central heating only comes on with h water, stumped engineer

bonkersbill · 2 Mar 2012

Boiler pipes

bonkersbill
2 Mar 2012
1

I ran the 3 tests today, some more than once because it showed the opposit pipe got hot for definate yesterday, i've marked off where each pipe from the boiler goes. I got the front off the fire and could just see that the right hand top port on the boiler was blanked off, i could see a pipe going to the left hand top port but could not see where the other went, it could have joined into left port or was hidden because of the angle i was looking from and probably went into bottom port. Been at this all day for last 2 days so i hope this is what you need.

doitall · 2 Mar 2012

Yes and No unfortunately, but we need to know where the bottom pipes connect.

So far we know the cylinder is piped wrong as is the common return as well.

Ok what you have is the return going to the MV from the boiler return tapping, and the flow going to the cylinder return.

The HTG return should join the cylinder return somewhere.

Not sure at this time where the htg return is connected.

As per my first drawing

View media item 43343

matt1e · 2 Mar 2012

18 pages!!

Hi bill, your drawing is still slightly confusing
by "to tank" do you mean "to cylinder"?

it looks as if the pump was originally on the return and still is! some one has altered the pipe work and turned the pump around

the pipe marked "tees into CH" are you sure this is going to the boiler and not past it into the floor to feed the downstairs rads?

Matt

doitall · 2 Mar 2012

It's exactly as my drawing Matt1e except we don't know where the return goes.

I edited my post above to add the drawing.

Norcon · 2 Mar 2012

If it T's to CH port A then isn't that a by-pass straight back to the boiler? Isn't there a leg of pipe that shouldn't be there?
There's connections missing on your drawing Doitall compared to the OP's.

bonkersbill · 2 Mar 2012

yes i do mean cylinder. the T to CH is the 15mm under the floor which goes down the conduit, this gets hot when Prog HW, 3pv mid and not when HW and 3pv HW. when the pipe to pump gets hot with 3pv set to HW,the pipe out of the bottom of the Cyl gets hot 2nd

Norcon · 2 Mar 2012

So just been looking at your earlier image of your system and you have a T on the CH leg.
One branch to the CH and the other back to the boiler.

Haven't read through all this and not sure what your problem is but I'd guess your CH is not working very well?

doitall · 2 Mar 2012

The first thing you need to do is swap the flow and return connections at the boiler around.

There will be another issue with the heating, unless you can identify where the they connect with a drawing, the way they are running I would say they could be connected to the other side of the boiler, or at least one will be.

Norcon · 2 Mar 2012

Complete the drawing Doitall. Something more than a fag packet sketch is needed for the full picture.

doitall · 2 Mar 2012

Norcon said:
Complete the drawing Doitall. Something more than a fag packet sketch is needed for the full picture.

My drawing is complete, and exactly the same as the OP's latest.

The exception being the htg return which is an unknown at this time.

Other the that the flow from the boiler goes to the cylinder return tapping on the bottom of the cylinder, and the boiler return tapping goes to the pump and port AB.

bonkersbill · 2 Mar 2012

is it not likely that the return is the bottom 22mm to the boiler, how can we find out if this is the CH return?
if i am to swap the 28mm pipes over, this would be so much easier to do between the conduit and the cylinder/pump.
Before i do this i think i will get the boiler serviced and try to find out more info then.

doitall · 3 Mar 2012

This is how it should be after you change the pipes over

View media item 43351
We need to know where the two pipes do/go in your drawing I have put a circle around them. Do not alter anything yet, as the pipe you have marked as going to Port A looks like it should be the htg return.

View media item 43467

matt1e · 3 Mar 2012

I'd say that would be the gas supply

Matt

Agile · 3 Mar 2012

bonkersbill said:
I got the front off the fire and could just see that the right hand top port on the boiler was blanked off, i could see a pipe going to the left hand top port but could not see where the other went.

Removing the firefront involves opening a live gas connection which is not something a DIYer should be doing.

Those encouraging you to do this do not seem to have excercised a sensible judgement.

Furthermore, its totally against the Forum rules and policies to gave advice or encouragement on DIY gas work.

The obvious advice is to call a gas registered engineer to check it out before you blow up yourself and your family.

picasso · 3 Mar 2012

I have not read all 18 pages (too much info!) so if its been mentioned before my apologies, I wonder if there is an old anti gravity valve on the heating circuit hidden away somewhere, just a thought.

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central heating only comes on with h water, stumped engineer

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