3 port valve faulty?

[Readingplumber]

Hi all,

Am I unlucky or have I done something wrong,

I installed a danfoss 3 port valve on a heating upgrade, but replaced it with a Honeywell one because when I switch on the hot water it was leaking through to the heating circuit.

so with the new Honeywell valve ,

when heating is on by itself works ok
when heating and hot water works ok
when hot water only system boiler fires up but valve not opening and boiler just overheats.

I have checked the wiring many times, is there something I'm doing wrong or is it another faulty valve?

 

[heliotrope]

I would say you have a wiring problem. Sounds like the pump not running when calling for HW.

3 port does not open when HW only called for. Valve is at rest and HW port open. Pump runs and
boiler fires.

Does the pump definitely run when calling for heat & heat/hot water?

 

[Roger Welton]

Agreed with a demand for hot water only there is no supply to the 3 port and it sits with all flow to the 'B' port boiler and pump are switched via the cylinder stat only (although the pump may be controlled by the boiler)

 

[jtsplumbing]

I know its a silly question but is the valve the right way round ? Port `B` to hot water ??

 

[Readingplumber]

Hi, yes port b is ho****er, When demand is on for hot water pump comes on - system boiler , just done Honeywell tests at back of book and it's indicating faulty valve.

 

[dave1]

Did you close the balancing valve on the return on cylinder?

 

[mountainman]

As has been said, the valve does nothing on hot water demand as at rest the AB and HW ports are open and the programmer and cylinder stat fire up the boiler.

Since a 'Y' plan valve always has at least two ports open at all times then if the pump is running then you should have circulation.
The boiler overheating indicates to me a circulation problem.

Which model Danfoss valve did you replace?

 

[Readingplumber]

Hi again,

Thanks for your help,

What I done has part of my elimination process is I switched valve around, ie port A for ho****er etc, when i put on ho****er it works (goes through heating circuit) But when i put on heating it overheats, so im thinking som major blockage in hw primaries, any ideas, there is no balancing valve on hw return.

thanks

 

[dave1]

Iomega others have said sounds like circulation issue, could just be full of air.

 

[jtsplumbing]

Is the pump running when on for hot water only ??

 

[mountainman]

The reason I asked the model of the valve is that some old valves had a different port configuration.
If you assumed that all 3port valves are piped the same then you could have piped the boiler flow into the Heating port which would be closed when on HW only.
hence no circulation and the boiler overheats.

 

[Readingplumber]

Hi Thanks for all your help.

I finally Solved the problem, It was me and a school boy error, i forgot to mark the existing pipes.

Where I had removed the f and e pipe work going into loft because of new system boiler going in, I connected up the 3 portvalve wrong I got ports a and AB mixed up.

Switched it all around and all working perfectly.

I wont make that mistake again - too time consuming!

But thanks all for help

 

[dave1]

Glad you sorted it, you'll always Learn from mistakes. They're the ones you never forget.