No green lights or Heat

Hi,
Just just bought a flat in Leeds with a Pulsa 3 system and no experience with these units although a competent DIY problem solver. Have looked at this site and understand the working of the system from manual, web and looking at what is there!
Have had the flat 3 weeks and use at weekends, so first weekend system was on from previous owner. Water scalding hot for a couple of gallons, then cold for a couple of gallons then comfortably hot. It was difficult to regulate shower but may have been due to its own thermostatic control. So researched system to better understand it and thought all was well. Turned off all heating and on again for second weekend visit with the system the same.
Weekend 3 turned on and no hot water Sat morning so turned on 24 hour heat no heat or lights on unit.
Checked FE tank plenty of water but added a couple of pints to be sure, float valve switch definitely made and wiggled it up and down with no light coming on.
The electrics have 3 switches- economy, 24 hour and a feed to a timer that then goes to the board. I don't know why it has a timer as the supply board has water heater trips on economy and mains with both made and the night storage heaters come on at 12.30 on the off peak system.
When the timer is on a "humming " sound is heard which comes from the pump as it reduces in noise when you switch to position 1 then quiet when the pump is off. The timer is a cheap unit with all sorts of options but I switched from auto to on to ensure I had a feed and not even sure why you would need one?
Opening the panel the LCD red light is flashing correctly so power is in the board as also evident by the pump noise.
It has the dry pockets for the thermostat sensors filled with white conductive "Glue" tried a waggle of both and they seem secure.
I suspect a faulty float switch and may try a loop to isolate it or a fault on the circuit board?
I guess the 24 hour immersion may be knackered and the off peak tripped so will have a look at the immersion thermostats next weekend but not sure why no green power light on as both trips in the supply board are good.
HELP PLEASE
Don

Thermal store needs to be left on.
The unit needs a mains supply to work / function properly.
Off peak for the bottom heater.
On peak for the top heater.
Ref to hot water / shower? What is it like coming from the taps? If ok its the shower.
Should not be that hard to sort out really.
Try leaving it on.
Mike
MGC/H2O
Norfolk

Hi Mike,
thanks for the reply.
My problem is I can't switch it on as no green light. I now believe the timer is for economy 10 afternoon top up so that is one question answered.
The bathroom has a mixer for the shower and separate taps for the bath. The bath also gives scalding/ cold and then ok after a seemingly excessive time.
If I do eventually get it on I will now leave it on off peak!
I did know the set up for the immersions positions thanks.
Regards,
Don

May help others?
This weekend I by-passed the cheap timer and then had a flickering green glimmer on the lights. I may have had a "weak supply" to the board before? I had not really noticed before and maybe they had always only been this bright. Also the relay was not pulling in the contacts for the immersions. The board only powers this if water level is OK and the overheat does not need resetting. My thermostats on the immersion must have been originals as they had no independent trips.
After isolating all the electrics, I stripped the relay by removing the plastic cover carefully and cleaned the contacts with a bit of folded wet and dry abrasive paper. I could hear the relay operate when the float valve was made and broken (by pushing the float under water in the H/E tank). This makes both the on and off peak immersion contacts since the selection is pre-determined by what unit you have turned on.
Result--- hot water at last but I have to say what a poor system with the heat exchange just sitting on the side of the hot water tank, no wonder they changed this in later models with an internal coil. If I could run a metal drain pipe for the Tundish drain I would put a Range unit or similar in. Technology for the sake of it, putting a chip in a board to control the pump speed by sensing temperatures. I know it helps prevent scale problems and is an easy if expensive fit in blocks of flats but I would bin it in a heartbeat if I could!
Don

Would prefer the PHE on the outside.
Internal coils can be more trouble.
PHE is easy for the diy person too.
Unless you lay out nearly £500:00p on a de scale pump.
Then the chemicals etc.
Nothing in life is ever perfect.

Hi Don,

Just saw your post and a comment about the internal coil. Please note that the internal coil can not be replaced unlike the Plated Heat Exchanger.