Hi capri,
The VR 65 control centre was replaced with a VR 61 control centre as this allows 2 central heating zones, plus hot water.
A VR 81 remote thermostat was installed in the new kitchen/dining/sitting area, which is the new area being heated by the underfloor heating. This thermostat has to be wired upto the VR 61 and it allows a temperature to be set separately to the existing VRC 430 weather compensator thermostat, although all settings can be changed through the VRC 430. So the VR 81 controls the temperature of the new UFH area and the existing VRC 430 controls the setting of the existing CH.
Unlike on newer systems, the VR 61 doesn't offer an additional heating curve, so there is only one and this controls the existing central heating and the new underfloor heating, although, as I mentioned there are two zones, so different temperature settings (and setback temperatures) can be set for the UHF and CH.
The manifold has a thermostatic blender and pump built in, but a new zone valve was required to control the flow of water to the manifold. I used a Guardian Smartzone Pro 22mm 2 Way Zone Valve, which I was advised was better for UFH circuits. It's a nice valve!
I haven't needed to install a Low Loss Header or a bypass valve and everything is working well (touch wood). In fact you could argue it is working too well as the floor tile nearest the point at which the three UHF circuits attach to the manifold in the garage has cracked, and I suspect this is due to the change in temperatures (this is the warmest area of the kitchen), although it may have been cut and fitted badly as it is an L shaped tile so does have a week point!
The VR 65 control centre was replaced with a VR 61 control centre as this allows 2 central heating zones, plus hot water.
A VR 81 remote thermostat was installed in the new kitchen/dining/sitting area, which is the new area being heated by the underfloor heating. This thermostat has to be wired upto the VR 61 and it allows a temperature to be set separately to the existing VRC 430 weather compensator thermostat, although all settings can be changed through the VRC 430. So the VR 81 controls the temperature of the new UFH area and the existing VRC 430 controls the setting of the existing CH.
Unlike on newer systems, the VR 61 doesn't offer an additional heating curve, so there is only one and this controls the existing central heating and the new underfloor heating, although, as I mentioned there are two zones, so different temperature settings (and setback temperatures) can be set for the UHF and CH.
The manifold has a thermostatic blender and pump built in, but a new zone valve was required to control the flow of water to the manifold. I used a Guardian Smartzone Pro 22mm 2 Way Zone Valve, which I was advised was better for UFH circuits. It's a nice valve!
I haven't needed to install a Low Loss Header or a bypass valve and everything is working well (touch wood). In fact you could argue it is working too well as the floor tile nearest the point at which the three UHF circuits attach to the manifold in the garage has cracked, and I suspect this is due to the change in temperatures (this is the warmest area of the kitchen), although it may have been cut and fitted badly as it is an L shaped tile so does have a week point!
