Pulsacoil 2000 - possible DHW failure?

Hi,

I recently moved in a flat, where a pulsacoil 2000 was installed.
I am not sure for how long the boiler has been inactive, but It looks to have been serviced/fixed in several occasions.
I can surely assume that the boiler is not NEW..

Just after moving in the new flat I followed the procedure of:

• Opening the water supply (2 - 3 bar constant)

• Topping up water to the water-tank

• Making sure that the thermostat is working (boost and timer work correctly)

The green/red leds are faulty (both broken) but the PCB led flashes, showing the normal pattern.

By playing a bit with the control dial of the thermostat and the boost control, the pulsacoil starts working correctly and the immersion heaters start working and heating up the water.
I also hear a crackling sound, probably indicating me that the immersion heaters are warming-up the water (the noise is very similar to the sound of a kettle).
After one hour or so, I can feel that the boiler is warm and the heaters are working.

As you can expect, and that's where the problem is, there's no hot water when I open the hot-water taps.

In some rare cases, the water pump starts working, but the pipes around the Plate heat exchanger are cold. It seems that there's no way for the stored hot water to go out of the boiler.
I tried to run the taps with different flow-intensity, but the result is the same.

After reading this forum my guess is that the DHW and PHE sensors are not working correctly. Because, if I understand correctly, if there's cold water "crossing" the DHW sensor, the sensor should send a signal to the PCB and switch on the pump.. This apparently doesn't happen.

I can try to replace the sensors, but I would like to know if there's a way to test my assumption.
I am happy to measure voltage/resistance, but I would like to know how to do it (I can use a multimeter, but I don't know where to make the measurement).

In alternative, is there a way to bypass the DHW sensor and send a signal to the PCB to force it to switch on the pump?

Thank you a lot!
Robert

Well it is;
DHW or PHE sensors.
Pump
Or pump drive PCB.
There is no way of testing the sensors.
You could try putting a supply to the pump?
Then if the pump works and the hot water too.
Is the pump free?
Is there a supply at the pump when DHW on?
Mike

Thank you Mike,

In understand that also the pump could be part of the problem.
In some cases I saw (or heard) the pump working.
It's a "british gas, multihead G" with three speed/flow settings. Probably it replaced the original pump.

It's a standard 230v voltage, so I think I can manually operate it by using an external supply.

when you say "Is the pump free?" what do you mean?

Thank you
Robert

Remove the big screw and find a screw driver which fits the spindle.
Turn and see if pump is free running / moving.
The pump fitted is wrong.
Look on this site I have warned about this many times.
Try a supply from a lead with a plug on it.
Be careful THINK!
If the pump works and you get hot water then you will be down to the sensors.
If so and are old change both.
Or the pump drive board.
Look for burning in the top left hand corner.
Again all this info has been posted many times before.
And if you take the time and trouble you will learn much more about your unit.
Mike

The pump you need for a Pulsacoil 2000 is a Grundfos 15-50X18 modulating pump. You can get one via this link: Gledhill Pulsacoil 2000 Spares