Filling up gravity central heating

The water to the header tank was turned off and the system drained down.
Swapped the mid position vale and it will now not fill back up.
The odd thing is the header tank did not drain off - it was still full when I went to turn the water on.
Suggestions?
--

Adam

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 13:00, ARW wrote:

Airlock.
No CH when I was a kid, but a routine at home every time a hot water tap washer had to be changed was to connect a hose between hot and cold water taps in the bathroom, and turn both on.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I don't suppose that was a cottage in Southwold?:-)
--
Tim Lamb

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 15:06, newshound wrote:

+1,
except that both those taps would be fed from the same tank so should have equal pressure.
Connecting the kitchen cold tap fed from incoming mains to a hot tap would be more like it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andrew wrote:

varies (by region?) ... no cold tap in this house is fed from the tank
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 16:12, Andrew wrote:

The HW tank is not relevant is it?
I never touched it.
--
Adam

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 16:19, ARW wrote:

In that case try connecting a hosepipe to the C/H drain cock, and see if that pushes water up into the C/H header tank ?.
You might have to manually move the 3W valve to the heating position.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 17:09, Andrew wrote:

There is usually (always?) a manual lever on the valve which allows both sides to be open and latched to facilitate filling. The latch on the manual lever should be overriden when the system is in operation by first switching to CH and then hot water only.
--
mailto : news admac myzen co uk

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 17:09, Andrew wrote:

I did. We filled the CH circuit up that way and eventually it started adding more water to the already full CH header tank via the expansion pipe.
I now realise the logical conclusion at this point would have been to block the expansion pipe and try to fill the header tank via it's feed pipe (ie the 15mm gravity feed pipe that the tank uses to feed the CH pipework from) or in other words (Star Trek and Scotty anyone, just reverse the gravity laddie) to prove that this pipe was blocked.
Cheers for the help. Much appreciated.
--
Adam

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 06 Oct 2019 16:12:03 +0100, Andrew wrote:

Doesn't work with the header tank, though.
--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
That only worked if the cold was from the mains. Brian
--
----- --
This newsgroup posting comes to you directly from...
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 15:06, newshound wrote:

Indeed a well tested solution, but worth mentioning that will clear an airlock in a vented hot water system, it won't help when there is one in the vented CH primary. You would need to find a way to connect your cold water tap to a rad tail or similar to have the same effect there.
--
Cheers,

John.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 13:00, ARW wrote:

Congealed sludge in the downfeed from the header? I had that a few years ago on a bend situated behind the hot water tank. Happy days.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 15:44, Andy Bennet wrote:

especially since the blockage might have suddenly released when the valve was removed :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sunday, 6 October 2019 16:13:30 UTC+1, Andrew wrote:

Mine did, as we were moving a full HW cylinder ;-)
Owain
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 15:44, Andy Bennet wrote:

Correct and a 15mm gate valve that I did not know (shelves full of towels etc) between the header tank to the CH pipework (joining into the CH pipework just below the air separator) that I did know about.
It looks like the valve was not fully open (and has probably been like that for 20 years) allowing crud and to fill the 15mm feeder pipe.
New gate valve and a bucket of water through the header tank and all is well.
Thank you to you and everyone else that has helped.
--
Adam

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 07/10/2019 18:43, ARW wrote:

Don't forget the inhibitor :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 07/10/2019 18:46, Andrew wrote:

I certainly did not. I have shit loads of the stuff as some new-builds I was working on had electric only heating. The bathroom and en suite had water filled towel rads with electric elements and they sent a full bottle of inhibitor with every house. One bottle did all 20 houses and I kept the rest:-)
--
Adam

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Gunged up T-Junction, where the feed pipe from the header tank joins the main heating pipework.
Mike
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 06/10/2019 13:00, ARW wrote:

Hi Adam,
I'm confused! Which bit is gravity? If there's a mid-position valve, the primary circuit is presumably fully pumped. It may be vented (as opposed to pressurised) if there's a small fill and expansion tank - but that doesn't make it "gravity". Is it thins tank which you're referring to as the header tank, or do you mean the large cold water header for the (presumably) gravity HW system?
Can you clarify just what you mean by "won't fill back up". Exactly what is happening or not happening?
As someone else has pointed out, the 3-way valve will be in the HW-only position when no power is applies to it. The manual lever moves it to the mid position, when you should get some flow to both circuits. You may need to do that if the primary circuit won't refill properly.
--
Cheers,
Roger
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.