I have tried everything to fix my Central Heating

[Toddyplumb]

Maybe try a Sentinal X400 use it with the upstairs rads isolated . Failing that a power flush, worst case is there is something wrong under that concrete. Its always difficult without being there. Is there no one local who can give it a look to make sure you havnt missed something ?

Or Fernox

 

[street elbow]

Smithy,

as you do not have the gate valves I asked about,

I would surgest that you follow the sequence I put in my earlier post.
but make sure that only the heating is on and not the hot water.

After reading your post again, you say that the D/S rads do get hot with the U/S switched off. This does make me think you have got an air lock in the pipe work.

I would run each D/S rad for at least an hour and also put the pump on to speed three (ignor the noise) after you have run each D/S rad put the 3port valve into the mid position to allow any air to get to the bleed valve and bleed it off.

The way the system has been plumbed in your airing cupboard does not allow any air in the heating to escape to a bleed valve with out the hot water being on. which is not helping your situation.

David


Hopefully this will move the air lock to a bleed valve somewhere on the system

 

[street elbow]

Smithy,

just thought, make sure the pump is off when you open the bleed screw in the airing cupboard.

David

 

[t_smithy]

Smithy,

just thought, make sure the pump is off when you open the bleed screw in the airing cupboard.

David

Thanks David,

I will try what you have suggested.
Is it true if you bleed the pump when it is running, it can it draw air into the system?

 

[Toddyplumb]

Yes it can

 

[Blackcatgas]

What size is the pipework? does it go from 22mm under the floor into 15mm wher you cant see it, ie have you got 15mm pipe trying to run 8 rads, if you turn off alll the upstairs rads do the downstairs rads get hot?.

 

[t_smithy]

What size is the pipework? does it go from 22mm under the floor into 15mm wher you cant see it, ie have you got 15mm pipe trying to run 8 rads, if you turn off alll the upstairs rads do the downstairs rads get hot?.

the pipe work is 22mm until it branches of to a rad. so the flow pipe from the mid position valve all the way downstairs is 22mm. when i turn off upstairs rads the down stairs do get hot.

 

[t_smithy]

It does sound like a partial restriction on the downstairs then
Just as a note to anyone looking at the photo , its not good to take a 15mm pipe straight into a cylinder coil on a reducer . You can get a section of air trapped along the top of the coil

Hi Toddyplumb, you mentioned its not good to take a 15mm pipe straight into a cylinder coil on a reducer because you get air trapped along the top of the coil. I did wonder why the water tank was so noisey, you can hear it bubbling and gurgling when heating the HW. Is there any way to get rid of the air trapped at the top of the coil?

 

[PLUMB-KING]

Hi Toddyplumb, you mentioned its not good to take a 15mm pipe straight into a cylinder coil on a reducer because you get air trapped along the top of the coil. I did wonder why the water tank was so noisey, you can hear it bubbling and gurgling when heating the HW. Is there any way to get rid of the air trapped at the top of the coil?

The best way for the flow to be piped to the cylinder coil is to take the pipe up above the tapping then drop down into it then a auto vent/or manual fitted at the upright of the feed.This is how old gravity hot water system were piped & worked well.

As for your d/s rads being drop fed as I thought in my last post,the u/s rads are getting priority heat,you need to balance the heat.IMO open all flow valves to u/s rads,& have all the return valves on u/s rads to just a crack ( hardly open but enough for the water to return ) this will slow down the heat returning to the boiler at a much slower rate,letting the heat flow on to other rads, IE d/s rads,make sure all d/s rad valves are fully open flow & return. Let this run for a good 30mins to an hour,then vent/bleed the system,always turn the pump off when venting/bleeding the system. Being you have a drop fed system IMO I would of fitted a 15/60 not a 15/50.

Small pic of the way I have been taught to pipe cylinder primaries.

 

[Toddyplumb]

The bubbling ang gurgling may not be air , are you sure that motorised valve is shutting off the HW when at temp ?
However to remove air from your coil top you would have to split the joint. It should run into the cylinder in at least 22mm to keep air entrained , on gravities we sometimes fitted a 28mm T at the connection to the cylinder flow to make sure coill was fully vented, ohh the good old days

 

[t_smithy]

The valve is definately shutting off the HW. I took the case off the valve and watched it move to the CH only position once the HW thermostat had reached the right temp.

At some point I will look to improve the water tank plumbing and add an auto vent fitted at the upright of the feed.

When I purchased a new pump I was unsure if I should purchase a 15/60. I think once I have run through the process of trying to get all the air out of the system, if there is no improvement I may well go a buy an 15/60.