New heating programmer

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Existing programmer is a Potterton EP2002, 2 wires going into it, Potterton Profile boiler, 3-way motorised valve, thermostat.

The programmer options give only 2 on/off periods per day and no independant control of CH and HW.

Can I simply replace this with a newer programmer which has 3 on/off periods and independant control of CH and HW?

The wires and programmer are all in the aring cupboard.
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  • locky123
    locky123 Posts: 471 Forumite
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    One cable has 5 wires - R/Y/Bl/Bk/Grn-Y, other cable one wire - Br.
  • Nilrem
    Nilrem Posts: 2,565 Forumite
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    edited 9 November 2009 at 12:14PM
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    Chances are, yes you can replace it fairly easily, certainly to get more on/off times.

    We replaced our old manual timer / valve few years ago with a modern controller including fitting thermostats, and a motorised valve, which wasn't too bad (the hardest part was working out how the old wiring related to the new controller*).

    You may want to look into getting a plumber in to do the job, but depending on where the controller/boiler/hotwater tank are in relation to each other it shouldn't cost much more than about £70-100 for the parts and a couple of hours of a plumbers time (it's not something I'd recommend doing yourself unless you are fairly confident with what you are doing and have the tools as it requires some plumbing + electrical knowledge and a fair few tools).

    When we did ours, we used a Danfoss pack from Screwfix that had the controller (up to 8 discrete period for both CH and HW + options of all day, and all the time, and boost buttons), motorized 3 way valve (to allow for independant automatic changing from CH to HW), room stat and tank stat, the kit cost about £70 at the time, and just needed some extra wiring.


    *I used to do electrical kits from circuit diagrams and trying to work out the wiring for the controller still threw me, at least until I got out a trusty pen and paper and worked it out in a "real" rather than "logical" manner :) (starting with what went where with the existing wiring, then how that compared to the new controller).

    [edit]
    A nice additional bonus with modern controllers, is that normally these days they have compatible backplates, so if/when the controller dies you can usually pop down to the plumbers (or even B&Q / Wickes) and get a replacement that will just drop into the backplate when the old one is taken off, and turns what was a pain in the neck job, to something that can be done almost as easily as changing a light bulb :)
    Not much help with your current situation (although it's possible you can get a replacement controller that will give you additional on/off periods easily, just not the independent control of CH and HW as that will probably need additional wiring/parts).
  • andrew-b
    andrew-b Posts: 2,413 Forumite
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    Most of the programmers come with wiring conversion tables between common programmers - though whether a straight swap is possible with the current setup is hard to say. That you already have the 3-way valve sounds promising though.

    We've got this danfoss programmer which does the job just fine and has upto 3 independent on/off times for CH or DHW..if you look in the instructions for that it includes wiring conversion from a Potterton EP2000...i'd hazard a guess the wiring is the same for the EP2002...though do please confirm this first and don't take my word for it as im no heating engineer! If in doubt just get a heating engineer in. If you do attempt a DIY swap then make sure all the power to the heating system is isolated!
  • locky123
    locky123 Posts: 471 Forumite
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    The is a mass of wites in the box under the programmer. I dont fancy tracing them all, so was hoping of a fairly simple swap. I think it should be but.....

    Looked at the Potterton back-plate. Has N, L, 1, 2, 3, 4, 5 and E connections.

    The 5th is a link wire from the Live

    There is no wire in 2.

    Have been looking at a Drayton LP522 or LP722.

    This back-plate appears to have N, L, 1, 2, 3, 4 connections. So no 5th?

    Found a Drayton wiring diag and they have no wire going to connection 2.

    Just puzzled about the link wire on connection 5. Maybe not needed on the Drayton.
  • EliteHeat
    EliteHeat Posts: 1,382 Forumite
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    Not really a DIY job when alterations are required, and not a job for either a plumber or (most) electricians. It's a job for a competent heating engineer. Decent ones will be able to do it without recourse to any manuals, bodgers tend to do it by numbers, relying on specific types of wiring centres. Many installations wiring centres were just 47mm surface mount boxes with 15 amp connector strips wedged in. These can look horrendous and are not for the faint hearted.

    All of the compunents in the wiring centre must be positively identified and then the alterations made for independent twin channel operation.

    Be aware that some older boilers will not allow you to do this, typically these are the ones with a gravity hot water circuit.
  • locky123
    locky123 Posts: 471 Forumite
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    Well I'm going to give it a go. Wish me luck and I will report back soon.
  • EliteHeat
    EliteHeat Posts: 1,382 Forumite
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    Hope it goes well.
  • andrew-b
    andrew-b Posts: 2,413 Forumite
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    Not sure if this is what you already found but look here under Time Controls -> LP Programmer -> LP Installation Guide (Direct download here)...in the wiring conversion chart there is a section for "Potterton Myson All EP2000’s" and mentions "(link L-5 and N-N)"

    Hope that helps..be careful though and double check everything and don't be afraid to chicken out before it's too late! Make sure you take a photo and carefully label which wire came from where on the existing programmer so if necessary you can put it all back again!
    If you !!!!!! it up it'll probably cost you more for a heating engineer to sort than if you'd let them do it in the first place!

    These conversion charts assume the previous programmer was wired correctly in the first place though!

    Good luck!
  • andrew-b
    andrew-b Posts: 2,413 Forumite
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    edited 9 November 2009 at 4:41PM
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    EliteHeat wrote: »
    These can look horrendous and are not for the faint hearted..
    Agree (just the once :rotfl:). Even the newer wiring centres look horrendous to me. I took the cover off mine said "oh" and promptly put it back on :rotfl:.

    Considering how complicated it looks at first sight.i'm actually quite surprised how quick the electrician who rewired our central heating system fitted the new wiring centre..despite it having to be upside down and in the back darkest corners of the airing cupboard! Plus he was chatting to the other heating engineer (the one who did all the rest!) and drinking lots of tea at the same time! It would have taken me all day..took him less than an hour (including tea drinking and chatter, tools in and out van etc!). Guess that's experience for you!

    I'd still probably DIY it myself but then i do have a masters degree in IT with alot of electronic engineering content so i'm not really your typical "wannabe heating engineer" bodger ..least i like to think not :D
  • C_Mababejive
    C_Mababejive Posts: 11,658 Forumite
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    In theory it sounds a goer. You appear to have a fully pumped system with a Honeywell V4073A diverter valve or similar.

    If your lucky,you'll get a compatibility/switchability diagram in the new programmer pack.

    If not,then obtain a diagram for the EP2002 and take it from there.

    It is not unknown for "qualified" engineers to !!!!!! this kind of stuff up.
    Feudal Britain needs land reform. 70% of the land is "owned" by 1 % of the population and at least 50% is unregistered (inherited by landed gentry). Thats why your slave box costs so much..
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