Flash thermostat and Motorized Zone valve

n0brain3r

Hi all,

I'm hoping someone can explain how the thermostats controls the zones in my heating.

It's simple enough setup 3 zones upstairs, downstairs and hot water.

Hot water is controller by a thermostatic valve and the others by motorized valves.

Heres the bit I don't get at the thermostat is a live and neutral with no return. I'd expected it to operate just like a switch and break a live feed to the valves in the hot press.

Heating on thermostat is closed 230v across the terminals
Heating on thermostat is open nothing across the terminals

I've attached a few pictures

How is this controlling the valve?

Thanks,
nb

aujopimur

It's a live and switch wire at the stat, stat closed energizes MV.

n0brain3r

I think I just figured it out

It is a switch when the switch is closed the same voltage is present on both terminals hence 0v and when open 230v is only on one side right?

n0brain3r

aujopimur wrote: »

It's a live and switch wire at the stat, stat closed energizes MV.

Thanks aujopimur it just dawned on me when you replied.

I'm looking to change the heating controls as it and the thermostats are rubbish.

Can anyone recommend something that can control zones independent of each other wirelessly via from the thermostat or directly at the motorized valve(e.g. even if the temp is below stat setting I can switch off the zone from the timer)

Is this possible? If not what can I do to get close?

shane0007

The problem you have with your thermostat is it is an older type with no neutral wire. It only has a live in, live out, switched to the NC position when there is a temperature demand.
With stats that are set up this way, they are inaccurate by 3-6C when they are switching on & off, so their reaction time is very slow.
Modern thermostats have a neutral so they can therefore have a load within them, i.e. an anticipator which is basically a miniature heater. It heats itself to counter-act the inaccuracy.

Wireless stats operate on two different frequencies, 433mhz or 868mhz. The lower are always in cheaper stats & are a continuous signal. They nearly always have interference with walls, other wireless appliances, etc. and are basically hardship.
868mhz stats are a pulse frequency as they can only operate under this frequency under a special manufacturing license. It is what they use in hospitals. They are very accurate.
Best I have used in the market is the Horstmann HRT-ZW.

n0brain3r

Thanks Shane I was looking at the Horstmann wireless stuff but couldn't figure out if I need to replace the valves too or can I retro fit them I.e. control them in the same fashion as now with new wireless stats?

shane0007

The receiver part of the wireless stat is hard wired into the motorized valve, i.e. brown of the MV. The grey of the MV will be fed as permanent live from the spur. The orange will be the switched love fed to switch on the boiler once the valve has opened.

n0brain3r

So does the whole valve have to be replaced? Or do they have a common base? The current ones are Danfuss.