/off as against it's presumably variable speed mode. The problems possibly started when the pump gave up and the E.tubes then reached stagnation temperature which can be up to 240C, when this happens the solar fluid starts vaporising and blows the remaining liquid down into the E.vessel, when the temperature falls the vapour condenses and returns to its liquid state, the problem is that air can form when this is happening, presumably when the liquid turns into a vapour, and then has to be purged from the system. E.tubes are far worse in this regard as F.Plates do not reach stagnation temperatures as easily because they are not as efficient.

I would agree that the system needs purging and probably refilling/recharging but the pump problem will have to addressed first, probably a new pump. another item that's overlooked is that when the system is being commissioned or/and recharged that not enough attention is paid to the pre charge pressure and the filling pressure, the filling pressure should be ~ 0.3 to 0.5 bar higher than the pre charge pressure to give a reserve of solar fluid, for example my 18 litre E.vessel was pre charged to 2.0 bar and filled to 2.5 bar which gave a reserve of around 2.5 litres and has never required topping up, (obviously, no leaks either).

Well if its a new pump would a variable speed be better ?
would be a like for like pump 25-60 180 ?

New pump will have to drain the system so will have to Change glycol

thanks for your advice

John.G · 01-05-2020 7:55pm

The older generation pumps like yours were fixed speed only but can/were run in variable speed mode by means of the controller variable speed output, R1, all new "smart" pumps are variable speed by the nature of their electronics so a bit of care must be exercised when choosing the pump to make it compatible with the controller variable speed output, I have seen where some of these pumps have a pulse width modulation (PWM) mode which can be used in conjunction with your controller, just ensure that the correct pump is selected, dathi might advise on this.

dathi · 02-05-2020 11:22am

John.G wrote: »

The older generation pumps like yours were fixed speed only but can/were run in variable speed mode by means of the controller variable speed output, R1, all new "smart" pumps are variable speed by the nature of their electronics so a bit of care must be exercised when choosing the pump to make it compatible with the controller variable speed output, I have seen where some of these pumps have a pulse width modulation (PWM) mode which can be used in conjunction with your controller, just ensure that the correct pump is selected, dathi might advise on this.

I have only changed my own pump changed it like for like sent link to gar had tried modern pump wilco yonos but the controller wasn't able work with it massive buzzing

dathi · 02-05-2020 11:30am

garyh3 wrote: »

also tubes are old is it possible to get replacements as I suspect that some of the tubes have failed

wimex pannels
58mm x1800mm
22 mm copper

if you check the bottom of the tubes if the silver has turned white the vacuum has blown was a guy on adverts selling them a while ago

John.G · 02-05-2020 12:32pm

dathi wrote: »

I have only changed my own pump changed it like for like sent link to gar had tried modern pump wilco yonos but the controller wasn't able work with it massive buzzing

My 9 year old system has a Wilo ST 25/6-3, 3 speed pump, set to minimum speed, the controller, a fairly basic Lago SD2, only sends a stop/start signal to the pump so the Wilo Yonos Pico set to one of the constant speeds should be OK for this signal but not for a variable speed (R1) signal.
I think that the direct replacement for the Wilo ST 25/6-3 is the Wilo ST 25/6-3P.

garyh3 · 03-05-2020 3:23pm

John.G wrote: »

My 9 year old system has a Wilo ST 25/6-3, 3 speed pump, set to minimum speed, the controller, a fairly basic Lago SD2, only sends a stop/start signal to the pump so the Wilo Yonos Pico set to one of the constant speeds should be OK for this signal but not for a variable speed (R1) signal.
I think that the direct replacement for the Wilo ST 25/6-3 is the Wilo ST 25/6-3P.

To be honest i think ill do a like for like pump change and jjst get the system purged and re pressured no point in trying to get a variable to work i def need to get the tubes looked as there are 72 of them and dont really get the heat anymore

Solar Pump Failure ? Help

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