hot water always on with new programmer

[timothydoran]

I have replaced an old manual programmer with a new (second hand) Drayton LP522. I have a mid position valve system and I have wired the programmer up as;

hw off pin 1 > 8, hw on pin 3 >7 and ch on pin 4 > 4

However the hotwater is always on no matter what state the programmer is in. The thermostat on the tank works correctly and turning it down shuts the boiler off. The mid possition valve appears to work correctly, by using the the hw termostat the valve moves happily between hw/both/ch.

I have a muiltmeter, but please can someone confirm that I am testing it in the correct way:
When hw is on there should be 240v across pins 1 and 3. When hw is off there should be 0v across pins 1 and 3?

If the relay was sticking open, is there something that could be causing it other than the programmer. If I replace it will I have the same problem? I have not had any other new components.

Or maybe I have got the wrong end of the stick and its something else - any ideas?

Many thanks in advance for your help.

 

[D_Hailsham]

hw off pin 1 > 8, hw on pin 3 >7 and ch on pin 4 > 4

Do you mean pin 1 of the LP522 is connected to pin 8 of the wiring centre (junction box)?

If so, are you following the standard Y Plan wiring diagram?

 

[timothydoran]

Yes I am refering to a Y plan.

- Pin 1 goes to 8 on the junction box/wiring center.
- Pin 3 goes to 6 on the junction box/wiring center.
- Pin 4 goes to 4 on the junction box/wiring center.

Does that make sense?

 

[D_Hailsham]

Yes I am refering to a Y plan.

- Pin 1 goes to 8 on the junction box/wiring center.
- Pin 3 goes to 6 on the junction box/wiring center.
- Pin 4 goes to 4 on the junction box/wiring center.

It makes sense, though you orginally said that pin 3 connected to 7 in the junction box!! Unfortunately your wiring centre is not wired in the standard way.

Have you checked that the programmer is set for pumped (P) and not Gravity (G)? It's set on the back. If it is set correctly, then it's a component or wiring problem. Do you have a multimeter and know how to use it safely?

 

[timothydoran]

I have checked that the unit is set for Pumped.

I have a multimeter an know how to use it. I dont know what results I would expect at each terminal. I am hoping that there is a handy guide somewhere.

I have swapped out for the old unit and the old one works fine. The old unit is a Horstmann 425 Diadem which does not have the same range of timing options which is what I wanted to improve.

Thanks

Tim

 

[D_Hailsham]

I assume that the Horstmann has a link between L and 2 and between L and 5 (or 2 and 5).

The terminal order is different on th LP522 backplate, so you need to make some changes on the backplate. No need to change the wiring at the junction box.

Here are the changes:

425 -- LP522
L ----------- L
N ----------- N
Earth ------- Not required: make safe, e.g terminal block.
1 ----------- 3
3 ----------- 1
4 ----------- 4

Terminal 2 on the LP522 is not used.

The links from L to 2 and 5 are not required.

 

[timothydoran]

You have correctly described how the horstmann was linked and how I had made the connections to the lp522.

I have swapped the unit for another second hand lp522 and get the same result. Got water switches on and off correctly for a few minutes then its stuck on.

Could this be caused by a. A wiring error. Or b. Another component misfunctioning.

Funny that the old basic one works. I really wanted the additional functions of the lp522

Do you have any more suggestions.

The mid position valve is a Drayton ma1 but badged as a British gas thing.
The cylinder stat is a honeywell l641a1039.

Thanks for your help so far

 

[D_Hailsham]

Do you have a multimeter and know how to use it safely?

 

[timothydoran]

I have a multimeter. I am familiar with using a muiltimeter for DC use. I have less experiance with AC.

If you could tell me what voltages to expect across different pins in the terminal block I would know what to do. Unless you can tell me differently?

Thanks

Tim

 

[D_Hailsham]

I have a multimeter. I am familiar with using a muiltimeter for DC use. I have less experience with AC.

Just remember that 240Vac can be dangerous.

If you could tell me what voltages to expect across different pins in the terminal block I would know what to do.

The problem is that your installation doesn't follow the 'standard' wiring.

Mid-position valve operation and fault finding tells you what to do, but you will have to work out the terminals for yourself.