Heating question: valve replacement and inhibitor

[MrFerrous]

Apologies for yet another post about a central heating problem.

My house's mid-point valve (an ACL 779H340-30L0) hasn't been switching properly for a while. I've disassembled the actuator, and there's extensive arcing damage to the microswitches, PCB and actuator casing, so I think it's time for a new one.

It seems that spare actuators for the ACL 779H340-30L0 are no longer available, so I've ordered one of these, which will require a partial drain down of the system:

have a couple of questions:

- There's nothing in the loft to indicate which (if any) inhibitor is currently in the system. Would something like Sentinel X100 be compatible with whatever is already in there when refilling?

- Does this sound like a plan? Does anyone know of a source of new actuators for the ACL 779H340-30L0 so that I don't have to drain down the system?

Thanks

[John Rumm]

> I have a couple of questions:

Generally yes - especially if its been some time since last dosed.

No, but if the valve is in the loft, then you won't need to drain much... on a sealed system a couple of pints is probably enough if the valve is toward the "top" of the system. On a vented one, shove bungs into the expansion tank F&E pipe and the vent pipe and that will trap most of the water in there as well - just have a couple of old towels positioned to catch the spillage.

[Tabby]

[Terry Fields]

a system, not relative the relative effectiveness in a test.

TF