baxi Bermuda water temp too hot

Wife mentioned that the water seemed a bit too hot so turned the boiler stat down but made no difference, new one bought and fitted and still the same although everything else seems to be working eg cylinder stat, 3 port valve, room stat, pump although the 3 port valve cover feels warmer than the body even after being off all night although it has always done this,is this to hold it in mid position?
baxi bermuda inset 50/3
Drayton lp722 programmer
Drayton wired room stat
drayton hts 3 tank stat
Drayton flowshare 2 3 port valve

ptarmigan said:

the 3 port valve cover feels warmer than the body even after being off all night although it has always done this, is this to hold it in mid position?

Click to expand...

With a Drayton Mid-Position valve, it will remain in the heating position if the heating was running at the time the system last switched off. So, if either in the 'mid position' (heating & hot water) or 'heating only' position, the valve motor will remain energised.

During the summer if the central heating isn't used at all, and the hot water remains in use, the valve will stay permanently un-powered at the 'hot water only' position

Thank you Stem that's one less thing to worry about.

Check the cylinder thermostat, has the immersion heater been left on/accidentally knocked on?

stem said:

A Drayton Mid-Position valve will remain in the position that it was in when the radiators / hot water were last being heated. So, if that was either in the 'mid position' (heating & hot water) or 'heating only' position, the valve motor will remain energised.

Click to expand...

That's only true if the last position was heating or hot water. If the valve is in mid position when CH or HW is satisfied, it will automatially change over to the function still required (CH satisfied, changes to HW; and vice-versa).

Chris, Immersion fitted but not wired in, the stat has always been set at 58c but today overode the the hw on the programmer and let it run then turned the tank stat to check it was still working which it was and now the boiler stat is working! how does that work because surely the water temp for hw and ch is controlled t the boiler and the cylinder temp at the tank stat although the tank stat is set to 58 as that gives us enough hot water for a day, shall i get another tank stat although i will wait till the ch comes on tonight and check the temp again.

D_Hailsham said:

That's only true if the last position was heating or hot water. If the valve is in mid position when CH or HW is satisfied, it will automatially change over to the function still required (CH satisfied, changes to HW; and vice-versa).

Click to expand...

My description was based on what would happen when the programmer switches off the heating and hot water at night. During normal operation, if one function is still running, then of course as you say the valve will move to the correct position as required.

At the end of the days heating cycle what happens depends upon where the valve is positioned at the time.

1) If the valve happens to be in the 'Mid Position' (heating on and hot water on) when the programmer switches off, immediately a live is applied to the grey wire (HW Not required) because the valve's internal microswitch has operated, that live will go straight through it to the valve motor and wind it across to the 'Heating Only' position where it will stay. [I have edited my first post slightly as it could be read that the valve stays in the mid position and not that it moves to heating only, but as far as the OP is concerned (& has noticed) the end result is the same, the motor is still energised.]

2) If it was in the 'Heating Only' position, it will stay there for the same reason, being powered via the grey wire. [The loss of the live on the white wire, in turn, removes the live on the orange wire and so the boiler goes off]

3) If the last position was 'Hot Water Only' there is no power whatsoever applied to the valve motor and the spring holds the valve in the 'Hot Water Only' position. When the hot water goes off and the grey wire becomes live, because the microswitch hasn't operated it doesn't get fed to the valve motor. So, during the summer if the central heating isn't used, the valve will stay held by the spring in the 'hot water only position' with the motor completely un-powered for the duration.

Sorry I do not like to rubbish any posts, and this one some I really respect, but with your set up whatever the Boiler thermostat is set at , the HW can never get hotter than that, , I think you have an electrical Immersion heater that someone has mistakenly switched on and that is where the problem is, if the water leaving your BBU is say maximum 50 degrees there is no way the water in your cylinder can get hotter than that

Ian, see post 6, the problem laid with the boiler stat but after turning the tank stat around and back to it's previous position the boiler stat now appears to be working and will wait till the ch comes on later and check that the boiler stat is doing what it should, controlling the water temp.

stem said:

At the end of the days heating cycle what happens depends upon where the valve is positioned at the time.

1) If the valve happens to be in the 'Mid Position' (heating on and hot water on) when the programmer switches off, immediately a live is applied to the grey wire (HW Not required) because the valve's internal microswitch has operated, that live will go straight through it to the valve motor and wind it across to the 'Heating Only' position where it will stay. [I have edited my first post slightly as it could be read that the valve stays in the mid position and not that it moves to heating only, but as far as the OP is concerned (& has noticed) the end result is the same, the motor is still energised.]

Click to expand...

You are assuming that the programmer's HW relay will switch over faster than the CH relay. There may only be a few milliseconds in it, but which ever is slower wins.

Put heating on tonight with hot water off and back to square one with the burner running constantly and the boiler stat not responding apart from off, 3 port valve is working with it in htg position, what to check next?

So the heating is now staying on? Could be a faulty room stat or wiring.

It's not the heating that is staying on it is the boiler stat that is not working although it is new' the water just gets hotter and hotter, just tried the room stat and that works

ptarmigan said:

Ian, see post 6, the problem laid with the boiler stat but after turning the tank stat around and back to it's previous position the boiler stat now appears to be working and will wait till the ch comes on later and check that the boiler stat is doing what it should, controlling the water temp.

Click to expand...

your problem is at the boiler and nothing to do with any external controls, if the boiler is correctly switching off at say 50 degrees as you say, it does not matter what any other control does the water in your HW cylinder can not possibly get hotter than that, you can put the HW on 24 hours a day but if the boiler is correctly switching off at the desired temperature, then the cYlinder water can never get any hotter than that, you either have a boiler thermostat problem (I know you said it has been changed, but by who ?) and I know you said there is no other heat source to the Cylinder , but these are the only two things that can cause over temperature, it has absolutely nothing to do with external controls

Ian,
I understand what you are saying and will take another look tomorrow and update as i am off for the weekend.