Sealed Heating System - Temperature relief valve?

[Readingplumber]

Hi all,

Just wondering, I am upgrading a open vented heating system to a sealed system because they are having an loft conversion but are keeping the old potterton profile boiler for the time being.

What I am wondering really is, back when i was a student we were told that the vent in the F and E tank would allow steam to escape and the cold feed would be a back up vent ie no valve allowed there.

When I purchased the unvented kit there is no temperature relief valve supplied with it only pressure relief I was just wondering why its not so important on a sealed system about over heating?

Thanks

Chris

 

[SimonG]

Hi limit stat on boiler takes care of over temp situations I believe.

 

[aplombier]

It is important you have three types off control on unvented cylinder
1 first control stat
2 non self resetting high limit stat
3 then last resort temperature relief valve
Pressure relief is on cold feed into cylinder

 

[aplombier]

Legally You should have gained your unvented ticket to install these things.

 

[BLOD]

Don't think the op said he isinstalling an unvented cylinder - just changing heating to sealed

 

[Whn1]

He did.

 

[Readingplumber]

Hi Thanks for reading - No only the heating system will be a sealed system - Will still have vented ho****er.

 

[Gray0689]

No need
Just Pressure relief valve needed

 

[lame plumber]

other issue is radiator full of water wont explode through your roof if it all goes wrong as there less water/steam involved

 

[aplombier]

Oppps Ok I'm with it now, sealing central heating and leaving hot water as cylinder. didn't read properly. Fit Pressure relief valve and fill loop and using boiler control and high limit

 

[thompsonbrown]

temp increase=pressure increase, as water expands when heated.

 

[aplombier]

Just asking. Out of interest
Can the potterton boiler be converted from f&e fed to a sealed system, I've never done it or heard of it being done. Because ure obviously turning it into a system boiler, are the boilers compatible.

 

[stoker122]

As long as the boiler has an overheat stat it should be fine. All the other system components are external.