Central Heating Problems

[shaf7060]

Here is the problem:-

1) If programmer put to H/W only, I get H/W and C/H on full blast
2) If programmer put to C/H only I get nothing at all (boiler&pump are off)
3) Room Thermostat doesn't seem to control rad temps - always on full blast
4)Mid point valve always in mix position

I have read previous forum entries and have replaced the motorised valve - pretty much like for like and repeated the existing wiring layout. However, the problem is still the same. I noticed that the wiring diagram that came with the valve is slightly different from the existing set up in my house e.g. there is no H/W only wire from the programmer to the valve.

Now summer is here I am going to have to turn all the radiators off manually, but this can't be the most efficient way for the system to run.

Please help!!!

 

[gas4you]

Did you replace just the head, or the complete valve?

 

[bengasman]

1) If programmer put to H/W only, I get H/W and C/H on full blast

Programmer turns boiler on and off, not high and low

3) Room Thermostat doesn't seem to control rad temps - always on full blast

same for roomstat.

4)Mid point valve always in mix position

That only shows it does not work. Could be that it is faulty, could be that it doesn't get the right signal, could be you have replaced it with the wrong valve.

 

[shaf7060]

I replaced the entire valve and actuator - like for like.

Thanks

 

[seco services]

what valve is it ?
sounds like a wiring issue.
hw wire from programmer gos to the cylinder stat .

 

[shaf7060]

Drayton Mid Position MAI/679-3

I wired it up exactly as previously installed, however, there lies the problem I think. I can only currently turn the C/H and H/W on/off at the same time and the valve will only remain in the mix position.

Does this mean water from the boiler circulates through the tank and radiators whilst either the room or tank thermostat registers a thermal demand?

The 5th wire required from the programmer to allow "heating only", as per the valve installation guide, does not exist (red, blue, earth and yellow are present and used).

I am less interested in "heating only" option and more interested in having "hot water only" during the summer. I presume the system if working properly should be able to run in hot water only, heating only and combined. When in combined, the valve should still operate to divert boiler water to the demand - either tank, radiator or both.

 

[seco services]

what programmer is it ?

 

[shaf7060]

British Gas Model UP1

 

[seco services]

did this problem just start or always been like it ?

is this system been converted at some time from gravity hw to fully pumped ?
seem like the programmer is wired up hw and ch both on hw switch.
and wall stat not wired.

 

[shaf7060]

The problem has always existed - we moved in about a year ago.

The house is only 15 years old so I doubt any conversion has taken place.

I think I need the controls wiring looked at by a professional