One for the HVAC Techs

[james10]

I know this is off topic, but i'm also aware a few of the members deal with heating systems aswell as A/C-Ref,
I have a Landis & Staefa RWB9 Central heating programer installed at present (controlling heating and hot water on a baxi back boiler), the only controll it gives me is timed or manual HW/CH, Is it possible to fit a room thermostat to this controller to controll on temp rather than time, at present the heating is on untill you sweat your whatsits off then off until they shrivell,
I have the IOM for this controller but it doesn't appear to go that far indepth,
Thanks in advance

[sedgy]

hi james,
easyest way to turn down the return water boiler stat,
hope that works , sedgy,

[james10]

Thanks Sedgy Is that the dial next to the pilot ignition?, sorry I'm a bit green when it comes to heating :)

[sedgy]

hi james
´ yes thats the one under the front of the gas fire in the middle, the above is only a short term fix you might get the room temp right , but you might have to keep adjusting as the ambiant drops , sedgy

[Grizzly]

Hi James

Just wire the room stat in series with terminal 4. (CH on) at time clock or before other connections in the junction box. Possibly in airing cupboard?
That way provided you are calling for CH via the time clock, your room stat will control your CH operation.
Grizzly

[james10]

Thought so I've tried that in the past but the hot water temp drops to low, the hot water I can set on a separate time schedule to the heating, and hoping to modify/upgrade the control so I can time the HW and run the CH off a tstat

[james10]

Hi James

Just wire the room stat in series with terminal 4. (CH on) at time clock or before other connections in the junction box. Possibly in airing cupboard?
That way provided you are calling for CH via the time clock, your room stat will control your CH operation.

Grizzly
Sounds spot on that Grizzly do you think any mechanical tstat would do the job?

[Grizzly]

Any stat will do as you are only using it to switch the control supply voltage.
I would of assumed your hot water was controlled by a tank stat?
If not you could fit one again in series with terminal 3 (HW On).

Some stats require a nuetral also, so that may determine where you site your connections.
Grizzly

[RSTC]

Is this going to Fan coil units or rads... it may be better to control temperature locally. (eg local thermostat for FCU or thermostatic rad valves)

[james10]

It's for my boiler at home if was fcus I might have an idea ;)
The hw and ch are of the same stat but I can time them individually

[Grizzly]

OK James.
Can you see any reason why you cannot individually control the DHW and CH?
It would help if you know whether you have a fully pumped system or a gravity DHW pumped CH system.
I would assume because you can time them individually that you have a fully pumped system.

For Manuals try http://www.centralheating.co.uk/Boiler-Manuals/baxi-boiler-manuals

You may find what you need.
Good luck Grizzly

[install monkey]

james just because u work on big green things,doesnt make u a domestic heating consultant, do you have your gas safe,part p and 17th edition, otherwise get a stoker in!!!haha

[MikeHolm]

James, is it a weather compensated control? Sorry for this but I 'm not sure what is meant by back boiler. I always thought it was a coil in the back of a wood fire.

[Brian_UK]

James, is it a weather compensated control? Sorry for this but I 'm not sure what is meant by back boiler. I always thought it was a coil in the back of a wood fire.Mike, a Baxi back boiler is normally a gas fired boiler fitted into the back of a normal household fireplace opening. In front of the boiler there is a radiant gas fire.

[MikeHolm]

Thanks Brian, we have no such thing over here.

I had a look at the control and it seems you cannot get space heating unless HW is on so, given Brians description, I assume the on/off times are designed to give hot water when needed to a cylinder. There is an input for tank aquastat and/or T-stat. I doubt it is a modulating boiler which would be needed for a WC control.

Try a t-stat but be prepared for less than ideal HW production. On the other hand, I may be totally full of s**t:D

[james10]

james just because u work on big green things,doesnt make u a domestic heating consultant, do you have your gas safe,part p and 17th edition, otherwise get a stoker in!!!haha
Have all of the above Monkey, I was waiting for that one ;)

[Greengrocer]

A bit late but this may help you.
http://www.gasman.fsbusiness.co.uk/fully_pumped_systems.htm

To get separate time & temp control of your HW & CH I think you need to have a fully pumped system. Most common type is a Y Plan. I installed a baxi boiler in an old house of mine years ago with a 3 port flow share valve, room t'stat, tank t'stat, programmer & single pump. Like Grizzly said if you have a gravity HW system then I'm not sure how you can control the HW temp with converting to a fully pumped system.