The timer wheel on the 30 year old electro-mechanical Randall 4033 CH/HW programmer has stopped rotating so that timed settings do not operate. Needless to say I didn't notice this during the Summer because the programmer was set to HW only and the timer packed-up rotating during the middle of an "On" period -  "Constant" and "Off" switch settings still work fine.

 

Replacement 4033 units, which plug straight into the existing wall backplates, without the need for re-wiring, appear to be  available off the internet, but are horrendously priced at anything from £80-£130 - presumably because they're ancient design and in short supply. 

 

Equivalent compatible digital electronic timers are available for half that price and should be fine, albeit that I will need to fit and re-wire a new backplate.

 

However, before going down this route, I just wanted to check about suitable locations for the new programmer. At present the  existing electro- mechanical programmer has been located (From new build) in the  airing cupboard on the 1st floor (Which has the downstairs flow and return CH pipes passing through it). Consequently, especially in winter, the airing cupboard interor gets warm. Sufficiently so, that, early on in the life of the existing programmer,  the high temperature dried out the factory lubricant on the timer mechanism wheels, making them quite noisy and I had to re-lubricate them.

 

Exam question is. Anybody got experience of fitting a digital programmer in a similar warm-hot  location ? How reliable will they be, how long will they last ?

 

The other issue is that the airing cupboard (Which is fully enclosed with a door) is located in a small bathroom, approximately a metre and a half from the centre line of the bath.

 

Under the new electrical regs will that come under Zone 1 (Wet location) . Will a professional need to undertake the work ?

 

N.B. My system fully pumped,  fully independent CHand HW, with air  and cylinder thermostat, Y-plan motorised valve (Dividing boiler output between CH and HW) and analog electronics facing a Glow Worm Fuelsaver boiler, all of the same vintage (30 years old).

 

 

Nick

Edited 10 November, 201411 yr by Clunkclick

Can't give much info but we got a wireless controller with our new boiler. Seems to be in two parts with one bit actually integrated into the boiler. Doesn't need any wires on the controller end.

 

We're went supposed to get it but the plumbing wholesaler supplied the wrong part to our benefit.

My airing cupboard has the HW tank and associated CH plumbing in it, and has had a Danfoss programmer in there for 10 years with no issues whatsoever. 

 

As regards the regs for Part P, I believe you should be ok as long as the programmer is in the airing cupboard and outside the 600mm zone from the bath/shower (so you could not reach it whilst in the bath for example), the regs are published here

 

http://niceic.com/contractor/downloads

 

If you're still unsure get advice from a qualified spark on the subject.

Cheers for the info. 

 

I think I am probably clear as far as the regs are concerned.

 

It looks like Danfoss took over/merged with Randall - some of the digital programmer replacements I have seen on the web are marketed as Danfoss/Randall. The  connection terminal diagrams I have seen for Danfoss's digital programmers don't seem much different from the Randall, so barring a fooky installation then the substitution should be straight foward. All the electrics are mains, 240v.

 

 

Nick

May years ago ,i had a similar problem- controller fitted in bedroom.No thermostat. So I took advice, and checked out the wiring. The wiring was simple, and I moved the control unit into the kitchen . Next move- a stat in the lounge. I removed the strap in the unit and put the stat inplaceof the S/C,

In this 10 year old house, the digital programmer is in the airing cupboard.

Other than the usual plumbers trick of putting it where you need mirror to read it, it works fine.

Cheers all.

 

Whilst waiting on a reply on my e-mail to  Danfoss for a recommendation on digital programmers that are compatible with the rest of my system, I read (Particularly on the Screwfix site) that some Danfoss digital programmers are very susceptible to voltage spikes (Caused by power outages) and power supply round here hasn't been too regulated since EDF took over. With that in mind, I had a further look around on the web and noticed that Horstmann seem to do some reliable and considerably cheaper stuff, - the only down side being that exact digital equivalent for my existing 24 hour timer is specified as set-up for "Volt-free" contacts only. 

 

Anybody know what volt free contacts in a programmer are ? Scanning the web, I see that specifications for digital programmers  using volt-free contacts  are mostly used in the context of Combi boilers ?

 

Anybody have experience of the Horstmann brand ?

 

On my reading of the literature it looks like you can't mix programmers with volt-free contacts with boilers that have high voltage electronics ( i.e. 230 AC or 24 AC)  - apparently  damage to the boiler electronics is possible if you mix the two.-   from what I can see from the wiring diagram the supply to my ancient  boiler (Glowworm Fuelsaver Mk 2) and to the Honeywell air thermostat and cylinder thermostats, motorised valve and Grundfoss pump seem be 230 ac.

 

 

Nick

Edited 11 November, 201411 yr by Clunkclick

Just fit a surge suppressor to the wiring plate.

Just fit a surge suppressor to the wiring plate.

That's an idea. From live to neutral on the programmer mains input ? Would a motor run capacitor be OK ? Maplin seem to do a reportedly good (And cheap) range of self-)_sealing metallised polypropylene capacitors at both 440 & 250 VAC. Is it better to select a slightly higher voltage for surge suppression ?

 

I'm guessing that's about 35 uf @ 230 vac, 3 amps or 18 uf @ 440 vac, 3 amps.

 

While I am at it I may as well do interference suppression on the pump.

Edited 12 November, 201411 yr by Clunkclick

I guess your system is switched 240v?

 

TBH they are quite easy to re-wire, theres only three, maybe four wires depending how rudimentary your heating system is.

 

I replaced the setup on my system with a wireless item.. like this: http://heating.danfoss.co.uk/xxTypex/287408_MNU17416279_SIT313.html

It was 30quid on ebay with the wiring-box and backplate.

 

Most controllers use a standard backplate these days - so if you are confident to DIY the wiring to suit, you will have many options. there are loads of wiring diagrams online to assist.