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Solar hot water system - pump faulty

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ljcox

Well-Known Member
I have a Chromagen domestic open loop Solar Hot Water system.

I've been suspicious for some months that it is not working properly.

So, yesterday (must not hurry these things), I measured the power going into the pump.

It was about 73 Watt. The pump was so hot that I could not hold my hand on it for very long even though it was an overcast mild day.

The pipes into and out of the pump were cool (actually - the pipe above the pump was sightly warm but I assume that was due to conduction from the pump). The controller indicated that the pump was running.

I could not hear the pump running (I assume I would hear something if it was) or feel any vibration, so I assume the pump is jammed.

I went out this morning at 6 am and the pump was cold & the controller indicated that the system was in standby - as it should have been.

Does anyone have any experience with this system?

Any advice will be appreciated.
 
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I dont have any experience in this system at all .
That said a water pump is a water pump after all . Turn any electrical power off . I'm assuming the pump is circulating water through the system So I would assume that on the storage tank side of this pump it should be very hot if all is working OK.

It seems this may be the pump
https://www.solartown.com/store/product/taco-bronze-recirculating-sweat-pump/#null;
looks like it is serviceable. Some sites give a Grundfos pump near the tank ,240 Volt.

Firstly is there a filter inline at all ? (it does not seem so) if so check it is clear by dismantling it and cleaning it . If you don't find a problem there remove and check and clean the pump . The usual problem with pumps is a worn or broken impeller. Its plastic it seems above and bits of it can break off and flow down the pipework, so check the impeller is whole not broken . The whole bit can be replaced it seems

To check the operation of the pump you must power it up and ensure it runs at full speed . I'll google your model and if I find anything I'll edit this post.Often the brushes on motors wear until no further contact can be made , or they stick with the same result so a clean and check of the brushes is always worthwhile . Its not hard but if you do not feel confident get someone to check it for you or replace the motor and impeller.

When all else fails read the "Owners Installation Manual"
down the bottom of this page
**broken link removed**
 
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Thanks very much for the prompt reply.

Unfortunately, the pump in the link is not mine. See the attached photos.

As you can see it is a sealed unit.

It looks as if I'll have to cut the water off to remove the pump to inspect it.

Yes, something may have broken inside & jammed it.
 

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Hi Len,
From taking a close look at the photos there does appear to be an isolation valve above the pump but none below the pump. This could mean you will need to drain the tank to get the pump off or have a nice mess to clean up. What I would do ( after isolating all power) is loosen the 4 allen head bolts and see if any water leaks. I showed a mate on irc your pic and he did say his looks the same and you can take the motor off and it is sealed from the water. By the sounds when you said it was too hot to touch there is a good chance the motor is burnt out. Hopefully you can take the motor off and not have a big mess but as you said it has been playing up so it may pay to start looking for a new inline pump. If you endup going that route do a bit of plumbing and put an isolation valve under the pump so if the pump ever goes again it will be easy to take it out.

Cheers Bryan
 
I notice this pump as with most these days has a thermal cutout -It is likely no damage has been done to the motor but a strip is necessary I suggest.

Before anything try the center screw on the pump ,turn it to 6M head and try -it may be that whatever circuitry they have in there is corroded or kaput and it may work on the 3M or 6M setting.

As far as water flow, its probable that little water will flow out if you can stop the air getting into the tank while you are checking the pump. with the upturned tube and fittings below the pump air will not be sucked in and therefore water cannot flow out as long as no water can get into the tank from the top while you are doing this -Think about it -Like an upturned beer bottle full of water in a dish full of water. Until the dish level falls to allow air to enter no water can flow out.

That said though the non -return valve above would allow air in .If it is an isolation valve as mentioned then make sure it is off.

https://www.sydneytools.com.au/shopexd.asp?id=9980&bc=no
$228 for a new pump is good news hey?

Heres some specs of the pump
Liquid:
Max. operating water temperature:80 deg C
Temperature:Class 110
Materials:
Pump body:Bronze, DR
Back Plate and Rotor Can:Stainless Steel
Impeller:pPO
Installation:
Maximum ambient temperature:40 deg C
Maximum operating pressure10 bar
Port Spacing:150 mm
Pipe connections suction/discharge:1-1/4” BSP M
Optional Union Set:1-1/4” BSP F/3/4” BSP F
Electrical data:
Rated voltage:240V
Mains frequency:50 Hz
Current Max:0.4 amps
Capacitor:3 uF
Power consumption speeds 1,2,3 46W, 67W, 100W
Motor duty:Continuous
Motor type:Canned rotor
Motor protection:In-built thermal overload
Ingress protection:IP 42
Insulation class:F
Power cable length: 1.2 m
Net weight:4.0 kg
 
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That looks like a standard cartridge style pump. They are easy to take apart and clean out. If you close the valve above the pump there is a good chance there will be minimum water loss or at least it will be greatly slowed down to the point that you may get lucky and be able to pack a few rags into the bottom port and stop the flow almost entirely.

The four screws are all that hold the motor in place and once they are out its just a good tap with a hammer at most to free it from the base. As far as replacing it most of those are built to an industry standard so that just swapping the motor unit from one to the next is usually possible even if its not the same brand.

The end screw is not likely the speed setting but an access port to get to the rotor shaft and spin it with a screwdriver. Try unscrewing it and see if you can free up the stuck rotor that way. If not you may have to disassemble the whole motor and clean it out. One its out of the base you should be able to take a punch and drive the rotor right out of the motor case unless its rusted in to badly.

If you where closer I would just sell you a spare one of mine. I bought a whole lot of surplus Grundfoss pumps a few years ago real cheap and will likely never use all of them.I cant say for 100% certain but the Grundfoss motor assembly probably would fit the base you have making a change out really easy. I think all of my pumps I have are the flange type fitting instead of the threaded style like you have though.

If you are interested I could sell you one cheap. $30 plus shipping is all I would expect being thats what I paid for all of them. I also have a bunch of used take offs that work or are good for parts if you wanted one, or a two or three, of them you could have them for the cost of shipping.
 
This is what she looks like inside.

Pump Dis-assembly.
 

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Thank you all very much for your comments, suggestions and information.

I had found the Sydney site that sells the pumps, but with the Manual provided by kilovolt and your other suggestions, I should be able to locate and fix the fault and, hopefully not have to replace the pump.

As for the point about stopping the water flow, I can:-

1. Turn the isolation valve off, as I think Bryan suggested, and
2. use the trick the water authorities use when they have to repair the tap (I think you use a different term in the US) at the water meter of someone’s house. I believe they put dry ice around the pipe on the supply side of the tap, to freeze the water inside the pipe thus stopping the flow while working on the tap. So my idea is to apply the dry ice to the T junction below the pump.

However, I don’t know where I can get dry ice these days (do you know Bryan?). Dry ice is frozen carbon dioxide (in case you don’t know what it is).

As an alternative, I could freeze some salt water in the fridge (since, as you know, it freezes at 0 degrees Fahrenheit compared to freshwater which freezes at 0 C) and pack that around the pipe below the pump.
 
Thank you all very much for your comments, suggestions and information.

I had found the Sydney site that sells the pumps, but with the Manual provided by kilovolt and your other suggestions, I should be able to locate and fix the fault and, hopefully not have to replace the pump.

As for the point about stopping the water flow, I can:-

1. Turn the isolation valve off, as I think Bryan suggested, and
2. use the trick the water authorities use when they have to repair the tap (I think you use a different term in the US) at the water meter of someone’s house. I believe they put dry ice around the pipe on the supply side of the tap, to freeze the water inside the pipe thus stopping the flow while working on the tap. So my idea is to apply the dry ice to the T junction below the pump.

However, I don’t know where I can get dry ice these days (do you know Bryan?). Dry ice is frozen carbon dioxide (in case you don’t know what it is).

As an alternative, I could freeze some salt water in the fridge (since, as you know, it freezes at 0 degrees Fahrenheit compared to freshwater which freezes at 0 C) and pack that around the pipe below the pump.

Ha Ha Ha - A joke I take it -ignore my post by all means . Good luck with the freezing of salt water ! You are obviously well informed
 
Ha Ha Ha - A joke I take it -ignore my post by all means . Good luck with the freezing of salt water ! You are obviously well informed

And that comment comes from the guy who recommended checking the brushes on a induction motor. :rolleyes:

To check the operation of the pump you must power it up and ensure it runs at full speed . I'll google your model and if I find anything I'll edit this post.Often the brushes on motors wear until no further contact can be made , or they stick with the same result so a clean and check of the brushes is always worthwhile . Its not hard but if you do not feel confident get someone to check it for you or replace the motor and impeller.


If I was ljcox I would probably not give you much credit either. :eek:
 
Hi Len,
Over here in Adelaide I can get dry ice from BOC so it may pay to contact them over there and hopefully they can help you out.

Regards Bryan
 
Ha Ha Ha - A joke I take it -ignore my post by all means . Good luck with the freezing of salt water ! You are obviously well informed

What did you consider to be a Joke? I did not intend anything I said in my posts as a joke.

I won't be ignoring your post. I intend toi read them all in detail this evening.
 
Before anything try the center screw on the pump ,turn it to 6M head and try -it may be that whatever circuitry they have in there is corroded or kaput and it may work on the 3M or 6M setting. I'll try that.

As far as water flow, its probable that little water will flow out if you can stop the air getting into the tank while you are checking the pump. with the upturned tube and fittings below the pump air will not be sucked in and therefore water cannot flow out as long as no water can get into the tank from the top while you are doing this -Think about it -Like an upturned beer bottle full of water in a dish full of water. Until the dish level falls to allow air to enter no water can flow out.

That said though the non -return valve above would allow air in .If it is an isolation valve as mentioned then make sure it is off.
I had a close look at the pump & T junction below it.

I see what you mean. When I remove the pump, the water level will be level, so no air will be able to get in - as you said - using the bottle example.

Provided that the isolation valve is closed, no air should be able to get in there either.

So I won't need the dry ice.

Thanks for the suggestion.
 
Hi Len,
BOC is the gas place where one gets oxy, acetylene etc cylinders

Regards Bryan
Thanks Bryan,
It looks as though I won't need the dry ice as in my previous post.

But have I wondered in the past if it can be purchased by ordinary mortals - when I thought I may have to replace the washer in the mains supply tap.

But it proved to be unnecessary at that time, but who knows what the future holds?

I know Melbourne Water should do it, but I assume they will charge a fee.

regards,
 
The attachment "System diagram" shows an extract from the Solar System Handbook (from the link kindly posted by killivolt) that shows a diagram of the plumbing.

You will see there are three non return valves (NRV) shown, but in the photo "Pump & Tank 1", there does not appear to be any NRV with the possible exception of the device indicated by ????.

However, the isolation valve and the pressure reducer may have non return valves inside.

I followed the instructions in the solar system handbook page 11, paragraph 8. Fault finding - causes and remedies.

This indicates that to test whether the motor shaft has jammed, to remove the vent plug & and turn the shaft with a screwdriver.

So I turned off the cold water supply, turned the isolation valve anti clockwise & depressurised the system by briefly opening the pressure release valve (not shown).

I then unscrewed the vent plug indicated by the green arrow and attempted to turn the motor shaft with a screwdriver.

The shaft would not turn either way despite applying a moderate to firm torque on the screwdriver.

So it would appear that something has jammed the shaft.

So I will have to remove the pump and dismantle it.
 

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I removed the pump using tytower's suggestion, thank you, and no water flowed out except what was in the pump.

As you can see in the Old Pump photo, the shaft was rusted so I assume the bearings were also rusted as it is lubricated by the water.

So obviously, they used mild steel rather than stainless. Thanks very much, Bianco Pumps.

I called the company that supplied the system, and they said they now supply a different, better pump made by Grundfos. See New Pump attached.

Hopefully it is made from stainless steel.
 

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