bleeding hot water cylinder coil on sealed CH system

[squowse]

went to fit a couple of rads at a friend's house. assumed wrongly the CH would be a vented system as the boiler looked so old (glow worm 65-80). went up to tie up the ball cock on the f&E tank and there isn't one.

can't find a filling loop anywhere. it's not near the boiler after ripping a couple of panels off so maybe it's behind a panel somewhere else? any one have any guesses where it might have been put?

also - assuming i find it, how will i bleed the hot water heating coil? there are just 2 pipes up to the loft and into the hotwater tank with no facility to let out the air that i can see?

am i missing something fundamental?? i have worked on fully vented systems (ie CH and HW) and sealed combi systems before.

 

[John506]

Is it the key type fill from directly under the boiler?

 

[squowse]

Is it the key type fill from directly under the boiler?

i can't see anything. it's an old floor mounted boiler and i can't identify a water supply pipe being anywhere near it, just flow, return and gas.
is it liely to be right underneath?

 

[seco services]

if theirs only one tank in the loft and its not a combi, and you can't see a red ex vessel you sure its a sealed system and not a primatic cylinder ?

 

[squowse]

if theirs only one tank in the loft and its not a combi, and you can't see a red ex vessel you sure its a sealed system and not a primatic cylinder ?

the hot water tank has a cold water tank above it and has all the same connections as the fully vented systems i've seen.

ok, i've looked at this http://www.salamander-engineering.co.uk/technicalcentre/faq/faq.htm#primatic
and it looks like this could be the case. will the cylinder be marked "primatic" somewhere?.

if it is, can anyone run me through the procedure for draining, refilling and bleeding? does the top cistern fill the CH system? and it bleeds itself once it has enough air for the bubble? this is starting to make sense now i think.

 

[seco services]

a primatic doesn't have a coil to bleed like an indirect cylinder.

if you only have one tank that fills the whole system you'll find when you drain the rads you will also loose hot water from your taps.
thats a primatic.

the art of refilling them is to fill them slow and you won't loose the bubble.
if you do loose the bubble your hot water will come out dirty.

 

[squowse]

a primatic doesn't have a coil to bleed like an indirect cylinder.

if you only have one tank that fills the whole system you'll find when you drain the rads you will also loose hot water from your taps.
thats a primatic.

the art of refilling them is to fill them slow and you won't loose the bubble.
if you do loose the bubble your hot water will come out dirty.

i plan to tie up the ball cock on the feed cistern then drain CH system, will the HW cylinder empty totally?
then when refilling let down the ball cock, filling the whole system from the top and how would i do this slowly? keep the ball cock suspended a little?

also if i do lose the bubble, how do i get it back?

thanks ever so much, i am sure that this is what we have here, i had heard of them but thought they were very rare and it didn't occur to me i might be looking at one.

 

[seco services]

i plan to tie up the ball cock on the feed cistern then drain CH system, will the HW cylinder empty totally?

if its a primatic yes.

then when refilling let down the ball cock, filling the whole system from the top and how would i do this slowly? keep the ball cock suspended a little?

is their not a gate valve on the pipe you can reduce the flow into cylinder

also if i do lose the bubble, how do i get it back?

drain and do again.

i try to keep away from them they are pain in the backside.

 

[squowse]

i plan to tie up the ball cock on the feed cistern then drain CH system, will the HW cylinder empty totally?

if its a primatic yes.

is there any other way to identify it for sure if it's not written on it (i am away from the house in question now)? otherwise could end up draining it and not being able to refill!
thanks again for all your tips. maybe i should stay away from it, but it's annoying as i have got all the new rads etc; ready to go.

 

[squowse]

if it was a regular sealed system with a coil in the hot water tank, there must be an expansion tank hidden away somewhere, probably with the filling loop, pressure release valve etc; attached?

then how would the hot water tank loop be bled? there should be a bleed valve above it?
there isn;t so this makes me think that this must be a primatic?

 

[seco services]

not even all indirect cylinders have a bleed valve fitted.

 

[diy]

Are these rads extra to the system, if so you may lose the bubble depending on the volume of primary water

 

[squowse]

not even all indirect cylinders have a bleed valve fitted.

how does the air escape from the coil when refilling the system?

 

[squowse]

Are these rads extra to the system, if so you may lose the bubble depending on the volume of primary water

yes they are. i don't quite understand what you mean though. which is the primary water? it's a 2 storey house with about 10 single, low and long radiators. adding 2 more 500 x 900 singles in the attic.

 

[holty]

as diy has said. adding extra rads to a primatic is not a good thing. if i remember a rule of thumb,it was no more than 4-5 rads on a system,but then it depends on the house size etc.