3 port diverter valve???

[Blue_Manc]

Older Mistral boiler is currently pumping out heat for the radiators, but not heating the water tank.

Have checked that there is no air lock to the tank, bled the supply point to the tank.

The strange thing is if I put the heating on the "Water only" setting the radiators still come on.

Any thoughts?

 

[Burnerman]

A 3 port diverter valve which has a faulty stepper motor, more than likely.
John

 

[Blue_Manc]

Wow - that sounds fancy

Is this a DIY repair, or do i make Like Ulrika Johnson after some Lambrini, and get a man in?

How do i diagnose that fault to make sure that's what it is?

 

[Ronald0]

Wow - that sounds fancy

Is this a DIY repair, or do i make Like Ulrika Johnson after some Lambrini, and get a man in?

How do i diagnose that fault to make sure that's what it is?

Switch off the electrical isolator to reset the motorised valve.

Turn on the isolator, select "hot water only" on the programmer,turn down room stat to min, make sure cylinder stat is calling.

Boiler will fire, put your hand on the hot water cylinder side of the motorised valve about 12 inches away from the valve and feel the pipe heat up. You will then know that the water in the cylinder will start to be heated up. The pipe on the other side of the motorised valve (central heating side) will be cold.

 

[Blue_Manc]

Okay thanks - have googled what one looks like - will do this when I get home. I am assuming that it should be fairly obvious where it is located (close to the boiler and external to it?) and easy to identify?

 

[Ronald0]

Okay thanks - have googled what one looks like - will do this when I get home. I am assuming that it should be fairly obvious where it is located (close to the boiler and external to it?) and easy to identify?

Re-reading your post it doesn't state that you have a 3-port valve, but if you have it will sit on top of a copper pipe tee.

Probably just after the pump, near the hot water cylinder in an airing cupboard.

 

[Blue_Manc]

No such valve located near the pump or in the airing cupboard. Did the IT solution and turned it off for a while at the mains - seems to be working right now. Will monitor and come back if not fixed - the vagaries of this heating system are beyond me......