Help Please - Pulsacoil 2000

[a9120152]

Hello all
Just found this site so thought i would seek some advice.
I have a pulsacoil 2000 which was installed 2004 (new apartment). This feeds the hot water for sinks and bath only (not shower). Basically in the past 3 years this will be the 3rd time it has went faulty - no hot water. First fault the eng changed both the immersion heaters and about 8 months ago the PCB was changed.
I have a green LED on the main unit and the red LED on the PCB flashing twice per second (apparently indicating normal operation). I would appreciate any advice as i`m a bit unwilling to pay the same guy another callout fee and pay for parts when it looks like he is just changing things for the sake of it. I am ok with working with electrics etc but didnt want to start pulling things to bits.
I would greatly appreciate any advice
Cheers

 

[Doctor Drivel]

Hello all
Just found this site so thought i would seek some advice.
I have a pulsacoil 2000 which was installed 2004 (new apartment). This feeds the hot water for sinks and bath only (not shower). Basically in the past 3 years this will be the 3rd time it has went faulty - no hot water. First fault the eng changed both the immersion heaters and about 8 months ago the PCB was changed.
I have a green LED on the main unit and the red LED on the PCB flashing twice per second (apparently indicating normal operation). I would appreciate any advice as i`m a bit unwilling to pay the same guy another callout fee and pay for parts when it looks like he is just changing things for the sake of it. I am ok with working with electrics etc but didnt want to start pulling things to bits.
I would greatly appreciate any advice
Cheers

What is wrong?

 

[Softus]

You need to determine whether your problem is:

a) Hot water not being heated; or
b) Heat not being correctly transferred via the heat exchanger.

Start by isolating the appliance and removing the cover.

Does the brass boss of the upper immersion heater feel hot?
If not then it's not being heated.

If it's hot, then open a hot tap and check whether or not the pump runs. You need to power the appliance again, and there are exposed live terminals, so don't touch any of the electrics.

If the pump runs slowly, then the fault is probably a failed sensor (very common), or PCB (quite rare).

If the pump doesn't run, then turn off again. Temporarily move the live wire for the pump to the permanent live terminal. Turn on again. If the pump still doesn't run then it has failed.

If the pump does now run, then you've effectively bypassed the wet sensor, and you should now have hot water. Turn the pump speed down to the middle position, replace the appliance cover, and order a new wet sensor.

If all that doesn't get you anywhere, post back with your findings and I'll help you track down the problem.

 

[a9120152]

Hi Softus, thanks for the instructions.

The Brass boss of the upper immersion heater is cold, so as you say its not being heated.

Any ideas ?

 

[Softus]

The Brass boss of the upper immersion heater is cold, so as you say its not being heated.

One of the following:

1. No power supply to the element;
2. Immersion thermostat faulty;
3. Immersion element faulty;
4. Immersion safety overheat thermostat tripped.

Do you have a multimeter and know how to use it?

If you detect a supply to the thermostat, then check the supply to the element.

If there's a supply to the element, then isolate and and check that the resistance of the element is roughly 19 Ohms.

Is the off-peak element switched on so that the water will heat up overnight?

 

[a9120152]

hello just to update. As i said before both the off peak and on peak immersion heaters were cold. I pressed the booster button for half an hour. The upper immersion heater then heated up and i then got hot water through the hot taps. the lower immersion heater although not freezing cold is just slightly warm.

appreciate any advice

 

[Softus]

As i said before both the off peak and on peak immersion heaters were cold.

You didn't say that before.

I pressed the booster button for half an hour.

Eh? Is this a Pulsacoil 2000, or an A Class?

And when you say that you pressed it for half an hour, was a button on the appliance or a switch on the wall nearby?

the lower immersion heater although not freezing cold is just slightly warm.

Then I would say that you have a problem with the off-peak immersion/circuit/function, so you should fault find that in a similar way to the above.

However, the A Class doesn't have a thermostat inside the immersion heater housing - it's a separate sensor.

 

[a9120152]

sorry mate your right I didnt say that before.
Heres the situation
the type of unit is a pulsacoil 2000 (it dosnt mention anywhere about it being A class or anything. There is a switch on the wall nearly which gives you the option of a half hour/1 hour or 2 hour boost.
when i preseed the button for half hour boost, the brass boss of the upper immersion went hot and i got hot water.
When the half hour was up the heater started to cool again, it is now slightly warmer than cold.
I have checked the voltages i have 240 mains coming in but 0v ac on both the on peak and off peak inputs. when i press the booster switch it then puts 240 v on the on peak inputs.
Would you therefore suspect the electrics?

 

[Softus]

You'll get an off-peak supply only during off-peak hours.

What tariff are you on?

For example, if the off-peak supply is active only between midnight and 7am, then you could do you live testing sometime in that period.

In the meantime, you can still test the thermostat and the element to eliminate those from the investigation.

 

[a9120152]

hi again

i think it could possibly be the lower thermostat that is faulty. I took the plastic cover off the bottom immersion heater to locate the thermostat. I measured 240 accross the live neutral (the live terminal on the input of the thermistor) with zero volts on the output - feeding the heater.

Then with all power disonnected i compared it with the top thermistor, did a continuity check across the in out terminals of the bottom therm. and read open cct whereas the top therm test showed short cct between the in out terminals. Would you say that these tests would point towards the therm being faulty.

I`m only guessing as really i have no idea how the system is meant to work normally with regards to what heater is mean to work when etc but from the testing done would you say that it is the thermistor to the off peak immersion heater??

as said before appreciate your help with this

cheers

 

[Softus]

Then with all power disonnected i compared it with the top thermistor, did a continuity check across the in out terminals of the bottom therm. and read open cct whereas the top therm test showed short cct between the in out terminals. Would you say that these tests would point towards the therm being faulty.

Yes.

I`m only guessing as really i have no idea how the system is meant to work normally with regards to what heater is mean to work when etc but from the testing done would you say that it is the thermistor to the off peak immersion heater?

Yes.

The only other feasible explanation is that the water temperature at the bottom of the cylinder is more than the current setting of the thermostat (not a thermister, by the way). If the 'stat is set to around 60°C then you can discount this possibility.

The part you need is a 7" rod thermostat. If you take my advice you'll buy two - one to keep as a spare.

If you buy the type that has with a "built-in manually resettable overheat thermostat" then you'll make things easier in the future when the Pulsacoil overheat thermostat goes faulty and needs bypassing.

If you're feeling adventurous after changing the thermostat, you could test it by temporarily swapping* (with the power all off) the relevant immersion heater connections in the terminal blocks at the bottom edge of the PCB. I can look up the terminal numbers if you need them, but they're all labelled with text as well so you shouldn't have any trouble. You can then operate the off-peak (bottom) element using your 'boost' switch/button. If you eliminate background noise and put your ear to the plastic immersion cover (i.e. not to the live terminals!) then you should hear it 'whistling' as it heats the water.

*For safety reasons you must swap both neutral and live connections.

Final tip: once you've determined that old 'stat was definitely faulty, bend it in half so that you can't possibly ever ever use it again by mistake.

 

[a9120152]

thanks mate for the advice, i will give your final instruction a go. One final question, what would be the effect of swapping the top thermostat (current working one) with the bottom one temporarily, would this give me any hot water at all until I get hold of the new Rod Thermostat, or does it need the two to work full stop.

Cheers

 

[Softus]

what would be the effect of swapping the top thermostat (current working one) with the bottom one temporarily, would this give me any hot water at all until I get hold of the new Rod Thermostat

Yes. That would work just fine.

or does it need the two to work full stop.

No. Use of the boost element is entirely optional.

 

[AlexVP]

I am a bit late to the game here but I have a similar issue. What is meant by: "If the pump doesn't run, then turn off again. Temporarily move the live wire for the pump to the permanent live terminal. Turn on again. If the pump still doesn't run then it has failed."

Read more: //www.diynot.com/forums/viewtopic.php?t=119963#ixzz3LWkAeARr

 

[ALCPlumbing]

Your link just brought me back to this thread. Was that a mistake?
It means linking the pump to a permanent live as opposed to a live that runs through a sensor. Therefore if the pump runs on the permanent live it is the sensor that is faulty. If it doesn't run then the pump is faulty.
If that doesn't make sense then I don't think this is a DIY job you should be doing as electricity is dangerous and not for messing about with.