Motorised 2 port valve; what has slowed it?

[windbagUK]

I just tested the new unit in position, opening it with the Samsung unit by invoking DHW.
It opened in 12.8 seconds
- the old one takes 12.5 seconds when not in a pressurised system on the bench.

Seems pretty much the same to me

>CH circulation pumps are well known for getting 'lazy' as they age.
The point is, why ? and is my old one actually "sluggish" at all ?
The reason for raising this thread is that I had to do a lot of work to completely fit that valve, and I really can't perceive what was wrong with the old one.
Simply labelling it "lazy" or "sluggish" doesn't point up the difference in behaviour that the Samsung controller is throwing an error on.

>

Why do electric motors fail?​

5 Reasons Why Insulation Deteriorates
us.megger.com

Thanks for digging that up, Madrab. It quotes an earlier "Motor Mayhem" blog, which I am unable to find an existing link to.
But in that article it quotes the reasons for "failure" as one of 5 factors:

• Contamination – If a chemical deposit gets into the windings, deterioration is very possible. Makes sense though, right? Chemical spills are usually not a great sign, and a good reason to panic. Unless – of course – you dropped a gallon of H2O or a pound of C12H22O11 on the floor. No need to panic, just grab a paper towel (or 50) or call your dog into the kitchen.
• Mechanical – Over time, vibration or movement in a motor’s windings (or the motor itself) will wear down the insulation system.
• Normal Thermal Aging – With normal operation, a winding’s insulation will naturally deteriorate – albeit slowly – throughout its lifetime. That’s just normal (expected) wear and tear, folks.
• Overvoltage Spikes – Switching, lighting, and VFD designs can all cause high voltage surges, which can lead to insulation aging.
• Early Thermal Aging – Ah, we are back to the topic of excessive heat. A hot motor is not a happy motor. If your motor’s winding temperatures are on the rise, premature motor failure is right around the corner too. Of course, you already know this because it was the very first sentence of this very blog.

So looking how they might fit in with my old unit:

• Contamination There is none in my old unit.
• Mechanical 1000 minutes total run time over those 6 years ? - not credible
• Normal Thermal Aging – With normal operation, just normal (expected) wear and tear, folks. see Mechanical
• Overvoltage Spikes voltage surges, which can lead to insulation aging.
  This could have validity, as the valve is powered (but not actively running) when fully open.
  Difficult to know whether really applicable in a normal domestic setup, so not really testable.
• Early Thermal Aging the topic of excessive heat. A hot motor is not a happy motor. My old one never got above 90°C

The article seems to be aimed at substantive testing of larger, industrial motors - which is fair enough, as their failure could be far more costly to their owners/operators.

I don't feel any nearer understanding why the ASHP controller was throwing the E911 "insufficient flow"error.

 

[Madrab]

It must be kept in mind that will scale down as well as up. I'm sure that 90Deg to small 5w syncron motor like in a 2 port valve is probably way too hot than it needs to be and when the system is on, it will be held at that constant hot temp too, even when not in powered up. Given it's size it's reasonable to presume that it's resistance to thermal degradation may be much lower.

I must be honest and say that I have never timed a motor from end to end, maybe something for a bench test at some point.

Real world running, I've had to replace syncrons in some S plan systems in less time than 6 years, that being said oldest has to be around 10 years. A 3 port valve, due to the nature of their operation, have sometimes been replaced in 2 or 3 year and they use the same type of motors

Why they fail, or go 'lazy' ... the 'wear and tear' explanation in relation to Thermal and Mechanical isn't unreasonable in my opinion.

If the E911 error, when replacement of the valve removed that error, then there really is only one conclusion to be drawn - only the old valve or motor could be to blame. Sometime running on the bench doesn't always simulate what was happening in the system. It may not have been the time taken to open, rather the travel of the valve may not have been correct or some other issue may have been the cause.

 

[flameport]

main rotor spins freely on the bearings

If you can turn the motor by hand and it moves freely, it's destroyed. They have a significant gearing so the output shaft turns very slowly, turning that by hand should be extremely difficult if the gears are intact.

 

[MeldrewsMate]

...CH circulation pumps are well known for getting 'lazy' as they age.

Electric car owners are paying a lot of money for a very high quality, very advanced and highly designed electric motors ... I couldn't say the same for 2 port valves or other electric motors used in the same type applications

Circulating pumps are the capacitor run type, usually it's the capacitor that ages and causes a loss of torque over time.
Synchronous motors are of the shaded pole type, no capacitor but the grease in the reduction gearbox can go hard/thick with age and temperature.

OP, have you considered a degradation of the 'Sika' switch that you mentioned....if the zone valve end switches are not used then the 'too slow' alarm (E911) must be triggered from another component. The suggestion is that the 'too slow alarm' time parameters are set too low, so that even a small degradation in performance (pump output, valve opening speed, etc.) will cause nuisance alarms.
Will Samsung provide details of this 'too slow' alarm timing? If so, is it down in the sub-10 seconds area?

One thing that you could try, as a test, is to physically delay the new valve opening time by a few seconds by holding the valve's gear quadrant with a screwdriver or similar. Does that reproduce the alarm E911?
A similar test on the old valve (too late now) would have been to hold it partially open on the MAN/AUTO lever, effectively giving it a head start in opening...would that have made the E911 alarm go away? If it had NOT then the suspicion must shift away from the valve onto the other components (Sika switch or pump or summatelse).

MM (no arm waving here)

 

[windbagUK]

OP, have you considered a degradation of the 'Sika' switch that you mentioned....if the zone valve end switches are not used then the 'too slow' alarm (E911) must be triggered from another component. The suggestion is that the 'too slow alarm' time parameters are set too low, so that even a small degradation in performance (pump output, valve opening speed, etc.) will cause nuisance alarms.

Hi MM, thanks for joining in.
I was firmly convinced it WAS the Sika switch, and kept saying it must be a likely candidate to Samsung technical.
Each time, they were adamant that those very rarely failed, and that it was almost bound to be the 2-port motorised that was the problem, by getting "sluggish".
I did spend quite a lot of time online trying to source a Sika replacement that I could have in my hand, ready, when we'd gone to all the effort to drain down & open up, in case that was really the fault after all.

Avoiding "previously used" units, I did see generic replacements for approx £15 - but was amazed to find how much of a "closed shop" it was trying to find a more "branded" flow switch at anything like a sensible price, as the key parameter, flow rate at which it switched, was nearly always unspecified.
Online, the only "true" replacement part that came up was Eu430+Netherlands Postage+VAT.
At that price, I thought I'd try one of the cheap generics that had instructions for how to cut the paddle to achieve switching at various flow rates - but that was from China - and has still to arrive (!)
There were loads of details at the Sika website - but they did not seem to offer to supply directly.

There were dozens of "true" Sika switches from other online suppliers, but NONE of them gave the flow-rate they were designed to switch at, only the make of boiler they were designed to complement - and I wasn't about to try & research the flow rates for every boiler type that came up, especially as that is often held very close to the manufacturers' chest.
Why this is so, when nearly every other detail is published, I can only guess at. Samsung are an honourable exception.
The little I could glean, indicated that boiler flow rates were (understandably) lower than ASHP flow rates, so wouldn't be a "swap out" anyway.
But the lack of flow-rate switching specs felt like one of the last bastions of "closed shop" that used to be prevalent before the internet.

Samsung Technical advised that Samsung do not carry spares, but were good enough to suggest 10 potential suppliers of their Sika valve.
Even though I had the extended Sika code part that showed it was supplied for a particular Samsung ASHP (SIKA Ea3000 VK325MOSAMSU17), not one had a catalogue on their website that enabled identification of the correct part online, and so there was no way to quickly find a price & order.
Cue contacting all 10 potential sellers (one evening after work).
Most did not even bother to respond to my query (email or website "Form query"), many more kept asking for which part it was in the exploded view of monobloc (it isn't in the monobloc).
Only one identified the right Samsung part # (later confirmed by Samsung Technical) and even then, it was £170 - for something Samsung Tech kept assuring me was unlikely to be the culprit.

So we did look very carefully at the Sika switch when were able to extract it (it was completely clean, like the rest of the system), and did check the electrical operation - which was fine.

Give Samsung Technical their due, replacing the motorised valve DID cure the problem, so it wasn't the Sika switch directly, even though, as you correctly say, it is the only instrument in the system that can be monitored by the software to give the "impression" of a low flow rate E911.

The reason for raising this thread is that my multi-£k ASHP system was brought down, at a difficult time to get parts or repairs, because it seems that a cheap £10 synchronous motor was getting "lazy" or "sluggish" without any visible cause and without any obvious difference in performance between it and a new unit. That this is a well-noted failure mode only makes that situation more ludicrous.

A motor that runs 1000 minutes over six years and can't be made well enough to maintain an easily achievable spec over that time without bringing down an expensive setup is not appropriate for the job, or should be installed with such a limited lifetime in mind.
If it was the main pump, I'd be OK, as that was fitted with isolation valves either side.
Ditto the Fernox filter.
But nobody can make a synchronous motor that can match that requirement ? Which millennium are we in ?
If Motorised valves can't be made to keep going well enough over that sort of timescale in a totally clean, domestic system, then they should be routinely fitted with isolation valves like the other "failure" components - but I don't see that in the installations I've been observing while investigating this issue.

 

[windbagUK]

If you can turn the motor by hand and it moves freely, it's destroyed. They have a significant gearing so the output shaft turns very slowly, turning that by hand should be extremely difficult if the gears are intact.

No, it isn't, as it does open the valve against the springs on almost identical timescale to the new unit now installed in the system.
It is that very low gearing system that enables a relatively low-torque motor to operate in such a way, slowly winding the main lever against the springs. That low gearing gives that freedom of movement to manually spin (and spin back after). It also gets fully spun backwards when the power is cut off by the spring energy it has stored during opening. Which also shows that the gearing mechanism is intact and performing as it should.

 

[windbagUK]

>

Will Samsung provide details of this 'too slow' alarm timing? If so, is it down in the sub-10 seconds area?
MM (no arm waving here)

I did ask them that, but they don't seem to know. I have also now pointed out that the new unit opens almost identically to to old one, but have yet to receive a response.
I suspect they are as arm-waving about the cause as everybody else.
But it does point up the situation that, on a software controlled system, like many are nowadays, a motorised valve should be installed with isolation valves either side to enable easy replacement when (whatever it is) causes the monitoring system problems.

 

[Johntheo5]

Why not remove the power supply, one wire will suffice, from the valve and note the time taken for the alarm to annunciate from the start signal since Samsung don't seem to know?
If the time is only say 3 secs or so then probably valve "problem".

 

[windbagUK]

Why not remove the power supply, one wire will suffice, from the valve and note the time taken for the alarm to annunciate from the start signal since Samsung don't seem to know?
If the time is only say 3 secs or so then probably valve "problem".

I know the alarm takes longer than the valve opening, because the red "fail" LED comes on several seconds after the valve has fully opened - old unit or new.
Also, the sight-flow gauge doesn't show any flow change when the valve goes through the whole opening operation - which is why this "sluggish/lazy" attribution is puzzling.

What counts as "sluggish" is what Samsung can't advise. I suspect it is nothing to do with timing, hence the OP.

There was some "arm waving" about flow juddering ? If that is the "cause", from what is it originating ?
And why doesn't a new valve do it ?
Reminder - the old valve was totally clean (inside & out).

 

[Johntheo5]

I know the alarm takes longer than the valve opening, because the red "fail" LED comes on several seconds after the valve has fully opened - old unit or new.

Is the failed LED still coming up with the new unit?.

 

[MeldrewsMate]

Thank you for your extensive report on the state of the supply chain and difficulties getting spare parts however, with respect, that level of verbosity may not help your cause since some may have lost interest.

If you are convinced that the only salient data received by the Samsung control module comes from the Sika switch then it seems reasonable to suggest that a series of tests around the operation of the Sika switch are appropriate. Does the Sika comprise a simple flow switch? Two wires? Maybe 3 wires?
You could try disconnecting it electrically and timing how long it takes for the E911 alarm to appear. Is this time period similar to the zone valve's nominal opening time?
You could try a similar test after disabling the circulating pump.
These tests and their results will highlight if the performance of the system is close to the alarm level (or not), giving the prospect of spurious E911 alarms in the future. If the Sika is purely a flow detection device (FLOW or NOT-FLOW) then things which will cause a reduction in flow over time should be investigated:-
Circulating pump performance?
Hydraulic circuit resistance?
Zone valve sluggishness? (see above)
Sika flow switch slow to register an adequate flowrate.

 

[windbagUK]

Is the failed LED still coming up with the new unit?.

No - as reported, the new unit eliminates the E911 error

 

[windbagUK]

Thank you for your extensive report on the state of the supply chain and difficulties getting spare parts however, with respect, that level of verbosity may not help your cause since some may have lost interest.

None of that "verbosity" was in the request for parts - just that it was a Flow switch, the part # on the wire tag, and that Samsung Technical had recommended them as potential suppliers.
That so many had no idea about the product, or could be bothered to reply at all, was telling, I feel.

Things are complicated, and where complexities have been thought of, tested for and eliminated, it is only fair to say to those who are willing to try & help in a forum such as this.
I feel that asking for suggestions when many have already been tried & found not useful would be irresponsible.
If that level of detail makes folks turn away, they probably won't have useful thoughts.

 

[windbagUK]

If you are convinced that the only salient data received by the Samsung control module comes from the Sika switch...
... then things which will cause a reduction in flow over time should be investigated:-
Circulating pump performance?
Hydraulic circuit resistance?
Zone valve sluggishness? (see above)
Sika flow switch slow to register an adequate flowrate.

Samsung Technical advise the controller only "knows" about the flow switch, and that it is via switch closure at the head end.
That is borne out, both by that being the only "flow" connection to the system, and by us electrically confirming the switch closure when both out of the system and when back in, as previously reported.
Since the new valve cured the "perceived" fault with no other system component changes, the suggestions 1,2&4 cannot explain why it no longer is "perceived" to have a fault.
The timings of the new and old valve appear to eliminate suggestion 3, which is the main driver for the OP.
As reported, the timing of the fail to appear is far longer than the opening time of either the old or new valves.

The one "arm waving" suggestion that remains is some sort of "flow bounce" or judder occurring with the old valve, which may flick the flow switch back & forth ?
If it does, it happens too fast to register on the sight gauge, which remains rock solid with both the old & new motorised valves, fault or no fault, as reported.

 

[Harry Bloomfield]

The 3-port, spring return valve, has always been the most unreliable part of my heating system. Which generally caused a failure every couple of years or so. Such was the regular failure, that I would always have a spare head ready to swap in. The spare would either be a brand-new head, or a head that I had refurbished myself, assuming it was a motor, or microswitch failure and I became quite expert at refurbishing them - though I would often find the mechanicals were often simply worn out, or the grease dried out. A major cause of the unreliability, I found, was due to the mechanical stress the parts were under, from the return spring and the motor being stalled, under power during heating demands.

Such was the poor reliability, that I had it in mind to attempt to devise a redesign of the head, which did away with the need for springs at all, but then - I came across a 3-port valve called a MOMO which didn't involve any return springs, or a need to stall the motor under power, which was a direct electrical swap for my spring return 3-port.

It is electronically slightly more complex internally, and requires a swap of both the valve and the head, because unlike the spring return - it only rotates in one direction, doing complete circles. Mechanically, it doesn't fight against the spring and the motor only runs to position then switches off, so it is under much less stress.

Early days yet, but so far the MOMO (Motor On, Motor Off) has been 100% reliable, though I do keep a spare head to hand, should it fail.