Three port diverter problem

[Howardws]

I've just replaced a pretty old Honeywell V4073A1039 three position diverter valve with a Drayton ZA3/679-3. Now the central heating won't start, although the hot water is fine. I've checked my new valve wiring a number of times and can find nothing wrong, having just swapped colours like for like. I'm wondering if perhaps the Honeywell one was old enough to be made before there was an industry wiring colour standard. Can anyone advise please?

Thanks in anticipation,

Howard

 

[D_Hailsham]

I've just replaced a pretty old Honeywell V4073A1039 three position diverter valve with a Drayton ZA3/679-3.

You have the wrong valve!

The V4073 is a mid-position valve (HW only, or HW and CH, or CH only). The ZA3/679-3 is a diverter valve (HW only or CH only).

You need a MA1/679-3.

The body (brass part) is identical; it's just the actuator (box part) which is different.

PS

The V4073A has five wires; the ZA3 actuator has 3 wires. Are you sure it's not the ZA5? Which ever, you need the MA1 actuator (5 wires)

 

[ianmcd]

I've just replaced a pretty old Honeywell V4073A1039 three position diverter valve with a Drayton ZA3/679-3.

You have the wrong valve!

The V4073 is a mid-position valve (HW only, or HW and CH, or CH only). The ZA3/679-3 is a diverter valve (HW only or CH only).

You need a MA1/679-3.

The body (brass part) is identical; it's just the actuator (box part) which is different.

PS

The V4073A has five wires; the ZA3 actuator has 3 wires. Are you sure it's not the ZA5? Which ever, you need the MA1 actuator (5 wires)

+1

you have just swapped a diverter valve with a mid-position valve they are not the same

 

[Howardws]

Thanks for the reply. You are quite right, I've looked again and it's the MA1 - it has five wires. Now I feel stupid!

 

[ianmcd]

A very common mistake mate have seen so called heating engineers making the same mistake just glad you got sorted out

 

[Howardws]

Ah, but I still have the problem of the CH not firing up - it was just identity of the valve that I've sorted out!

 

[D_Hailsham]

Ah, but I still have the problem of the CH not firing up - it was just identity of the valve that I've sorted out!

So you gave us the wrong info in your opening post? The valve currently installed is the MA1/679-3?

Can you get heating and hot water at the same time?

Have you double checked your wiring?

 

[Howardws]

Correct, I gave the wrong info in my first post.

I've checked the wiring a number of times but intend to do so again tomorrow - the system is at my son's home a few miles away.

I can get CH when the hot water is heating but not by itself.

 

[D_Hailsham]

I can get CH when the hot water is heating but not by itself.

That means there is no voltage on the valve's Grey wire.

This can come from either the programmer HW OFF terminal or from the Cylinder Thermostat SAT terminal.

There should be three wires connected together: Grey, HW OFF, cylinder SAT

1. Turn HW and CH on at programmer
2. Turn cylinder stat to lowest position
3. Check if you get CH only.

If no: the wire from cylinder SAT is faulty.

If yes:

4. Set cylinder stat to high, so HW is also heated
5. Turn HW OFF at programmer
6. Check if HW stops heating

If no: the wire from HW off to Grey is faulty.

 

[Howardws]

Thank you, I'll check that out tomorrow.

 

[matt1e]

I can get CH when the hot water is heating but not by itself.

That means there is no voltage on the valve's Grey wire.

or a wiring fault on the orange return

What was wrong with the original valve?

Matt

 

[Howardws]

The small gear wheel on the end of the motor sheared off. B&Q were the only people open at the time and didn't stock a replacement power head so I bought what they had. On reflection I should have waited until the next day!

 

[D_Hailsham]

That means there is no voltage on the valve's Grey wire.

or a wiring fault on the orange return

So easy to overlook that.

 

[Howardws]

I returned to my son's this morning - the results -

1,2,3 test done, nothing happens, 240v on grey, wire continuity checked back to stat and ok.

4.5.6 test done HW stops heating.

With both CH & HW stats on high I get the following -

All off - 240v G 0v O
CH switched on - won't start 240v G 0v O
CH & HW on together - starts, v/v cycles to HW position - 0v G 240v O
HW off, all stops, v/v cycles and CH restarts 240v G 240v O
HW on by itself - 0v G 240v O

If have both running and I turn the HW stat down the CH keeps going but won't restart after a stop.

HW is working fine by itself.

Could I have a faulty cylinder stat that isn't switching properly?

Help!

 

[D_Hailsham]

I missed an important bit of the tests.

no 6 should read:

6. Check that HW stops heating and CH continues to work.

If NO: the wire from HW off to Grey is faulty.

(Tests 1 to 3 proved that the switch inside the valve which controls the Orange wire is working - Matt's suggestion)