Hortsmann ChannelPlus H37XL Series 2 programmer fault query

[deansplit]

Hi, we have 2 of these to control 6 zones as follows:
Unit i:
Channel 1 - always on as it controls underfloor heating in kitchen
Channel 2 - On timer for rest of ground floor
Channel 3 - On timer for Living room

Unit 2:
Channel 1 - On timer for Office/bathroom
Channel 2 - On timer bedrooms
Channel 3 - On timer H/W

This system has been in operation in our Victorian home since 2012. Recently, the advance and boost functions have failed on Unit 1, channels 2 & 3. When pressed you hear a wiring sound (like the sound of something mechanical rotating, a buzzing noise) and it fails to activate the zones. However, if I then press advance or boost on any of the channels/zones on unit '2', the heating turns on and if I then switch those ones off the boiler continues to run for unit 1 – it's as if unit 1 needs a kick start from the unit 2. Then everything else works fine. They work fine on the normal timer but aI assume that unit 1 only does due to the same reason, that unit 2 is giving it a nudge.

Any advice on what's happening here or has it has it's day?

Many thanks

Dean

 

[Avo Mk8]

Hi, we have 2 of these to control 6 zones as follows:
Unit i:
Channel 1 - always on as it controls underfloor heating in kitchen
Channel 2 - On timer for rest of ground floor
Channel 3 - On timer for Living room

Unit 2:
Channel 1 - On timer for Office/bathroom
Channel 2 - On timer bedrooms
Channel 3 - On timer H/W

This system has been in operation in our Victorian home since 2012. Recently, the advance and boost functions have failed on Unit 1, channels 2 & 3. When pressed you hear a wiring sound (like the sound of something mechanical rotating, a buzzing noise) and it fails to activate the zones. However, if I then press advance or boost on any of the channels/zones on unit '2', the heating turns on and if I then switch those ones off the boiler continues to run for unit 1 – it's as if unit 1 needs a kick start from the unit 2. Then everything else works fine. They work fine on the normal timer but aI assume that unit 1 only does due to the same reason, that unit 2 is giving it a nudge.

Any advice on what's happening here or has it has it's day?

Many thanks

Dean

I'm familiar with the Horstmann immersion controllers, but not so much the ChannelPlus units.
I'm not sure I understand why the interaction of the units is happening as you describe, but here are some thoughts anyway!
The former immersion earlier models have a 'backup' battery which can eventually die, which sometimes causes side effects such as bringing down the voltage supplied to the electronics, promoting odd behaviour. Your unit has such a lithium battery in it which could be end of life by now! The battery is likely soldered in place - Edit, that may not be the case if it's a 'button' cell.
My other comment is that your unit doesn't have anything 'mechanical' in it (which would cause the noise you describe) other than the small changeover relays that, according to the instructions, perform 'micro-disconnection'. It sounds as if one is misbehaving, but whatever the cause, if it's buzzing with a load on its contacts, the contacts may have suffered.

If you have a multimeter you could check the state of the battery. If you feel confident repairing electronics, then the option of tracking down the problem is open to you, but I don't think the circuit diagram or component layout and information is easily obtainable.
There's no doubt a plethora of Youtube videos explaining how to fix it or not!
There's probably someone out there offering a repair service, seeing as the units seem to fetch £300 to £400 on eBay!
Edit - Yes, there is, search eBay for item: 156571588974

Otherwise the Sangamo 'Choice' I believe has the equivalent functions, but may require shuffling some of the wiring.

Sangamo Choice Central Heating Programmer - 3 Channel 24hr 5/2day 7day | Sangamo (CHOICE PR3N)

 

[brianmoooore]

Interesting! I have one of these in on of the holiday cottages, and last week, when I turned it on for the incoming Christmas guests, I tried unsuccessfully to 'boost' the channel controlling the UFH, since it takes 24 hours to get up to temperature, and I was a bit late turning it on. Didn't worry about it and moved on, but it looks like this could be a known fault?
Why on earth are these so valuable on ebay? There's nothing special about what they do, and they're an absolute pig to program, compared to the FS715s in the other cottages and in my own house.

 

[Avo Mk8]

Why on earth are these so valuable on ebay? There's nothing special about what they do, and they're an absolute pig to program, compared to the FS715s in the other cottages and in my own house.

I suspect it's a combination of DIYers looking for a direct 'plug-in' repair solution, coupled with sellers out to exploit that market, experimenting to see how far they can push the price!
What I've only just done is search for those that actually sold, which seem to range from £29 (dim screen but working!) to £299. Some sold for under £100. Lots in the £150 - £200 area!

Maybe the Danfoss FP735 would be a better proposition as a replacement?

 

[Moley]

My first port of call on a unit that old would be the dropper capacitor. If the cap has gone low you won't get the correct voltage/current to operate the unit. Replacement would be a couple of quid. If anyone wants to send me a unit to play around with I'll see if I can fix it (no guarantee that I can) and then return for the cost of the capacitor and return postage.

 

[brianmoooore]

The Sangamo one in the link looks much easier to program than the Horstman, judging by a quick look at the instructions.
What I'd really like is a two channel and a three channel where the programming can be locked, either by a physical lock on the flap, or by a PIN or button sequence.
One of the banes of my life are guests who 'get at' every adjustment in a cottage that they possibly can.
Agree with Moley that the dropper capacitor will be the #1 suspect, along with any rechargeable battery.