problem iflo 3 port valve install? help required please.

[twgas]

Cold feed should be between open vent and pump and less than 6 inches from the vent

 

[twgas]

Alarm bells started ringing when I read this:

if I set hot water only valve travels across

The valve doesn't move for HW only as the HW port is open when the valve is not powered.

It will if the last demand was for CH.

 

[sifly2]

Cold feed should be between open vent and pump and less than 6 inches from the vent

It's been like that for 40+ years, running fine now, is it critical?
I did move the vent as it was pumping over in its original position on high pump speed.

Yep, I was talking about it moving from CH demand through mid position to HW..

 

[St0rmer66]

It can suck air through the vent how you've got it. It's a slow process, won't show itself until a few years down the line when your system is full of sludge! Shame the boiler doesn't have an overheat stat or you could just combine them.

 

[sifly2]

Shame the boiler doesn't have an overheat stat or you could just combine them.

Boiler does cut out when set water temp reached in system, but guess that's not what you mean as I don't see how that's linked to the feed pipe?

 

[twgas]

Agree with stormer!

 

[St0rmer66]

Overheat stat is a manual reset if the boiler reaches a set limit (usually 90 degrees or so) to stop boiling. Combining cold feed into the open vent is literally as it sounds... Just T'eed in! But shouldn't do it without an overheat stat on the boiler.

 

[sifly2]

Agree with stormer!

Will move it, as can see how that would happen if a restriction occurs.

 

[sifly2]

Overheat stat is a manual reset if the boiler reaches a set limit (usually 90 degrees or so) to stop boiling. Combining cold feed into the open vent is literally as it sounds... Just T'eed in! But shouldn't do it without an overheat stat on the boiler.

If I get the make/model of boiler, would you know if it had a manual reset? As it would be easier to combine than to move it!

 

[St0rmer66]

Yes, if it's the later back boiler with a PCB then it will have one. The early (and most common) ones do not.

 

[sifly2]

OK ta, I'll have a look later in the week as away first thing tomorrow for a few days.

I guess t'ing in right next to the vent tee still needs the stat?

 

[45yearsagasman]

and feed pipe is plumbed to cylinder return.

That's not where it should be connected. The correct order is:- Boiler/open vent/cold feed/pump/3port, all on the primary flow.