is it worth replacing old mechanical heating timer?

[AlF2008]

Our system has an old Randall central heating timer where the CH and DHW can be either On/Off/Timed and they come on at the set times twice a day. Of course the problem at the weekend is that unless I change the settings the heating comes on at 5:30 for a couple of hours and the house is cooling again by the time we get up (normally around 9:00)

I've been looking at getting a replacement 7-day Programmer with independent CH and DHW so we can have full control over them. I'm also hoping that it will help cut down the heating bills a little as we dont really need to HW on for 5 hours every evening as we dont generally use any apart from washing up (showers in the morning normally), although I'm aware that if the thermostat is working then it shouldn't really cost anything once the water is heated.

I've been looking at a Danfoss FP715 which seems to meet my needs. Question is am I just kidding myself on the potential savings or is it worth trying it as the central heating will be replaced at some point, hopefully later this year?

 

[D_Hailsham]

Question is am I just kidding myself on the potential savings or is it worth trying it as the central heating will be replaced at some point, hopefully later this year?

Any upgrade of the heating controls now will mean that you will not have to do it when you put in a new system later.

As to what you can do now will depend on your existing system, so a few questions:

Do you have a fully pumped system with motorized valves and a cylinder thermostat?

or

Do you have a pumped CH, gravity HW system?

It would also be worthwhile deciding now if your new boiler will be a combi (instant hot water, therefore no time control required) or a heat only boiler, which will use your existing HW cylinder and can have time controlled HW.

This could affect the choice of programmer.

 

[AlF2008]

thanks for the reply.

The CH system is fully pumped with 2 x 2 port valves.

I've been trying to decide between a combi and conventional boiler. At the moment its a back boiler which will be going no matter what. If we go with a system with a HW cylinder then we'll almost certainly need a new one as the one we currently have is an odd shape to fit into the press (slim cupboard) next to the back boiler and it looks like 2 small cylinders that are joined at the top.

 

[D_Hailsham]

The CH system is fully pumped with 2 x 2 port valves.

And, presumably a wall thermostat to control one valve and a cylinder stat to control the other valve.

I've been trying to decide between a combi and conventional boiler.

If you go for a combi, you will only need a single channel programmer, to control the central heating. But, if you opt for a heating boiler with a separate HW cylinder, you will need a two channel programmer or two single channel programmers.

While you are making up your mind about the boiler, may I suggest a solution which covers both options?

Buy a single channel combined thermostat-programmer such as a Honeywell CM900 series and use this just to control the central heating. The old Randall timer can still be used to control the HW times separately.
When you have made up your mind about the new boiler, you can either throw the Randall away (combi) or buy a cheap single channel timer for the HW to go with the shiny new boiler and HW cylinder.

Have a read of Honeywell Application Guide 110

 

[AlF2008]

And, presumably a wall thermostat to control one valve and a cylinder stat to control the other valve.

Thats the one

I've been trying to decide between a combi and conventional boiler.

If you go for a combi, you will only need a single channel programmer, to control the central heating. But, if you opt for a heating boiler with a separate HW cylinder, you will need a two channel programmer or two single channel programmers.

While you are making up your mind about the boiler, may I suggest a solution which covers both options?

Buy a single channel combined thermostat-programmer such as a Honeywell CM900 series and use this just to control the central heating. The old Randall timer can still be used to control the HW times separately.
When you have made up your mind about the new boiler, you can either throw the Randall away (combi) or buy a cheap single channel timer for the HW to go with the shiny new boiler and HW cylinder.

Have a read of Honeywell Application Guide 110

Thanks for the advice, the only reason for thinking about replacing the timer with the Danfoss was that I'd seen one for a good price. Hence if I throw it away in 6 months then its no great loss. I'll have a read of the Honeywell guide and see if that helps make my mind up.

Thanks.