Hello all, a penny for your thoughts on combi boilers...

[BigBo1975]

I have had a loft extension built with (wet) underfloor heating however I have come to a bit of a halt. It seems that my existing combi boiler is on its last legs so Im looking at getting a new one (and also relocate it in a different part of the house as the part it is in now will be knocked down in the forseable future).

In the rest of the house I have radiators so would very much like to separate the heating zones however, whilst manufactures tell me that I can do this with the combi boilers, they don't tell me how (in layman terms), I have been told that I need a twin chanel controller, and also a control valve!

Therefore any info / advice would be greatly appreciated.

 

[Garfeild]

Last one i did (while ago now) i altered the system into a s plan with two two port valves,then used a standard CH programmer,and the sparky wired it so the CH channel controlled the radiator zone valve,and the HW channel controlled the UFH zone valve.
You still need the mixing valves and pump etc for the ufh.

 

[BigBo1975]

Thanks vm for that, I have the pump/mixed for the ufh, it's just the boiler to manifold where i'm getting somewhat lost! Anyway, will print out your reply and take it to those that know so many thanks! Any other thoughts welcome!

 

[dal5band]

Since you don't have to worry about timing the hot water, the best way would be to have a programmable thermostat for each zone. Each thermostat would control it's own zone valve and call for heat from the boiler+pump as and when required, via the voltage free contacts on each zone valve. Wiring could be tricky so some expertise needed.


Thermostat1 ---> Zone Valve1 ON ----> Boiler+pump ON
Thermostat2 ---> Zone Valve2 ON ----/

 

[bengasman]

You use exactly the same system as a heat only boiler with 2 valves controlling the rads and the cylinder, only in your case you use the "cylinder" half for the second zone instead of the dhw.

You will need an independent twin channel timer like honeywell st 9400, that allows completely separate times.