Horstmann 2 Channel Programmer won't allow different hot water and central heating settings

[SenileGit]

Hi everybody, I have just replaced an old Horstmann Channel Plus H27 programmer with a Horstmann Channel Plus H27XL Series 2 programmer, but the new programmer duplicates whatever settings I put on the hot water channel, onto the central heating channel, and vice versa. Whichever one I change the settings on, when I go to the other one, all the times are now the same on there too! I notice that on page 5 of the manual it says:

"As both channels are totally independent it is possible to have them set differently if necessary. *"

"* It may not be possible to programme heating and hot water independently on certain systems."

But on the old programmer I could easily set different times for heating and hot water. Is it likely that the wiring into the pins that go into the back of the new programmer need to be changed? Or would it be easier for me to just try to get another programmer? I've just desoldered the old battery from the older programmer, and soldered it into the newer programmer, because the newer programmer's battery was only giving out 1V, and any time I turned off the mains electricity, the newer programmer lost all the timer settings (although the date and time remained correct, strangely enough.)

Would I be able to use another make of programmer and just fit it onto the wall mount that the Horstmann uses? That's all I had to do when I replaced the older one with the newer one, the wall plate with the pin sockets was the same, so it was an easy job. Unfortunately getting the wretched programmes to work isn't so easy!

(I had to replace the old programmer because I couldn't get the 3 way motorised valve to switch to 'Hot water' when I set the programmer to turn hot water on, and after taking it apart, I found that there were four burn marks on one side of the circuit board, on the other side were four small rectangular components, surface mounted, which looked like they had either overheated or burned out.)

Many thanks in advance to anybody who can help me.

ps is there an industry standard backplate for modern programmers, so that I could safely buy another brand if necessary?

 

[ianmcd]

Sonds like your programmer is set to Gravity, you need to set it to fully pumped

 

[SenileGit]

Hi ianmcd, I have a cold water tank in the loft that feeds the hot water system, doesn't that mean I have a Gravity fed system? But I'm very willing to try setting it to fully pumped if it will make it work!

 

[dal5band]

If you have a pump and a three way valve OR a pump and two valves then your system is fully pumped. Some older systems the HW side was gravity circulation (nothing to do with gravity fed) and you could not have separate CH times hence the option on the timer.
Anyway what was your old timer set to ?

 

[stem]

Hi ianmcd, I have a cold water tank in the loft that feeds the hot water system, doesn't that mean I have a Gravity fed system? But I'm very willing to try setting it to fully pumped if it will make it work!

There is often confusion about what the term 'gravity' actually means when it comes to heating systems.

Gravity circulation is where water circulates around a circuit without a pump, using the principle that hot water rises as it is less dense and cooler water falls by the affect of gravity as it is heavier. This is the description of 'gravity' that would effect the setting of the programmer i.e. it's not 'fully pumped' system, it only has pumped central heating with gravity circulation of hot water around the hot water cylinder as per the diagram below.

PUMPED CENTRAL HEATING WITH GRAVITY CIRCULATION OF HOT WATER

Gravity fed describes a system that is filled with water from a storage tank (usually in the loft) and has nothing to do with how the programmer is configured. Gravity fed systems can be and frequently are fully pumped in that the hot water circuit and heating are both pumped.

 

[SenileGit]

Dear all, many thanks for explaining that to me, I had no idea! I definitely have a 3 way motorised valve (Drayton, I think), and definitely have a pump next to it, so I will change the setting on the back of the programmer and try again! I will let you know how I go.

 

[stem]

I definitely have a 3 way motorised valve.

In that case your system is definitely fully pumped.

 

[ianmcd]

You have a mid position valve so you have a fully pumped system and you programmer needs to be set to fully pumped

 

[SenileGit]

Sorry for the late reply - thanks Stem and inamcd, it's working perfectly, now that I changed the setting to fully pumped!