Combi boiler installation - can i use hw without ch being complete ?

[mediy]

Hi,

I'm in the process of installing a new central heating system and in the best tradition of diy the job has taken a "little" longer than anticipated. With the weather getting colder and three young children returned home after some time away having practically no hot water (except from the electric shower!) doesn't go down too well. So I was wondering since I have plumbed in the condensing combi (Worcester Bosch Greenstar 28i Junior) though not completed the CH testing yet is it possible to fire it up and operate it just in HW mode without any water in the CH part of the system, my understanding is that it should be possible just wanted a second opinion ?

Thanks,

mediy

[Andrew Gabriel]

No. It uses the central heating water internally to heat the hot water. Some combi's also dump out excess heat to the central heating when the demand for hot water ceases. You could probably get away with just one radiator, or possibly even just a loop of pipework from flow to return (but check installation manual for minimum length -- some boilers require a minimum volume of water in the closed loop).

[John Stumbles]

As Andrew says you need water in the system but a loop between flow and return, pressurised and bled (via that stupid bit of ribbed rubber hose connected to a bleed nipple inside the boiler casing ). Ensure there's no call for CH by disconnecting the bridging link on the connector on the PCB to be sure.

[mediy]

Thanks for all the replies, I think I will go with the one rad option as I can isolate it off from the rest of the system.

Does anyone know where I can get a short (1m) length of 28mm plastic pipe, don't want to buy 10x3m lengths!

Thanks,

mediy

John Stumbles wrote:

[John Stumbles]

BES online or plumbers merchants