SUNAMP relay failure - 2018 PCM58 FINDER 22.22.8.230.4000

[Nickfromwales]

2 minutes ago, Onoff said:

Is there a Finder's fee? 

Did you bring a coat? if so, I can go get it for you? 

[Reiver]

5 hours ago, Nickfromwales said:

They could just fit a bloody SSR and all this goes away in a 'flash'.......

Indeed.... but that would put the manufacturing cost up some. It's obviously "cheaper" in their eyes to fit a rather stretched mechanical relay and then pay an employee to send out a replacement when it fails. Having spent most of my working life designing electronic/electromechanical stuff I do bash my head on the bench in despair sometimes these days.

[Nickfromwales]

16 hours ago, Reiver said:

Indeed.... but that would put the manufacturing cost up some. It's obviously "cheaper" in their eyes to fit a rather stretched mechanical relay and then pay an employee to send out a replacement when it fails. Having spent most of my working life designing electronic/electromechanical stuff I do bash my head on the bench in despair sometimes these days.

Not much uplift if you don’t buy the doomed ones first! 
SSR’s aren’t that expensive, and if purchasing on a large scale the bean counters can get that down a bit I suspect.

Otherwise it’s pretty reliable.

[Andrew Bissell - Sunamp]

I hope its okay to make couple of comments on this thread without it being seen as commercial.

 

@readiescards I am sorry you and your tenants had a frustrating experience with hot water failure. You were a week out of warranty on the controller which could have been doubly infuriating. So when you spoke with Neale from our team, he sensibly offered you a free replacement relay as a goodwill gesture. You specifically requested the ‘most up to date’ relay - so we sent the spade-terminal relay as this is the one used in the current B100 controller. I appreciate this differed from the one in your box which fits on a DIN rail. (Note: There has never been a safety-related recall campaign - we did upgrade to make the product somewhat quieter in operation.)

 

 Feel free to contact us directly and we will swap it for a DIN-rail part.

 

From Sunamp’s CTO, Sandy Gataora (with my emphasis added in italics) on Solid state relays (SSR): 

 

Quote

 

Before we throw these into the arena I would like to point out the following facts:

 

1. These devices have near equal probability of failure in ON and OFF mode so it cannot be used as main switching device for a heater (for controlling power yes). 
2. The current flow through the device is a function of resistance of the deice. Therefore when the connected device is switched off the resistance across in/out terminal is very high and visa versa. Therefore these devices (SSRs) do not provide galvanic isolation between input and switched output terminal. Therefore can not be used as part of safety circuit for a heating element.
3. These devices will produce more heat and EMC emissions.

 

 

For these reasons we do not use SSR. It is nothing to do with cost and everything to do with safety.

 

(Do note that if we had a penny-pinching approach I would never have specified Vacuum Insulation Panel to get an A+ low heat loss ... I would have just used PUR and got a B, C or D like a hot water cylinder. I wanted Sunamp to do better.)

 

On ‘arcing’ this is completely normal for relays or contactors of any kind.

 

On all the other safety related notes in this thread we use the same safety-first design philosophy. Hence relays not SSR; hence overheat stat as a last line of defence if relays or controllers fail in an ON state. Finally we have independent test lab validation of the safety choices we have made.

 

@readiescards do feel free to contact us directly if you have any residual concerns.

 

[Nickfromwales]

19 hours ago, LA3222 said:

Well, from reading this it seems that SunAmp has had its day on this forum. I've seen enough to put me on the 'well trodden' path of ASHP & UVC for DHW ?‍♂️ 

Are you saying that you’ve looked at the UVC history over the last 20 years? I can tell you now, that isn’t a history that reads exceptionally well so I’d look at this afresh to be fair. 
Last terminally ill UVC I went to was in a £1m+ property and the results were devastating. This was completely down to lack of G3 maintenance/ inspection, and totally avoidable, but if Joe Public isn’t aware of how vital these regular checks are then they don’t know what potential there is for disaster. 
Or look at something which doesn’t have such requirements. 
UVC’s have been around for a long time, and if you go looking for the many tales where they’ve failed you may think twice! 

Would you choose a car which could break down and you need to call the AA, or would you buy one that could blow up and make a crater in the road ( with both needing replacing ) 

 

Edited July 29, 2020 by Nickfromwales

[Onoff]

We only ever use Releco, Omron or Schneider relays.

 

Just saying.

[readiescards]

37 minutes ago, Andrew Bissell - Sunamp said:

I hope its okay to make couple of comments on this thread without it being seen as commercial.

 

@readiescards I am sorry you and your tenants had a frustrating experience with hot water failure. You were a week out of warranty on the controller which could have been doubly infuriating. So when you spoke with Neale from our team, he sensibly offered you a free replacement relay as a goodwill gesture. You specifically requested the ‘most up to date’ relay - so we sent the spade-terminal relay as this is the one used in the current B100 controller. I appreciate this differed from the one in your box which fits on a DIN rail. (Note: There has never been a safety-related recall campaign - we did upgrade to make the product somewhat quieter in operation.)

 

 Feel free to contact us directly and we will swap it for a DIN-rail part.

 

From Sunamp’s CTO, Sandy Gataora (with my emphasis added in italics) on Solid state relays (SSR): 

 

 

For these reasons we do not use SSR. It is nothing to do with cost and everything to do with safety.

 

(Do note that if we had a penny-pinching approach I would never have specified Vacuum Insulation Panel to get an A+ low heat loss ... I would have just used PUR and got a B, C or D like a hot water cylinder. I wanted Sunamp to do better.)

 

On ‘arcing’ this is completely normal for relays or contactors of any kind.

 

On all the other safety related notes in this thread we use the same safety-first design philosophy. Hence relays not SSR; hence overheat stat as a last line of defence if relays or controllers fail in an ON state. Finally we have independent test lab validation of the safety choices we have made.

 

@readiescards do feel free to contact us directly if you have any residual concerns.

 

 

Thanks @Andrew Bissell - Sunamp much appreciated. Not sure I count the invoice date as the start of the warranty period but however I appreciated the upgrade part being sent - which my electrician has just swapped the unit over too.  My primary concern is not having my future customers experiencing a loss of hot water (and potentially leaving a negative review) in two or three years time I'm assuming the upgrade relay resolves that.

[PeterW]

7 hours ago, Andrew Bissell - Sunamp said:

On ‘arcing’ this is completely normal for relays or contactors of any kind.

That’s not entirely accurate -  whilst it is normal for that to occur due to the current present, it is best practice design when switching loads to fit snubber or arc suppression circuits. 
 

7 hours ago, Andrew Bissell - Sunamp said:

Before we throw these into the arena I would like to point out the following facts:

 

1. These devices have near equal probability of failure in ON and OFF mode so it cannot be used as main switching device for a heater (for controlling power yes). 
2. The current flow through the device is a function of resistance of the deice. Therefore when the connected device is switched off the resistance across in/out terminal is very high and visa versa. Therefore these devices (SSRs) do not provide galvanic isolation between input and switched output terminal. Therefore can not be used as part of safety circuit for a heating element.
3. These devices will produce more heat and EMC emissions.

On (a) MTBF and the erosion of the terminals due to sparks would indicate that a EMR (relay) has a much shorter life and therefore failure due to mechanical issues is more likely than SSR failure, notwithstanding the propensity for a closed fail

 

On (b) suggest he speaks to the vast number of electric boiler manufacturers who use SSRs to drive their heating products. The relay or SSR should never be part of the safety circuit - that is why you have failsafe devices such as overheat thermostats. 
 

On (c) a zero crossing SSR produces no more EMF than a relay - in fact it’s probably less as there is no induction coil to generate a magnetic field and EMF. 
 

Given the way an SSR can be used to drive proportional heat cycles, it seems a logical step for Sunamp to use them - even if it is in series with a power isolator relay - as the benefits of being able to ramp up and down the heat load by driving a semiconductor would mean that the raw binary on/off for initial heat loads could be much better controlled. 

[Onoff]

Going belt and braces I'd be fitting a relay with a specific 240vac coil rather than 230vac bearing in mind UK voltages are generally still around that. 

[Nickfromwales]

25 minutes ago, Onoff said:

Going belt and braces I'd be fitting a relay with a specific 240vac coil rather than 230vac bearing in mind UK voltages are generally still around that. 

Just fit 40a or even 60a relays, simple. >Twice the CCC of the stock offering and much, much higher longevity. That's what I have had to do to 'load shift' SA's in the past on dual-fuel installs, fitting relays outside in project boxes and got my spark to fit the highest rating we could get hold of in a single module ( as it was a couple of tenners uplift for a lot of sleep ). On a previous SA install with their bespoke 'load shifting' controller, there was a time-clock inside the OEM equipment which made a lot of sense ( so the system only regenerated during the 3 x E10/24hr windows ). Options for that on the HW+I or eDuals would be handy as the electricity grid is becoming quite attractive for recharging, or at least topping up, even when gas is the primary fuel.

[Onoff]

1 hour ago, Nickfromwales said:

Just fit 40a or even 60a relays, simple. >Twice the CCC of the stock offering and much, much higher longevity. That's what I have had to do to 'load shift' SA's in the past on dual-fuel installs, fitting relays outside in project boxes and got my spark to fit the highest rating we could get hold of in a single module ( as it was a couple of tenners uplift for a lot of sleep ). On a previous SA install with their bespoke 'load shifting' controller, there was a time-clock inside the OEM equipment which made a lot of sense ( so the system only regenerated during the 3 x E10/24hr windows ). Options for that on the HW+I or eDuals would be handy as the electricity grid is becoming quite attractive for recharging, or at least topping up, even when gas is the primary fuel.

 

Honestly, a 230vac coil is running at the higher end of its voltage range at circa 240V. A dedicated 240vac contactor is better "suited" here in the UK. Might seem a small thing but it is a thing. 

[scottishjohn]

8 hours ago, Onoff said:

Honestly, a 230vac coil is running at the higher end of its voltage range at circa 240V. A dedicated 240vac contactor is better "suited" here in the UK. Might seem a small thing but it is a thing. 

I think the voltage 230 or 240 is neither here nor there as mains voltage can go up and down like a yo-yo - and since the regs for supply has changed some years ago the suppliers are allowed much wider range of voltage  variation.

if voltage drops  -relay will still  pull in just draw more current to do so 

but yes bigger amperage relay will  give a better margin  of service life 

you see it much clearer when working with low voltage dc --as in cars -where current is much more --engine cooling fan relays --they can spike 60 /80amps on start up  

although running current could be only 10amps or less --so you fit big 40amp relays to extend contact life -and big cabling to stop heat build up on connections .

If i were going to get really tricky then some sort of soft start device so there is no BIG initial current load at start up.If there is such a thing for that type of load 

 try running an electric kettle on a small generator -although 3.5kw output -will trip every time if you plug an electric kettle to it --for the same reason -surge is just too much -thinks its a dead short

[Onoff]

1 hour ago, scottishjohn said:

I think the voltage 230 or 240 is neither here nor there as mains voltage can go up and down like a yo-yo - and since the regs for supply has changed some years ago the suppliers are allowed much wider range of voltage  variation.

if voltage drops  -relay will still  pull in just draw more current to do so 

but yes bigger amperage relay will  give a better margin  of service life 

you see it much clearer when working with low voltage dc --as in cars -where current is much more --engine cooling fan relays --they can spike 60 /80amps on start up  

although running current could be only 10amps or less --so you fit big 40amp relays to extend contact life -and big cabling to stop heat build up on connections .

If i were going to get really tricky then some sort of soft start device so there is no BIG initial current load at start up.If there is such a thing for that type of load 

 try running an electric kettle on a small generator -although 3.5kw output -will trip every time if you plug an electric kettle to it --for the same reason -surge is just too much -thinks its a dead short

 

In the interests of harmonisation with Europe they simply changed wherever it said 230 to 240. Nothing changed here in the UK infrastructure wise as far as I'm aware (unless it's been locally transformed deliberately to 230V).

[ProDave]

1 hour ago, Onoff said:

 

In the interests of harmonisation with Europe they simply changed wherever it said 230 to 240. Nothing changed here in the UK infrastructure wise as far as I'm aware (unless it's been locally transformed deliberately to 230V).

Indeed about 245V is pretty normal around here and I start to get worried there is a fault if I ever see under 240V

[Onoff]

17 minutes ago, ProDave said:

Indeed about 245V is pretty normal around here and I start to get worried there is a fault if I ever see under 240V

 

Same here. Tested some fixed wiring in my M&Ds (local) last Saturday and it was 246V. Can't remember it ever being much different. 

[scottishjohn]

you miss the point -the range which it is allowed to vary is  now wider than it used to be 

they will of course try to keep it correct ,but in outlying areas ther can be big swings and its within the tolerances allowed

[Onoff]

16 minutes ago, scottishjohn said:

you miss the point -the range which it is allowed to vary is  now wider than it used to be 

they will of course try to keep it correct ,but in outlying areas ther can be big swings and its within the tolerances allowed

 

Towards the end, what I was getting at:

 

https://www.se.com/uk/en/faqs/FA174800/

[readiescards]

Upgraded relay installed, seems to be working fine.

[dpmiller]

Eeek!!! Are those uninsulated terminals facing upwards?

[Onoff]

So does the enclosure lid squash that earth wire?

[ProDave]

29 minutes ago, Onoff said:

So does the enclosure lid squash that earth wire?

That'll be the flying lead bonding the lid won't it?

[Onoff]

1 hour ago, ProDave said:

That'll be the flying lead bonding the lid won't it?

 

? Ignore me, I thought it was a bond to the pipe. 

[readiescards]

16 hours ago, ProDave said:

That'll be the flying lead bonding the lid won't it?

Correct

[Onoff]

Just a small, pedantic point but I'd have used bootlace ferrules on all the wires going into the terminal blocks. Also those black and white leads, I'd have trimmed the insulation back to have just 10mm poking above the gland. And that brown wire going to the top of the relay is a bit taut. And yes, use insulated crimps. Some cable markers would be good too...

 

?

[readiescards]

5 hours ago, Onoff said:

Just a small, pedantic point but I'd have used bootlace ferrules on all the wires going into the terminal blocks. Also those black and white leads, I'd have trimmed the insulation back to have just 10mm poking above the gland. And that brown wire going to the top of the relay is a bit taut. And yes, use insulated crimps. Some cable markers would be good too...

 

?

 

Cheers if I have to get an electrician to disturb this box again I'll pass on the comments - for sure cable markers or even a scribble on the inside of the box lid would have been very handy recently!