wiring for lp111 and thermostat

[ashm]

Hello and thanks to all that answer,this is a follow on from a post earlier this week but i've started a new thread to prevent confusion.

I'm changing a broken drayton programmer (not digital) for a drayton LP111 connected to a vaillant . The backplate is wired exactly the same so an easy swop.But i had a few questions/confirmations:

1) Why is terminal 2 live when the programmer isn't demanding heat?Its not connected to anything on my set up. My guess is its for boilers with other functions?

2) At the moment terminal 3 (programmer switched live) runs to the boiler to demand heat.To wire a honeywell thermostat i will wire terminal 3 to the thermostat returning to the boiler for the demand when the thermostat requires it?

3) The Thermostat requires a neutral, is this for the anticipator? and can i utilise the N on the programmer backplate or do i have to run it to terminal 5 on the boiler (as the vaillaint manual suggests) which is also a nuetral but not used so far.

Anythoughts appreciated.

 

[ericmark]

The single and double programmers do not use same terminals

Central heating clock 1

• ericmark
• 3 Dec 2009
• 1

Central heating clock 2

• ericmark
• 3 Dec 2009
• 1

As a result it is easy to make a mistake. The single version needs link as volt free contacts. When used with hot water the same programmer needs to give output when heat is not required to work motorised valve.

The neutral can be used from programmer but why would anyone use a single programmer and a thermostat today?

The Horstmann DRT2 Room Thermostat at £23.25 combines both time and temperature in one device and instead of just on/off allows you to change temperature at set time so no need for frost stats and you can have lower temp in day to evening.

It does not need a neutral and is size of thermostat or slightly smaller.

 

[ashm]

I'm liking the look of that! I got blinkered into fixing the programmer fault and then adding a stat. Instead of solving them both at the same time!

Is this device widely used for this set up?

thanks for answering the other questions.

 

[ashm]

Any other opinions on this option(DRT2). I like the idea, nice and simple but battery operated puts me off, anyone used/installed these. Any comments welcome.

cheers

 

[ericmark]

My son, My Daughter, and myself all have these installed. Batteries last about 2 years but when they go flat you lose heating so we change every year to be on safe side.

Mon to Fri has 4 times but all the same so I have set to come on low 17 degs at 6:30 for those very cold days then 18 degs at 7:30 then 20 deg at 18:00 and at 23:00 drops to 16 degs overnight.

Sat and Sun are separate but only two times so 7:30 at 19 deg and 23:00 at 16 deg I have both the same but you could use different times for both days.

You can set temp by 1/2 degrees and we have all found them very good. Normally override which reverts back at next time change.

Only problem we have had was first time battery went flat we did not work out what was wrong as battery indicator did not come on. But changing every year no problems.

 

[ban-all-sheds]

Normally override which reverts back at next time change. .

That's good.

We've got the Worcester Bosch badged Drayton Digistat, and the first one had a great fault - if you'd overridden a temperature, at the next scheduled change it would apply the delta that was programmed.

e.g. at a particular time let the programmed temperature be 18, and the setting in the next time period be 23.

Override the 18 to 20, and at the time it should have gone to 23 it would go to 25 instead.



Got it replaced under warranty, but we had quite a few weeks of "why have you turned it up again/down again" "I haven't" "well I haven't so you must have done" conversations before we worked out what was going on.

 

[ericmark]

I did start building a 5-20ma unit to go with PLC but when I saw that unit is seemed a little pointless to go to such lengths.

I wrote the program to store over shoot data and adjust output so a smooth graph of temperature would be produced mainly with an eye on stress relief but only ever ran it as simulation.

However with a little experiment I have got that programmable thermostat to do same thing by switching on in morning in two stages. And it works well.

 

[ban-all-sheds]

The Drayton supposedly has learning ability, i.e. if it finds that today it took until 06:30 to get to the temperature setting for 06:00 it will kick in at 05:30 tomorrow.

IHNI if this actually works.

 

[ericmark]

I have a simpler system now. I stay in bed longer!

 

[ashm]

Thanks for all the input,

Went with the lp111 and thermostat in the end, Only because they were already in the post form screwfix! All done today and working well.

Further questions for you all if you fancy them:

1) Explain why the thermostst has a neutral, I think its for an anticipator but how does that actually work?

2) When the boilers operating the stat works perfectly and opens/closes the circuit instantly. But when you adjust the stat (slowly) its does crackle and the LED flashes momentarily until it decides off or on. Is this Normal?

3) Random: When testing/confirming the terminals at the boiler I found I had 218v ish, as expected at terminal 3 (permanant live out of boiler) but i expected 0Vs at 4 (switched live- in to boiler) i got 5v ish- where did they come from?

Cheers

 

[ericmark]

Thanks for all the input,

Went with the lp111 and thermostat in the end, Only because they were already in the post form screwfix! All done today and working well.

Further questions for you all if you fancy them:

1) Explain why the thermostst has a neutral, I think its for an anticipator but how does that actually work?

The way the bi-metal strip is arranged means it will click over and as a result the difference between on and off temperatures is quite large. The heater connected to output and neutral reduces the difference between on and off temperatures the electronic models don't have them. The electronic tell you the span between on and off is 1 deg C but the mechanical type don't tell you as it will vary between even different ones in same batch.

2) When the boilers operating the stat works perfectly and opens/closes the circuit instantly. But when you adjust the stat (slowly) its does crackle and the LED flashes momentarily until it decides off or on. Is this Normal?

When in use they are designed to flick over like the old clicking beetles you get in Christmas crackers but that does not happen when manually altered. Yes normal my old one would upset TV not a problem with electronic type.

3) Random: When testing/confirming the terminals at the boiler I found I had 218v ish, as expected at terminal 3 (permanant live out of boiler) but i expected 0Vs at 4 (switched live- in to boiler) i got 5v ish- where did they come from?

Cheers

Capacitance and inductance between cables nothing to worry about.