Another Q around Up2 to Hive Swap...

[Damp_Squid]

Hi All,

Recently moved into a house that has a British Gas Up 2 timer, along with Honeywell room stat. House has a hot water tank (I believe in S plan as there are two valves) so was looking to swap over to dual band Hive. I know the backplates are compatible, so should just be a case of swapping the units over, then removing the wiring for the additional room stat, however...

Is there any reason why there would be a bridge between the permanent live & hot water off terminals (potato quality photo below)?

I'm also waiting for a cable tracer to turn up before I investigate spaghetti junction to remove the old Honeywell stat (second pic), but if anyone can decipher it in the meantime, it would be greatly appreciated!

 

[flameport]

Is there any reason why there would be a bridge between the permanent live & hot water off terminals

The installer was an idiot?

spaghetti junction

Confirmation of the above.

 

[Damp_Squid]

The installer was an idiot?


Confirmation of the above.

I'd go with that (as well as daylight robber) - the previous owner left a load of paperwork; £3500 & a week's work apparently for a Greenstar 30CDi, grunfoss pump and honeywell TRVs. It was just a replacement of the boiler - all existing piping was kept!

With the bridge, does that mean that the hot water is constantly on (unless the thermostat in the cylinder is up to temp)? Really trying to get my head round what's going on here!

 

[flameport]

That connection will do absolutely nothing. It will be permanently live all the time, no different from putting the red wire that's to the left side of the terminal 1 into L instead. It's 100% pointless.

 

[Damp_Squid]

Interesting development. . . I'd taken that bridge out, put the Hive unit straight onto the backplate (and bridged out the old room stat temporarily) and thought all was well.

Have just realised how cold it is and noticed that the boiler isn't on. Turning the power off & on to it makes the boiler get power for about a second, then die (checked the connectors on the plate to make sure they were all a decent contact) . . stuck the bridge back on, and the boiler has got power. Now just got to wait for it to come back out of commissioning mode.

No idea what's going on, but think I'll have to wait until the wife isn't yelling about being freezing before I try to swap it out!

 

[flameport]

I'd taken that bridge out,

If doing that, the other red wire in that terminal will need to be moved to L.
It presumably powers some other part of the system.

 

[Damp_Squid]

the other red wire in that terminal will need to be moved to L.

Sorry - probably should have taken a clearer picture. Do you mean the red wire on the "1" terminal (which should be HW off)? I was assuming that it was actually the HW off; now I'm guessing it's just triggered by demand on the HW on, and the guy who fitted it just used the connection to bridge whatever else that live is feeding?!
Thanks for the help btw

 

[ericmark]

This is a guess, but wonder if you have Y Plan not S Plan, as with Y Plan hot water off is used?

 

[Damp_Squid]

I thought Y plan needed a 3 port valve (although this is the first time I've had to deal with anything that wasn't a combi, so I'm more than likely wrong)!!

 

[CBW]

It’s an S-plan. You could do with getting the wiring sorted before connecting anything up as an expensive mistake.

 

[Damp_Squid]

It’s an S-plan. You could do with getting the wiring sorted before connecting anything up as an expensive mistake.

Cheers for the confirmation! Completely agree - waiting for a cable tracer to turn up to see what's been connected to where

 

[ericmark]

Motorised valves in the main are standard colours on wires, so:-
Brown = Supply from thermostat.
Blue = Neutral.
Green/Yellow = Earth.
Grey = Line supply.
Orange = supply to boiler.
You have two thermostats, one for CH and one for DHW, it seems likely the core colour to DHW is yellow, and CH is red, but pictures are not really good enough to trace with, personally I fitted Nest Gen 3 in the summer, so any teething problems done at leisure, my central heating is C Plan with two motorised valves one for flat and one for main house, there is no control for DHW other than time, I also have two pumps. So just because two motorised valves fitted does not auto mean S Plan.

Very likely it is S Plan but when I moved in this house was a mess, it seems at some point garage converted to granny flat, and it was a case of as long as flat OK to heck with the main house. I am still trying to sort it all out. Still can't believe the people doing it all actually put their name on the consumer unit, I would want to disown such workmanship.

But point is you need to work out what you have before you can alter. I ended up using cables in the wall but completely rewiring. It turned out there should have been a three core and earth main house to flat, which changed core colours on the way, so some where hidden there is a junction box, and only two cores work, my whole reason for fitting Nest is can control both CH and DHW with two cores, and keep thermostat charged.

So since you had a link wire that did not make sense, it seems reasonable to think some thing wrong and some one has done a fix to keep it running. With daughters house the micro switch in the motorised valve was faulty, and it had been latched open to keep it working.

I can see an owner saying we are selling the house, just make it work for now. It did not really worry me, but for an owner who was not an electrician I do wonder how they would have fixed it.