draining down to remove heated rail,is my system mongrel??

I am new so please bear with me!! I am in the process of knocking through my toilet and bathroom in to one,and this site has been a great help so far . I have taken down the partition wall and now have a lonley towel heater sitting room center,i wanted to remove and cap the pipes under the floorboards where they protude to meet the rail.
I have an emersion heater we use for hot water and a boiler we use for the central heating. i was under the immpresion they were two seperate entities but after advice to find a header tank in the loft ( or anywhere!) for the boiler ( I have one for my immersion heater)a small one they said IT MUST BE THERE!!I cant find one anywhere!! I closed off the valve on the old boiler (also no gauges to read on this thing just two square nuts to fit a red wheel on to close/open valves.it is a glow worm 45-60. ran rubber hose from the low drainage point on ground rad but nothing came out! I also attempted to undo a pipe on the towel rail and got a faceful of black water! (serves me right I know!)
But heres what I dont understand the most, I had turned off the water supply to my immersion heater during this attempt and when I turned it back on water flooded out of the top airscrew I had loosened on the towel rail. So I dont understand how I can have no header tank, a boiler
for just the radiators yet my water heating emmersion heater is involved in someway also!! my boiler is very old and is a Glow worm 45-60.
I thought combi boilers dont have immersion heaters,well in my old house they removed that and the header tank so im abit confused ,what system have I got here and how do I get to remove the heated towel rail?
One wheel on the boiler allows you to drain clear water and the other I think is an inlet (its just below the pump). I cant think of anymore info than that,hope you can help ,thanks.oh yes How do i know if the system has been refilled by me,is it ok just to check the rads bleed from the topscrew as I said there are no gauges on this one.

Sounds like you have "Primatic" cylinder. Do a search and you'll find lots, and lots...

sounds ominus,here I go>.>!!
cheers.

just read loads of primatic posts, jeez what a can of worms!!
thanks again anyway!!

Well I took the plunge and drained it down removed towel rail capped it off then as all the other posts said I filled up the system really sl;owly
and so far so good ,clean hot water from all taps,rads all working and no leaks!!
thanks for the leads and tips,even a plumber I know hasnt got a clue
about a primatic!!
Is there any after effects I should be aware of,like 3 weeks down the line the header tank explodes or something!!
thanks again diynot,no on to my next job ,the ceiling I think!!

3 weeks down the line the header tank explodes

Click to expand...

Don't be silly.

It's the boiler that explodes. You can't put corrosion inhibitor in a Primatic system, so you wake up one day to piles of rust where your radiators used to be, and no boiler, which goes into orbit when the rust blocks it up.

cheers chris,
it is a wacky system though init!!
was this out before the average combi boiler and if i did just change the emmersion heater and keep the boiler would that be ok?
or would I have to get a new boiler and an emmersion heater or are they both linked to the primatic set up?
I think in my own mind ( not much luck there then i know!) that the primatic is just the tank and not the boiler is that correct??
cheers again.

You could surely convert it to an ordinary indirect cylinder, though I don't understand how.

Youwot, John?

Mickell - terminology problems:
Immersion heater is just the electric heating element element in the HW cylinder.
HW cylinder is the round copper thing! Yours is a Primatic type. Ordinary ones are called indirect, vented cylinders, and don't have central heating water in them (apart from in a coil of pipe which heats it up) and the CH doesn't fill through them.
If you changed it to a normal cylinder, you'd need an extra small tank (cistern) as a header tank for the CH.

If you change to a combi, you don't need any tanks or cylinder, but there are downsides.

yes I get you ,If I change the tank the ch water still needs somewhere to go as the boiler is linked to the primatic,without the primatic and with a combi installed no such problem.