Hot water Cylinder replacement. Help please

[mik118811]

Hi all,

i have what i hope is a very easy question to answer but i have a back boiler which heats my central heating and water. i've had a problem with the f/e tank permanently overflowing and have been told that it is more than likely the coil in the tank. i drained the central heating system down at the weekend as i had to take off a radiator to flush it out as it wasn't heating up and yesterday evening went to have a bath and the water came out a tinted yellow colour, now i had thought that the water from the heating could not get into the hot water and it was the hot water getting into the heating that was the problem but can it go both ways?

my main question though is about the cylinder i have just purchased a new cylinder (with lagging) almost the same size as the one i already have (old copper cylinder no lagging), unfortunately the 2 of the holes are in different positions to the old cylinder but my query is i can only see 3 holes in my old cylinder as there are in the new cylinder but what i cant understand is the coil inside as i cant see inside my old cylinder which is currently installed there is a small pipe going into the bottom of it then a box going into the centre then the hot water pipe coming out of the top, on the new cylinder it has what looks like the coil in at the bottom and coil out in the middle then the hot water pipe at the top, is this the correct cylinder to my old one?

Thanks in advance for any answers.

 

[helpsy]

You have either an indirect or direct cylinder.
Direct no coil
Indirect coil
Direct flow/ return usually distance between these pipe entry/exit points further apart than a indirect. You need an indirect cylinder.
You will have cold feed in at the bottom of cylinder, hot draw off on top of cylinder, flow and return entry/exit points and immersion entry.

 

[mik118811]

so as i bought the indirect cylinder, i have the correct cylinder then? i presume it will make sense once i have taken it all out and i will be able to see into the old cylinder. just didnt want to take it all out and realise i bought the wrong cylinder.

 

[helpsy]

Yes correct.

 

[Toddyplumb]

So your old cylinder only has 3 connections ?

 

[mik118811]

as far as i can see unless there is a connection at the back at the bottom, the new cylinder seems to have 4 connections one on top two on the front and a fourth on the back at the bottom, could my old cylinder have these 4 connections?

 

[philtheflush]

your old cylinder sounds like a primatic system cylider where the hot water and the heating is seperated by an air gap when you drained down you probably lost the seal or gap and thats why you had yellowish water i think you need a plumber

 

[helpsy]

your old cylinder sounds like a primatic system cylider where the hot water and the heating is seperated by an air gap when you drained down you probably lost the seal or gap and thats why you had yellowish water i think you need a plumber

He said he had an F&E so it couldn't be a primatic!

 

[philtheflush]

helpsy i have a feed and expansion tank with a primatic system thats why i know it also happened to me i drained down and i recovered the seal

 

[helpsy]

I was taught that they were indirect single feed cylinders, fed from the CWSC.

 

[kay-jay]

if the seal goes on a primatic draining fully and re-filling should do the trick

 

[philtheflush]

helpsy i thought feed & expansion was the same as a cwsc

 

[Billy Bob Bob]

primatic has just one tank the larger size f+e and yes this is the same as a cwsc

 

[philtheflush]

so i was right in thinking he has a primatic system and has possibly bought the wrong tank

 

[Billy Bob Bob]

so i was right in thinking he has a primatic system and has possibly bought the wrong tank

yes he may have the clue would be just 3 pipes going up from the a/c pics would clarify things

 

[mik118811]

just to confirm it was the correct tank and was not a primatic cylinder

 

[spanner]

I reckon single feed were the best thing in there time by my studies!!, but aint one anywhere,, have you seen one before???
Say if I'm correct!!, to drain one of these systems, is to open an MT cock 'T'd, by the cold feed pipe at the bottom of the cylinder? ?? That's all I can remember!!!