Replacing Honeywell ST699 CH/HW Programmer with ST799 Model

[ashburnham]

I never touch electricals, plumbing, heating, etc but times are hard and I'm looking to try and do some work myself for once and save some cash and tea bags

Basically my Honeywell ST699 Central Heating and Hot Water Programmer is working but the time display has gone "doolally" (I think that's the technical term) meaning my only options are Off or Constant therefore want to replace it.

I've read up that the ST799 uses the same backing plate and looks to be pretty much the same unit with the only difference being it offers 7 day programming rather than just 24 hours on the ST699.

Finally, my question, is the installation of this as simple as disconnecting the wires from the ST699 and reconnecting them to the ST799 in the same fashion? It may even be as easy as removing the ST699 front cover and replacing it with the new ST799 cover (i.e. leaving the existing wiring on the backing plate in place and just replace the front screen)?

Like I say, I never touch electricals normally but I'm quite technically minded and this "looks" like a simple job either way. Can someone confirm if what I am saying is correct or if I should be calling in a electrician?

 

[spacethegas]

yep.

turn off juice.

pull old one off (can be quite interesting if you've never done it before) & push new one on.

 

[ashburnham]

yep.

turn off juice.

pull old one off (can be quite interesting if you've never done it before) & push new one on.

it's a shame i can't just buy the front cover really if this is the case but new st799 now on order.

i'm glad it's the "easier" of the two options. i assume when i get the cover off there is some kind of wire connecting it to the backplate and that is the only one i need to disconnect and then rewire to the new cover (leaving backplate and all other wiring in place)?

thanks for your help

 

[spacethegas]

no. it just plugs in.

 

[ashburnham]

looks like i'll be doing it with my eyes closed then

thanks