Room Stat

[jstephens251]

Hi all

Just after some info regarding a room stat I've installed.

I don't do heating controls at all really so you might have to bare with me.

Customer has a Worcester Greenstar 24I Junior Combi boiler and asked me to install a stat.

I purchased a Drayton RTS8 room stat which says suitable for most 2 & 3 wire installations.

At the boiler l i removed the link between LS & LR

At the stat I connected to L and to 3 (in the manual it said to connect to 3 if pulling more than 1.6A which this is)

Now the stat clicks the boiler on and off but customer says that its not recognizing the room temperature

Is there something silly i've missed here?

thanks for help


Jonathan

 

[Welchyboy]

On some stats not connecting a neutral makes the stat a lot more insensitive

 

[Deleted member 26818]

How does the stat click the boiler on and off?
How exactly is the stat not recognising the room temprature?
Are there thermostatic valves on the Rads in the room with the stat?

 

[jstephens251]

when i left the stat was clicking off at 10 and on at 16

i presumed that once the temperature in room had increased to say 18 it would click off at 18.

and yes there is a rad in the hallway with a thermostatic valve


cheers

 

[Deleted member 26818]

I guess you have to determine what the customer actually means when the say 'not recognising the room temperature'.
Is it a case of the wall stat operating before temprature is reached?
Is it a case of temprature is reached but the stat doesn't operate?
Is the stat in the coldest part of the house, or the warmest?
There should not be a valve stat on the Radiator where the wall stat is sited, if the valve stat cuts the flow of water before the wall stat temprature is reached, the wall stat will never switch off the boiler.

 

[Geordie Spark]

when i left the stat was clicking off at 10 and on at 16

i presumed that once the temperature in room had increased to say 18 it would click off at 18.

and yes there is a rad in the hallway with a thermostatic valve


cheers

OK ... first things first. You say the stat is clicking off at 10. Do you mean the stat is switching the boiler off at 10 degrees?
You say the stat is clicking on at 16. Do you mean the stat is switching the boiler on at 16 degrees?

Think very carefully about that!!!

Now you say there's a radiator in the hall which is fitted with a TRV. Is the thermostat in the hall where there is a radiator with a TRV??

Think carefully about that too !!

Post your answers to these questions here & we'll take it from there ...........

 

[snowhead]

Most of what Geordie says,
Plus is the Control circuit for the boiler really taking more than 1.6a?

http://search.yahoo.com/r/_ylt=A0oG...ols.co.uk/WorkArea/DownloadAsset.aspx?id=4231

 

[Guest111]

never use a room stat and trv's one will defeat the other,also stats have a lag on them so if it cuts out at say 18 degrees it may drop to around 14 or lower before it cuts back in,also some stats still use a bi,metal strip and require a neutral for the onboard heater,this affects its response to temperature change.If the boiler controls are 24v and its a bimetal stat that needs a neutral then it wont work properly as these stats were designed for 240v.

 

[Geordie Spark]

never use a room stat and trv's one will defeat the other,also stats have a lag on them so if it cuts out at say 18 degrees it may drop to around 14 or lower before it cuts back in,also some stats still use a bi,metal strip and require a neutral for the onboard heater,this affects its response to temperature change.If the boiler controls are 24v and its a bimetal stat that needs a neutral then it wont work properly as these stats were designed for 240v.

Well it's looking like our friend has two problems here.

The first is that the room stat is fighting with the TRV on the radiator - as Phil d has suggested - and secondly the room stat is wired backside first or as I often say "arse about bollox" so that when the room temperature is low it's switching the boiler off (instead of on) and vice-versa.

CHECK the wiring of the stat to ensure it's the right way round and IF the stat is in the same room / hallway as the radiator fitted with the TRV remove the head of the TRV or ideally replace the entire TRV with an ordinary wheel head radiator valve.

 

[Guest111]

On a room stat indeed any heating controls the connections are sometimes described as BOR and MOR,break on rise(normally closed) make on rise(normally open).

 

[gazzamikes]

I had the exact problem on a larger worcestor boiler. Manf said to check the neutral on the terminal blocks in the boiler are common, apparently they not always are so boiler does odd things. We had one firing up when on a peice of flex on a plug but not when wired all down to the neutral not being common in the wiring centre of the boiler

 

[wildgoose]

First look to see what type of stat Worcester are recommending. They also have a very good tech helpline, which I've used in the past - the number is usually on their installation brochure.

One quick telephone call to explain your situation will probably identify the issue very quickly - no more theorising!!