centratherm tfm 20a

[Dave Walker]

evening all went to a job today where these were installed never seen them before and havent got a clue how they work.
so i was wondering if anyone here nows of them and if i can get a english version of the user instructions.

 

[Dave Walker]

Does this mean that no one else has came across these before. I really could do with some help on this as it's in a local social club and they are struggling to get there heating working correct.

 

[stani]

Have you had the front off?

 

[TomLane]

Are you sure this is the problem?

Is there no way to override/bypass this to find out?!

 

[Dave Walker]

I did but it never help me any

 

[stani]

From the temperature settings I would imagine its a frost stat, so would also imagine it is only 2 contacts, make or break,

 

[TomLane]

Typical.

Would it not be easier to just replace it with something similar!

I'm sure Noah would appreciate it back anyway to put back in the Ark! ;-)

 

[Dave Walker]

I was thinking frost stat myself but was not sure and only internet search is non English.

 

[stani]

In that case it would normally only be 2 wires in and out, why not try a honeywell frost stat in its place. Although it should not stop the heating system working as it normally bypasses the heating controls

 

[Dave Walker]

There were 4 wires if I remember wright. It's the top switch that has me confused above the temp control it has a setting for what looks like a sun symbol and a auto setting

 

[stani]

Take that as a summer/winter switch as on older type combis,

 

[Dave Walker]

Why would you need a Sumer winter switch on a frost stat. I was thinking that in auto it's a frost stat change it to sun and that brings heating on in that zone as there is one of them in each area of club

 

[Killy Bing]

All i see is honeywell 😉

honey wells heating controls in the 70's were called centratherm in europe.
thats actually an early froststat/programmer/weather compensation (if the outside sensor is fitted) hybrid.
totally outdated.

good luck getting any information on it!
if it isnt broken leave it be, let the customers work it out by playing with it

Bear in mind that thing is likaly almost twice as old as i am....

 

[zzzjim]

Have you had the front off?

If mechanical does it go click , If purely a frost stat - a can of freezer to envestigate ?
( Frost stats should bypass most controlls ! )

 

[doitmyself]

Is that the only control?

A quick search suggests that it is part of a larger comprehensive control system.

 

[doitmyself]

Done a bit more digging. It seems to be part of the Honeywell Centra RS10 weather compensation control system, which seems more like a BMS.

The required internal temperature is set on the main unit, but can be varied using the TW20A. That's why it shows -20 to 0 to +20. If the temperature is set to 21C on the main unit and you set the TW20A to -1, the resulting temperature will be 20C.

When set to Auto, the system will switch between day and night temperatures according to the settings on the main control unit.

The * symbol means it will run continuously at the day temperature - no night setback.