Anyone know how one of these works?
Grundfos Central heating Pump The reason for asking is we recently had out old failed pump replaced for this one. Beforehand we could get at least 2 hot baths from our hot water tank and had a decent supply of hot hot water.
Since this was fitted we do get hot water, but we struggle to get one bath. As we don't have a shower, lots of hot water is key.
Any ideas or guidance would be great.
The pump is fairly straight forward. It either pumps or it doesn't. In my system the pump keeps running even if the thermostat has told the boiler to stop supplying heat. This assumes that the CH controller is on and demands hot water or CH. Normally you can select the speed, and therefore flowrate of the pump. I believe this pump has 3 speeds. Usually the pump has an isolation valve located on either side of it so that you do not have to drain the complete system to change the pump. Maybe one of these valves has not been opened fully after the pump was replaced and this is reducing the flowrate in the system. Possibly the pump may require to be bled. This can be done by turning the silver disc in the middle of the pump counter clockwise with a screwdriver until only water, not air, comes out. Please do this when the water is cold and also only turn the disc a small amount, as if you remove it you will get a huge amount of water exiting the hole.
To be honest any other fault-finding is difficult as it depends on the design of the rest of your system. Are there separate motorised valves for your radiators and hot water? Are they opening fully? If not they can usually be manually overridden etc etc.
I think I have probably confused the issue for you, but hopefully some of the above will help.
Les