New Drayton LP722 dual programmer help

[mikemac]

Hi, Im upgrading my old Drayton dual programmer for my hot water and central heating (Fully pumped, with ideal classic boiler) with the new LP722 and 3+ digital room stat. The programmer is the same model but new version. Now, for some reason the old tenants had a mechanical (very old) thermostat wired into the old programmer, (into ‘Live’ and into a chocolate block which is wired to a neutral) which I thought was very odd as there is also an old mechanical stat in the living room. So I removed this stat. They had no wires in Terminal 1 or 2, HW OFF and CH OFF.

So I swapped over the programmers, and the central heating worked but not the Hot water. Is this why the previous guys had the stat wired into it? I did some digging around and found that if I connected ‘Live’ into ‘Terminal 1’ (HW Off) then it the hot water seemed to work. Is this going to be ok? The manual says to only link live to 1 if using a ‘time switch’, and mine is a dual programmer, in which it says the link is not needed.

Any advice greatly appreciated 

 

[D_Hailsham]

You say the system is fully pumped. How many motorized valves and which type - left pic or right?

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Is there a cylinder stat?

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[mikemac]

Thanks for the reply, I will have a closer look tonight and let you know, Im not too 'hot' with central heating technicals

 

[mikemac]

OK, sorry for the late reply, I have the one in the right picture, and I do seem to have the cylinder stat on the side of my hot water tank.....

 

[D_Hailsham]

OK, sorry for the late reply, I have the one in the right picture, and I do seem to have the cylinder stat on the side of my hot water tank.....

Just one valve as in the RH picture? If, so is it connected to the pipe coming out of the bottom of the cylinder?

On the back of the programmers is a switch marked P and G. Which is it set to on the old one? The new one needs to be the same.

 

[mikemac]

OK, sorry for the late reply, I have the one in the right picture, and I do seem to have the cylinder stat on the side of my hot water tank.....

Just one valve as in the RH picture? If, so is it connected to the pipe coming out of the bottom of the cylinder?

On the back of the programmers is a switch marked P and G. Which is it set to on the old one? The new one needs to be the same.

the valve in the right picture goes to the top pipe of the cylinder.

The previous was set to pumped, as is the new one.

Thanks.

 

[D_Hailsham]

the valve in the right picture goes to the top pipe of the cylinder.

Thanks for the info.

That does not sound right. You say that you have a fully pumped system, but only have one valve. If that is true, you would not be able to have hot water by itself in the summer as there is nothing to stop the water circulating through the radiators.

If the system is fully pumped, the water leaving the boiler will go through the pump and then divide into two at a T junction; one branch to the HW cylinder, the other to the rads.

Have a look at these diagrams:


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