Use of Shelly 1PM plus to control water heater

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#3083392 1-Jun-2023 18:12

I had to have a laugh at this:

Bluetooth Hot Water Cylinder Control Kit - Buy Online - Eurotech NZ (kiwisparks.co.nz)

One little problem with the above:
files (schneider-electric.com)

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eluSiveNZ

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#3083502 1-Jun-2023 21:39

But only one module is installed?

Edit. Just realised you mean 15A vs 10A.

SpookyAwol

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#3084447 3-Jun-2023 16:50

Ive been using a 1PM for nearly 2 years, no issues here. Started with a 1PM and changed it for a plus a couple of months ago, fo no reason other than upgrade.

My 3Kw cylinder pulls about 2.8 and stays well under the operating temp (in the wall cavity) for the 1-3 hrs that I run it

For automation, I also use the temp add on for cylinder water temps.

Personally I have had no issues with wireless and the switch can be left to default on or off on reboot, its ultimately controlled by the thermostat anyway.

In an ideal world, youd want it to control a relay

neb

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#3216280 9-Apr-2024 16:40

This started in the solar thread, but this one is more appropriate: It looks like it'll be OK to do this, just not with a Shelly doing the switching of the load. What I was thinking of doing was have the Shelly drive something like a Finder 22.32 contactor, which is DPST so will still disconnect the circuit even in the case of contact welding of one contact. However it's DIN-rail mount so presumably will need some sort of surface-mount switchboard enclosure to go next to the HWC (which isn't a problem, plenty of space there, just more complexities).

Any sparkies able to comment on what's involved here in terms of getting the electrical plumbing in, and what is and isn't allowed? So using a Shelly or equivalent to drive a contactor to provide the equivalent of ripple control for a HWC so it only runs off free power or solar excess generation.

elpenguino

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#3216289 9-Apr-2024 16:50

I can't answer your question .......... but this is the internet so I'll add something anyway.

For those interested in tidying up their installations, you can find 3D-friendly designs on thingiverse etc - they allow you to mount your shelly on the DIN rail next to your contactor instead of floating around.

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pipe60

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#3216514 10-Apr-2024 12:21

neb: This started in the solar thread, but this one is more appropriate: It looks like it'll be OK to do this, just not with a Shelly doing the switching of the load. What I was thinking of doing was have the Shelly drive something like a Finder 22.32 contactor, which is DPST so will still disconnect the circuit even in the case of contact welding of one contact. However it's DIN-rail mount so presumably will need some sort of surface-mount switchboard enclosure to go next to the HWC (which isn't a problem, plenty of space there, just more complexities). Any sparkies able to comment on what's involved here in terms of getting the electrical plumbing in, and what is and isn't allowed? So using a Shelly or equivalent to drive a contactor to provide the equivalent of ripple control for a HWC so it only runs off free power or solar excess generation.

Have not come across a Shelly before, assume there is a Sdoc for them? Have a look at a Catchpower Control relay as another option for contactor control or look at using a catchpower green for maximizing surplus solar(0 to 3.5KW)

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hairy1

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#3216543 10-Apr-2024 13:42

I am using a PM2 Pro to control the hotwater. It has overcurrent, overheat and overvoltage protection.

Shelly PRO 2PM Double Relay and Motor Controller - SmartHome

These guys are really good to deal with.

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neb

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#3216691 10-Apr-2024 19:24

pipe60:
Have a look at a Catchpower Control relay as another option for contactor control or look at using a catchpower green for maximizing surplus solar(0 to 3.5KW)

There's a bunch of similar devices, e.g. NZ's own homegrown Paladin, but I don't need anything like that since I've already got all the monitoring and control I need for this. All I need for my case is an ability to apply or remove power to the HWC.

neb

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#3216697 10-Apr-2024 19:51

hairy1:
I am using a PM2 Pro to control the hotwater. It has overcurrent, overheat and overvoltage protection.

Shelly PRO 2PM Double Relay and Motor Controller - SmartHome

From the teardown photos I've found it looks like it still has the same relays as the simpler models, which is this Hongfa model, single-pole not double pole, nominal 16A, no indication of power lost, etc. For the Finder one I was looking at they're double-pole, 20 or 40A, and 3.1W loss at the full rated current, dissipated through something that's got about twice the mass of the entire Shelly device the Hongfa relay is part of. The whole Shelly construction reflects that, they're running 16A through a PCB-mount relay while the Finders have 6.3mm spade lugs for the same thing. Like a lot of Aliexpress and similar electronics, it probably works OK most of the time, in particular if you're using it to turn lights and other low loads on and off, but for a HWC I'll just be using it to drive something that's properly rated for the job.

Username1

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#3216750 10-Apr-2024 22:03

My Shelly Plus 1PM lasted about 2 months with the HWC before tripping the breaker.

elpenguino

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#3216756 10-Apr-2024 23:19

Whoa. Not good. What was the HWC heater rating ?

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#3216759 10-Apr-2024 23:36

Username1: My Shelly Plus 1PM lasted about 2 months with the HWC before tripping the breaker.

That bit on the right with the vapourised tracks is exactly why I'm not using the Shelly to control the HWC directly :-).

Edited to add: Guesstimates plugged into design software, for a standard 1oz PCB at 16A and max 20 degree temperature rise you'd need a minimum 25mm wide trace. And that's without being conservative and derating things by 50% for a good safety factor...

eonsim

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#3216938 11-Apr-2024 09:49

Username1: My Shelly Plus 1PM lasted about 2 months with the HWC before tripping the breaker.

This is why Shelly's should only be used to manage contractors for high or sustained loads. Don't put shelly's directly in the path of any load higher than about 1kW. The shelly's are decent if used properly.

EgorNZ

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#3216940 11-Apr-2024 09:54

Any recommendation for a suitable contactor that can be controlled by a Shelly?

SirHumphreyAppleby

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#3216941 11-Apr-2024 10:00

On a slightly related note, are there any relays (preferably DIN) that accept logic level input from low-current GPIO pins? Presumably they'd need an additional power source to operate.

If you need a Shelly, plus a contactor, I question the sense of using a Shelly in the first place given the additional complexity that comes along with it (e.g. Wifi dependency, odd MQTT naming based on the device ID). I'd rather just drive a relay with a GPIO pin on a Pi or Arduino.

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