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CENTRAL HEATING..BOTH SWITCHES ON OR NOT?

hello, this may a stupid question to some but to me it is not...i have recently moved into another house...the current central heating system is run with a ...RANDALL 4033 PROGRAMMER....it has 2 switches...one that controls the hot water...the other controls the central heating ( radiators)...what i can gather the PROGRAMMER is approx 20yrs old...but still seems to work perfectly...my question therefore is....do i need to put both switches down to run just the central heating ?..for just the hot water i only put 1 switch down...but someone said that to run the radiators i had to put both switches down...even if i only wanted radiators on and NOT hot water,we also have a BAXI gas fire with a back boiler ( if that is of any importance)..many thanks in advance :)

Reply to
altheman
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Can you say whether you have gravity HW or is it all pumped?

Reply to
EricP

hi, thanks for the speedy response....i am not sure if i have gravity hw or all pumped..the set up is as follows....i have in the loft a main tank...and a header tank....and also in the airing cupboard there is a big tank that actually holds the hot water...not sure if that is the type of information that will help...but personnaly i have no ideas about central heating..sorry...thanks again

Reply to
altheman

It depends on how the system has been plumbed and wired. Usually (and I'm not familiar with that particular programmer) if there is no heating-only option then the switches are interlocked so if you put the heating on the hot water switch is also moved to on.

Put the heating switch on and see what happens. If the boiler starts firing on-and-off then the call for heat is reaching the boiler but not running the pump, in which case either the switches should be interlocked or the system replumbed/wired to prevent this happening.

Owain

Reply to
Owain

Ay it's simplest installation, the HW switch simply turns the boiler on and the other switch just turns the CH pump on to pull the water through the radiators.

Turn both switches off and let the boiler cool down.

Turn the HW switch on and the boiler should ignite. Turn that off and turn the CH switch on. You should just hear the pump whining away somewhere but the boiler won't ignite.

Thus you have an unpumped HW system with the pump turning the radiators on.

If the second switch also turns the boiler on as well as the pump, you will have some motorised valve in the pipework somewhere.

You really need someone mildly familiar with CH to have a look at it and identify what does what.

Reply to
EricP

In message , altheman writes

Probably yes, if this is an older system, as it sounds like.

My current system is like that - waiting to be upgraded next year. The HW is a gravity circuit. This means it circulates just because the HW rises from the boiler in the pipes. There should be pump pumping water around the heating system. My timer is such that you have to have both the HW and CH on to get the boiler to fire

I plan on upgrading to a fully pumped system probably next year.

Reply to
chris French

In the unlikely event that you have a fully pumped system - in which case you will have one or two motorised valves and a tank stat - you will have independent control over HW and CH and will be able to have either without the other - or both together.

In the more likely event that you've got gravity HW and pumped CH, they are

*not* independent. You can have just HW (by running the boiler without the pump) but you can't have just CH - because you need the pump *and* boiler for this, and get HW thrown in whether you want it or not.

You can probably still select just CH on the programmer, and it will work - because most programmers used on this sort of system have an internal link which switches HW - i.e. the boiler - on even though *you* haven't switched it on.

As others have suggested, why not suck it and see?

Reply to
Set Square

On my programmer in the new house the switches aren't interlocked, not sure if they were/should be/could be though.

But hat doesn't happen, the [pump just runs in heating only mode.

Reply to
chris French

Most simple programmers have the switches for both heating and water fed via removable links. For a gravity circulation system it's usual to feed the heating switch off the output from the hot water one so the heating only option you have with a fully pumped one does nothing on its own.

Reply to
Dave Plowman (News)

hi again, i have now read your advice......i have now switched on "hot water" only...and the pump fires up.....i then switched off hot water...and just switched on central heating.....again the pump fired up.....so i am now guessing that both switches work independantly of each other...so it is safe to just switch on central heating on its own without having to switch on hot water also...would that be right?....many thanks yet again in advance :)

Reply to
altheman

Yes, if it works.

Owain

Reply to
Owain

If the water is heated by gravity circulation then it will be heated any time the boiler is firing, regardless of any switch setting. Is it getting too hot?

Reply to
Dave Plowman (News)

But you haven't told us whether the *boiler* fired up. Did it? The pump on its own will just circulate cold water - which is a complete waste of time!

If the pump runs in HW only mode, it suggests that you've got a fully pumped system. Have you got any motorised valves anywhere - maybe in the airing cupboard? Is there a thermostat strapped round the hot water cylinder (not the one in an immersion heater)? How many water pipes connect to the back boiler behind the gas fire?

Reply to
Set Square

so then...if i switch on just central heating..it will either ..work or not work?.....and i cannot do any damage to system..that correct?...sorry about all this but i really have no idea :(.thanks yet again in advance :)

Reply to
altheman

It's possible to be fully pumped but still not have independent control of HW and CH.

Owain

Reply to
Owain

You are correct in the above assumption.

Would you care to elaborate on exactly what you're trying to achieve, and on what prompted you to ask the initial question?

Reply to
Set Square

hi again..what i am exactly trying to achieve..is the following...as it it a new central heating system to me....i thought that in this cold weather i would have to put on both HOT WATER & CENTRAL HEATING switches to run the central heating...but then i thought as i had a seperate switch for both surely i would not have to switch on HOT WATER switch to run the HEATING ( therefore saving some money as to not have to have both on at once).hope you understand what i am explaining here.but thats the gist of it...many thanks again :)

Reply to
altheman

That would be extremely foolish!

Reply to
Set Square

Fair enough. Assuming you have independent control - and we still don't know, because you haven't answered the questions about motorised valves etc. - you can certainly save money by *not* heating the hot water cylinder. But you won't then have any hot water available at your hot taps for washing, showering, bathing, etc.

Assuming you *need* hot water, the best way of saving money is by heating and storing it efficiently. This means that you need a proper control system which automatically stops heating it when it gets hot enough - and you need a well-lagged cylinder so that the water *stays* hot after you have heated it.

People here can advise you about the best way to control your system - but only after you've given details of what you've actually got.

Reply to
Set Square

The "Youth Opportunities Scheme" neds who plumbed these flats for the council in the 1980s *were* extremely foolish.

The main stopcock is on backwards, to start with ...

Owain

Reply to
Owain

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