Choice of intelligent switches ?

ChopperST

That's my thoughts as well. However since dialling down the stat to 50 it has not cut out. It makes me think the thermostat is either labelled incorrectly or has an intermittent fault.

orrery

Dave_Fowler wrote: »

I can't think of any reason why the 70C thermostat should trip out before the 60C one just because you're using the Immersun. Either the 70C one is tripping out at under 70C or the 60C one is faulty and allowing the water to heat up to over 70C.

Is it possible that the main stat is detecting at the bottom of the immersion and the overheat stat is at the top? In addition, if one of the contacts is poor there could be local heating at the top. Clutching at straws, really.

ChopperST

orrery wrote: »

Is it possible that the main stat is detecting at the bottom of the immersion and the overheat stat is at the top? In addition, if one of the contacts is poor there could be local heating at the top. Clutching at straws, really.

No definitely not that as its a bottom situated immersion heater (a new Tribune HE) the cut out is integrated into the immersion element with a removable Theeta thermostat controlling the temperature.

[Deleted User]

jeepjunkie wrote: »

Hi All,

My solar immersion is disconected at the moment. The symptoms exhibited... The ecodan would appear to be trying to boost the hot water to 60c even though it can't go beyond 50c and Dip switches on the FCT2 are sw2-7 changed to on and sw1-4 changed to off. These changes tell the ecodan it no longer has an immersion. Others at default. This stops the heating coming on after a DHW cycle. For the sunny months this is not an issue but obviously is for the cooler months...

With it disconnected all works perfectly but with spring round the corner I'd like to resolve this issue.

Any fellow users with a similar setup?

Cheers

After many experiments with the EcoDan the solarimmersion.co.uk MKIII is connected again and working well producing huge amounts of hot water. If anyone has this issue and needs the DIP switch settings let me know. Cheers

orrery

ChopperST wrote: »

Having some problems with the thermal cut out in our immersion tripping with the Immersun. Thermostat is set to 60 ...

I'm interested in how this panned out. I've just had the same problem. Top mounted immersion, went away for the weekend, plenty of sun, came home to tepid hot water. I had to reset the trip.

I've now set the thermostat down to 55C.

The immersion is only 21" so I only get the top 1/3 of the tank heated. I've just got a quote from a local plumber to fit a de-stratification pump around the tank to be driven from Solarimmersion output. Brass pump, non-return valve, flow control valve and pipework for £390. We'll see how that works in filling the tank and it may help stop the immersion cut-out triggering.

I wonder if the variable output can lead to very low convection currents in the water and therefore a lack of local cooling around the element at the top ... ?

legoman62

Have you thought about buying a made to measure immersion heater?
I bought a 1kW immersion to suit my cylinder.....I had it made for £65.00 + delivery:D

orrery

legoman62 wrote: »

Have you thought about buying a made to measure immersion heater?
I bought a 1kW immersion to suit my cylinder.....I had it made for £65.00 + delivery:D

Yes thanks, but the tank can take a maximum 30" immersion which is still not the whole volume of the tank. Keeping the existing immersion allows the best of both worlds - rapid heating of the top 21", or slower heating of the whole 150L simply by switching the de-strat pump on or off. Turning it off may be useful in the winter, but in reality I doubt it. I maximise my saving by allowing the maximum volume to be heated - I can always turn on the gas to complete the job. In fact, the de-strat pump allows the effective heating volume to come down below the h/w stat - thereby suppressing the gas h/w from turning on.

The de-strat pump will be fitted next Tuesday, so I'll tell you more after that. In fact, on the same day as BG come to fit the electric car charging point.

ChopperST

orrery wrote: »

I'm interested in how this panned out. I've just had the same problem. Top mounted immersion, went away for the weekend, plenty of sun, came home to tepid hot water. I had to reset the trip.

I've now set the thermostat down to 55C.

The immersion is only 21" so I only get the top 1/3 of the tank heated. I've just got a quote from a local plumber to fit a de-stratification pump around the tank to be driven from Solarimmersion output. Brass pump, non-return valve, flow control valve and pipework for £390. We'll see how that works in filling the tank and it may help stop the immersion cut-out triggering.

I wonder if the variable output can lead to very low convection currents in the water and therefore a lack of local cooling around the element at the top ... ?

Hi,

Ours was a new build property so the whole heating system was under warranty. The engineer that came out to us was really honest and helpful (it was useful as he also had a solar pv and solar thermal system at home too as the company fit both). He explained that the Immersions that have a thermal cut out in the body of the heating element as opposed to within the removable stat are prone to significant error and cut out for fun.

He exchanged our heater for one without a cut out and replaced our thermostat with one with the safety cut out built in as part of the stat (link - http://www.ukhps.co.uk/products/Immersion-Thermostat-18-Inch.html?gclid=CL3s0oP1wb0CFeXLtAodSRkACQ) and it has been working fine ever since. He quite honestly stated that the ones with the cut outs built into the heating element are simply fitted as an emergency back up and are not suitable for day to day use for this reason. Ours was a bottom mounted heater.

Hope this helps.

orrery

I've tried to set up a clip-on monitor (using an Owl Micro+) on the solar immersion to see how effective it would be and the results are very mixed - pretty much as I expected.

I've set up a short extension lead with the neutral wire (with an additional insulating sleeve) looping back out of the 13A plug to clip the sensor around and fitted that in the feed to the SolarImmersion box.

This works as follows:
- zero is displayed when there is insufficient generation
- 16W is displayed when just the de-strat pump is running
- when the immersion is being powered the readings are wildly optimistic. It gets accurate as it nears the full output - 3kW, but the lowest reading it ever shows is around 1kW.

This is to be expected, as the SolarImmersion 'chops' the mains to vary it, so confuses the meter. Having said that, it does tell me what is going on remotely so does the job I need it to do.

ASavvyBuyer

We looked at the expensive diverters and worked out that the payback time would be too long for us. But we found a device from REUK which monitors the red LED on the import meter. The red LED on the import meter stays on when we are exporting, rather than flashing when we are importing. When it stays on for more than a set length of time, (programmable between 1 and 10 minutes) it switches a relay in the circuit to the immersion heater. If the immersion heater (or anything else) uses more than the excess power, the import meter LED goes out/starts flashing and switches the relay off automatically within a couple of seconds. Device only cost £30 and was easy to fit into existing wiring.
Conservative estimate of about 4kw a day for about 200 days a year to provide all the hot water we need from March till September. We already had a less than 1.5kw element in the base of the tank. plus added a 2kw dimmer in the circuit to adjust power for poor days of generation.
Therefore, with gas at about 2p/kw and at best 80% efficient, 10p/day for 200 days = £20. So diverting pays for itself in a couple of years.

Realise that not everyone would already have the lower wattage element in the hot water tank or same setup, but what we have works for us