Potterton Profile 80E

[Lloyds]

I've got a Potterton Profile 80E about 10 years old. All working ok. All the rads have trv's and there is a Honeywell CH/HW timeclock for on/off operation.
I want to fit a roomstat as well. Where do I connect this to on the boiler?
Any info would be appreciated.
Thanks, Gerry

 

[Puddle]

Well you do not connect to boiler,you should interupt power curcuit from heating demand on programmer which goes to motorised valve,this is usually done in wiring centre
To give more details would need model of programmer and make of motorized valve and is two or three port valve

 

[Bernie2]

Puddle is right,

All a room stat is, is an on/off switch activated by air temperature. So its logical to put it in the power supply line from the programmer which is also an on/off switch but activated by a clock.

And to get a heating system going you have to activate two or three things i.e. motorised valves if it has any, pump and boiler.

They have to be done in sequence of course, its pointless turning on the boiler by itself, it would just get hot and shut down.

You have to have the pump working to keep the boiler cool. And the water has got to circulate, so you have got to have the motorised valve open for the water to go out on the circuit.

So the programmer tells the room stat "Turn on or off" and the room stat tells the pump, motorised valve and boiler "Turn on or off, its hot or cold in here"

Sorry about the childish way I wrote this, its part of the way I try to think about things.

Please don't take offence.

 

[stevetheplumber]

actually the clock energises the motorised valve and the auxilary switch turns the boiler and pump on loads of wiring diagrams available on the honeywell web site google it

 

[Bernie2]

Yes that is true enough Steve it can, but he wants to put a room stat in the circuite, I was trying to make it easy to understand so the concept could be grasped rather than the actual exact workings.

I thing Honeywell wiring diagrams may be a bit confusing to a newbie if they don't know the basics about what is supposed to be happening.

 

[Lloyds]

Dear Puddle, Bernie & Steve....thanks for your replies.
My current programmer is a Honeywell ST799.
I want to fit a Honeywell CMT927 wireless programmable roomstat because all the existing TRV's are behind radiator covers which are screwed to the wall. This makes adjusting them a real nuisance job.
I can easily fit the wireless receiver unit by the boiler or by the existing ST799 located in the airing cupboard.
I'm an alarm engineer by trade (little volts) so fully understand relays and interconnections but couldn't find any definitive info on the net.
Any info would be gratefully received.
Regards
Gerry

 

[stevetheplumber]

Dear Puddle, Bernie & Steve....thanks for your replies.
My current programmer is a Honeywell ST799.
I want to fit a Honeywell CMT927 wireless programmable roomstat because all the existing TRV's are behind radiator covers which are screwed to the wall. This makes adjusting them a real nuisance job.
I can easily fit the wireless receiver unit by the boiler or by the existing ST799 located in the airing cupboard.
I'm an alarm engineer by trade (little volts) so fully understand relays and interconnections but couldn't find any definitive info on the net.
Any info would be gratefully received.
Regards
Gerry

ok as simple as i can
the stat is just a temp operated switch which needs to break the existing feed from clock heating live terminal, there will be a wiring diagram for the clock on the rear of clock
the tranmiter of the wirless also needs power so youll have l and n into tranmiter and switch line from heating live terminal on clock and second switch line needs to connect to wire that was previously connected to heating live terminal
depending on how your systems laid out you can do this either at the clock or at the junction box
hope this helps

 

[Lloyds]

Thanks for the info Steve, this weekends project will now be fitting the stat (which gets me out of the christmas shopping, thankfully).
Regards
Gerry

Hope you don't mind this call-back Steve, but am I correct that I leave my existing Honeywell ST799 programmer permanently in the ON position (CH only) so that the new roomstat takes control?
Gerry

 

[Puddle]

Dear Puddle, Bernie & Steve....thanks for your replies.
My current programmer is a Honeywell ST799.
I want to fit a Honeywell CMT927 wireless programmable roomstat because all the existing TRV's are behind radiator covers which are screwed to the wall. This makes adjusting them a real nuisance job.
I can easily fit the wireless receiver unit by the boiler or by the existing ST799 located in the airing cupboard.
I'm an alarm engineer by trade (little volts) so fully understand relays and interconnections but couldn't find any definitive info on the net.
Any info would be gratefully received.
Regards
Gerry

Well
The St 799 was a direct replacement for the ST699 and the heating output conection for that is terminal 3
so if you place your wireless CMT927 receiver below your ST799 in airing cuboard or just outside if possible and using a four core cable if possible

core one ..link live in programmer to live in wireless receiver

core two ..link neutral in programmer to neutral in wireless receiver

This will power wirless unit

core three .. remove existing wire at terminal 3 on programmer,connect existing wire to core three at programmer end and L2/L out at receiver box

core four ..connect to terminal 3 on programmer and L1/L in at receiver box

This will control you heating via switching relay

you can leave heating on all the time on programmer as this will over ride room thermostat if turned off
However you may wish to have times off at night on programmer and thus give you more varible temp options in day

 

[Lloyds]

Thanks for the further infomation Puddle.
I believe (hope) the CMT927 is 24-hour and 7-day programmable so by leaving the existing ST799 (that's in the airing cupboard) permanently in the ON position I should be able to operate the CH on/off times and temperature control from the ground floor Hall where I will site the CMT927 transmitter.
Does my theory hold water?
Regards
Gerry

 

[Puddle]

Thanks for the further infomation Puddle.
I believe (hope) the CMT927 is 24-hour and 7-day programmable so by leaving the existing ST799 (that's in the airing cupboard) permanently in the ON position I should be able to operate the CH on/off times and temperature control from the ground floor Hall where I will site the CMT927 transmitter.
Does my theory hold water?
Regards
Gerry

yes ,no problem
now get to it