Heating/DHW Control Timer Question

[adh2020]

Hello,

I just got round to replacing the mechanical timeclock in my house, it had a pretty loud and annoying ticking characteristic. It was a Horstmann 423 diamond 2 on/off settings (same every day), and same for dhw and ch.

We had no thermostat in our house either, the dhw is gravity with pumped htg. I purchased a Danfoss TP9 programmable room thermostat with domestic hot water timer, hoping it would do the job. I have wired this up as the diagram, see image.

There are three on/off periods for the central heating, and also the clock its 5d/2d or 24h. There are only two DHW on/off periods based just on time which are the same for each day. It is now possible for the central heating to be set to come on independent of the DHW. However if this happens then just the central heating pump is switched on, not the boiler, so the rads don't get hot!.

My questions really are these?

Could I have wired it better, so the heating switches the boiler on too if it's not within a period when the DHW is switched on?

Is the solution just to set the dhw and ch to follow the exact same periods?

Any info would be appreciated. I understand the make/model of the boiler might be useful but I don't know that to hand. Will post if needed.

Thanks

Andy

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[ChrisR]

Have you got a motorised valve in the system ?

 

[ollski]

Hello,

It is now possible for the central heating to be set to come on independent of the DHW.

Its not, that is a restriction of the system not the programmer, isn't there a little switch or jumper on the clock to switch it between gravity and fully pumped?.

 

[adh2020]

I don't think there is a motorized (zone?) valve in the system. The pump is inline on the CH circuit. The DHW is gravity heated up to a chlorifier hws storage cylinder in the loft. The boiler & controls are first floor level.