Hello,
I own a Worcester Bosh HE 28 System boiler, it was installed a few years ago using an S-plan: two zone valves next to the boiler with a room thermostat and a Cylinder thermostat - no problems at all with hot water or CH.
One problem with the installation though... say the boiler was running for a while with a flow of 75-80 then suddenly both cylinder and CH stats shut off the valves, the boiler temps will start to rise as the water is not moving anymore until around 92c when the boiler pump will start running (overrun) again to seemingly move the water around, but as it can't (because no bypass is installed and both valves are turned off) the boiler temps keep rising until the max display of 99 (I guess they rise a lot more than that)... and eventually after a LONG while when the temps decrease to about 70 the pump stops and all is well.......
Now I could have found that about this a long time ago but have not as everything works so never looked at temps an what have you.. but purely out of coincidence, basically I bought an energy saver gizmo that tells you how much electricity you are consuming, and that prompted me to try and understand why the boiler pump was on so often and thanks to reading this forum realised that it was due to the above installation problem.
I am surprised that this boiler or the pump have not exploded after nearly 7 years and even more surprised that all the engineers that serviced the boiler over the years have never mentioned this as to the original installer, he is out of business now (I wonder why!).
Now I need to fix this and was hoping that one of you guys can help me in my quest.
This is what I could do - install an automatic bypass valve before the valves on the flow pipe and connect it to say the hot water flow pipe after the zone valve - this will work well as if I manually open the valve when the overrun kicks in the temps quickly drop and the pump will then stop after no more than 10 or 15 secs (basically when temps go back to 75 or so).
I understand that the above is the most common way of doing this and this is what the installer should have done when installing the boiler in the first place.
But.... why can't I simply connect the zone valve to the overrun signal (I have no clue how but I'm theorising) so that instead of installing this bypass valve I can simply have the normal zone valve open when the pump goes into overrun mode... this basically would be ideal as it will save on both having to buy the £40 bypass valve and the piping required to accommodate for it.
Please tell me if I can do this and your thoughts about my theory.
Thanks in advance !
Regards,
M
I own a Worcester Bosh HE 28 System boiler, it was installed a few years ago using an S-plan: two zone valves next to the boiler with a room thermostat and a Cylinder thermostat - no problems at all with hot water or CH.
One problem with the installation though... say the boiler was running for a while with a flow of 75-80 then suddenly both cylinder and CH stats shut off the valves, the boiler temps will start to rise as the water is not moving anymore until around 92c when the boiler pump will start running (overrun) again to seemingly move the water around, but as it can't (because no bypass is installed and both valves are turned off) the boiler temps keep rising until the max display of 99 (I guess they rise a lot more than that)... and eventually after a LONG while when the temps decrease to about 70 the pump stops and all is well.......
Now I could have found that about this a long time ago but have not as everything works so never looked at temps an what have you.. but purely out of coincidence, basically I bought an energy saver gizmo that tells you how much electricity you are consuming, and that prompted me to try and understand why the boiler pump was on so often and thanks to reading this forum realised that it was due to the above installation problem.
I am surprised that this boiler or the pump have not exploded after nearly 7 years and even more surprised that all the engineers that serviced the boiler over the years have never mentioned this as to the original installer, he is out of business now (I wonder why!).
Now I need to fix this and was hoping that one of you guys can help me in my quest.
This is what I could do - install an automatic bypass valve before the valves on the flow pipe and connect it to say the hot water flow pipe after the zone valve - this will work well as if I manually open the valve when the overrun kicks in the temps quickly drop and the pump will then stop after no more than 10 or 15 secs (basically when temps go back to 75 or so).
I understand that the above is the most common way of doing this and this is what the installer should have done when installing the boiler in the first place.
But.... why can't I simply connect the zone valve to the overrun signal (I have no clue how but I'm theorising) so that instead of installing this bypass valve I can simply have the normal zone valve open when the pump goes into overrun mode... this basically would be ideal as it will save on both having to buy the £40 bypass valve and the piping required to accommodate for it.
Please tell me if I can do this and your thoughts about my theory.
Thanks in advance !
Regards,
M