- Messages
- 45
Hello all
I'm replacing 2 unvented cylinder a which are (a) end of life and (b) installed in a way which is clearly not right (no 2 port shut off valve on the heating coils just for a start, and there are other issues).
The heating coils are currently controlled with 3 port valves that are power open/power close. When 'closed' the water bypasses the coil rather than being shut off completely. The backup immersion heater is installed but has never been connected. The built in cylinder stats (both the demand stat and the over temp stat) have also never been connected. There is a pipe stat on the outlet that serves as the demand stat. Yes I know this is dangerous which is one reason why I want to change it. It's what I inherited when I bought the house.
I'm going to get this professionally installed, but it needs to work with what is already here, so...
When I get the replacement cylinders, every one I've seen has the 2 stars wired in series, so either demand or over temp will cut off the heat to the coil.
My question is - can I electrically seperate these 2 stats so I can have the over temp stat cut off the flow using 2 (currently non-existent) 2 port valves as its supposed to, but have the demand stats control the bypass valves as they do currently? This will obviously work, but is it permissable to break the factory installed link between the 2 stats on each cylinder? I don't want the 2 port valves to operate unless there is either a power failure, or there is a genuine overheat condition.
I'm replacing 2 unvented cylinder a which are (a) end of life and (b) installed in a way which is clearly not right (no 2 port shut off valve on the heating coils just for a start, and there are other issues).
The heating coils are currently controlled with 3 port valves that are power open/power close. When 'closed' the water bypasses the coil rather than being shut off completely. The backup immersion heater is installed but has never been connected. The built in cylinder stats (both the demand stat and the over temp stat) have also never been connected. There is a pipe stat on the outlet that serves as the demand stat. Yes I know this is dangerous which is one reason why I want to change it. It's what I inherited when I bought the house.
I'm going to get this professionally installed, but it needs to work with what is already here, so...
When I get the replacement cylinders, every one I've seen has the 2 stars wired in series, so either demand or over temp will cut off the heat to the coil.
My question is - can I electrically seperate these 2 stats so I can have the over temp stat cut off the flow using 2 (currently non-existent) 2 port valves as its supposed to, but have the demand stats control the bypass valves as they do currently? This will obviously work, but is it permissable to break the factory installed link between the 2 stats on each cylinder? I don't want the 2 port valves to operate unless there is either a power failure, or there is a genuine overheat condition.
