Open CH system but no vent

[DIYedboy]

I've only worked on 3 systems, but they've all been wrong!.............I wonder if that means 8 out of 10 heating systems are wrong?

Having sorted out my family's systems, I'm now starting on mine. The boiler is upstairs in a bedroom, the expansion tank is sitting on the loft floor (about 2 feet higher) but 10 foot over. There isn't a vent pipe going into it! the flow pipe comes out of the boiler and there is just an automatic airvent before it goes into the cylinder. Am I right in thinking I basically have an unexploded bomb waiting to happen?

 

[mickyg]

the cold feed should be piped in 22mm. Its a combined feed and vent and a pain in the ar53 to get air out of when filling. Popular with clueless contractors on newbuilds.

 

[DIYedboy]

My house is 1930's, boiler suprima 50, cold feed 15mm going into the return next to the pump..............

 

[mickyg]

thats not good if correct. Are you sure the vent is not vented to the cwsc?

 

[DIYedboy]

The cylinder vents into the CWST, but that's it I'm afraid.

 

[mickyg]

doesn't sound at all healthy. increasing the pipe size of the cold feed to 22mm should give you some piece of mind, but a seperate vent wouldn't be a bad idea.

 

[DIYedboy]

I'll do the job right, so I'll bung in the vent, but what about the height of the expansion tank? I presume it needs to be a lot higher........but how much higher?

 

[mickyg]

check the MIs for the boiler it will tell you the minimum. Some only need 1m head. But a bit more wouldn't hurt. similarly with the height of the OV.

 

[DIYedboy]

Nice one, thanks Micky, I'll look in the manual, but what's an OV?

 

[mickyg]

OV= Open Vent

 

[DIYedboy]

Doh

 

[XKESTONMAN]

SUPRIMA HAS OVERHEATSTAT & CAST IRON HEAT EX,SO OK TO RECOMMENDTO CONVERT TO SEALED SYSTEM.MUCH BETTER THAN OPEN
VENT SYSTEM.MUCH LESS CHANCE OF AIR INGRESS,& CORROTION.

 

[XKESTONMAN]

ps sorry about capp locks.

 

[kevindgas]

xkestonman try the caps lock button and turn off the shouting

combined cold feed and expansion is very common in old systems, a lot have been done like this from the outset. but several have been converted to single pipe in a half arsed attempt to stop pumping over in poorly installed or maintained systems.

 

[kevplumb]

the old servowarm systems spring to mind