can combi boiler run with the rads feeds cut

Ok so I thought this was a simple one; I thought that if the heating system is switched off, ( on the thermostat and on the dial on the boiler), I could cut the pipes feeding to the rads and continue to operate the boiler for hot water for showers etc. But the shower water is cold.

This could just be me being impatient as I switched the electrics to the boiler off when I cut the pipes, (in case they spurted and drenched things), and only switched them back on 15minutes ago..... but I thought the point of a combi was that it heated water instantly?

PS If you're wondering why I wanted to cut the radiator pipes it is because I'm doing a major house refurb and the radiators will all need to be moved. As it was a retrofit CH system the pipes are all over the place so will need to be re run under floors etc. Pretty much redoing from scratch. The boiler also needs to move at a later date- (I'm aware boilers don't move well and I'll probably need a new one!) So I drained down the system, removed the rads to storage, and cut the pipes to the boiler.

I wish I'd checked I hadn't sabotaged the hot water before going for a long cycle ride this evening. I want a hot shower!

So;
QUESTION 1- Can you run a combi boiler with the rads pipes cut?
QUESTION 2- If there needs to be water in that part of the system can I join the 2 cut pipes into a mini loop, refill them with water and then run the system
QUESTION3- By trying to run the boiler for hot water just now am I liekly to have fried/ destroyed something?

Thanks

1.No
2.Possibly, depends on manufacturer
3.Yes, most likely the pump unless dry-fire protected.

So;
QUESTION 1- Can you run a combi boiler with the rads pipes cut?
depends on the make/model
QUESTION 2- If there needs to be water in that part of the system can I join the 2 cut pipes into a mini loop, refill them with water and then run the system
yes that should work as it will allow you to repressurise the system (put a tee and drain valve instead of one of the bends)
QUESTION3- By trying to run the boiler for hot water just now am I liekly to have fried/ destroyed something?
dont think so

Thanks[/quote]

Details depend on your boiler, but basically you shouldn't run it without water in the central heating portion of the system. In most newer boilers it will just be impossible.

Again depending on your boiler, you should be able to connect the out and return pipes and then fill with water to the right pressure. The boiler instructions may require a minimum quantity of water or length of piping, just to keep the pump happy. Don't actually try to run the heating in the state.

Any relatively new boiler should just refuse to operate without water in the system, so there shouldn't be damage. Still, best not to push your luck.

Wow, thanks for the quick replies guys!

I shall try and put a small loop on to the cut rads pipes tomorrow and repressurise and see if that lets me have hot water again. ( I guess I haven't impressed you enough to make it obvious that I wouldn't try and run the heating!)
There were no heinous noises coming from the boiler but I have switched it off completely at the mains now so in daylight I can have a closer look and see if I have already got my answer as to whether I'll need to buy a new boiler! (I'm about 4 months away from fitting the new boiler though)

I'm very pleased to have found this forum- I have a feeling you will hear more from me as my renovations progress!

Again, thanks for the replies and I'll post tomorrow ad let you know how I got on.

Susie

Well I'm a bit sheepish as I started connecting the mini loop to get the boiler working again but the pipework was fiddly in a limited space and as the wall it is on is coming down in a couple of weeks anyway I just gave up.
My plumber came this morning and capped the gas pipes so it is now all ready to come out. (He did say I was nearly there!)
So I'll be showering at friends' houses and at the gym for the next few months.
Anyway I promised an update, however lame! Thanks again for your swift replies.