Immersun repair

joeirish

Hi

I have an immersun unit that I have had for nearly three years. The original supplier/installer is not longer in business.

The problem seems to be that a lot of the electricity that is being generated is being exported while the thermal store cylinder is still only below max temperature. Yesterday my PV system generated 13.5 kWh and diverted to the cylinder 9.2kWh and exported 1.2kWh. Today so far it has exported 5.6kWh and only diverted 3.6kWh even though the temperature in the cylinder is around 61 degrees. I only noticed this recently and I'm not sure how long it has been going on.

I live in Clare so was wondering if folks knew of anybody fairly local who might be able to check it out. I didn't get a lot of help from immersun in the UK when I phoned.

Also I read on another thread that there could be issues with the type of immersion element. Mine has had to be replace twice in the past two and a bit years so not sure if this is a problem.

Thanks

Effects

What was the issue with the element? Any visible damage?

joeirish

Effects wrote: »

What was the issue with the element? Any visible damage?

Previous issue was that the element developed a crack. But this may have been due to low water level. The level had dropped in the cylinder without me realising. I can't remember what the issue was the first time the element had to be replaced. This time the problem comes and goes. Some days everything seems to work fine but not others. So this morning lost of leccy was exported with cylinder only 58 degrees. I fiddle with the thermostat a few times, checked the overheat trip etc. This afternoon seems to be ok except for the occasional times when it flips and starts exporting even though temp is not up to max.

KCross

So, what is max temp? 58-61 sounds like max to me.

Now, if you said it was at 45 I'd say you had an issue but 58-61... looks like max to me.

joeirish

KCross wrote: »

So, what is max temp? 58-61 sounds like max to me.

Now, if you said it was at 45 I'd say you had an issue but 58-61... looks like max to me.

The max is set to 80 degrees. That is the temp that it got to on sunny days last summer. Yesterday it got up to 70 degrees but this morning was cutting out around 58 degrees even though the sun was shining. This afternoon it has now gone up to 65 degrees as I speak (after I fiddled with the thermostat and trip button - not sure if that did something or if this is just a temporary improvement.
So the issue is that it is not working as it should and I am exporting (for no payback!!) units to the grid when they could be stored as heat in my thermal store.

joeirish

So I've had the immersion checked and all fine. The problem seems to be with the immersun. It seems to be exporting more electricty than it is generating and also not diverting this to the immersion as would be expected even when the cylinder is way below max temperature. Attached image of the data so far today!

quentingargan

I would suggest connecting a regular heater to the Immersun in place of the immersion, or on the second output and see what happens.

Setting your cylinder to 80 is very high. The stat may be cutting out because of localised heating. Do you get limescale in your kettle? If so, your immersion should always be at 60. But try the second load such as a dimplex heater and if that fixes the export, then it is the immersion side and not the Immersun. If you are still exporting with a luke warm dimplex, it is the Immersun..

Carrickbeg

Im signed up for this option on my new build...I have 12 PV panels on roof and I am going for the immersun option for hot water...what size tank do you have...I never expected it to be heating full tanks to 60 degrees...if so this would be great...

quentingargan

Carrickbeg wrote: »

Im signed up for this option on my new build...I have 12 PV panels on roof and I am going for the immersun option for hot water...what size tank do you have...I never expected it to be heating full tanks to 60 degrees...if so this would be great...

If you have 12 panels on a south facing roof, assuming at least 275w per panel, you can expect total energy from the system of 2700 to 3000 kw hrs per year. That compares to about 900 kw hrs per typical flatplate or tube panel. Assuming you use 1/3rd of this for powering electrical loads, you should have enough for a 200l to 300l cylinder. Solar PV is slightly less seasonal than thermal, so less of a peak in the summer / trough in winter. The best option is a 300L cylinder with two immersions, one in the middle heating the top half and given priority, then one in the bottom heating up the surplus.

joeirish

Carrickbeg wrote: »

Im signed up for this option on my new build...I have 12 PV panels on roof and I am going for the immersun option for hot water...what size tank do you have...I never expected it to be heating full tanks to 60 degrees...if so this would be great...

I also have 12 panels rated to give a max of 3.6Kw. However in practice the max has been more like 3 which is fine for my immersion heater. I have a 500 litre tank and at times it heats up to 80 degrees before the cut off. Usually less in winter which is why I also have a backup oil boiler. I have found that this has worked well for me for the past 3 years except when there has been the occasional glitch in performance with the unit. If the price of heat pumps becomes more reasonable my plan is to replace the oil boiler with one of these but at the moment the numbers don't add up. I used about €600 of oil in the past 12 months.

Carrickbeg

Sounds ok to me...I went with gas as I have access to natural gas on site and PV panels for my renewables...ive been regreting that decision a little lately with all the talk of heat pumps in the past few months...my thinking was I know a gas boiler and what it can and can't do but I didnt know anyone with a heat pump...

Carrickbeg

In order to pass my BER I would have needed 5 tubular solar panels and I thought the PV might be a better option as it will give me both hot water and electricity...??

joeirish

Carrickbeg wrote: »

In order to pass my BER I would have needed 5 tubular solar panels and I thought the PV might be a better option as it will give me both hot water and electricity...??

And as you will get no money for excess electricity generated that is exported to the grid you might as well store it as heat in your cylinder. I also have underfloor heating which means that the stored heat is later used to keep the house warm and save me money on my heating bills. Using batteries to store excess electricity is just not cost effective at the moment.

Carrickbeg

joeirish wrote: »

And as you will get no money for excess electricity generated that is exported to the grid you might as well store it as heat in your cylinder. I also have underfloor heating which means that the stored heat is later used to keep the house warm and save me money on my heating bills. Using batteries to store excess electricity is just not cost effective at the moment.

Does your PV panels provide heat to your UFH?

joeirish

Carrickbeg wrote: »

Does your PV panels provide heat to your UFH?

Indirectly yes. The excess electricity from the PV panels (any electricity not being used in the house) is used to heat the cylinder with the immersun unit diverting this to the immersion heater. The hot water in the cylinder is used for the domestic hot water and also the underfloor heating. If the temp in the cylinder goes too low and there is no power from the PV panels (say at night) then the oil burner tops it up.

Carrickbeg

joeirish wrote: »

Indirectly yes. The excess electricity from the PV panels (any electricity not being used in the house) is used to heat the cylinder with the immersun unit diverting this to the immersion heater. The hot water in the cylinder is used for the domestic hot water and also the underfloor heating. If the temp in the cylinder goes too low and there is no power from the PV panels (say at night) then the oil burner tops it up.

So by the sounds of it you are happy with your pv panels array? What size is it?

joeirish

Carrickbeg wrote: »

So by the sounds of it you are happy with your pv panels array? What size is it?

I also have 12 panels rated to give a max of 3.6Kw. However in practice the max has been more like 3 which is fine for my immersion heater. I have a 500 litre tank and at times it heats up to 80 degrees before the cut off. Usually less in winter which is why I also have a backup oil boiler. I have found that this has worked well for me for the past 3 years except when there has been the occasional glitch in performance with the unit. If the price of heat pumps becomes more reasonable my plan is to replace the oil boiler with one of these but at the moment the numbers don't add up. I used about €600 of oil in the past 12 months.