Horstmann 425 tiara timer not moving/working.

[GoodOne]

We didn't buy it, it was here in a pack when we bought the house.

Now i am considering to buy the one the that you recommend from Screawfix, however do you have any sample or simplifiy drawing how i can attach the wires to the backplate, because i don't really understand the electrical diagram.

 

[jackthom]

Going across from left to right in the old backplate, I can tell you where each of the existing wires will connect to the new C27 backplate.
Note that both of the short red link wires are no longer required in the C27 and these can be discarded.

3 core Cable No 1..........

The green/yellow Earth wire will no longer really be needed but a connection point is provided lower right on the new backplate to hold it out of the way.

The Neutral (Black) goes into the N terminal on the C27.

The Live (Red) goes to L.

There are no connections to the C27 terminals 1 & 2.


3 core cable No 2............

Yellow goes to terminal 3.

Red to terminal 4.

(The blue wire remains unused and taped up as before).

 

[jackthom]

It's also time I asked if there are any motorised valves like this one in your heating system.

Untitled

• jackthom
• 4 Nov 2011
• 5

 

[GoodOne]

I have not notice anything like that (motorised valves). Will check the boiler room tomorrow morning. If there is, where would be the common place installed?

 

[GoodOne]

Excuse my ignorance. Due to an old boiler and i am so new to this, i found out that we have, Myson unit five pump. Will that be consider as motorised valves?

I find nothing that looks like the image you send.

 

[jackthom]

Thanks for that, no motorised valves there.

Can you also post some pictures of the pipework (and any wiring) near or attached to the hot water cylinder?

 

[GoodOne]

 

[jackthom]

OK it's a basic gravity system then.

(There's a switch or jumper on the back of the C27 programmer which you can easily change to the correct setting for Gravity Hot Water when the time comes.)

 

[GoodOne]

Once i installed the C27 programmer, should i do anything with the Honeywell FrostStat?

 

[jackthom]

No need to change anything else, the boiler room wiring stays the same and any other thermostats should just carry on working as before. Assuming they do all work OK at the moment.

Looking back at the wiring I can't see anything else connected. No room thermostat?

 

[GoodOne]

Yes no room thermostat, just the Honeywell FrostStat above the switch - on the photo.

 

[GoodOne]

Hi Jackthom, I fit the C27 and i all works. Thanks you very much for help me through all this. Really appreciate your help.

One more thing if not troubling you, is it possible to add a room thermostat at this point?

 

[jackthom]

Yes it's certainly possible.

A basic honeywell wired thermostat is cheapest but the hard part is working out how to get a 3 core cable from the boiler wiring box to the hall or lounge, or wherever you want it to be fitted. It will be carrying mains voltages so needs to be safely installed.

There are also a number of wireless units of varying quality and price. Then the only wiring required is between the receiver unit and the boiler. It looks like you might have plenty of room on the wall to the left of the boiler to mount one of those.
The actual room thermostat for a wireless system is usually battery powered, so can go almost anywhere.

 

[GoodOne]

Maybe not room thermostat yet probably in future.

I notice that after changing to c27 the CH seem to be really slow to heat up. Is there any possible reason?

 

[jackthom]

No it shouldn't make any difference to the time it takes to get the radiators hot.

Next time the heating is fired up, preferably starting with cool radiators, keep a close eye on the boiler and check it is firing permanently until the radiators get reasonably hot.

If the boiler is going off and on regularly before the radiators have become fairly warm you may have a problem.