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[holey head]

i'm a sparky and i work doing heating systems. you won't have another header tank for heating. what i'll suggest is go to your cylinder cupboard and turn off yur imersion heater and your heating by the switch fused spur. your 3 port diverter valve will then close to water only. turn off any valves in the cupboard as well. then try opening drain cock if nothing happens then try isolating the radiator via the valve on the end. then when you are sure it's isolated undo the nuts holding the rad to the valves. you will lose the water from the rad so be careful. then get your bucket and open one of the valves see if anything comes out.  then let me know and i'll advise further

[smoothomega]

The drain valves have a larger nut that holds the valve into the body of the drain cock, slowly undo this larger nut ( it may be a serated nut) but not fully, this should draw out the stopper part of the valve and let the water drain, keep plenty of towles handy just incase you undo it a little to much. Unless you have a combi boiler, which you dont if it is a back boiler system then you will have another header tank to feed the central heating system. 60L of water is one hell of a lot for a central heating system to hold unless you have a twelve bedroomed house, this would indicate that the header tank is continueing to fill, its a bloody big tank or its a mains fed system which is unlikely. Hope this is of some help, any more questions then drop me a PM Good luck  

[JesterRT]

FINALLY!!!  It's stopped coming!!

I'd turned off the immersion heater before I started to prevent it burning out/overheating.  Can't see any valves in the cupboard.  It's as if the header tank serves both the heating and water system.  Maybe that's the way it works, with the '3 port divider' - no real idea what that does (but did see it in a diagram on the pages Baron Von-Miggy posted).

Looks like I'm pretty much there.  Just need to find some PTFE tape to screw in the valves to the new bathroom rad - and guess what I can't find at the minute

Anyway - thanks for the help.  Throwing ideas around here has soothed my nerves no end.  I've started jobs like these before and why is it that SWMBO always thinks they should take 5 minutes?

Thanks all....  top stuff, as usual  

[miggy]

FINALLY!!!  It's stopped coming!!

I'd turned off the immersion heater before I started to prevent it burning out/overheating.  Can't see any valves in the cupboard.  It's as if the header tank serves both the heating and water system.  Maybe that's the way it works, with the '3 port divider' - no real idea what that does (but did see it in a diagram on the pages Baron Von-Miggy posted).

Looks like I'm pretty much there.  Just need to find some PTFE tape to screw in the valves to the new bathroom rad - and guess what I can't find at the minute

Anyway - thanks for the help.  Throwing ideas around here has soothed my nerves no end.  I've started jobs like these before and why is it that SWMBO always thinks they should take 5 minutes?

Thanks all....  top stuff, as usual  

Your central heating water will not be the same as your hot water, if for some strange reason it is you need to get it sorted asap, for a system with 15mm pipe as you said, you will be supprised on how much water is in there.
I thought it would stop as stated as you header tank was not filling.

[miggy]

The 3 way valve only allows your water in your immersion to be heated by the pipework on the heating system, it does not feed water direct into your immersion, when your immersion gets to the temp the valve operates back to heating only.

 

[smoothomega]

Well done mate  
Strip and clean those drain valves out before you refill  
One header tank  :-? that is very naughty if its the case, unless the hot water tank has its own header tank built in.  :-/

[miggy]

When filling your system back up, remember to bleed each rad to allow air to escape, open the air bleed screws individually or you will have water everywhere and you will not close them all fast enough. Do them one at a time. if you dicide to flush your system, make sure you read the instructions on the products as you must get the correct flushing fluid.

 

[miggy]

Well done mate  
Strip and clean those drain valves out before you refill  
One header tank  :-? that is very naughty if its the case, unless the hot water tank has its own header tank built in.  :-/

He must have 2 tanks, one for heating and one for hot water tank feed, if he only has one then billy bronco must have put it in with his horse helping.

 

[Marks DTM Calib]

There must be two tanks (unless its a pressurised cenral heating cylinder or combined unit)....and it wont be 15mm for all of it.....well it shouldnt be, the main bolier pipe work inlcuding the main feed and return should be at least 22mm with 15mm drops to the rads.

Check the boiler pipe work and valve and pump pipes, bet there all 22mm.

[miggy]

There must be two tanks (unless its a pressurised cenral heating cylinder or combined unit)....and it wont be 15mm for all of it.....well it shouldnt be, the main bolier pipe work inlcuding the main feed and return should be at least 22mm with 15mm drops to the rads.

Check the boiler pipe work and valve and pump pipes, bet there all 22mm.

Looks like he has 15mm up to the rads also, a lot of water in that system if he has.

[JesterRT]

Well, here's the weird bit...  I cut the water supply so there's no separate feed to the boiler.  It's a back boiler, so I guess it's not a pressurised system.  I've got a hot water cylinder with an immersion heater and only one header tank in the loft.  Definitely.  It's clear apart from one tank and I've got a 4ft tube to light it so I can see everything...
Upstairs, no radiators are attached, but normally there'd be three.  I've pipework to fit a fourth, small towel rad in the bathroom.  Most the pipework under the floor is 15mm.  There is 'some' 22mm around, but most pipework under the floors appear to be in 15mm.  Downstairs rads (only 2) are dropped from the upstairs piping.

With both drain valves clogged on the downstairs rads I figure that I only really need to half drain the system anyway to fit the new upstairs rad.  So I stopped the header tank filling and drained all the water by running the hot water taps downstairs.  They were left open.  With an empty header tank I went to where I had an upstairs rad and opened a valve.  Water comes out.  Fair enough, there'd be a bit left in the pipes.  But it kept coming...  and kept coming...  but the oddest thing was that it ran from warmish (since the heating had been on a little while before I started, and then went colder.  Then, after I got rid of loads and loads of water the pressure seemed to ease slightly and it began to run warmer and warmer.  A gurgle from near the hot water cylinder and not long after it stopped...

Here's hoping that when I put the rad on tomorrow I can get the system all filled up and air free by lunchtime!  Got to head North tomorrow and need to leave the missus with hot water and central heating!  

[Kevin Wood]

Either the primary circuit is pressurised (does it have a filling loop, a pressure gauge or a pressure vessel anywhere?) or you have a primatic hot water tank where the two systems share a header tank, the heating system fills via the hot water tank and the systems are not entirely separated. I'm guessing it would be a lot more than 5 years old in this case.

In the latter case, the hot water taps wouldn't drain the hot water tank, only the header tank, so you have probably drained the hot water tank via the radiators!

If it's the former, you need to find the filling loop and pressure gauge and fill and bleed the system to the correct pressure before firing the boiler as just filling the header tank will leave the boiler dry.

Either way, it sounds like you're in a position to fit your rad now. Once that's done, seal the system up, fill the header tank and see if you can bleed air from the radiators. If you can it's a primatic system and you're away. If not you need to find the filling loop.

... and you can't add an inhibitor to a primatic system.

Kevin

[miggy]

Either the primary circuit is pressurised (does it have a filling loop, a pressure gauge or a pressure vessel anywhere?) or you have a primatic hot water tank where the two systems share a header tank, the heating system fills via the hot water tank and the systems are not entirely separated. I'm guessing it would be a lot more than 5 years old in this case.

In the latter case, the hot water taps wouldn't drain the hot water tank, only the header tank, so you have probably drained the hot water tank via the radiators!

If it's the former, you need to find the filling loop and pressure gauge and fill and bleed the system to the correct pressure before firing the boiler as just filling the header tank will leave the boiler dry.

Either way, it sounds like you're in a position to fit your rad now. Once that's done, seal the system up, fill the header tank and see if you can bleed air from the radiators. If you can it's a primatic system and you're away. If not you need to find the filling loop.

... and you can't add an inhibitor to a primatic system.

Kevin

How does that work Kev, does that mean you are washing etc with hot water thats in the heating system or is that part of the system independant, :question :question

[Kevin Wood]

How does that work Kev, does that mean you are washing etc with hot water thats in the heating system or is that part of the system independant,

Well, both systems initially fill via the common header tank, the radiators fill via their connection to the boiler and thus the hot water tank.

Once the hot water tank is full, air is trapped either side of the direct connection to the boiler, which exists inside a cylinder shaped insert in the main tank. So, the two systems are separated by air, which takes up the expansion and contraction as they heat and cool and, assuming everything is working OK, the radiator water doesn't mix with the hot water.

The problem is, if something goes wrong, or even if the tank didn't fill quite correctly and the air barrier was not established, the waters do mix, which doesn't do the heating system and boiler much good because it's a constant source of hard, aerated water. The hot water can also be discoloured by sludge from the primary system.

This is compounded because you can't treat the primary system with an inhibitor in case it gets into the secondary.

The systems were popular in the 60's and 70's but are totally obsolete now. If I had one, I'd assume that the tank was probably pretty full of scale as it'll be 30+ years old and I'd replace it with an indirect one and add a second header tank in the roof for the heating. A fairly straightforward DIY job.

Kevin

[Marks DTM Calib]

If I had one, I would replece it with a pressurised central heating setup.....much better and much less likely to get air in as there is no point in the system which is lower than atmospheric pressure.