Can a combi safely be used for DHW with the heating drained?


This could be a really stupid, obvious question, but.....
I have currently got the heating drained down to remove a couple of rads.
Can the combi still be used (safely) for hot water?
Or does draining the heating drain the primary circuit which heats the hot water?
It's an Ocean Style FF, btw. (Destined for replacement as soon as I can get around to it....)
thanks Richard
-- Richard Sampson
email me at richard at olifant d-ot co do-t uk
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RichardS wrote:

It most likely will not even run in this mode... so it will be safe :-)
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Hmmm. it fired up when the missus marched in and promptly turned the kitchen hot tap on 30 seconds after being told that the heating was drained down and that we shouldn't use the hot water until I got a definitive answer or finished the job....
-- Richard Sampson
email me at richard at olifant d-ot co do-t uk
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RichardS wrote:

The two combis that I've fitted specifically said in the instructions that they would not run if there was no pressure in the CH circuit... To test a combi boiler without rad a loop of a few metres of pipe is often used.
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On Tue, 06 Jan 2004 20:25:01 +0000, BillR wrote:

If the boiler has isolating valves on the primary connections you may well get away with it provided the boiler is still filled and pressured. If the loop is external it will be difficult to fill it. Also the manufacturers may rely on the promary circuit being connected to dump excess heat into after DHW mode.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
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Yes, and there is normally a water pressure switch which won't allow the boiler to fire up if the pressure is too low

If you tell me exactly what boiler, I can go and check the manual
email me offlist, I have the manuals on a computer here at home
--
geoff

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Thanks, Bill, Ed, Geoff
All back and working now, so the question of DHW doesn't arise tomorrow morning....
It seems that the boiler firing up when SWMBO turned the hot tap on might have been a momentary fluke due to some wierd pressurisation in the vicinity of the pressure switch. It didn't do it again (I was curious).
At 11:30 PM when I have just managed to dislodge the compression joint on one of the lockshields, I find myself very glad that I stopped, scratched my head, and thought "yes, better get some just in case" when passing the 15mm olive section of wherever I was 3 years ago!
The room ought to be a little warmer now that there is some skirting board on the radiator wall - there were 2 air bricks that were 1/3rd above floor level and venting straight into the room....
-- Richard Sampson
email me at richard at olifant d-ot co do-t uk
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