Hot water running into F&E from vent pipe

[leatherboots]

Hi,

The moment I turn on the hot water and the boiler starts firing up,
water(cold or hot, depends how long the boiler is on) starts running(not just dripping) from vent pipe into F&E.

However when I turn on the heating this does not happen and all the rads are nicely warm.

The system is fully pumped with 3 port mid-position valve. Boiler is Potterton Profile 60e.

At the moment I have the hot water turned off, because the cylinder does not seem to get warm with so much hot water going into F&E.

Any help will be highly appreciated.

 

[JohnD]

is this with a mixer tap, having just one lever, like a joystick?

Does it happen with other taps?

 

[Agile]

So what happens with CH and DHW both on together?

Tony

 

[D_Hailsham]

What setting is the pump on?

Do you have one or two motorized valves?

Is there a bypass pipe (after the pump and before the motorized valves) connecting the flow to return?

If so, is there a valve on the bypass, and what type?

 

[leatherboots]

Hi Agile,

Thanks for your reply.
When both heating and hot water are on, the water starts running (properly running) into F& E via vent pipe. It's very strange that this only happens when the hot water is on.

 

[leatherboots]

Hi D_Hailsham,

Thanks for your reply.
The pump currently is set at 3. It also happens when the pump is set at 1, just takes a bit longer for the water to start running into F&E.

There is only a 3 port mid position valve. I did not see any by pass between the flow and return

 

[Agile]

Normally caused by a blockage and that is usually close to where the feed pipe joins the system. Most often because the correct pipe layout has not been followed.

To correct it is normally necessary for a section of pipe to have to be cut out, cleaned and refitted.

If you have a powerful magnet you will often feel an attraction to the dirt inside.

Can by solved as a DIY job but many choose a professional.

Tony

 

[leatherboots]

Hi JohnD,


Thanks for your reply.
I mean when I want to heat up the hot water (not open the hot tap) the water start running into the F&E.

 

[JohnD]

OK, not the tap then.

As the water is still running, you could start with a chemical clean. It has the advantage of being quick, easy and cheap. If the problem remains, you will not have lost anything, and at least you will have loosened some of the sediment and sludge so that you can drain it out.

 

[leatherboots]

Hi, Tony,

Thanks for your reply again. Forgive my ignorance, if the blockage is at where the feed pipe joins the the system, surely it will affect both heating and hot water, not just hot water.

 

[Agile]

No, your system water is being pumped through a different route depending on what you have selected!

Rads or cylinder or both! So different flow resistances and pressures!

Tony