PV Immersion heater question

[styleruk]

Hi
I have fitted a PV Immersion heater to heat a single element in my tank when there is daylight. The installation seemed very simple and it appeared to generate some energy when I first fired it up, but a very small amount, since, it has not switched on the heater. The control box is displaying 'tank water hot'. But clearly it is not. I'm not sure how it would know this as all it has is power to the element and no loop to a thermostat.
My only thought is that it thinks it's getting power from the solar panels but is not switching on because the element will not power up.
I recently fitted a new thermostat, could it have simply stopped working?
The device that plugs around the cable I have clipped around the feed from the main meter to the fuse box, but there is a box between these two that connects the solar panels to the fuse board. I would assume that when the sender detects power going back into the meter, it switches on the heater. But this is not happening.

 

[Zerax]

You need to supply more details of your installation... pics always help.

 

[styleruk]

You need to supply more details of your installation... pics always help.

I guessed that would be the first question back, but was hoping for someone who had similar issue to point out the obvious. I'll have another look and test it with just a lamp or something first to see if power is getting to the heater then I'll take some pics of everything. My problem is, I can't really test it until the sun is out and i don't get home from work until 7pm. So I'll have a good go over the weekend.

 

[Deleted account]

You say there is no loop through a thermostat.

Then you say you have changed the thermostat.

Could you elaborate.

Cheers

 

[styleruk]

You say there is no loop through a thermostat.

Then you say you have changed the thermostat.

Could you elaborate.

Cheers

My hot water tank has a thermostat that is fitted into the tank and wired to the element, I only started using the hot water tank 6months ago to make use of the free solar energy, when I first tried it, the water temp went to max, so I bought a replacement thermostat as the old one had sat and done nothing for 8years. This worked fine with power coming from a standard socket with it's own power line to fusebox, with a fused plug.
To improve things, I fitted a smart plug to act as a timer and this has worked fine as well. Switching on for 2hrs during the day, but then I thought I'd gain more by using a PV controller.
So I got this PV immersion heater controller and simply wired that to the socket (with fused plug) and sent power from that to the heater. In theory, no difference.
Again, I will supply some pictures with more detail when I get the chance. But the fact that the unit is displaying that the tank has hot water bemuses me, how can it know? The only way I can think this could happen is that the immersion heater is simply not taking power, so when the unit gets the go ahead to use some free energy, it pumps it to the heater and the heaters says, no thank you, I don't need any.
So either...
a) the thermostat has crapped out again
b) the heater element cannot handle anything but 3kw. So the solar is sending say 300w and the heater element maybe does not take it? Can't imagine that would be the issues but I am running out of ideas.

 

[Boydy88]

What is the brand of the offending device, I worked with this kind of stuff a lot, and might be tell you of a few tricks, depending on the brand.

Rob

 

[styleruk]

What is the brand of the offending device, I worked with this kind of stuff a lot, and might be tell you of a few tricks, depending on the brand.

Rob

PV mate. Link below. A very simple device really, didn't think it would cause me problems.

This product is no longer available.

This product is no longer available.

www.alibaba.com

 

[snowhead]

Is the timer still connected to the Heater?

I would guess if the controller detects no current flowing to the heater it assumes the heater thermostat is satisfied.
If the timeswitch has isolated the heater then the controller won't see current flow.

 

[Boydy88]

OK, so a sneaky trick to see if it is working is to reverse the clamp and put your kettle on. This will trick the device into thinking that you are exporting and switch the immersion on.
If the device switches on and heats, it is working OK, if not, then something else is amiss.
It could be that the device is picking up an open circuit where it is expecting the load to be(hence saying "tank hot")

 

[styleruk]

Is the timer still connected to the Heater?

I would guess if the controller detects no current flowing to the heater it assumes the heater thermostat is satisfied.
If the timeswitch has isolated the heater then the controller won't see current flow.

That's what I suspect, but no, the timer is not connected. I aim to test this weekend when/if the sun comes out with something else wired up to see if it is actually sending power.

 

[snowhead]

Has the clamp got an arrow on it?

 

[styleruk]

OK, so a sneaky trick to see if it is working is to reverse the clamp and put your kettle on. This will trick the device into thinking that you are exporting and switch the immersion on.
If the device switches on and heats, it is working OK, if not, then something else is amiss.
It could be that the device is picking up an open circuit where it is expecting the load to be(hence saying "tank hot")

ah, yes, reverse the clamp...of course. I could do that and plug in my EV to test rather than wait for the weather. My suspicion is that the heater is simply not accepting power, as you say, it's displaying 'hot water', so it can only be that. But I have no idea why it would do that, was working fine before.
I could wire up the heater to a 3pin again and test it to be sure it is still working.
I don't suppose some elements refuse to work at low load do they? I could try the reverse clamp to prove that I suppose.

 

[Boydy88]

None that I'm aware of. Reversing the clamp and putting on a load is the way iBoost recommend to test in low light/ generation conditions.

Rob

 

[Deleted account]

My hot water tank has a thermostat that is fitted into the tank and wired to the element, I only started using the hot water tank 6months ago to make use of the free solar energy, when I first tried it, the water temp went to max, so I bought a replacement thermostat as the old one had sat and done nothing for 8years. This worked fine with power coming from a standard socket with it's own power line to fusebox, with a fused plug.
To improve things, I fitted a smart plug to act as a timer and this has worked fine as well. Switching on for 2hrs during the day, but then I thought I'd gain more by using a PV controller.
So I got this PV immersion heater controller and simply wired that to the socket (with fused plug) and sent power from that to the heater. In theory, no difference.
Again, I will supply some pictures with more detail when I get the chance. But the fact that the unit is displaying that the tank has hot water bemuses me, how can it know? The only way I can think this could happen is that the immersion heater is simply not taking power, so when the unit gets the go ahead to use some free energy, it pumps it to the heater and the heaters says, no thank you, I don't need any.
So either...
a) the thermostat has crapped out again
b) the heater element cannot handle anything but 3kw. So the solar is sending say 300w and the heater element maybe does not take it? Can't imagine that would be the issues but I am running out of ideas.

Thanks that makes sense.

It’s definately not option B the purely resistive immersion element will work if it’s getting just 50 watts or 3000watts.

An approved voltage indicator will let you know if the immersions thermostat is working in moments.
[automerge]1569426713[/automerge]
Is this install an iboost?

 

[ex 2 Base]

On modern immersion heaters there are TWO switches. The normal one, which slips inside the immersion heater proper, the second is a small BLACK button near one of the connection terminals. This is a safety device, and if for any reason the normal switch contacts fail closed. the water would boiler, but before that takes place the second one would open. The small BLACK button type switches have been known to open and as it in series with the main one, current cannot not flow to the element. NO heat. Before removing the immersion heater cover ENSURE the supply is OFF.
[automerge]1569433182[/automerge]
Forgot to add, to reset the BLACK button switch, press it down and you will feel a click. To do this you have to remove the top cover.
Before removing the immersion heater cover ENSURE the supply is OFF.

 

[styleruk]

OK, some good advice on here to help me try a few things. So I turned off and had a look and pressed any button that looked like it could reset, nothing obvious. Then I notice the second thermostat, I think that is an override one, I adjusted the temp on that, but that should not make the difference as it worked before.
Then I flipped the clamp to trick it into daytime and it fired up! odd. First sent 85w then went higher...obviously because it was drawing power itself and increased to suite etc. Went up to 2.7kw. So I've flipped it back and will check tomorrow night to see if it has drawn anything from daytime.

 

[Boydy88]

Yah, so it is working as it should. Chances are it hasn't been working recently due to a lack of export, the weather is starting to change and days are shortening. Also you mentioned an EV charger, if this has been on during the day to tie in with the solar, then export will be significantly lower.

 

[styleruk]

Yah, so it is working as it should. Chances are it hasn't been working recently due to a lack of export, the weather is starting to change and days are shortening. Also you mentioned an EV charger, if this has been on during the day to tie in with the solar, then export will be significantly lower.

I hear what you are saying, but last sat was a very sunny day and it was doing nowt with energy going back into the grid. Maybe I managed to reset something, I did not notice any of the push out switches 'out', but there are 1 on each of the poles for the element, they both seemed 'in'. The second thermostat clicked a little bit when I pushed in the actual dial for temperature and the thermostat has a very small push in so I pushed that too. Maybe one of them had tripped out somehow, with all my fiddly. Anyhoo, I will check properly during the daylight this weekend and report back.
Once again, thanks for the support, sometimes, you just need a lot of suggestions. 2 minds better than 1 and all that.

 

[styleruk]

OK, after some testing and trialing. I believe it's a communication error from the wireless sender to the box. It will not sync every time and I have to turn it off and on again for it to sometimes work. I have asked the supplier to send me a higher range version (even though I have a clear line of sight at approx 10m), the one with the kit should cover 20m, the one they are sending 40m! So I'll test this one next. Most frustrating as I'm wasting all that sun

 

[Memen14]

Hello,

I am new in this Forum, because I'm French. I had the same issue as STYLERUK.
I had contacted him, and his answer was that the unit was faulty.
As I bought an used PV Mate, I wasn't able to send it back to the supplier. So I tried to repair it, and I succeed.
The TRIAC BTA10-600 was faulty.

You can test if the Triac is faulty, event if you don't have the right one. You have to connect correctly A1/A2 and the gate.

Thanks for your Forum.

 

[arebee70]

Hey styler, how did you get on after the thread died down, i found this by searching for pvmate-immersion related problem and have basically a similar problem where the pvmate sensor collar is fitted correctly and is triggering the pvmate immersion controller to start up when excess pv elec power goes to the grid, however the immersion just kicks in at full draw ~2-3kw which is way more than the excess power (~300-700w) its not much power but was led to believe it will just heat water slower than at full wack. Obviously this aint what i wanted as i wanted the energy of the pv to be the source of power to heat the tank.

Do some elements only draw their max power or could it be faulty?
Also the pvmate is wired directly to the element which has its own built in stat, which i was told to turn to higher than the existing setting as that may have caused 'water tank hot' messages on the pv mate unit, but as u have said above, there is no way it can know this unless its aware that theres someway it knows just by having the stat 'block' it, but im unsure this is really how it would do that.

 

[styleruk]

Hey styler, how did you get on after the thread died down, i found this by searching for pvmate-immersion related problem and have basically a similar problem where the pvmate sensor collar is fitted correctly and is triggering the pvmate immersion controller to start up when excess pv elec power goes to the grid, however the immersion just kicks in at full draw ~2-3kw which is way more than the excess power (~300-700w) its not much power but was led to believe it will just heat water slower than at full wack. Obviously this aint what i wanted as i wanted the energy of the pv to be the source of power to heat the tank.

Do some elements only draw their max power or could it be faulty?
Also the pvmate is wired directly to the element which has its own built in stat, which i was told to turn to higher than the existing setting as that may have caused 'water tank hot' messages on the pv mate unit, but as u have said above, there is no way it can know this unless its aware that theres someway it knows just by having the stat 'block' it, but im unsure this is really how it would do that.

Hi
Currently, during the winter, I don't use the pvmate at all. I have a timer that comes on for a period of time at night to heat the hot water. Then when winter ends, I'll plug it back into the pvmate and use the sun to heat the water. I wanted 2 elements really, that way I get the best of both worlds, but to do that I'd need a new tank and that's just silly. There appears to be no such thing as a twin element heater, apart from commercial offerings and it's simply too hard to do myself safely. So I've gone for the simplest route, change it manually twice a year. For the summer, I have it set to come on for anything over 800W, that way, the house and the house battery still get power, for the winter, it's off and I plug the element into a smart socket that switches it on at full 3kW. I may consider dropping down to a 2kW as I feel 3kW is a bit too high.
Sorry, but unless you buy a smarter system, this is what you are stuck with. there are ways of doing this better, but spending £100s more is not best for me.

 

[arebee70]

Hi
Currently, during the winter, I don't use the pvmate at all. I have a timer that comes on for a period of time at night to heat the hot water. Then when winter ends, I'll plug it back into the pvmate and use the sun to heat the water. I wanted 2 elements really, that way I get the best of both worlds, but to do that I'd need a new tank and that's just silly. There appears to be no such thing as a twin element heater, apart from commercial offerings and it's simply too hard to do myself safely. So I've gone for the simplest route, change it manually twice a year. For the summer, I have it set to come on for anything over 800W, that way, the house and the house battery still get power, for the winter, it's off and I plug the element into a smart socket that switches it on at full 3kW. I may consider dropping down to a 2kW as I feel 3kW is a bit too high.
Sorry, but unless you buy a smarter system, this is what you are stuck with. there are ways of doing this better, but spending £100s more is not best for me.

Ok thanks for the input, how exactly do you set it to come on when its >800w, i dont think my pvmate has any setup details like that.. best regs

 

[styleruk]

Ok thanks for the input, how exactly do you set it to come on when its >800w, i dont think my pvmate has any setup details like that.. best regs

Oh sorry, I ended up buying another one that worked. The PVmate I originally bought was rubbish and simply let me know. So I bought one that connects direct rather than wireless signal. I was mixing my threads.