Faulty CH programmer

[glocal]

A couple of days I switched on my Sunvic 107XL programmer for central heating. The programmer now makes loud clicking noises and flashes at random times during the switched on period. It's like it switches on/off in a loop for a few seconds or minutes failing to stay on, then stays on for minutes or hours, and then starts clicking again. I reset it but nothing's changed. I am not sure if this is a common fault. Am I right thinking it's probably time to replace it?

Strangely, the water heater next to it is controlled by a separate Horstman Economy 7 switch, and the Sunvic 107XL is single channel. They could have used a 2-channel programmer for CH and HW but I think I would rather leave the setup like that to keep replacement simple and avoid putting all my eggs in one basket.

Am I right looking at these https://www.heatingcontrolsonline.co.uk/timeswitches-c-25_40.html , probably the Siemens and Honeywell Pro? Would the backplate be compatible for easy swap-over? Installation looks very straightforward but is that something an end user can do? Or is getting an electrician necessary?

 

[ericmark]

I have not used a programmer in years, when the tungsten light bulb went, I found wanted the heating higher in the evening than through the day, as no inferred from the bulbs any more. So I moved to programmable wall thermostats and TRV heads, as each room independently controlled, the standard backplate,

can take a hub, programmable thermostat, or programer, as you can see the wiring changes as to single, double, or thriple channel, but most are interchangable, what you need to decide is what will suit your house.

My programmer was in the unheated utility room, so stright swap to programmable thermostat would not work.

 

[Exedon]

From memory your time switch is on a common backplate.
So anything that uses that should fit straight on.
We tend to use EPH stuff good price very reliable and 5 year warranty.

 

[glocal]

I can't use a thermostat unfortunately. I am on Economy 7 and use storage heaters, so I don't have dynamic switching on/off. It seems a crude timeswitch (single-channel) is what I can get. Drayton L111 is apparently a direct replacement for my discontinued Sunvic 107XL. Both implement the one channel wiring in your schematic.

 

[ericmark]

Confused, looked at the manual and it says it has 3 amp contacts so it will not take to load to storage radiators.

Unless it only powers a fan, and then a thermostat would still work.

Seems I have missed something. So basics, something turns heaters on overnight for 7 hours. Power goes into iron bricks, bound with cement or clay, until they reach maximum heat when some thermostat turns it off. The bricks are well insulated so very little heat escapes, until wanted, when a flap or fan opens or turns one to release the heat. The flap or fan can be either manual or automated with programmers, thermostats, or programmable thermostats.

For most central heating, control is mark/space ratio, so for a set time period the heating is either on (mark) or off (space) and one is made shorter and the other longer to increase or decrease output. There are exceptions with the likes of OpenTherm where the output changes, and inferred where more or less heaters are used, but most uses a mark/space ratio.

The length of the mark space combined varies, with oil it is longer than gas, and gas longer than electric, and some thermostats have a setting for oil or gas.

Storage radiators with fans could alter fan speed, but the whole idea of analogue control is so the boiler can gain the latent heat from flue gases, so with electric no need for analogue control.

Homes designed to work with stored heat when built, had a large central heat store with fans, which can often stay warm for a week when not used, homes converted to work with stored heat, often use storage radiators which do not stay warm even when not used for more than a day, and it relies on the occupants wanting heat 24/7 as it simply will not really turn off.

If the occupants go out to work, it does not work very well, as heating an unoccupied home for much of the day. There comes a point where to heat home direct as and when required works out cheaper, due to energy lost when the home not occupied.

But the walls, floor, and furniture also stores heat, so there is no cut and dried formula.