Hot water flowing from vent pipe into loft tank

[wardr77]

Here is a pic of the pump, hopefully you can see the arrow pointing towards you with the feed and then the vent in the background

 

[denso13]

Also it's under a greater pressure from a tank full of water.

It started when I called this out as wrong and you are now on to this...

you have not understood angles and small diameters are bad for flowing.

Yes, pipe diameter and fittings can restrict flow, but not in this case.

 

[wardr77]

If you did not have this venting problem with the old pump, the culprit could be the new pump.

Well with the old pump I had 4 rads that would not get hot and one was permanently cold, (I did take these off a few months ago and blast them through in the garden with a few whacks with a rubber mallet, but no difference); with the new pump, all rads are hot so I'm assuming that's a step forward and it's the power of the new pump + possible constriction that's causing pump over..?

 

[BlueLoo]

https://www.diynot.com/diy/media/untitled.897/

 

[wardr77]

OP, check the gate valves. Make sure both are fully open. You can do that with a spanner, counter-clockwise is to open. Open fully, then close a tiny bit.

Just to double check, the gate valves are the two valves either side of the pump? Thanks

 

[JohnD]

they are. After opening, back them off half a turn so they are not tight against the stop. This reduces the risk that they will seize. Judging by the colour of the brass yours are brand new so unlikely to be faulty yet. If water is circulating freely round your radiators there is no reason to suppose they are obstructing flow, and there is no reason to suppose that, even if they were, they would cause pumping over.

Poisson rouge.

 

[Madrab]

x400 can stay in your system for weeks but the system will need fully drained and flushed eventually.

it's the power of the new pump + possible constriction that's causing pump over

Yes

 

[Dereekoo]

https://www.diynot.com/diy/media/untitled.897/

Ah, point B

 

[Madrab]

Oh and the pump orientation is correct

 

[wardr77]

Just to confirm gate valves were fully open and had been backed off 1/4 turn, so all good there.
Its pointing to the crud build up in the feed pipe junction isn't it, as advised by Madrab?

 

[denso13]

Its pointing to the crud build up in the feed pipe junction isn't it, as advised by Madrab?

Yes, sort that first.

 

[BlueLoo]

Make sure the pump is on the right setting. Look at the manual.
Usually you just keep pressing the mode button cycling through the various modes.

I don't know what the pros here recommend (please do!) But your pump should be on a constant speed setting because it has an ABV. It only needs speed 1 imo as these pumps are strong but you can check that easily by observing performance.

If you add cleaner, set the pump to max speed (fixed). Whilst it horses through the pipes. Have everything open for a hour 1st, then do the opposite, opening one rad at a time only. Set the ABV to max when doing this (return afterwards).

This should give your system a good flush through using the pump.

Quite happy to hear other thoughts on this approach. It worked well for me

 

[wardr77]

As previous poster suggested I'll get some X400 in the system and leave it there for a while until I can organise plumber and if that doesn't sort the problem , I'll get the junction section replaced, and if that doesn't fix perhaps link the feed to the vent, as per earlier discussion. Thanks again all.

 

[wardr77]

Make sure the pump is on the right setting. Look at the manual.
Usually you just keep pressing the mode button cycling through the various modes.

I don't know what the pros here recommend (please do!) But your pump should be on a constant speed setting because it has an ABV. It only needs speed 1 imo as these pumps are strong but you can check that easily by observing performance.

If you add cleaner, set the pump to max speed (fixed). Whilst it horses through the pipes. Have everything open for a hour 1st, then do the opposite, opening one rad at a time only. Set the ABV to max when doing this (return afterwards).

This should give your system a good flush through using the pump.

Quite happy to hear other thoughts on this approach. It worked well for me

Yes I will do this, thanks

 

[HERTS P&D]

Where are the Mods when you need them, come on Mods delete the diyers giving out false information.

Andy

Here - you should have raised an alert