Switchmaster SM 600

[wjdbrega46]

I intend upgrading a Switchmaster sm 600 controller to a Lifestyle LP522.
All of the information I have obtained on the switchmaster shows " no connection" to terminal 4 in the backplate. I opened mine and I have a wire terminating at 4 as well as wires at Terminals 1 and 3. The system is fully pumped and heating source is an oil boiler. Is anyone able to advise as regards the terminal 4 wire location in the new controller?

 

[D_Hailsham]

Do you have a motorized valve with three connections, similar to this pic?

If so, the connection to terminal 4 of the SM600 is correct.

View media item 5946

You will need to change the wiring when you install the LP522 backplate

SM600 ---- LP522
L ------------- L
N ------------- N
1 -- CH ON -- 4
2 (Not used) - 2 (Not used)
3 -- HW ON -- 3
4 -- HW OFF - 1

Make sure the switch on the back of the LP522 is set to P (pumped)

 

[wjdbrega46]

D Hailsham,
Sincere thanks for the information. Yes the system has an Honeywell valve identical to the one in the picture.

 

[wjdbrega46]

D Hailsham,
Sincere thanks for the information. Yes the system has an Honeywell valve identical to the one in the picture.

I seem to have discovered another "concern" as regards this change. The existing Switchmaster timer is supplied from a switched fused spur fitted with a 5 amp fuse. ( The boiler is a Firebird 90 s and the installation instructions state this is to be supplied via the 5 amp fuse so-- correct??) The LP 552 instructions state that it is to be protected via a 3 amp fuse and I can't see how I can protect the unit and run the boiler if I change the spur fuse to 3amp. Do I have to take the chance and supply the new programmer via the 5 amp fuse?

 

[D_Hailsham]

The existing Switchmaster timer is supplied from a switched fused spur fitted with a 5 amp fuse. ( The boiler is a Firebird 90 s and the installation instructions state this is to be supplied via the 5 amp fuse so-- correct??)

Presumably you have a wiring centre (junction box), with the motorized valve, thermostats etc connected, fed from the L and N terminals of the Switchmaster.

The LP 552 instructions state that it is to be protected via a 3 amp fuse and I can't see how I can protect the unit and run the boiler if I change the spur fuse to 3amp. Do I have to take the chance and supply the new programmer via the 5 amp fuse?

Most gas CH systems only need a 3A fuse to protect the boiler, programmer, motorized valve and circulation pump. Presumably the Firebird needs a 5A because it has an oil pump as well.

The ideal way would be to supply the mains direct to the boiler from the fused spur with a 5A fuse and have a take off from the boiler's mains terminals to the wiring centre protected by an in-line 3A fuse.

Click to enlarge, then right click to save

Untitled

• D_Hailsham
• 21 Dec 2013
• 1

Alternatively, contact Drayton and ask their advice.

 

[wjdbrega46]

D Hailsham esq.
Contacted Invensys-- 5amp Fused spur ok.
In process of installing at this moment and have hit a snag. Transferred wiring as your instructions in original post but Hot water will not start unless CH is either on ONCE or On. Hot water cylinder is cold so thermostat must be calling for heat. Further advice will be appreciated.

 

[D_Hailsham]

Contacted Invensys-- 5amp Fused spur ok.

That useful to know.

Transferred wiring as your instructions in original post but Hot water will not start unless CH is either on ONCE or On. Hot water cylinder is cold so thermostat must be calling for heat.

Check that the valve is the correct way round: Port A (marked on the brass part) to the heating; port B to the cylinder.
Did you swap the wires on terminals 1 and 4?
Have you checked that the switch on the back of the LP522 is set to P?
Does the boiler go off if you turn the cylinder stat down, and vice-versa?

Was the LP522 second hand (from ebay?)?

 

[wjdbrega46]

I feel such an idiot involving you in my incompetence. It turned out that the HW Cylinder Thermostat had closed at it's set temperature. As soon as I increased the setting--- power to boiler for HW .
I really appreciate your assistance and wiring was A1 as per your post.
Invensys Technical guy said quote-- As long as it is a MINIMUM of 3 Amps. I didn't discuss this with him as I was happy to receive his answer. You would think the literature would have said " a minimum of 3 Amps" and it would have saved me a lot of bother and involving yourself.
Thanks again.
WJD

 

[D_Hailsham]

It turned out that the HW Cylinder Thermostat had closed at it's set temperature. As soon as I increased the setting--- power to boiler for HW .

I think you meant to say that the stat was open at its set temperature.

When the water in the cylinder is below the set temperature the stat should close, the boiler light and the cylinder warm up.

Stats should normally be set to 60C.

Invensys Technical guy said quote-- As long as it is a MINIMUM of 3 Amps.

The Tech guy is not very technical then.

If you took his advice you could put in a 13A fuse, which wouldn't protect anything. The wiring would probably catch fire before the fuse blew.

 

[wjdbrega46]

Yes You are exactly right. The heating had been on for a short period before I started the changeover. I didn't realise that it had been on long enough to bring the HW cylinder up to it's set temperature via the tank stat.
I have tried to calculate all of the load supplied via the fused spur and my total is 485watts. If I am correct the system could run on a 3 amp fuse but I am going to continue with the 5 amp at present. When I have time I will try running the system on a 3 amp fuse for a prolonged period.