Thermostat

bouicca21

My boiler has a clock type control for setting the hours it heats water and/or the radiators. It also has a temperature control (1-6).

In the hall is a salus thermostat which has times and temperatures. It is possible to have different settings for weekdays and weekends.

Each radiator has a thermostatic valve.

Which of these actually controls my heating?

Crinkmeister

Possibly all three - but it would depend on how it's been wired up. My guess would be that you need both clock and your Salus controller to be "on" to get heating. TRVs will control each rad independently. The room where your thermostat is situated should NOT have a TRV or if it does, it should be set to MAX.

Le_Kirk

It most definitely is possible to have different settings for week and week-ends but you need a time switch designed for this such as the one is this link: -
http://www.screwfix.com/p/drayton-lp522-mk4-programmer/20673?kpid=20673&cm_mmc=Google-_-Product%20Listing%20Ads-_-Sales%20Tracking-_-sales%20tracking%20url&cm_mmc=Google-_-Shopping%20-%20Heating%20and%20Plumbing-_-Shopping%20-%20Heating%20and%20Plumbing&gclid=CK6MkJfo0coCFaLnwgodCeUPUg
There are other makes and suppliers and this one might not necessarily be suitable for your installation; you would need to compare the installation manual of the timer with the circuit diagram of the boiler.

TheCyclingProgrammer

Does your boiler timer have an always on setting for CH? If so, and your thermostat works properly, I would set the timer to always on and program your thermostat to the heat you want and at what times. This can be as complex or simple as you like.

I like to have the temperature slightly higher for a few hours in the morning (22) then 20.5 for the rest of the day until 11pm and then have it set much lower (17 but it could be lower) overnight. In practice the house never cools down significantly over night (I think 18.5 is the lowest it has dropped even in the recent cold weather) so the heating never comes on overnight.

The thermostat will call for heat when the air temperature around the thermostat drops below the set temperature but it relies on the boiler timer also being on which is why I suggest setting this to always on and just letting the thermostat do its job.

Finally the TRV can be used to regulate the relative temperatures in each room as the temperature probably won't be consistent across the house compared to the location of your thermostat. Turn them down in infrequently used rooms. If you aren't sure, turn them all to max and then adjust accordingly. If the thermostat is at the set temperature but the room feels too hot, turn the TRV down by one. Keep adjusting until the whole house reaches a consistent temperature.

For example, our thermostat is in the hall and whilst it isn't particularly colder than the rest of the house, it is subject to fluctuations if the front door is open, drafts from the kitchen etc. And of course heat rises upstairs. This could trigger the heating even though the living room temp is fine. Turning the TRV down stops the room from overheating.

I have a Nest thermostat which has various smart features to help it be more efficient. In general we have found over the last month, which has been the coldest since we moved here, our heating fires on average for 3-4 hours a day. At worst 5-6 hours if it's really cold, or the front door is opened a lot etc. (We currently lose a lot of heat through our drafty rear porch door). Back in Nov/Dec our heating was only on for 2-3 hours a day at most!

I_have_spoken

Hard to tell without looking.

The control on the boiler may have the HW set to 'always on', after which firing the boiler will be triggered by the programming on the Salus calling for heat.

Ectophile

All of them.

The clock controls when the heating comes on.
The temperature control on the boiler controls how hot the water is.
The wall thermostat also controls when the heating comes on.
The TRVs control whether or not any given radiator is on.