Programmer replacement -- Switchmaster 600?

[ptrevor]

Hello,

I currently have a Switchmaster 600 programmer, which has stopped working (the clock has given up).

I would like to know what people would recommend as a replacement programmer. I know you can buy a Switchmaster 605, but ideally I'd like an electronic programmer, rather than electro-mechanical, and I'd also like to be able to set separate timers for HW and CH; currently, I can only set the ON and OFF times and have to manually select a function to be timed. Can I use something like a Honeywell ST6400C?

Thanks in advance for your help.

 

[gas4you]

If you are comfortable with wiring then fit what you like.

What type of system do you have, Gravity or fully pumped?

If it is gravity then chances are that you will not have any zone valves in the system so will not be able to gain seperate HW and CH control without upgrading to fully pumped.

 

[ptrevor]

Thanks for your reply.

I think it is a fully-pumped system. Certainly our boiler and hot water tank are on the same level, i.e. both on the ground floor.

Our current programmer, the Switchmaster 600, only allows HW only or CH + HW simultaneously. So we can't have CH only. Am I right in thinking with a fully-pumped system we can have CH only if we have a programmer that permits this?

 

[gas4you]

If you only have 2 pipes off your boiler and zone valves then yes it will be fully pumped.

You will need 2 2port valves or a 3 port mid position valve to be able to take full advantage of a new programmers capabilities.

 

[ptrevor]

I have 2 pipes coming off my boiler. I only have one 2-port valve, a Honeywell V4043. I think what is happening is the HW signal from the programmer goes to the pump and the boiler, and the CH signal goes to the valve. So there should be no CH signal without a HW signal. Does that sound right?

I guess then there'd be no point in getting a fully featured programmer. Anybody recommend any that would be suited to this system?

 

[gas4you]

You could get a full programmer but as you say its full advantages will not be realised, but you will have it there if you update the system at a later date.

You may well find that the full programmer is cheaper or the same price of a basic one these days. I don't know why, perhaps they are more nass produced.