Ok so this problem is now doing my nut in!
The System
22mm Surrey valve on a vented system hot water tank supplying a grundfos/watermill 1.5bar twin impeller centrifugal pump pushing water up to a Hansgrove thermostatic mixer with a 4 setting showerhead.
The Problem:
The hot water flow seems to be insufficient to start the pump. In order to start the flow or pump operating i need the turn the mixer setting to full cold, then when the pump kicks in - turn the temp knob to required temp setting - the pump does not start when the temp knob is left at desired settting.
Tried solutions so far:
I have done some research and suspected it could be a broken surry valve - removed this and found no plastic bubble eliminator at the base of the 22mm pipe inlet and the plastic bleed nipple in the vent hole was missing. Replaced with new one and had no effect!!
The pump was replaced at the same time as the surry valve (problem had been occurring months before this.)
System was bled after new pump/surry valve installed for 5mins to eliminate all air bubbles.
Problem still occurs
Fault finding:
With shower head removed and pipe in basin of bath the pump and water flow does activate pump. It is only when shower head is fitted and placed in holder high on wall that the problems start occurring.
This points at insufficient head limits or minimums - the website for grunfos/watermill says that a min head is 1metre and i think my set up has just this.
Other observations - The previous pump had slightly wider bore connector hoses which i have kept on this new pump, the ones that came with it look thinner - whilst i realize the flow rate may be slightly reduced by using them - would this have any effect on the pump kick in pressure?
All comments/ hints/tips/ criticism welcome!
The System
22mm Surrey valve on a vented system hot water tank supplying a grundfos/watermill 1.5bar twin impeller centrifugal pump pushing water up to a Hansgrove thermostatic mixer with a 4 setting showerhead.
The Problem:
The hot water flow seems to be insufficient to start the pump. In order to start the flow or pump operating i need the turn the mixer setting to full cold, then when the pump kicks in - turn the temp knob to required temp setting - the pump does not start when the temp knob is left at desired settting.
Tried solutions so far:
I have done some research and suspected it could be a broken surry valve - removed this and found no plastic bubble eliminator at the base of the 22mm pipe inlet and the plastic bleed nipple in the vent hole was missing. Replaced with new one and had no effect!!
The pump was replaced at the same time as the surry valve (problem had been occurring months before this.)
System was bled after new pump/surry valve installed for 5mins to eliminate all air bubbles.
Problem still occurs
Fault finding:
With shower head removed and pipe in basin of bath the pump and water flow does activate pump. It is only when shower head is fitted and placed in holder high on wall that the problems start occurring.
This points at insufficient head limits or minimums - the website for grunfos/watermill says that a min head is 1metre and i think my set up has just this.
Other observations - The previous pump had slightly wider bore connector hoses which i have kept on this new pump, the ones that came with it look thinner - whilst i realize the flow rate may be slightly reduced by using them - would this have any effect on the pump kick in pressure?
All comments/ hints/tips/ criticism welcome!