No hot water - thermostat on water cylinder clicking - third replacenent valve!

[BigBurd]

We are in a new build. Boiler 2 5 years old. We have gone through x3 zone controller valves and 2 thernostats. Our boiler is serviced annually- 2 months ago.

We have no hot water - thermostat on megaflow gets to 29 degrees and continues to click despite thermostat being set to 55 degrees. Esi thermostat and valve. Zone valve isnt moving- faulty?

Have we been unlucky with the valves or is there some other issue?

Any ideas on what this issue is - advice greatly received & appreciated!

 

[CBW]

It could be that you are unlucky, and I’d expect the valves to last at least 1/2 years, but some don’t. Might be worth getting them swapped for a decent brand.

 

[BigBurd]

Thanks for your advice. Is it easy to change to a different manufacturer? The plumber we had last time seemed unkeen to do this. Thanks!

 

[CBW]

It’s not uneasy, but not a 10 minute job either. It’s relatively easy for a G3 plumber.

 

[BigBurd]

I am wondering if our zone valves have been miss wired? I think the last plumber copied the previous wiring.

What would be a better replacement brand - honeywell?

Thanks for advice!

 

[dilalio]

I'd be having the wiring checked over.
New builds come with all sorts of issues because there is no "customer" when the work is done.

 

[Johntheo5]

That looks like Honeywell, when the valve is not actuated, you should feel a fairly stiff resistance when you pull the manual lever across to latch the valve manually open, if the valve is already programmed open then you will feel no lever resistance.

 

[oldbuffer]

1. Without a dimple on the cover, I suspect that is not a Honeywell valve but a "cheapo" look-alike.
2. I'd suggest getting it changed to a genuine Honeywell V4043 22mm compression valve. E.g. Screwfix 31480.
3. It's not a DIY job, and requires someone with a current membership of a recognised G3 accreditation body, such as Gas Safe or NAPIT.
4. It will require draining the boiler's primary circuit, which includes the central heating, unless the system can be "bunged" or frozen. Likely to be between 1 and 3 hours depending largely on accessibility.

 

[Johntheo5]

Cheapie or not, if its opening then not a valve problem?

 

[ianmcd]

That looks like Honeywell, when the valve is not actuated, you should feel a fairly stiff resistance when you pull the manual lever across to latch the valve manually open, if the valve is already programmed open then you will feel no lever resistance.

It is an Esi zone valve not Honeywell, usually quite reliable to be honest.

OP what do you mean by cylinder thermostat "Clicking" do you mean it clicks when the temp is switching on and off, or clicking all the time ?

 

[PhilGS]

Like many others, I have had to replace many three port valves after failure.
All the brands operate the same way as the Honeywell and mostly, other than mechanical failure, go because the synchronous motor fails.
The three port valve design is fundamentally flawed in using a spring return and synchronous motor move to position.
Once the valve has reached position, the motor is deliberately stalled to keep it in position against the spring tension.
Normally, the motor is fed with 240-V AC at 50 Hz. In the stalled position, a diode is switched in that does the stalling.
The bad news is that in the stalled position, the motor starts to run hot and eventually the windings fail.
I pulled one Honeywell out and found that all the motor leads insulation had discoloured from the heat and the insulation just crumbled away to expose live copper.
It's possible that if the valve isn't getting much use as in summer months, it can sit there slowly burning out for months.
To stop this, I fitted a WiFi (Sonoff) switch in the boiler system supply.
Once a day, the power is turned off for one minute, which allows the valve to return to it's default position under spring tension, and now runs cold rather than hot.
The three port valve design must be decades old now, clever at the time, but well dated as well as flawed.
If I were redesigning the valve now, there must be better solutions to moving and positioning the valve, maybe a sturdy stepper motor which could do away with the spring altogether.
Just a thought.

 

[Johntheo5]

It took me a long time to gigure out how the mid position works, a DC current ia supplies
which is actually a brake as like poles attract each other, whatever its faults its
really ingenious and there ate methods of making g it revert to HW only position whenever any heating programme is finished. It must be remembered that a 2 port valve is truly stalled as well when energised, my 16 year old Honeywell all consume 8 watts while stalled in the energised state.
I wouldn't care to try and design a 3 port using all AC power to truly stall it in mid position against spring tension.

 

[oldbuffer]

1. Its a two port valve, not a three port.
2. The advantage of a spring return valve is that it fails to closed.
3. An unvented hot water system requires a valve that fails closed.

 

[Harry Bloomfield]

Once a day, the power is turned off for one minute, which allows the valve to return to it's default position under spring tension, and now runs cold rather than hot.
The three port valve design must be decades old now, clever at the time, but well dated as well as flawed.

I agree completely!

If I were redesigning the valve now, there must be better solutions to moving and positioning the valve, maybe a sturdy stepper motor which could do away with the spring altogether.

That was a process I went through, when I got fed up with the regular job of replacing and repairing my own actuator, but there is a better design, which is a direct replacement - look up MOMO 3-port valves and actuators. The water valve plus actuator needs to be swapped as a pair, but you get much better reliability, from less stress on the mechanism.

The unit only rotates in one direction, motor is only powered when it needs to change position, if it is already in the correct position it doesn't move. Slightly more complex electronically, and more susceptible to water, so really they need to be mounted actuator above valve, just in case.

 

[dilalio]

Jeeezuz!
Wanna fix it or dissect it?
Change the part or what's causing the part to fail!
We don't make em.
We just fit em.
I'm accordance with MI's.
FFS.