Wiring up new room thermostat

Fitzy71:

Hi guys


Hope you’re all keeping well and safe?


I need some help with wire colour identification for my new Flomasta and 6259G wired thermostat.  I have worked on any heating/water installs yet, so I’m not familiar with the wiring colours.  My old analogue Honeywell thermostat has 5 wires, Gn/Y, blue, black, light grey and brown.  The Honeywell is wired 1 gn/y, 2 blue, 3 black, 5 brown, light grey isn’t used.  New flomasta uses only 3 wires, Com, NO & NC, I know the NO & NC means open/closed, but which colour wire goes to which terminal?

Normally manual room thermostats have just three needs. L to Com. Switch L to calling for heat, N to N terminal. Which gas heating wiring system have you S plan or Y plan?  Traditionally Red went to Com. Blue to N and Yellow to switched L.  So now it is probably Brown to L, black sleeved blue to N, and grey (sleeved brown) to switched L.


Z.


 

Fitzy71:

I’m not sure if it’s S or Y plan to be honest.  It’s a combination boiler with the big expansion cylinder above the hot water tank. 

You should be guided by the boiler's wiring diagram then. It might even be E.L.V.


Z.

Fitzy71:

I’m not sure if it’s S or Y plan to be honest.  It’s a combination boiler with the big expansion cylinder above the hot water tank. 

Are you sure it is a combi? Sounds like you have an un-vented cylinder for the hot water. Anyway, which model is your existing honeywell room thermostat? We should be able to find the wiring diagram for it somewhere

OlympusMons:

Fitzy71:

I’m not sure if it’s S or Y plan to be honest.  It’s a combination boiler with the big expansion cylinder above the hot water tank. 

Are you sure it is a combi? Sounds like you have an un-vented cylinder for the hot water. Anyway, which model is your existing honeywell room thermostat? We should be able to find the wiring diagram for it somewhere

I believe its a system boiler, because when you having a shower and someone flushes the toilet, the showers changes temp and that never happened in our old flat with a conventional boiler, plus, we dont have a cold water tank in the loft, but cold water is not direct from the mains in kitchen either.

 but cold water is not direct from the mains in kitchen either.

Cold water to a kitchen tap MUST originate from the cold water main for health reasons. It should be mains pressure and not from a tank. It is drinking water.


Z.

Fitzy71:

OlympusMons:

Fitzy71:

I’m not sure if it’s S or Y plan to be honest.  It’s a combination boiler with the big expansion cylinder above the hot water tank. 

Are you sure it is a combi? Sounds like you have an un-vented cylinder for the hot water. Anyway, which model is your existing honeywell room thermostat? We should be able to find the wiring diagram for it somewhere

I believe its a system boiler, because when you having a shower and someone flushes the toilet, the showers changes temp and that never happened in our old flat with a conventional boiler, plus, we dont have a cold water tank in the loft, but cold water is not direct from the mains in kitchen either.

So a system boiler and un-vented cylinder run from mains water. What makes you think the kitchen cold tap is not fed from the mains if you have no tank in the loft?

Do the showers change temp or flow rate? sounds like the showers are not thermostatically controlled, which they really should be since you could get scalded.