Changing Mechanical Programmer to Digital

[bazzzar]

Hi all

This is just a hyperthetical question at the moment...

My heating system at home consists of a standard boiler with cylinder and cylinder stat, pumped with one 2 port zone valve (think it's 2 port), no room stat, TRV's on all rads and a Danfoss Set3M programmer

I have been given a Horstmann C27 and wanted to know how easy or difficult it would be to change the wiring.

The Danfoss has a 9 pin backplate - E N L 1 2 3 4 5 6

The C27 has a 7 pin backplate - E N L 1 2 3 4

Without taking the thing off the wall, from memory I have 2 3 core cables consisting of different colours going into the programmer, but if you need more info on what wires are connected to what pins I will take it back off.

I have been told by Horstmann that the system will have to be re-wired to accomodate the new programmer and unfortunately in no posistion to pay someone. As you can tell by the links above, the Danfoss is quite a beast and because I am moving the programmer to the hallway outside the kitchen I wanted a more slimline digital one. Many thanks in advance for your input.

 

[sparkytim]

Hi

From what you have posted You appear to have all the information available for a competent person to be able to do the job and no more details are required.

If you are unable to understand the information then I am sorry it would appear you require the services of someone who does.

 

[bazzzar]

and the answer to my question is....?

 

[kme]

OK - I can`t actually see "a question", but think you are asking if it can be easily done?

If so; here are the answers:

By yourself: inferring your technical ability from your opening post - no, not easily.

By a "competent person" - yes, not a serious problem, AFAIAC

As Tim says above: it is "doable", if you know what you`re doing. I don`t believe "the whole system has to be rewired", but there may be modifications to make.

HTH

KME

 

[SPECIAL LOCATION]

and the answer to my question is....?I have been given a Horstmann C27 and wanted to know how easy or difficult it would be to change the wiring.

Easy...... if you know what you are doing....

and can read the wiring instructions and diagrams provided by the manufacturer!

the Danfoss is no beast.. just a standard two channel programmer

"and unfortunately in no posistion to pay someone."

I sometimes try this at the garage with my car... but I still have to pay to get the work done properly so me family done get injured using an unsafe vehicle.....

OK... Back to your heating....

If you look at the wiring instructions you have posted ALL of the terminal connections a clearly identifiable...

A central heating control timer is simple one two or three Two-Way switches controlled electronically or mechanically to switch power to various parts of the heating control at different times of the day....

The heating controls need 230v signal triggers to position the appropriate valves to allow water down the correct pipes to radiators and/or hot water..

SOME OF THESE DEVICES NEED 230v IN THE OFF POSITION, NOT JUST THE ON POSITION.

which is why there are TWO_WAY switches at the control center.

if you look back at your drawings...

Water ON = term 3(Horstman) / term 1(Danfoss)

Water OFF = term 1(Horstman) / term 3(Danfoss)

heating ON = term 4(Horstman) / term 4(Danfoss)

Heating OFF = term 2(Horstman) / term 6(Danfoss)

Quite straight forward if doing a like for like swap.......

BUT...

you also mention moving and extending some of the control wires...

In which case alteration to 230v central heating control wiring is notifiable work under part P building regulations..

this should be fully tested certified and a compliance certificate obtained to verify compliance with all relevant safety regulations....

If I was amending someone elses existing wiring I would want to verify all cables are appropriately connected...

NO earths used as switched lives

ALL terminations secure mechanically & electrically

Verify ALL vales & thermostats are operating correctly prior to disconnecting old programmer...

etc..

etc..

then just do the work..

test it..

do certificates..

notify to LABC..

Jobs a goodun!

Golden rules to remember:-

1. Heating systems are often wired in a ad-hoc non-standard sort of cable/colour method..... (Plumber & his mate or DIY dan!)

2. Heating system involve cables/ flexes near to very hot parts, this can cause deterioration of cables if incorrect installation methods were originally employed.

3. Although modern system can use extra low voltage signaling, traditional systems are using the full 230v mains supply voltage between the control devices.

4. ALL essential isolation precautions must be followed for safe working, just as if working on any other circuit supplied from a domestic distribution box.

5. Wired incorrectly it is possible to make metal pipework go live.... Which can be a potential fatal accident waiting to happen... but generally in these situations... only one person gets killed because then it normally becomes a bit more important to verify its both SAFE and working.. not just working!

In summary...

what you want to do can be done, it is not difficult for a qualified person or even a competent DIY...

But as Always....

If in any doubt, for your own safety, employ professional help.



p.s.

Welcome to the forum.

Guinness

 

[batty]

Welcome to the forum Bazzzar as others have said central heating systems controls are ok if you know what you are doing although a lot of sparks can even struggle with them. Do you have a test meter because if you don't you really should not be doing it. I am a little concearned you do not know the difference between a two port and three port valve this is very basic stuff. Reading between the lines I do not think you are up to moving programmer yourself. The thing is if you do mess it up it will cost you twice as much for someone to sort it out for you.

 

[bazzzar]

Thank you so much for the very helpful replies.

As I stated, it was a hyperthetical question and have taken on board your replies.

And because of your replies I managed to find a direct replacement :^O - Drayton LP241 and will probably stick the Horstmann on the bay.

As for the zone valve, it is a three port, the airing cupboard is the wife's department and I never look in there...lol

Again, thanks for the replies. Guinness

 

[Doc Hudson]

Welcome to the forum Bazzzar, Your post highlights a big problem with heating systems, where there are no standard colours used for each function. Such that a Blue wire on one system may be request for hot water, on another installation next door it may be Red or Yellow, or Grey. So forum members cannot reliably give advice to put the Blue wire on terminal 'X'!

Doc H.

 

[SPECIAL LOCATION]

will probably stick the Horstmann on the bay.

Flea bay!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!



We have our very own online auction site............

maybe worth a shot?

O) :innocent :Blushing

http://www.talk.electricianforum.co.uk/forumdisplay.php?f=62