Timer for UVC immersion

[Crofter]

Back when our cottage was being built, my otherwise very good sparky had a brain fart and was unable to spot that the UVC had two immersions. Consequently we ended up with one circuit wired from the CU (this is used for the upper boost element, with a 30 min timer switch). The bottom element ended up being run off the normal ring main, using a plug in timer.

 

This is obviously far from ideal for a number of reasons. The simple mechanical timer will go out of sync with the off-peak time if it's turned off for any reason (e.g. a power cut). We've also had a couple of timers fail on us- I guess that although they're rated to at least 3kw, they don't actually like running a big current on a daily basis.

 

Anyway I think it's time to upgrade this.

1) can the overnight and boost elements run off the same MCB on the CU? I'm assuming not, otherwise the sparky would have just done that at the time.

2) I see you can get MCBs with built in timers, with battery backup. Looks like a neat solution. Are they any good?

3) In an ideal world, I'd like to have remote control over the immersion, as we are away from the house a lot especially over winter, and we don't really need to keep the tank hot for weeks when the place is empty. We also have guests staying who can have a habit of running away all of the water, so the ability to remotely boost it would be useful (I'd rather have a higher electricity bill than a bad review!). What options do I have for a wifi-enabled timer that will be robust enough to stand up to a 3kw load every day?

[TerryE]

This might be overkill for what you want, but this is what we did:

[Alan Ambrose]

You can use two Heatmiser stats with a bit of a bodge on the thermistors for remote control. Probably wouldn't want to bother unless you use the Heatmiser set-up elsewhere.

 

What rating is the MCB and do you have a way to measure the cable? Comparison with known cable sizes will work. Each immersion will take ~13A. Would it be easy-ish to run new cable?

[Crofter]

21 hours ago, Alan Ambrose said:

You can use two Heatmiser stats with a bit of a bodge on the thermistors for remote control. Probably wouldn't want to bother unless you use the Heatmiser set-up elsewhere.

 

What rating is the MCB and do you have a way to measure the cable? Comparison with known cable sizes will work. Each immersion will take ~13A. Would it be easy-ish to run new cable?

It's only 16A which explains why we didn't just put the second immersion on it. 

The CU is right next to the tank and has a couple of spare slots for MCBs so it's probably easiest to just add a new circuit.