Boiler & Underfloor Heating - Confused

[jurassic86]

Hello,

I have a Worcester Bosch 35cdi (Greenstar) boiler, which works on a programmer "BOSS THERM - BUT2".

The ON / OFF times are programmed and it works nicely, or so I thought.

In a living room I have underfloor heating installed and this is controlled by a thermostat "BOSS THERM BPS242".

Now until this morning I was under the impression that once the program for CH was on, the thermostat for the underfloor heating would become active.

But it has now become apparent that the thermostat of the underfloor heating controls the u/floor heating regardless of the ON/OFF status of the program!!

Is this normal for setup?

It has a "FIRST ON/OFF", "SECOND ON/OFF" adjustable parameter with two temperature set points.

Also any recommendation for a economical setting for the "SETBACK" temperature?

Thanks

 

[SimonH2]

Sounds like the UFH controller has it's own programmer, and this has been wired up to operate the boiler independently of the main heating programmer. That sounds OK, you just need to set the UFH controller as you need it.
Of course, that does assume that the UFH is correctly wired so that it can fire the boiler.

 

[jurassic86]

It does spark up the boiler, because when I crank up the stat above room temperature 10 seconds later the boiler clicks and starts warming up.
Their is some other thing next to boiler called Drayton RB1 Relay Unit. I think that must have something to do with it.

Ironically upstairs their is a similar thermostat but without all the toggle switches on it, and this when set above room temperature does not start the boiler, so maybe this controls a diverter valve.

 

[Agile]

The UFH needs to have seperate time controls because it has a very long time constant and requires to be activated about 1-2 hours before you want to use the heat!

Tony

 

[SimonH2]

It does spark up the boiler, because when I crank up the stat above room temperature 10 seconds later the boiler clicks and starts warming up.
Their is some other thing next to boiler called Drayton RB1 Relay Unit. I think that must have something to do with it.

Quite possibly. It could be as simple as a relay wired in parallel with the UFH pump - so when the pump is running, the relay pulls in, and that fires the boiler.

Ironically upstairs their is a similar thermostat but without all the toggle switches on it, and this when set above room temperature does not start the boiler, so maybe this controls a diverter valve.

it should be wired from a channel on the programmer - so it'll only fire the boiler if the programmer says the heating should be on. If you have an S-Plan then the stat will power the motor in the upstairs zone valve, and the switch in the zone will fire the boiler - if not an S-Plan then it could be more complicated.

 

[jurassic86]

no the stat upstairs doesn't fire in that boiler unless its programmed to power CH?
Is that good or bad?

 

[SimonH2]

That's normal and correct. The programmer sets WHEN your heating is on, and the stat controls HOW WARM the space is kept while on.