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Discuss New home owner...old.boiler in the Central Heating Forum area at UKPlumbersForums.co.uk.

  1. Jimmyfyeah

    Jimmyfyeah New Member

    Hi everyone, I am a new home owner, that came with an Old baxi bermuda 401 back boiler.

    I currently do not have the money, to upgrade to a condensing combi. However....the old boiler works great, with the gas engineer claiming that it is excellent condition.

    I would like to upgrade the old programmer ( a Drayton lp112) with something newer. The current system has no room thermostat, so I was wondering if something like the Drayton 720r, with wireless room thermostat would be compatible with my old system....with gravity fed hot water.

    A smart system would be excellent, but a programmer with wireless thermostat, would be much better than my blotchy old programmer!

    My current old programmer has a mind of its own, and I can't seem to turn off set programs either.

    Thanks for reading!
     
  2. fixitflav

    fixitflav Active Member

    I don't know much about wireless stats, but I assume it gives a signal to a receiver within the boiler (so would usually come with the boiler). Clearly your boiler won't have a receiver. If you can get hold of a wireless stat plus receiver, the receiver having relay contacts, you could wire the relay into the boiler-fire lead.
     
  3. Last Plumber

    Last Plumber Plumber GSR Top Contributor!!


    Presuming this is and old Gravity Hot water/Pumped Central Heating system, then you need a programmer with two channels. One for DHW (Domestic Hot Water) and one for CH (Central Heating).
    The programmer you would use for that set up needs to be able to run on what we refer to as 10 programmes. this means that you are able to switch on the Boiler on for DHW or if you want CH then both channels will operate, DHW & CH. You cannot have CH on its own.
    Most systems like yours were wired Switched live to Boiler for DHW and Switched live to Pump for CH. You need a Programmer that is capable of preventing CH only coming on as that would just run the pump.

    I do not know if the RF (Radio Frequency) stat you are looking at will do 10 programmes. They may well be 16 only (able to switch CH & DHW independently of each other). If you speak to Drayton technical support, they will be able to tell you.

    You should also ask about the switching capacity of the thing you're looking at. It will need to be a 240V switch that will carry the amperage of your Pump and Boiler.
     
  4. fixitflav

    fixitflav Active Member

    Sorry, should have said put the relay in the pump lead, not the boiler.
     
  5. Jimmyfyeah

    Jimmyfyeah New Member

    Thank you both for the responses! much appreciated!! Yes, it is an old gravity fed hot water system, and yes its CH+DHW or DHW only. I wouldnt personally take on the work myself, but having a thermostat would be nice, as this sytem currently does not have one.

    A smart programmer would be excellent, as I dont work regular patterns....but even just a programmer, with a wireless thermostat...like the Drayton mi time 720r would be fantastic!

    My current programmer just does what it likes...puts the heating or hot water on, by itself at random times! I have reset it, with the same results.

    £300 on a decent programmer sounds far more reasonable than a 3k combi upgrade! especially when the boiler is in good shape, and I am told they are very reliable.
     
  6. Last Plumber

    Last Plumber Plumber GSR Top Contributor!!

    They are very reliable. They have very few parts to go wrong and you can still get most things if not all. If it were mine, I would keep it until it it's done!
    If you can install a stat, that would save you on your fuel bills.
     
    • Winner Winner x 1
  7. doitmyself

    doitmyself Well-Known Member

    I do not know of any smart programmable stat which will handle gravity HW systems. That's probably because gravity systems are no longer allowed by Building Regulations.

    You have three choices:

    1. Replace the LP112 with an identical model and add a separate room stat (wireless if required).

    2. Upgrade system to a C-Plan. This inserts a motorized valve in the boiler connection to the HW cylinder, which allows control of the cylinder temperature and allows separate CH and HW times. A wider range of programmable/smart thermostats are then available

    3. Upgrade the system to fully pumped (you will have to do this when you upgrade the boiler - unless you go for a combi boiler). The same smart/programmable stats as for C-Plan are then available.
     
  8. Rob Foster

    Rob Foster Top Contributor!!

    You could just leave it alone and rig the main supply to a cheap mechanical timer from home and bargain for a fiver
     
  9. Jimmyfyeah

    Jimmyfyeah New Member

    Last plumber: not the first time I have heard that, and I am heeding this advice. I live alone, so its not needed much... and I'm rarely in the house due to work hours. Just trying to get used to that God awful fire front! Thanks for your input!

    Do it myself: converting to a C plan sounds like a good idea! Why are gravity fed systems no longer up to building standards? I presume inefficiency? Thank you for your detailed response!

    Rob Foster: I may end up going this route, as I will have to upgrade at some point! But my current setup seems to do the job well, although I am slightly concerned about the boilers age.. and it going boom lol. Appreciate your input!
     
    • Like Like x 1
    Last edited: Oct 10, 2018
  10. doitmyself

    doitmyself Well-Known Member

    Your presumption is correct.

    "Gravity" systems rely on the difference between the density of hot water and cold water for circulation through the coil of the HW cylinder. This is slow, compared to pumped circulation, so cylinders take a long time to heat up, which consumes a lot of gas.
     
    Last edited: Oct 12, 2018
  11. doitmyself

    doitmyself Well-Known Member

    Here is the pipe layout and a wiring diagram, which is a bit out-of-date as it doesn't show programmable stats.

    [​IMG]

    [​IMG]
     
  12. stevetheplumber

    stevetheplumber Plumber GSR

    theres no point going to the expense of going to fully pumped on a boiler that old you can wire a programmer and thermostat to this setup clock needs to be set to gravity and theremostat will switch the pump on and off you can not select heating only with this system
     
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