Hot Water runs hot for 30 seconds then goes cold? Whats happening & how do I fix this one?

Hello Mike,

I have a Gledhill Systemate 2000, which was installed in July 2003 and we have a Water Softener fitted which reduces limescale in the cold water system.

The problem I have is as follows:-

Withe the Systemate in 'Normal' Operation, when you turn any of the hot water taps on, the water runs exterenely hot for about 30s and then goes cold, and doesn't heat up again. Turn the tap off, and the same thing happens when you run the water.

When you take the front cover off the Systemate 2000, you can hear the middle (Boiler) pump running continuosly, even though the mechnical timer is not 'demanding' heating and the boiler is not operating. The boiler thermostat is set on maximum, but when you run the hot water taps, the boiler doesn't fire to top up the system i.e. the DHW LED 3 doesn't light.

If you switch the Systemate into Emergency HW, the middle pump (Boiler) stops and the right hand (DHW) one starts up, presumably pumping the HW.
If you switch the Systemate ino Emergency Heating and HW, this appears to be OK with both Boiler and Space Heating pumps coming on

The ACB LED read outs are as follows:-

Normal Operation, ON and Bar 1 HT and Bar 2 ST LED's are lit. In addition, Green LEDs 1 and 2 (Boiler On and Boiler Pump On) are lit.

Store T1 = 67 T1 on= 71 T2 off= 74
PHE T2 = 58
DHW T3 = 65

We have had the ACB board changed and also the T3 sensor to the top right of the Heat Exchanger too.

Any ideas what the problem can be with the HW?

Cheers

Can someone please advise as it will be of great help.....thanks!

Hi I too am having same sort of problem, no hot water but I do have heating. I got told the boiler is not receiving signal for hot water, the sytemate works with the electric back up. Does anyone else think I need a new board. I have changed hotwater pump and heat sensor. The boiler fires up for heating which is working brill, but no hotwater.
Thanks

kingsbury wrote:Hi I too am having same sort of problem, no hot water but I do have heating. I got told the boiler is not receiving signal for hot water, the sytemate works with the electric back up. Does anyone else think I need a new board. I have changed hotwater pump and heat sensor. The boiler fires up for heating which is working brill, but no hotwater.
Thanks

Could be the backup pcb, check if there is going any power to the pump at all. On the "Switch" ( electric backup boiler) models, the power from the hot water pump is coming from the PCB on the left hand front panel, not from the central pcb.

hope this helps Mario