Worcester MT10RF Mechanical Timer Thermostat

grumbler

My elderly friend has a boiler with this thermostat - and the electro-mechanical clock in it failed - keeps stopping unpredictably even with new batteries.


Questions:

• If we buy a new set, does the receiver has to be replaced or the new thermostat can be paired with the existing receiver? If it needs replacing, how easy/difficult is it?
• Can it be replaced with anything more reliable than this battery-operated mechanical crap that costs about £200 to replace (excluding  labour)?

ThisIsWeird

This is a 'wireless connect procedure',  so I'm guessing a new programmer of the same type can be used with the existing receiver.
Page 10: https://www.worcester-bosch.co.uk/professional/support/literature/worcester-mt10rf-installation-instructions-1

Will look for better prog - no idea at the mo'. Yes, that's an expensive pile of poo.

ThisIsWeird

Grumb, do you know the model of the actual boiler?

grumbler

Thanks.

No, I don't know the model. Will have a look next time I'm there.

ThisIsWeird

At a glance, the receiver appears to have a similar size and that wee sticky-out tab at the top that's the same as your friend's, but no idea beyond that. Should be easy to confirm, tho', once you have the boiler model.

https://www.amazon.co.uk/RT510WBC-Worcester-Programmable-Thermostat-Compliant/dp/B08FDR5FQD/ref=asc_df_B08FDR5FQD/?

grumbler

And Dryton seems to make something similar and compatible:

"Drayton Digistat LP10RF+2RF Clip-In Worcester Wireless Room Thermostat 24hr"

ThisIsWeird

If they both fit, then the essential difference would appear to be that the RT510 is a PROG Stat, so you can set a series of specific temps for chosen times, whereas the Drayton would appear to be separate timer and stat. Ie, you can preset only the 'on/off' times, and then manually turn the temp up and down as required during the 'on' periods.
Prog Stats are much better - they take most of the hassle out of controlling your house temp. 

FreeBear

ThisIsWeird said: Prog Stats are much better - they take most of the hassle out of controlling your house temp. 

According to some research, a programmable thermostat could save up to 10% of energy. Certainly, when I switched to a fully programmable system, I made a significant saving on gas usage.

ThisIsWeird

Yup, proper prog stats are thoroughly recommended.
The saving in hassle - never mind energy - is worth it.

grumbler

It's worth saying that the original thermostat was programmable to some degree - two temperatures, day and night - instead the common ON/OFF and one temperature.

And the above Dryton is programmable despite the specifications being not clear about this - see p.13 of the

LP10RF & Digistat+2RF User guide

However am I right thinking that it's excessive for a combi boiler as the receiver has water heating programming capabilities? I'm asking because my boiler isn't combi and I want the replacement to be as simple as possible for my friend's boiler.

ThisIsWeird

grumbler said:

It's worth saying that the original thermostat was programmable to some degree - two temperatures, day and night - instead the common ON/OFF and one temperature.

And the above Dryton is programmable despite the specifications being not clear about this - see p.13 of the

LP10RF & Digistat+2RF User guide

However am I right thinking that it's excessive for a combi boiler as the receiver has water heating programming capabilities? I'm asking because my boiler isn't combi and I want the replacement to be as simple as possible for my friend's boiler.

Ah, I seeeee!

I did wonder what the heck was going on with that Drayton, as it had a timer on the receiver, and obviously a timer on the thermostat/control unit. But, it looks to be as you say - the receiver's timer is for DHW which, as you say, a combi just won't need. 

Edit: It looks as tho' the receiver's DHW timer will control the combi's 'pre-heat' feature. With pre-heat, the boiler will fire up every few minutes in order to keep the boiler 'hot' ready to provide DHW at the tap. I have disabled that feature on my GlowWorm, as the boiler would fire up dozens of times per day and night for this - what a waste. But, with this timer, you could set it to only P-H in the morning, and say at washing-up time in the eve, so potentially actually quite a nice feature.

The Salus - which doesn't have the DHW timer - won't be able to do this, so your friend will either 'have' this feature enabled on their boiler all the time, or will disable it - presumably done via the boiler controls (like mine).

So, that could be the decider between the two devices? Do they fancy a timed pre-heat feature?

The Salus is much cheaper, and the main unit smaller and neater - but hardly a big issue. I'd personally be inclined to go for the Salus as it's simpler in that regard, provided it will actually fit - I think it will. (Seemingly it'll suit the Greenstar i range, CDi Classic, CDi Compact, Si Compact, and the CDi Highflow. If your friend's is non of these, then ask Salus if the RXWBC605 receiver will fit, and work with their RT510WBC Prog Stat on their boiler.

You are right in that their current electro-mechanical controller is partly 'prog', but barely! A proper PS like the Salus, Drayton (and many others) will do a much wider range of temps at whatever times you want. For example, they could set it to 21oC at 6.30am, down to 15oC at 8am, back up to 20oC at 5pm, up a tweak to 21oC at 7pm, back down to 14oC at 11pm - that sort of stuff, and easily over-ridden at any point.

What often separates them is how many on/offs (up/downs) you can have per day, and whether you can have each day different - if that's important. All will at least have separate timings for week and weekend.

They are GREAT!