This is a puzzle for the clever ones amongst you with wiring circuits know-how. Firstly, I realise that my setup is a very non-conventional one but it has generally worked well for 20 years so I don't want to radically change it for zone valves etc etc. I'm just looking for a simple way (if there is one!) to make it a bit more efficient.
I fitted a glow worm 30ff open vented system boiler 20 years ago. The previous boiler had pumped heating and gravity feed to the indirect DHW tank. The glow worm, however, refused to heat the DHW circuit with gravity feed so I fitted a second pump on the DHW circuit to help the flow (as advised in installation instructions). I also fitted a cylinder stat to make it more efficient (or so I thought).
In the summer months this works well and the DHW temp is controlled by the stat. However, I've noticed that in order to have the rads on (controlled by a room stat) The programmer has to be set for the DHW to be on all day and the pump for the DHW is running the whole time that the C/H is demanding water for the rads. The programmer is a Danfoss FP715.
I've tried almost every permutation but the best I can do with this setup is to have DHW priority which I don't want to do (I want the heating when needed). I've therefore concluded that I need to add some kind of relay (I'm a real novice with relays) to bring everything under control. The main problem is that there are 2 pumps and only one boiler.
Any clever suggestions? I've attached a phot of the wiring circuits (sorry crudely drawn).
PS Another reason for wanting to modify is that I've noticed some pumping over to the header tank from the DHW circuit during the winter when heating on a lot.
I fitted a glow worm 30ff open vented system boiler 20 years ago. The previous boiler had pumped heating and gravity feed to the indirect DHW tank. The glow worm, however, refused to heat the DHW circuit with gravity feed so I fitted a second pump on the DHW circuit to help the flow (as advised in installation instructions). I also fitted a cylinder stat to make it more efficient (or so I thought).
In the summer months this works well and the DHW temp is controlled by the stat. However, I've noticed that in order to have the rads on (controlled by a room stat) The programmer has to be set for the DHW to be on all day and the pump for the DHW is running the whole time that the C/H is demanding water for the rads. The programmer is a Danfoss FP715.
I've tried almost every permutation but the best I can do with this setup is to have DHW priority which I don't want to do (I want the heating when needed). I've therefore concluded that I need to add some kind of relay (I'm a real novice with relays) to bring everything under control. The main problem is that there are 2 pumps and only one boiler.
Any clever suggestions? I've attached a phot of the wiring circuits (sorry crudely drawn).
PS Another reason for wanting to modify is that I've noticed some pumping over to the header tank from the DHW circuit during the winter when heating on a lot.
