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1 hour ago, Crofter said:

Thanks Jeremy, I get a bit confused because my current house uses a rather peculiar dual circuit system.

If I could drift the thread a little, I have yet to get my head around the wiring of the UVC- there are two immersions, and I gather that the lower one is designed to go on the E7 supply, with the top one used for boost. There must be multiple ways of skinning this particular cat, e.g. a simple switch for the boost (pref one that times out after an hour, so it can't be left on all the time), and a timer on the lower one set to sync with the E7 times- or is it better to get a fancy all in one box to control both? Perhaps a question for @Nickfromwales?

Pic of your  meter / CU?

 

I wonder if you are on the "Total Control" tariff, something I think was unique to SSE areas and no longer available a a new install.  The give away will be a comlicated looking CU with 3 main switches often labelled "A circuits" and "B circuits"

 

If you do have that setup then one bank (I forget which one) will be specifically for "heating appliances" and will be available and metered 24/7 at the cheap rate. This is where you connect focal point heaters, the immersion boost, showers and towel rails.

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14 hours ago, Nickfromwales said:

Normally I'd say yes, but as this is not a huge UVC in a nice rental I'd say stick with the lower for maxing the UVC out on e7 and just have the upper as boost ( eg you can put a sign saying "please press once before showering for continuous hot water" if it was deemed necessary of course. It ( the boost heater ) could even be triggered by flow to the shower via a flow switch and contactor, and a timer. 

Its just one of those things where there are a lot of eventualities that need to be considered. A boost switch is a simple backup / contingent.  

 

That makes a lot of sense. If there is a stat in the top heater it will only actually come on if the water previously heated by E7 has already been used.

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Indeed. This is, in fairness, not a typical scenario so shouldn't be taken as 'regular' advice. 

 

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Back on this one again...

My sparky is wanting to wrap everything up soon so can't put this off any longer.

 

This is a sort of "does this exist" question:

- for the towel rail, what I would ideally like is a one-gang timer switch that I can set to sync with the E7, but the controls for which are then locked down behind a blanking plate. Thinking a simple mechanical timer hidden behind a 1G blank. Something like this: 15493efea54ebc.jpg.jpg

although I'm not sure if that unit is designed for you to screw a blanking plate over the top.

What would be even better would be if a timed boost facility could be added, for the user to operate.

 

The DHW should be much easier- just a timer for the main immersion, and one of those one-big-button boost controls for the top immersion. Hopefully nobody will want to tamper with the E7 timer if I give them  a big button to press.

 

 

Edit to add: here's a thought. Buy an unfilled towel rail, fit it with *two* immersions, one for boost and one for the timer. Other than looking a bit gallus with the two flex coming out of it, is there anything wrong with this idea? I presume each immersion has its own thermostat anyway so it wouldn't actually matter if they both came on at the same time.

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Go for a digital timed fused spur allinone jobby. Non volatile memory so power cuts won't upset it. 

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You can get tamper proof enclosures for time switches, like this: https://www.heatingcontrolsonline.co.uk/lockable-programmer-timeswitch-guard-p-344.html

 

With a bit of ingenuity, you could probably drill a hole in the lockable cover that would only allow access to the boost button that some timers have. 

 

This was just the first one I came across, but there are probably others around, as I suspect that it's pretty common to want to lock down controls in rented accommodation.

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Guest Alphonsox
On 30/08/2017 at 09:36, Alphonsox said:

 

Minor update on this subject ......

I fitted 4 of these Greenbrook T205 units a year or so ago - One failed within 6 months, another has just failed. Looking at the product reviews on the screwfix website this seems to be a very common occurance. I'll be replacing them all with the Timeguard FST77 as mention by @PeterStarck above. These now come with 5 Year guarantees so I have some hope they will still be working in a few years time.

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