Electric shower controlled by "burst fire" mains?

[Flyback]

Interestingly, The following electric shower..

Mira Decor Dual (10.8kW) by Mira Showers

More choice. More sprays. More experience. More performance. Get more with Mira Decor Dual.

www.mirashowers.co.uk

..has an extremely fine resolution in its temperature setting, so it must be doing mains burst fire control…(ie skipping variable amounts of mains cycles so as to get temperature regulation)….there is pretty well no other economically feasible way to do fine adjustment temperature control in an electric shower. Would you agree?

 

[Pommie]

Why not use the 100Hz (120 in US etc.) to provide 0 to 100% heating (switch every loop). The thermal mass of any system is longer than 100th of a second.

Mike.

 

[alec_t]

there is pretty well no other economically feasible way to do fine adjustment temperature control in an electric shower. Would you agree?

Triton showers just have water flow rate adjustment for fine temperature control, and switching in of 1 or 2 heater elements for coarse control.
I agree that burst mode control would be better than phase angle control.

 

[Diver300]

Why not use the 100Hz (120 in US etc.) to provide 0 to 100% heating (switch every loop). The thermal mass of any system is longer than 100th of a second.

Mike.

The thermal mass is far longer than 0.01 seconds, so there is no need to switch as fast as 100 Hz. By switching with complete half-cycles, there will be far less electrical noise emitted by the shower, or less need for filtering. Switching at zero voltage will reduce the heating of the switching device.

 

[Pommie]

The thermal mass is far longer than 0.01 seconds, so there is no need to switch as fast as 100 Hz. By switching with complete half-cycles, there will be far less electrical noise emitted by the shower, or less need for filtering. Switching at zero voltage will reduce the heating of the switching device.

100Hz (or 120 in US) is complete half cycles or did I miss something?

Edit, when I worked in the switchgear industry, half cycles were referred to a loops, which may be the cause of confusion.

Mike.

 

[Flyback]

Triton showers just have water flow rate adjustment for fine temperature control,

Yes most electric showers regulate temperature by flow rate control......but it is a poor method...

What I would add is, that I have lived in some 35 different rental accomodations, and in virtually all of them, the electric shower had been pranged by the landlord to always run on maximum flow.
The reason for this is because adjusting the flow rate of an electric shower can lead to problems…..because if one restricts the flow rate too much, too suddenly, then the heater element overheats…and even though there is a thermal shutdown, it never really operates fast enough, and so cumulative damage is done to the heater element and other parts.
Another point about slow flow rates is that it increases limescale build….more so than faster flow rates.
This is why shower temperature adjustment by flow rate adjustment is a poor, el-cheapo solution to the problem.

The trouble with mains burst fire control is that it can violate the flicker regulations, EN61000-3-11

 

[KeepItSimpleStupid]

That's probably an instant hotwater heater and cold water. It's going to be a LOT easier I would think to mix hot an cold.

 

[Flyback]

That's probably an instant hotwater heater and cold water. It's going to be a LOT easier I would think to mix hot an cold.

Thanks, but you then need a hot water supply...something that many cannot afford....at least not often enough to be able to have a shower at any time of day.

 

[alec_t]

The trouble with mains burst fire control is that it can violate the flicker regulations

Why would a shower flicker? Are you planning to use the water jets as light pipes?

 

[Flyback]

Thanks...not a bad idea, a bit of shower water diffraction.....
But yes, you understand that if a device draws mains in bursts, then nearby incandescant bulbs may flicker....due to the changing peak mains....and there is actually a regulation limiting the amount of such flicker....EN61000-3-11

I think Greta Thunberg would get well angry about it....because burst fire mains control has power saving features, if used in the right places.

I think Greta would say tough luck to the incancescant bulb users

 

[alec_t]

Since incandescent bulbs and compact fluorescents are going the way of the dinosaurs, is burst-mode flicker likely to be a problem with LED lighting?

 

[Pommie]

Surely, burst mode flicker = inadequate wiring.

Mike.

 

[Nigel Goodwin]

Surely, burst mode flicker = inadequate wiring.

Mike.

A lot depends on the supply to your house - mine is quite thin (as the house is about 120 years old), and some of the lights certainly dim when you turn the shower on In particular the front bedroom lights, which are dimmable LED on an old analogue dimmer, and set fairly low (should have ordered lower wattage dimmable LED's!).

 

[Pommie]

A lot depends on the supply to your house - mine is quite thin (as the house is about 120 years old), and some of the lights certainly dim when you turn the shower on In particular the front bedroom lights, which are dimmable LED on an old analogue dimmer, and set fairly low (should have ordered lower wattage dimmable LED's!).

So, inadequate wiring.

Mike.

 

[shortbus=]

Glad I don't live in a third world country. I have hot water and can take a hot shower any time I want.

 

[Nigel Goodwin]

So, inadequate wiring.

Mike.

But not mine!