system boiler hot water question

[Speedy471]

I have a worcester greenstar 18i system boiler which is attached to a honeywell programmable unit. The programmer has the ability to heat water and central heating at set times. Is it advisable to set the hot water to heat at a time when the heating is not on, or can they both be on at the same time? If they can be on a the same time does the heating or water take priority ie does it take longer to heat the water?

Thanks

 

[John506]

If you have a mid position 3 way valve then it can do both at the same time.

Hot water will always take priority over heating

 

[Andygasman2010]

Hot water doesn't take priority over heating unless it's wired up in such a way and usually uses a diverter valve, not mid position valve. You've most likely got a standard non-priority Y-plan as it's much more common.

Best set your hot water to come on 30 minutes or so before the heating.

 

[Speedy471]

from memory it has a motorised diverter valve and a black honeywell box which is wired up - looks like a big power brick.

 

[Speedy471]

but thanks, only just moved into the property with the set up so just getting the hang of it. I did have it set up for the hot water to come on 30 min before the heating which seemed to work fine. I tried it tonight with heating and water on at the same time and the wife complained that the water ran out quickly. Was just wondering as it seems more economical if both could be done together.

 

[Andygasman2010]

Have it come on 30 minutes before the heating to give full boiler power to the cylinder, then when the heating comes on it only needs to top-up the hot water as and when required.

Depending on the size of your cylinder, how many radiators you have etc... your boiler may not be up to the job of heating both at the same time.