Help me troubleshoot why I have no hot water with an iBoost

Cottage_Economy

EricMears wrote: »

Do you have another way of switching the immersion heater on ? Or has whoever fitted the iBoost wired it such that there's no independent way of running it ? If there is an alternative way, that should establish whether the immersion element/thermostat is faulty or if it's the iBoost to blame.

I don't know I'm afraid.

As far as I'm aware, the immersion is on all the time and the water is supposed to be heated by surplus generated electricity. In the evening the DWH comes on for an hour after dusk to boost the hot water after we've run the tank down with our showers.

To my knowledge this is the way it has been functioning for months but I have no 'proof' that it has except to say my electric bill has dropped from £85+ a month to £45 or less and my oil level has barely dropped in six month (but then we're not using CH).

The iBuddy looks like it has recorded savings for a while and then stopped. Certainly nothing in the last month.

I've certainly seen and heard the iBoost click in and show diversion of surplus electric but cannot recall accurately when that last was, I think last week. Certainly not longer than that. I remember that the amount shown on the iBoost was 0.16kwh surplus so it appeared to be doing something.

Cottage_Economy

It is a very murky dark day today and we are only operating at about 170kw-ish above our current load according to iBuddy, which is green /orange as the dishwasher is running.

The iBoost message is that it is diverting 0.00kwh to the tank.

Cottage_Economy

Can I just turn off the iBoost then see if the immersion heats up the water?

pinnks

I (and I think EricMears) have the immerSUN but the principle of the two diverters should be the same, i.e. you put a "clever" switch in the circuit that feeds the immersion heater, which is why you leave the other switch in the same circuit "on" all the time. When there is no surplus PV the iBoost switch is "off" and nothing flows to the immersion heater. When there is surplus, the switch comes "on" but the clever stuff means that only that surplus is sent to the immersion heater. If you activate the manual or boost setting you are essentially turning that switch "on" but bypassing the "clever" stuff so you feed 3kW to the immersion heater for that period of time.

If you do not have a separate circuit as Eric questions, I guess your electrician could just disconnect the iBoost and connect its input cable to its output cable to essentially reinstate what the wiring looked like before the unit was installed. If the immersion works then it's the iBoost… But then, he or she might have other means to test the immersion...

As of writing this on this cloudy day, with my base load and TV running, I am generating 730W, using 300W, diverting 380W to the immersion and exporting 50W from my 5.25kWp system. With your 6kWp you should be experiencing something similar. Even with the weather today and absent any washing machine, dishwasher or drier activity I would expect to get a hot tank and to keep it hot enough to shower tomorrow morning for 3 or even 4 people (though we are but 2 on a daily basis). On a sunny day even at this time of year I would expect the tank to be hot by about 10:00 and to be topping it up as necessary until about 18:00.

My point about using your boiler to top us was more about the relative inefficiency of firing it up for such a short time than about topping up at all. With oil I think this is even more relevant as I think such boilers have a high heat mass (my brother told me all about his at one point). Based on my records, I save about £70 to £80 by turning off the gas as already mentioned. If you do the maths this means I used to use about 6kWh of gas per day to heat the tank whereas I divert just over 2kWh to do the same with the diverter. The 4kWh difference is down to losses in the boiler and pipework, so firing up all that copper just to top up would be costly.

You may therefore find it cheaper to use the boost function (I assume you can put it on a timer in the iBoost) to top up using the immersion heater rather than firing up the oil guzzler, no least because you will power the immersion heater element on until the thermostat says the tank is hot..

Hope the fix turns out to be quick and cheap.

Cottage_Economy

I've had a look on the consumer unit and the I think the iBoost is wired straight in. The unit is directly above the iBoost and the immersion has its own fuse. So unfortunately it means someone will have to come in and have a look at the tank first and troubleshoot the issue from that way. That's ok, the heating engineer is pretty good with his prices and probably wouldn't even charge me if he took a look and nothing was wrong.

Thanks for the info Pinnks. I just went with what the installer told me. At the time I felt a bit under the weather and just wanted it to work and never bothered experimenting with it but I'm feeling brighter now and can give it more thought.

Regarding the boost function instead of the boiler, you're quite right. Now I see that written down it makes perfect sense to use the Boost function not the boiler. I haven't checked whether the iBoost has a timer but will.

JKenH

I have an isolator switch between the IBoost and the immersion heater. Do you have one? If so it might have been switched off.

pinnks

Good thought. I too have such switch - the original isolator switch from when the house was built.

silverwhistle

As a point of comparison - 4kWp system, electric shower, single occupancy - so not a great deal drawn off, I have saved:
Today 2.37 kwh
Yesterday 3.27
Week 18.62
28 days 97.46


No use of gas since March, although now the football season has started I'll be using a bit more water for post-game and training baths. It probably won't be until October that I need to use gas for top up. I did half an hour the other day, but more for checking the system.

Cottage_Economy

Just a quick update.

Trying to change the immersion element has turned into a nightmare.

It appears the former owner (who used all secondhand stuff and did his own work) used something to seal the element into the tank so well it wouldn't come out, no matter what was done. Nearly an hour of us trying various ways and means resulted in a split tank as the element took part of the tank with it.

So in addition to the new immersion (with isolation switch), we are having a new tank.

An electrician is coming to check the wiring as well, as it appears that the live wire isn't live, the neutral is.

The stopcock in the airing cupboard above the tank sheared off in the engineer's hand.

Oh and the stopcock under the kitchen sink has seized.

Happy days.

JKenH

That sounds like a nightmare. You have my sympathy.

I have had problems with seized stop cocks over the years and last time my plumber fitted me an Surestop stop !!!! with a remote switch on the house side of the existing under sink stop !!!!. Similar to the one in the link below. It is so convenient that I use it whenever we go away on holiday.

https://www.amazon.co.uk/Surestop-SS-22-RPL-Stopcock/dp/B00D9SCJUY