boiler problem on heating system

bwvm · 22 Mar 2008

Help! we have a Gloworm micron 50ff boiler fiited with Gloworm 7 day programmer and a two motorized valve set up. Hot water is fine valve,pump & boiler all responding to stat on tank.
But heating not o.k. after advice from mate tried fitting new Drayton ZA5 valve actuator but no difference.
Room stat makes valve and pump operate but boiler will not kick in.
Have just fitted new Grundfoss pump (old one knackered)and that is running perfectly.
Any ideas

seco services · 22 Mar 2008

sounds like a wiring issue to me.

gas4you · 22 Mar 2008

I thought, from memory, that the micron pcb controls the pump, not the zone valve.

From here it sounds like the sw/l to the boiler from the ch zone valve, has been wired to the pump instead

bwvm · 4 Apr 2008

Thanks for your replies

When I changed the Drayton actuator it was a one wire at a time job so should be correct
We still have the same problem heating only when H.W. is on !
I put a multi meter across the grey and orange wires from the micro switch on the new actuator and when wife switched on the main supply only showed power for a few seconds then dropped away to zilch.
According to the Drayton leaflet the switch is a spst type does that mean it should only work for a few seconds ?
Do I try anew Gloworm programmer next ?
P.S. room stat turne way up when testing micro switch

twgas · 5 Apr 2008

I put a multi meter across the grey and orange wires from the micro switch on the new actuator and when wife switched on the main supply only showed power for a few seconds then dropped away to zilch.

i think you're not too competent with meter.

as soon as switch closes there wont be any voltage reading on meter, but it does sound as though its working

D_Hailsham · 5 Apr 2008

Here is the wiring diagram for an S-Plan, which is what your type of system is called. Use it to check that your installation is wired correctly

It shows the pump wired to the junction box but, as gas4you says, it might be wired directly to the boiler; so don't worry if the pump is not wired to the junction box.

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boiler problem on heating system

bwvm

seco services

gas4you

bwvm

twgas

D_Hailsham

DIYnot Local

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