Downstairs heating only working when upstairs is on

[rich19754]

I take it the (D/stairs) valve is opening but not firing the boiler?, if so then even though a new valve head I would confirm that its micro switch is closing by removing the valve head grey&orange wires and with the M.meter on resistance check for continuity between them, should read maybe 0.1/0.3 ohms or the same as when you touch the two probes together, this is with the valve energised and open.

Yeah that’s exactly it

 

[terryplumb]

WARNING.
Do not attempt to measure resistance on live conductors

I take it the (D/stairs) valve is opening but not firing the boiler?, if so then even though a new valve head I would confirm that its micro switch is closing by removing the valve head grey&orange wires and with the M.meter on resistance check for continuity between them, should read maybe 0.1/0.3 ohms or the same as when you touch the two probes together, this is with the valve energised and open.

 

[Johntheo5]

I did say to remove the valve head grey and orange wires before testing, maybe should have said "remove from the terminal block"

 

[terryplumb]

I did say to remove the valve head grey and orange wires before testing, maybe should have said "remove from the terminal block"

With the valve " energised" as per your instruction ,the orange wire could well carry 230/240 volts irrespective if it is in a terminal block.
John ,your instructions are not very clear and could possibly lead someone to try to measure resistance on conductors carrying mains voltage ,might be worth you amending the post ?

 

[rich19754]

230/240 volts between the orange wires terminal and earth terminal when downstairs valve only is on calling for heat.

Merry Xmas everyone

By way of an Update - have tested as per the advice above and I only get 240v when the upstairs is on. Could it be that h new Honeywell valve head I have installed is faulty or maybe it’s an issue with the thermostat wiring (but not sure how it can be as the thermostat is defo opening the valve when it’s turned on and I am getting 240v at the thermostat on the brown perm live (but not tested the grey wire going out the thermostat which I assume is the switched live going back to the control box). Any further ideas please?

 

[rich19754]

I am getting 240 on terminal 8 when the downstairs thermostat is turned on (and 240 on terminal 9 when upstairs stat is turned on) so I assume that rules out the wiring from the thermostat. Sounds like it can only really be a bad valve head switch or could it a bad valve that’s not opening enough to click the switch - not really sure

 

[rich19754]

 

[rich19754]

This is the stat (I had taken the earth sleeve off) - am getting 240 on the brown and 240 back in the main control box when switched on

 

[gas112]

take your new head off the valve body and try it see if it fires

 

[rich19754]

I am starting to think I may have got one of the grey wires mixed up between terminals 5 and 6 - do the grey wires from the valve head get connected in the same terminal as the orange?? This could be my issue as at the moment the grey wire from the new downstairs valve head is connected with the orange into terminal 6 but the grey wire from the upstairs valve head is connected into terminal 5 - if someone could have a look at this it would be greatly appreciated - thanks

 

[dilalio]

And while the head is off... Give the spindle a twist back and forth... See how easy it moves... Not a lot of travel in °s but should be easy.

Valve may too stiff for synchron.
Give it a squirt of a lubricant.

 

[dilalio]

I am starting to think I may have got one of the grey wires mixed up between terminals 5 and 6 - do the grey wires from the valve head get connected in the same terminal as the orange?? This could be my issue as at the moment the grey wire from the new downstairs valve head is connected with the orange into terminal 6 but the grey wire from the upstairs valve head is connected into terminal 5 - if someone could have a look at this it would be greatly appreciated - thanks

Very likely a wiring fault... Usually is.

Greys do not go in with oranges in terminal strip... Because... They should only be connected electrically... When the microswitch in the power head "makes"!

 

[Harry Bloomfield]

I am getting 240 on terminal 8 when the downstairs thermostat is turned on (and 240 on terminal 9 when upstairs stat is turned on) so I assume that rules out the wiring from the thermostat. Sounds like it can only really be a bad valve head switch or could it a bad valve that’s not opening enough to click the switch - not really sure

Did this system ever work properly, or is this a new problem?

 

[dilalio]

Put the greys together and the oranges together... As I said above "commoned"

If you had 4 x 2ports you'd have 4 greys in together and 4 oranges together!

 

[rich19754]

Did this system ever work properly, or is this a new problem?

It’s a new problem - it started with downstairs stat not turning on the boiler but fault seemed intermittent at first but then it wouldn’t tum boiler on at all but it all works perfect when upstairs is on. I replaced the downstairs stat and the valve head but problem persists.