Programmable Logic Controllers in your Home?

macphisto

Hi All,

I am at the very early stages of planning for an extension and renovation of our house. I want to future proof the the electrics so I don't have to muck about afterwards getting stuff added. I read this thread and its given me some really good things to look out for.

I'm thinking about using something like a Siemens LOGO! PLC to control the lights (both internal and external) and maybe integrate heating which is Oil Fired. I'll likely program it to automatically control lights if i'm away from the house for few days, holidays as an additional security measure (LOGO! seems easy enough to do this)

Has anyone used a PLC for domestic purposes, if so how have you found it and what was it used for?
Would something like the LOGO! range be a good choice to use or should I be looking at something like a Siemens S7-200? I programmed PLCs for a while about 15 years ago so i'd get to grips with it if needs be but would prefer to keep it as simple as I can.

Thanks,
Macphisto

2011

How many I/O are you talking about ?
Do you require analog as well as digital I/O ?
What kind of HMI do you have in mind ?

The Siemens S7-200 is excellent, but it might be a bit OTT and prohibitively expensive.

Have a look at Lutron.
Not cheap, but they are impressive.

2011

In terms of analog I/O:
1) It would be nice to install a temperature transmitter in each room
2) Measure the light level outside to control outside lighting.
3) Control the light level with an analog output.
4) Measure water temperature flow and return from the boiler

Could be used to:
1) Control zone valves to maintain different temperature set points for each room and DHW
2) Tie the intruder alarm system into the PLC so that it would implement a block of code each time the alarm is set.

I am sure there is plenty more you could do (particularly in terms of energy saving) if you put your mind to it. We are using a solid state switch instead of a contactor to switch heat tracing (as well as far larger loads) in work using our DCS. That may be something else to look at.

macphisto

Hi 2011,

Plenty of food for thought there, thanks I hadn't come across Lutron so i'll do some digging there.

Since I was thinking about using the Siemens LOGO! soft comfort for automation I was thinking about using a Siemens SIMATIC HMI. I haven't even thought about pricing up anything just yet.

In terms of I/O I am still undecided. I'd like to research some more on the pros and cons of digital vs analog (including cost). I'd like to control all internal and external light circuits (approx. 10 internal and 3/4 seperate external lighting circuits at the front/back of the house and outside the garage.) My concern with the alarm is that if I got an alarm company in to install they will baulk at the PLC and not integrate it (I haven't talked to alarm companies just yet though).

I hadn't considered analog I/O points 2 and 3 that you mentioned. That would be very handy indeed. In your estimation would something like the the LOGO! OBA6/7 PLC's be adequate for lighting/temp/flow control? I just came across them while reading and the interface / software seems pretty straight forward hence my preference for it.

What solid state switches do you use? That'll probably be a new learning curve for me.

Thanks again,
Macphisto

DublinDilbert

You should be able to take two io lines from the alarm to the plc, one for system armed and another for activated (just take internal bell signal).

Are you going to control a bank of contactors or ssr to drive the lights?

It would be nice if your plc had some sort of wifi / Ethernet hook up so you can access via smart phone from anywhere, rather than a hmi in one room. With this you can email yourself when the alarm goes off etc...

Defo read back temps of main rooms, tank, attic, outside. Light levels will be good too.

Would be nice to throw in some cheap wired pir sensors so you can do occupancy detection. If no one detected for 10 mins, dim lights, turn off after 30 mins etc....

There's really no end to where you could go with it.

DublinDilbert

Oh put a flow meter on the incoming water main and run it into a counter on the plc, it could also control a shut off valve in coming supply.

macphisto

Thanks DublinDilbert,

Cost and reliability will be the main driving factors in the choice between contactor or solid state. Is there much of a difference in terms of reliability?

I'd never even considered ENET/Wifi as part of a PLC setup but after a quick google search I think its fair to say that it'll be a bit of a no brainer...

You and 2011 have given me much more to think about...I just started with an idea to control the lights and now theres flow, PIR and wifi in the mix...
You are both right in that there are many more possibilities so it'll be back to drawing board and a rethink about what I want to control before I make my next move.

Thanks
Macphisto

2011

DublinDilbert wrote: »

You should be able to take two io lines from the alarm to the plc, one for system armed and another for activated (just take internal bell signal).

Exactly. Typically an alarm system would be able to drive dry contacts when it is armed/disarmed or alarming. These contacts wpuld be able to activate DIs to the PLC. The PLC would then read these inputs, solve the logic and act accordingly. It may also be possible to arm/disarm the alarm through the PLC over the Internet.

The possibilities are endless (depending on your budget).

2011

Selecting a PLC / control system will start by generating an I/O list. Why not post your I/O list here and let other posters add to it?

macphisto

2011 wrote: »

Selecting a PLC / control system will start by generating an I/O list. Why not post your I/O list here and let other posters add to it?

Good Idea 2011...
Ok, so this is what I think I need...

Lights
Downstairs - 5 Rooms:
5 sets of lights
1 set of downlighters under kitchen units

Upstairs - 5 rooms including the landing:
7 sets of lights (includes hotpress and master bedroom ensuite)

Outside back:
2 lights controlled from the one switch

Outside front:
2 lights controlled from the one switch

Seperate Garage:
Ability to switch on all lights from inside the house.

Based on your suggestions I would be likely to include:

Plumbing / Heating
Reading of Individual Room Temps
"call" signal from individual rooms to know what rooms are calling the boiler
Cylinder Temp
Boiler-On signal
Storage Tank Full Signal in the attic
Private Well "pump-on" Signal and Pressure Reading

Alarm
Armed and Activated signals

Thats all I can think of for now but like you've already said the possibilities are endless so I'm sure that'll change as time goes on...

EDIT: one last thing would be that I'd intend on having manual override with traditional switches, etc in the event of a PLC/Sensor failure

Thanks,
Macphisto

melon_collie

I wouldn't recommend a Siemens PLC for this application. They are much too over priced. You should take a look at the PLC range from Unitronics. They are becoming very widely used these days because they are so cost effective. In particular have a look at their HMI/PLC Combo unit. You could create a SCADA application of your heating, alarm and electrical system and put the touch screen unit in your kitchen??? The beauty of using the Unitronics stuff is that you can download the programming software from their website which you can't do with Siemens. Also, should you need additional I/O units they can be purchased very cheaply and simply snapped onto the back of the main unit. If you have any more questions PM me.

http://www.unitronics.com/Series.aspx?page=Vision570

macphisto

I'll take a look at the unitronics website...the idea of having the software to experiment with appeals to me. i'll download that and have a look.

Thanks,
macphisto

2011

OK, so now you can start to generate an I/O list and start to insert I/O type, addresses etc.

Here is something to start you off:

Digital Outputs
Downstairs Lights set 1 DO
Downstairs Lights set 2 DO
Downstairs Lights set 3 DO
Downstairs Lights set 4 DO
Downstairs Lights set 5 DO
Upstairs Lights set 1 DO
Upstairs Lights set 2 DO
Upstairs Lights set 3 DO
Upstairs Lights set 4 DO
Upstairs Lights set 5 DO
Upstairs Lights set 6 DO
Upstairs Lights set 7 DO
Downlighters under kitchen units DO
Outside Back Light 1 DO
Outside Front Lights 1 DO
Garage lights 1 DO
Boiler Run/Stop Command DO
Intruder Alarm Arm Command DO
CH Zone Valve for Room 1 DO
CH Zone Valve for Room 2 DO
CH Zone Valve for Room 3 DO
CH Zone Valve for Room 4 DO
CH Zone Valve for Room 5 DO
CH Zone Valve for Room 6 DO
CH Zone Valve for Room 7 DO


Digital Inputs
Switch for Downstairs Lights set 1 DI
Switch for Downstairs Lights set 2 DI
Switch for Downstairs Lights set 3 DI
Switch for Downstairs Lights set 4 DI
Switch for Downstairs Lights set 5 DI
Switch for Upstairs Lights set 1 DI
Switch for Upstairs Lights set 2 DI
Switch for Upstairs Lights set 3 DI
Switch for Upstairs Lights set 4 DI
Switch for Upstairs Lights set 5 DI
Switch for Upstairs Lights set 6 DI
Switch for Upstairs Lights set 7 DI
Switch for Downlighters under kitchen units DI
Switch for Outside Back Light DI
Switch for Outside Front Lights DI
switch for Garage lights DI
Boiler Run Feedback DI
Water Pump Run Feedback DI
Intruder Alarm Arm Feedback DI
Intruder Alarm Activation DI
Position Feedback CH Zone Valve for Room 1 DI
Position Feedback CH Zone Valve for Room 2 DI
Position Feedback CH Zone Valve for Room 3 DI
Position Feedback CH Zone Valve for Room 4 DI
Position Feedback CH Zone Valve for Room 5 DI
Position Feedback CH Zone Valve for Room 6 DI
Position Feedback CH Zone Valve for Room 7 DI



Analog Inputs
Room Temperature Transmitter 1 AI
Room Temperature Transmitter 2 AI
Room Temperature Transmitter 3 AI
Room Temperature Transmitter 4 AI
Room Temperature Transmitter 5 AI
Room Temperature Transmitter 6 AI
Room Temperature Transmitter 7 AI
Hot water tank Temperature Transmitter AI
Pump Water Pressure Transmitter AI


Note
1. Room temperature set points to be entered using HMI/SCADA
2. Boiler status (manual on/off or auto) to be entered using HMI/SCADA

EDIT: one last thing would be that I'd intend on having manual override with traditional switches, etc in the event of a PLC/Sensor failure

PLCs are quite reliable nowadays and the installation should be designed to "fail safe". However this can be achieved with a HOA switches ideally located local to the PLC.

Obviously this needs a lot more work, but this is only to start you off.
Once the I/O list has been nailed down I would typically allow 25% extra I/O for future use.

Before writing the code you need to write a functional description.

Other things to consider:
1. Perhaps a single DI could be used to switch on or off all lights for example when the intruder alarm goes off.
2. A photocell may also be connected as a DI for energy saving
3. The immersion may be switch on/off also
4. Some appliances could be switched off by a single DO when you leave the house.

homelogic.ie

2011 wrote: »

It may also be possible to arm/disarm the alarm through the PLC over the Internet.

Highly NOT recommended and against EN rules, unless done by a code with direct communication to alarm panel. I'm not an expert in PLC so not sure can you get any of alarm panels on BUS line. There are other products to consider dedicated for home automation with visualization and integration options, all depends of how much you want to spend.

2011

homelogic.ie wrote: »

Highly NOT recommended and against EN rules, unless done by a code with direct communication to alarm panel.

Really, for EN50131? Please provide a link.
My understanding is that this is permitted once installed correctly (with tamper etc.)
I fail to see the issue.
Remember a user name and password will be required to login remotely to the PLC.

I'm not an expert in PLC so not sure can you get any of alarm panels on BUS line.

No BUS line required. Many alarms can be armed by simply closing a conatct (such as HKC and Astec).
This could easily be achieved by using a relay that is driven by the PLC.

There are other products to consider dedicated for home automation with visualization and integration options, all depends of how much you want to spend.

True. However it is often possible to buy 2nd hand (possibly dated) PLCs on the internet for small money. They may not be fit for purpose for a modern plant, but will be more than adequate enough for home automation.

Is full plc for lighting not over kill?
sounds great in theory but a well thought out electrical plan is the way to go.
Waste of money switching one way bedroom lights on a plc/contactor.
and its hassle if you have a failure every thing goes out.you'll have to keep a spare around.

what ever your into i suppose!

One thing I would do is wire for some IP cameras around the house.

2011

urbanledge wrote: »

Is full plc for lighting not over kill?

As I suggested in post 2 there are lighting control systems such as Lutron. These are specifically designed with lighting control in mind. I guess the OP wants to be able to program the control system himself as he has considerable experience in this area.

I agree it is not for everyone.

Waste of money switching one way bedroom lights on a plc/contactor.
and its hassle if you have a failure every thing goes out.you'll have to keep a spare around.

My experience with PLCs is that they don't fail. I would think that there is a much greater chance that the main fuse would fail.

I would not use a PLC to control lights in my house either to be honest.

macphisto

Thanks everyone for all your responses,

urbanledge, point taken about the cost but I guess ideally what I wanted to do was select something that would allow me to get "under the hood" and fully understand how exactly it works so that maintenance and changing system setup would be easier (and hopefully cheaper) than alternatives in the future.

I am at the very early stages of planning for an extension and renovation and used PLCs as a starting point to see if anyone had used them and this thread is giving me plenty to think about which is always good
I haven't really delved too much to see what alternative solutions and companies there are just yet but that is on the cards.

2011, your suggestion to get a functional description down is definitely something I'll do as it will force me to make decisions about what exactly I want from the system so I can proceed.

Thanks again
Macphisto

homelogic.ie

2011 wrote: »

Really, for EN50131? Please provide a link.
My understanding is that this is permitted once installed correctly (with tamper etc.)
I fail to see the issue.
Remember a user name and password will be required to login remotely to the PLC. .

Let me put it like this - if you do all yourself - security, PLC and integration, you can do whatever you want because most likely your system won't be certified.
If you want to employ a good licensed alarm installer, I would be very surprised if they agree to extract alarm status to 3rd party systems or to control (arm/disarm) alarm by 3rd party system. Reason - system could be compromised. That is what regulations are saying - you are not permitted to display alarm system status (no more red led's or anything like this on keypads when system is armed) nor arm/disarm alarm through 3rd party controls.
As to link to EN, full EN regulations are available in paid electronic version, so I won't provide a link, but ask any GOOD alarm installer and they will confirm.
As to myself I could live with arming alarm system via HMS/BMS systems on special projects, but I wouldn't take responsibility for disarming. You have to take in consideration many other factors for example power failure - what will happen in that scenario? All alarms have a backup supply, but what if a relay that is responsible for arm/disarm action would change state because of that? A physical intrusion into wiring is not the only threat, therefore as I have said before - if it's a job for yourself you are o.k., but if doing this for a client, you may get badly caught.

2011

homelogic.ie wrote: »

Let me put it like this - if you do all yourself - security, PLC and integration, you can do whatever you want because most likely your system won't be certified.

I was not suggesting that the OP install the alarm. What I am suggesting is that the alarm installer can connect a cable from the PLC so that the alarm could be armed/disarmed remotley by loginig in.

If you want to employ a good licensed alarm installer, I would be very surprised if they agree to extract alarm status to 3rd party systems or to control (arm/disarm) alarm by 3rd party system. Reason - system could be compromised.

Well, yes it could if someone were to get hold of the user name and password, just like it could be comprimised if they got hold of the alarm code.

That is what regulations are saying - you are not permitted to display alarm system status (no more red led's or anything like this on keypads when system is armed) nor arm/disarm alarm through 3rd party controls.

Perhaps you are correct, but I can find nothing suggesting this. I also asked some alarm installers and they are not aware of it either.

As to link to EN, full EN regulations are available in paid electronic version, so I won't provide a link, but ask any GOOD alarm installer and they will confirm.

I will ask a few more, but so far their only concern is that the cable might be intercepted. Once I explained that the cable would include a tamper as would the entire enclosure containing the cable and the PLC, they could see no issue with it. Coupled with that the PLC, interconnecting cable and PLC would be installed within a protected zone. That way the alarm would be set off before anyone could get to the room containing the alarm panel and PLC.

You have to take in consideration many other factors for example power failure - what will happen in that scenario?

All you have to do is have the relay fail to the fail safe position.

All alarms have a backup supply, but what if a relay that is responsible for arm/disarm action would change state because of that?

See above. Also much like the alarm a back up supply is not impossible.

A physical intrusion into wiring is not the only threat, therefore as I have said before - if it's a job for yourself you are o.k., but if doing this for a client, you may get badly caught.

I am not doing this for myself or anyone else. I am simply suggesting a few ideas to the OP.

Remote access to alarm systems is not a new concept.

KoolKid

As I see it , an open close pair into an input for arm/disarm is fine. As always all the cable & enclosures must be within the protected areas & tampered for grade 2 or higher. I personally would also ensure the cable is located in such a way that a confirmed alarm would be generated before the cable could be accessed anywhere.
Remote access its self must also come with some form of authorization, that could be code or login etc.

homelogic.ie

2011 wrote: »

I was not suggesting that the OP install the alarm. What I am suggesting is that the alarm installer can connect a cable from the PLC so that the alarm could be armed/disarmed remotley by loginig in.


Well, yes it could if someone were to get hold of the user name and password, just like it could be comprimised if they got hold of the alarm code.


Perhaps you are correct, but I can find nothing suggesting this. I also asked some alarm installers and they are not aware of it either.


I will ask a few more, but so far their only concern is that the cable might be intercepted. Once I explained that the cable would include a tamper as would the entire enclosure containing the cable and the PLC, they could see no issue with it. Coupled with that the PLC, interconnecting cable and PLC would be installed within a protected zone. That way the alarm would be set off before anyone could get to the room containing the alarm panel and PLC.



All you have to do is have the relay fail to the fail safe position.


See above. Also much like the alarm a back up supply is not impossible.


I am not doing this for myself or anyone else. I am simply suggesting a few ideas to the OP.

Remote access to alarm systems is not a new concept.

Right... I believe this is going in wrong direction, instead of quoting and responding to my sentences try to get overall picture of what I'm trying to say, but let' s play your game.

2011 wrote: »

I was not suggesting that the OP install the alarm. What I am suggesting is that the alarm installer can connect a cable from the PLC so that the alarm could be armed/disarmed remotley by loginig in..

Yes, and everyone know's that this is possible. Try to get my point - it's not up to standards! Best way - try to get a licensed alarm installer to sign off this solution. We'll see how many of them will do this job knowing that it may be a subject to audit.

2011 wrote: »

Well, yes it could if someone were to get hold of the user name and password, just like it could be comprimised if they got hold of the alarm code.

Ok. So tell me how do you protect remote access to PLC? what type on encryption is used? Do you have duress option? You still not getting my point - alarm will be disarmed OUTSIDE alarm panel/alarm system identified components. It's not compliant with rules. A question to you - There is a switch to disarm alarm system in a lockable box protected by 2 x combination locks. Is this ok or not?

2011 wrote: »

Perhaps you are correct, but I can find nothing suggesting this. I also asked some alarm installers and they are not aware of it either.

Perhaps? Really?... Perhaps I'm wrong? I would suggest to ask GOOD alarm installers; I'm not in this game anymore, but I can assure you there are ones out there.

2011 wrote: »

but I can find nothing suggesting this..

I can give you a hint where to find it - new EN standards.

2011 wrote: »

I will ask a few more, but so far their only concern is that the cable might be intercepted. Once I explained that the cable would include a tamper as would the entire enclosure containing the cable and the PLC, they could see no issue with it. Coupled with that the PLC, interconnecting cable and PLC would be installed within a protected zone. That way the alarm would be set off before anyone could get to the room containing the alarm panel and PLC..

No comment - don't ask, let them show you or read EN rules yourself. Oh, you better ask first how many of them actually have new EN rules.

2011 wrote: »

All you have to do is have the relay fail to the fail safe position.


See above. Also much like the alarm a back up supply is not impossible.


I am not doing this for myself or anyone else. I am simply suggesting a few ideas to the OP.

Remote access to alarm systems is not a new concept.

Don't get me wrong - I'm not trying to outsmart anyone, I'm just pointing an important fact - situation you have presented is not safe and not compliant with EN rules. Remote access to alarm is not new, but take a look how is it done - there are apps/software made by alarm manufacturers and there is a reason for it.
Again - I'm not against connecting alarm system to PLC/HMS/BMS or other systems, but there are rules to follow to make sure alarm system won't loose Grade (I hope you know what it is) or cert by such modification.
If you think this is not important, then I can't say more. Hope that there will be no situation where insurance company have to educate someone trying to get a claim.

2011

homelogic.ie wrote: »

I would suggest to ask GOOD alarm installers; I'm not in this game anymore, but I can assure you there are ones out there.

I did ask a GOOD registered and experienced alarm installer (in fact I asked several). Koolkid is also a moderator on boards.ie for Home Security Systems.
He gave his reply here.

KoolKid

I am curious as to what part of EN50131 you are interpreting as the problem .
I had an inspection done the year before last where a guy had a gate controller connected to his alarm (Grade 2). The relay on this is controlled via text . This disarms the alarm & opens the roller shutter. When another text is sent it closes the shutter & arms the system. The Panel controller & all the cabling were all within the protected area & tampered. The inspector asked what this was & I explained its purpose & operation. No non-conformances were wrote up for this .

DublinDilbert

Some interesting points raised here.

I think I would go for x10 light switches so the can be overridden locally. Also if you ever move out, the place doesn't need to be rewired, just change a few switches...

lostlad

I think the main point of all this is its only realistic if the OP is going doing all the electrical work himself.

But at the end of the day its still a house what changes are you really going to do after its all finished?

If I was you Id go to town on your switching eg all your bed room and en-suite lights controlled from both sides of your bed etc.

The suggestion for wiring for IP cameras was a good one defiantly woth doing.

2011

DublinDilbert wrote: »

Some interesting points raised here.

I think I would go for x10 light switches so the can be overridden locally. Also if you ever move out, the place doesn't need to be rewired, just change a few switches...

I know what you mean.

If I were to install a PLC in my home I wouldn't use it to control lights.
I would use one of the Legrand Astro Timers for the outside lights. They can be programmed to switch on lights at sunset or at a predetermined time after than. Then the can switch the lights of at say 1am. I installed a 2 channel unit before and it worked very successfully. It also has a manual override function. For me old fashioned light switches and dimmer switches do just fine. The most impressive lighting control systems for domestic that I have seen are by Lutron, but I think they are not worth the money. Each to their own I guess.

I like the idea of having a small PLC controlling a more complex heating system such as a geothermal heat pump with a zone valve per room. This can be achieved with a relatively cheap PLC that just has digital I/O. Digital room stats can be used like this. These valves can be used to provide position feedback to the PCL. This information can then be displayed on a HMI to produce realtime information such as this:

homelogic.ie

2011 wrote: »

I did ask a GOOD registered and experienced alarm installer (in fact I asked several). Koolkid is also a moderator on boards.ie for Home Security Systems.
He gave his reply here.

Not much of a constructive reply. EN 50131-1 and EN 50131-3 is what you are looking for. I believe we should end this discussion on public forum considering the topic. As to alarm game - there are LICENSED installers out there stating that for example GSM diallers can't be jammed. This is all from me on this topic.

KoolKid

I would still be interested in hearing what part of the standards you are interpreting as the problem here.
I agree with you re GSM digis and jamming. It's also interesting that GSM is still acceptable going by the standards.

Stoner

homelogic.ie wrote: »

Not much of a constructive reply. EN 50131-1 and EN 50131-3 is what you are looking for. I believe we should end this discussion on public forum considering the topic. As to alarm game - there are LICENSED installers out there stating that for example GSM diallers can't be jammed. This is all from me on this topic.

homelogic, with respect to constructive replies please note that the OP asked a question and if you read the thread from start to finish like I have I think that 2011 has provided a number of constructive replies including some educated PLC advice to the OP, this is why the OP created the thread in the first place. 2011's intention was to help.

I do see your point and it is valid, however it was a response to someone helping a boards user, it offered some counter advice, brought up the concept of a "GOOD" intruder alarm installer etc. You have also mentioned "EN" regulations but said you wont quote them, users should in your opinion go off and read them or ask for the advice of a "GOOD" alarm installer.

2011 has asked alarm installers and they replied on the thread, I'm happy with the response. Therefore I agree that this need not be discussed further here, there is an element in some of the posts coming through that we try to avoid here, its a discussion forum. The discussions here need to be as open, friendly and helpful to the OPs as possible.

Slight side note, slightly off topic but here goes anyway.
If someone takes the time to reply to an OP with detailed information, that is considered to be a good thing here, not an opportunity for others to dissect the reply. Reason being that it creates an atmosphere where users who could help others are reluctant to do so because they are mindful that there are other users, that did not take the time to assist the OP but will take the time to point out issues/faults/disagreements with a post that was offered as help.

It also adds a lot of time to any replies that people offer, because they have to write the reply in way that can't be pulled apart by other users even though it is directed at (in some cases) people with general questions about their particular house or issue. It's a discussion forum where ideas and views on a particular issues can be exchanged. It is OK for something to be left as a difference of opinion. Users can read and make their own mind up.

homelogic.ie

Stoner wrote: »

homelogic, with respect to constructive replies please note that the OP asked a question and if you read the thread from start to finish like I have I think that 2011 has provided a number of constructive replies including some educated PLC advice to the OP, this is why the OP created the thread in the first place. 2011's intention was to help.

I do see your point and it is valid, however it was a response to someone helping a boards user, it offered some counter advice, brought up the concept of a "GOOD" intruder alarm installer etc. You have also mentioned "EN" regulations but said you wont quote them, users should in your opinion go off and read them or ask for the advice of a "GOOD" alarm installer.

2011 has asked alarm installers and they replied on the thread, I'm happy with the response. Therefore I agree that this need not be discussed further here, there is an element in some of the posts coming through that we try to avoid here, its a discussion forum. The discussions here need to be as open, friendly and helpful to the OPs as possible.

Slight side note, slightly off topic but here goes anyway.
If someone takes the time to reply to an OP with detailed information, that is considered to be a good thing here, not an opportunity for others to dissect the reply. Reason being that it creates an atmosphere where users who could help others are reluctant to do so because they are mindful that there are other users, that did not take the time to assist the OP but will take the time to point out issues/faults/disagreements with a post that was offered as help.

It also adds a lot of time to any replies that people offer, because they have to write the reply in way that can't be pulled apart by other users even though it is directed at (in some cases) people with general questions about their particular house or issue. It's a discussion forum where ideas and views on a particular issues can be exchanged. It is OK for something to be left as a difference of opinion. Users can read and make their own mind up.

I also believe 2011 has provided a few good ideas and I agree with him, my only objection was to the way of controlling alarm system. This is my opinion based on experience and knowledge. I have also suggested where to search for information but unfortunately in this case backing up point reaches beyond discussion on a public forum. I'm trying to help even if that means presenting different opinion and discussion/debating with other users and can only hope that my intentions are not misunderstood.